Qilinyu had three bones, the dentary, maxilla and premaxilla, that characterize the modern vertebrate jaw seen in bony fish, amphibians, reptiles, birds and mammals, though they are absent in the cartilaginous sharks and rays.
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Reconstruction of the jaws of Razanandrongobe sakalavae, including the original left dentary, right premaxilla (courtesy of the Natural History Museum of Toulouse ), and their counterlateral copies (in grey), printed in 3-D from CT data by FabLab Milan, and then mounted at the Natural History Museum of Milan.
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The posterior process on the dorsal surface of the dentary is present, incipient or absent and the dentary terminates abruptly in front of the first dentary tooth. The dentary itself contains thirteen to fourteen teeth and the pterygoid has seven to eight teeth. The medial wing from the coronoid contacts the angular, the anterior process on the coronoid abrupts over the surangular and makes contact with the posterior process of the dentary or ends with the surangular without contacting the dentary. The retroarticular process is rectangular in outline, medially inflected or laterally lacing.
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The predentary is joined at the back by the dentary, which constitutes most of the lower jaw. There is a short recess, or diastema, between the articulation of the predentary with the dentary and the first tooth position on the dentary, which is observed in Equijubus, Probactrosaurus, and other hadrosauroids. The front of the dentary characteristically deepens, as in Protohadros, Ouranosaurus, and Bactrosaurus. Two bulges are present on the outer surface of the dentary, one of them representing the coronoid process as in Probactrosaurus and other hadrosauroids.
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The longitudinal groove on the outer surface of the dentary is wide. The third tooth socket of the dentary is not enlarged. Seen from above, the dentary is straight without an expanded jaw tip. The interdental plates, reinforcing the teeth from behind, of the lower jaw are tall.
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The former relation was supported by the lack of constricted tooth crowns and the contact between the dentary and splenial, while the latter was supported by the deep dentary, the similarly-sized and symmetrical serrations, the concavity of the dentary, and a dip in the dentary below the level of the tooth sockets at the middle of the tooth row. Their resulting phylogenetic tree (the majority-rule consensus tree) is partially reproduced below.
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The left dentary is fragmented but still has almost all teeth present, whereas the right dentary is incomplete and has most of the teeth. The left dentary is 11 mm long and has multiple broken teeth or tooth positions. The coronid process is missing, but there may be a suture present where the dentary was joined to the surangular. A small groove is present on the lingual side of teeth 16-18.
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Within the context of phylogenetic history, the diets of bats determine the structure of the dentary. When comparing the cross sectional shape of the dentary of frugivorous bats to nectarivorous bats, the data illustrates that the dentary of frugivores has an increased resistance to bending and torsion. These results confirm the predictions made by researches based on data collected on the diets of bats and inferred phylogenetic history. Frugivorous bats possess a feeding strategy that requires a strong dentary due to their extended periods of chewing and frequent unilateral biting during feeding, which imposes increased torsional stresses on the dentary.
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The right dentary is only partial, unlike the left dentary where all the fragments are present, but the piece preserved is 9 mm long. The posterior teeth are displaced ventrally, but at least 16 teeth are present, probably 18. The right dentary also shows the presence of at least five nutrient foramina ventral to the teeth.
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Schwarz and Fechner (2008) described a new dentary from the Uña coal mine of Cuenca province, Spain. Its teeth demonstrate that it belongs to Lisboasaurus. This dentary was the first Lisboasaurus fossil from the Barremian age of the Early Cretaceous. The new data extracted from the dentary make it more certain that Lisboasaurus was a neosuchian crocodylomorph.
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Aase Roland Jacobsen published a description of a Saurornitholestes dentary in 2001. The dentary is about 12 cm long and preserves fifteen tooth positions, of which only ten preserve teeth. Three toothmarks were visible on the inner "lingual" surface of the dentary. Two of the three marks are series of grooves made by the serrations on the maker's teeth.
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In some of the maxilla, the teeth are short and swollen (almost round in cross section) and become smaller towards the rear of the bone. The dentary teeth are similar but more asymmetrical. The middle of the dentary has the largest and most denticulate teeth in the jaw. There are 12 maxillary teeth and 14 dentary teeth.
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A pair of crests runs between the quadrate and the pterygoid on each lateral side of the braincase. The lower jaw is U-shaped, to match the upper jaw; the dentary bears twenty-one teeth on each side. The dentary becomes broader transversely than dorsoventrally as it turns the corners of the U-shape, due to wide and vascularised dentary shelves and alveolar margins. The two dentary bones are interdigitating at their symphysis, meaning that the lower jaw is entirely inflexible.
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Anteriorly situated pterygoid teeth approaching marginal teeth in size. Quadrate with fused suprastapedial and infrastapedial processes. Distinct projection of dentary anterior to first dentary tooth. Coronoid concave above, posterior wing with medial C-shaped excavation.
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Cranial and dentary morphology suggests that anomochilids probably eat small invertebrates.
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Robertia has a short secondary palate, with the choana anterior and at the same level as the tusks. The dentary shelf does not protrude as much as in Emydops, and the concave dentary tables hold five to six pointed teeth medially. Robertia is one of the pylaecephalids with the most dentary teeth, which occlude with the palatine pad (a ridged region posterolateral to the main secondary palate) upon jaw retraction. A beak is located anterior to the tusks and the outer side of the dentary.
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This, coupled with the robust dentary, indicates that Pelagiarctos probably had a large bite force. Though no postcranial remains have yet been found, the size of the dentary suggests an overall length of approx. 2.5–3 meters.
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The dentary symphysis is tall and sharply angled forming a distinct chin.
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However, the dentary of the unnamed mesosuchian is much broader and spatulate.
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Palaeontology 34(3):653-670 The dentary is noted as being of massive proportions, similar to the massive and robust dentaries found in Globidens and Prognathodon. A medially located shallow recess on the dentary indicates the groove for the splenial.
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Saurornitholestes skeleton. A. R. Jacobsen published a description of a dentary referred to Saurornitholestes with tooth marks. The dentary is about 12 cm long and preserves fifteen tooth positions, ten of these have teeth, with five of those teeth fully erupted and intact, two broken but functional as evidenced by the presence of wearfacets, three are only partially erupted. Three toothmarks were visible on the lingual surface of the dentary.
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The upper margin of the dentary was arched in profile, but not as much as in Camarasaurus. The interdental plates of the dentary were somewhat oval, with diamond shaped openings between them. The dentary had a Meckelian groove that was open until below the ninth alveolus, continuing thereafter as a shallow trough. Each maxilla had space for about 14 or 15 teeth, whereas Giraffatitan had 11 and Camarasaurus 8 to 10.
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It also has very few teeth for a lizard, with only eleven tooth positions in the dentary. Other unusual anatomical features include the shortness straightness of the jaw, the lack of a Meckelian groove on the inside of the dentary, and the enlargement and lateral compression of the posterior-most dentary teeth. Pyrenasaurus may have been a fossorial or burrowing lizard because a short, straight dentary with few teeth is also present in numerous living fossorial lizards, having evolved independently in many lineages. However, the extremely small size of Pyrenasaurus may have inhibited its ability to burrow.
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Morganucodontidae and other transitional forms had both types of jaw joint: dentary-squamosal (front) and articular-quadrate (rear). During the Permian and early Triassic the dentary of therapsids, including the ancestors of mammals, continually enlarged while other jaw bones were reduced. Eventually, the dentary bone evolved to make contact with the squamosal, a bone in the upper jaw located anterior to the quadrate, allowing two simultaneous jaw joints: an anterior "mammalian" joint between the dentary and squamosal and a posterior "reptilian" joint between the quadrate and articular. This "twin- jointed jaw" can be seen in late cynodonts and early mammaliforms.
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The dentary (the main toothed bone of the mandible) had a rounded front end which is also expanded upwards. The first two teeth of the dentary were very large, overlapping the snout at the level of the maxillary/premaxillary diastema. This contrasts with other ornithosuchids, which have a smaller tooth in front of the two enlarged teeth. The two enlarged dentary teeth of Venaticosuchus were unserrated and oval-shaped in cross section.
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The premaxilla and the dentary had large inner teeth and irregular array of tiny outer teeth.
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It differed from other troodontids in that the front end of the dentary of the lower jaw was downturned, similar to what is seen in therizinosaurian theropods. The (the area where the two halves of the mandible connected at the front) was short, and this region was slightly curved towards the middle. Two rows of foramina ran along the outer side of the dentary, just below the first seven dentary teeth (only one of the rows continued hindwards past the seventh of these teeth). The foramina lay in a groove, which is a distinct feature of troodontids, while the inner surface of the dentary was smooth.
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Between dentary, surangular and angular a rather tall triangular mandibular fenestra is present. The dentary bears twenty-one teeth, which are slightly larger than those of the upper jaws. All teeth of Jiangjunosaurus are symmetrical with a triangular profile. Front and rear edges have both seven denticles.
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The dentary bone is long (occupying half of the jaw's length), shallow, and triangular, and it bears a groove that widens towards the back of the bone. A distinct fossa on the top surface of the surangular bone separates Jianianhualong from other troodontids. The angular bone projects upwards behind the dentary, like Sinovenator and various other members of the Deinonychosauria. The maxilla of Jianianhualong bore 21 teeth on each side, while the dentary bore 25 on each side.
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Brachyprosopus is similar to Endothiodon, Niassodon, and Pristerodon in having absence of anterior median palatal ridges; maxillary tooth rows bounded laterally by a shelf; unfused vomers; raised margins of the interpterygoid vacuity; broad intertemporal region; pineal boss; dentary tables; and a long, wide posterior dentary sulcus that extends posterior to the dentary teeth. However, it can be distinguished by the autapomorphy of a curled lateral edge of the squamosal that forms a lateral wall of the external adductor fossa.
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The Meckelian groove ran along the lower border. The curvature of the dentary shows that the mouth of Giganotosaurus would have been wide. It is possible that each dentary had twelve alveoli (tooth sockets). Most of the alveoli were about 3.5 cm (1.3 in) long from front to back.
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The lower jaw as a whole is laterally compressed and curved anteroposteriorly, so that the narrow ventral surface is convex and the jaw forms a half-moon shape. The mandibular fenestra is elliptical, and does not excavate the dentary noticeably, rather remaining between angular and surangular. The dorsal end of the dentary extends posteriorly around part of the surangular; the outer surface of the dentary is entirely smooth. The surangular has a triangular cross-section and is tallest in the anterior portion.
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The height of the dentary diminished towards the hindmost extend of the tooth row, whereafter it sharply fanned out to contact the bone behind it; by contrast, the hind part of the dentary in Erlikosaurus gradually approached the surungular in a gentle arc. Right half of the holotype mandible in outer and inner view, with component bones marked by different colors; the (green) bore the teeth. Segnosaurus was distinct among therizinosaurs in that the hindmost part of the dentary was toothless.
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The majority of the lower jaw is formed by the dentary, which possess diverse teeth similar to those of the maxilla and premaxilla. The first few are large and conical, and the fourth or fifth tooth is yet another enlarged caniniform tooth. Unlike the maxillary caniniform tooth which is serrated on both the front and rear edges, the dentary caniform is serrated on only the rear edge. Dentary teeth past the caniform are similar to those in the rear part of the maxilla.
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Probainognathus skull The jaw of Probainognathus is of particular phylogenetic importance. Morphologically, the dentary makes up most the lower jaw, and it curves and extends down posteriorly to the area of the articular and jaw articulation. Correspondingly, in the upper jaw, the squamosal bone becomes situated next to the quadrate. The posterior end of this enlarged dentary fits into a small nook in the squamosal of the upper jaw, and displays the beginning of the evolution of the squamosal-dentary jaw joint.
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The teeth were restricted to the front two-thirds of the dentary, which bore 24 (tooth sockets) in a manner similar to Jianchangosaurus but different from Erlikosaurus, in which nearly the entire dentary was toothed, bearing 31 alveoli. The tooth row of Segnosaurus was inset and demarcated by a shelf on the outer side as it was in all derived (or "advanced") therizinosaurs. Unlike in other related taxa, the shelf was restricted to the hind part of the dentary and the raised rim that defined it was not as pronounced. Segnosaurus was unique in having a low ridge rising between the fifth and fourteenth alveoli that divided the dentary into two almost-equally sized front and hind parts.
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Partial right mandible of Pluridens calabaria from the upper Campanian Nkporo Shale of Nigeria, West Africa The type specimen of P. walkeri is BMNH R14153, an almost complete dentary recovered from the Maastrichtian Farin-Doutchi Formation near Mount Ilatarda, Niger. Lingham-Soliar (1998) also assigned BMNH R9804, a partial dentary with poorly preserved teeth (one out of which is almost complete) from the late Campanian of the Nkporo Formation near Calabar in southern Nigeria, to P. walkeri. The Nigerian specimen BMNH R9804 was reassigned to its own species by Longrich (2016) as it lacks many of the derived features that characterize P. walkeri, such as a high tooth count and extreme elongation of the dentary. The Calabar dentary also lack the extreme lateral protrusion and subcircular section of the dentary and the strong transverse expansion of the dental thecae, both of which are present in BMNH R14153.
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Also, a longitudinal ridge that is seen in some basal sauropodomorphs (e.g., Massospondylus, Coloradisaurus and Plateosaurus) is not preserved in Leonerasaurus. However, this may be related to the damaged state of the specimen. Lateral and medial view of the dentary On the dentary, 13 teeth or tooth fragments were found.
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The part of the dentary in front of the large outer side opening is horizontally elongated. The dentary lacks a lower branch at the front, contributing to the symphysis. A separate coronoid bone is present. On the thighbone the minor trochanter is separated from the major trochanter by a clear cleft.
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There is also a certain degree of variation in tooth number, P. solvayi has 12 teeth on the maxilla and 13 on the dentary whilst P. overtoni has 14 dentary teeth. Of all species, P. solvayi has the most different teeth from other members of the genus. The tooth crowns are generally large and quite strongly striated and the anterior teeth are more procumbent than in any other mosasaurs. The premaxillary teeth are almost horizontal and the anterior dentary teeth only slightly less so.
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The skull of Riojasuchus Ornithosuchids can be identified by the presence of an arched diastema, a gap between the teeth at the front of the snout. When the jaw is closed, two large curved dentary (lower jaw) teeth fit into the diastema, which is positioned between the premaxilla and maxilla. There are two shallow depressions on the wall of the diastema to accommodate these teeth. The large dentary teeth of Ornithosuchus and Riojasuchus are placed behind a smaller procumbent dentary tooth that sticks out from the jaw.
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The dentary rings are counted in much the same way a tree is aged. Dentary studies suggest that some individuals can live 60 years or longer, and that females typically live longer and grow larger than males. American paddlefish are smooth-skinned and almost entirely cartilaginous. Their eyes are small and directed laterally.
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Known column counts for the two species are: 51 to 53 columns per maxilla and 48 to 49 per dentary (teeth of the upper jaw being slightly narrower than those in the lower jaw) for E. regalis; and 52 columns per maxilla and 44 per dentary for E. annectens (an E. saskatchewanensis specimen).
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The holotype was collected near Presidente Prudente city, São Paulo state. It consists of a dentary, cervical and sacral vertebrae, one ungual, and remains of the pelvic region. The mandible has an 'L' shaped morphology, with the symphyseal region of the dentary slightly twisted medially, a feature never recorded before in any titanosaur.
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The dentary bone is pneumatised. The lower rear branch of the dentary is twisted, causing its outer side to be somewhat directed to below. The first metacarpal is long and slender with its transverse width equal to a fifth of its length. The hand claws have prominent lips on their upper rears.
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Neohelos is known from many specimens, assigned to all the species. N. tirarensis includes a partial skull, premaxillas, maxillas, teeth, and dentarys; N. solus is known from a maxilla and dentary; N. davidridei includes teeth and a maxilla fragment; and N. stirtoni is known from a mostly complete skull, a maxilla and a dentary.
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Emydocephalus is a genus of sea snakes in the family Elapidae. Unlike most sea snakes, all species of Emydocephalus, have an absence of teeth on their dentary and palatine bones, and lack venom. The dentary and palantine bones bear only a row of papillae. Emydocephalus does, however, bear fangs and many small pterygoid teeth.
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The dentary is about one sixth the size of Steropodon, and wear facets indicate an "orthal" occlusion with the upper molars.
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Iguanodontids are generally limited to the possession of single replacement tooth at each position, although exceptions exist. The most primitive example bears positions for 13 maxillary and 14 dentary teeth. More derived forms have a larger number of positions per row. For example, I. bernissartensis is able to accommodate up to 29 maxillary and 25 dentary teeth.
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The lateral groove and associated foramina are located high on the outer surface of the dentary. The anterodorsal margin of the dentary is curved downward. The symphysis of the lower jaws is heavily built while the leading edge is vertical in side view. The front jaw points are wide in plan view, encountering each other at an obtuse angle.
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Pachygenys has a few defining characters, of which include a distinct foreshortening of the dentary tooth row and a reduced amount of dentary teeth. P.adachii differs from P.thlastesa in a few aspects; P.adachii has a shorter tooth row than P.thlastesa, as well as anterior and middle teeth that have uncuspid crowns and posterior teeth with simple, uncuspid conical crowns.
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The mandible has a long and slender shape with grooves and pits on the skull roof. The dentary is long with a posterodorsal process that extends into the lower jaw and overlapping the surangular. The angular and prearticular bones are long with the splenial almost as long as the dentary. The coronoid was unidentifiable in this specimen.
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Pachygenelus is an extinct genus of tritheledontid cynodonts. Fossils have been found from the Karoo basin in South Africa and date back to the Early Jurassic. Pachygenelus had both an articular-quadrate and dentary-squamosal jaw joint characteristic of ictidosaurs. Only mammals possess the dentary- squamosal articulation, while all other tetrapods possess the typical arcticular-quadrate articulation.
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A dinosaur's dentition included all the teeth in its jawbones, which consist of the dentary, maxillary, and in some cases the premaxillary bones. The maxilla is the main bone of the upper jaw. The premaxilla is a smaller bone forming the anterior of the animal's upper jaw. The dentary is the main bone that forms the lower jaw (mandible).
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Rauhut (2003) considered it and Eustreptospondylus to be the same genus, because the two share a similarly expanded front tip of the dentary and enlarged third dentary tooth. He therefore renamed Eustreptospondylus oxoniensis a Magnosaurus oxoniensis but this has not been generally followed. Reviews have found it to most likely be a basal tetanuran, probably a megalosaurid.Paul, G.S. (1988).
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293 Each maxilla (main tooth- bearing bone in the upper jaw) contained ten teeth, and each dentary (tooth- bearing bone in the lower jaw) contained twelve teeth.Osborn (1903), p. 460 The tooth rows of Ornitholestes were short, with the dentary (lower) row being even shorter than the maxillary (upper) row,Paul (1988b), p. 3; Norman (1990), p.
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The beak is separated by a low notch from the lower maxilla edge, which is toothless. The front of the lower jaw is low and slightly upward curving. In the left dentary the remains of three or four low conical teeth are visible; of these damage obscures most detail. The dentary has a small opening in the side surface.
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The left and right dentary are preserved, along with a fragmentary left maxilla and probable palatal bone, on two blocks of stone.
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The holotype and only specimens are a well preserved right maxilla, right dentary, and the holotype, a section of the jugal bone.
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In 2007, Upchurch and colleagues published a comprehensive description of the dentary and the teeth and declared Chinshakiangosaurus as a valid taxon.
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Palaeontologia Africana Vol. 25; 181-201. The type and only species is A. plemmyridon and is represented by teeth and several dentary bones.
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The teeth are more or less uniform across the dentary and the largest one measures approximately 27 mm high and 22 mm wide.
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On the labial (outer) surface of the dentary, there is one large mental foramen (opening). The mandibular symphysis, where the two halves of the lower jaw meet, is poorly preserved, but there is nothing to suggest that the left and right dentaries were fused. The lower margin of the bone is convex at the front, but concave further back, so that the depth of the dentary is 8.3 mm (0.33 in) below the diastema, but only 7.0 mm (0.28 in) below the third cheektooth. The origin of the coronoid process, a projection at the back of the dentary, lies far to the front.
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The dentary is peculiarly curved, making it a characteristic of this genus. The peculiar twist is designed to swing the posterior lower cheek teeth inward to ensure proper occlusion on the upper teeth. The dentary is greatly thickened, both internally and externally along the series of cheek teeth, much more than the transversely broadened teeth and their roots demand. The posterior part of the dental row is displaced inward so the dorsal margin of the coronoid process descends some distance laterally to the hindmost teeth and continues down and forward across the lateral face of the dentary virtually to the chin.
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Xinpusaurus is a thalattosaur, a group of triassic marine reptiles with long, paddle-like tails and short legs with independently movable digits. Specifically, it is a member of the group thalattosauroidea, which are characterized by their downturned premaxillae. Xinpusaurus had a short neck, a massive quadrate, and one of the few braincases preserved in thalattosaurs. The lower jaws of this genus show two different forms of dentary-surangular sutures, either a v-shaped suture with the surangular cutting into the dentary from the side (type 1) or an oblique suture with the surangular underlying the dentary (type 2).
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Further preparation of the specimen in the time since his last study regarding it revealed the uniqueness of the dentary had been exaggerated significantly by reconstruction of the specimen when it was first prepared in the 1990s. The Tsintaosaurus specimens showing the similar condition were found to have been distorted from a similar process. Correcting for the inaccuracies, the Los Llaus dentary is indistinguishable from that of multiple lambeosaurines, and shares no particular connection to Tsintaosaurus. With this, their reasoning for assignment of the specimen to Pararhabdodon was voided, and the specimen is now considered a completely indeterminate lambeosaurine dentary.
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Each lower jaw dentary bears ten teeth. Where the dentaries touch each other, at the front of the lower jaws, they possess a common "chin", equalling a third of the front height. The horizontal groove in the inner side of the dentary, the fossa Meckeliana, largely opens to below. The anterior middle neck vertebrae are pierced by a foramen in the rear side.
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In non-mammalian synapsids, the jaw is composed of four bony elements and referred to as a quadro-articular jaw because the joint is between the articular and quadrate bones. In therapsids (advanced synapsids including mammal), the jaw is simplified into an articulation between the dentary and the squamous part of the temporal bone, and hence referred to as a dentary-squamosal jaw.
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A Meckelian foramen ran along the outer side of the dentary. Dilophosaurus had four teeth in each premaxilla, 12 in each maxilla, and 17 in each dentary. The teeth were generally long, thin, and recurved, with relatively small bases. They were compressed sideways, oval in cross-section at the base, lenticular (lens-shaped) above, and slightly concave on their outer and inner sides.
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Each dentary has at the top inner side a rudimentary triturating shelf pierced by four small oval occlusal foramina. The same shelf has a weakly developed ridge running along its inner edge. The coronoid bone wedges into the underside of the top rear process of the dentary. Additionally, a unique combination is present of traits that in themselves are not unique.
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They appear to have been flat and rectangular. The only skull fragment that is certainly Calyptosuchus is a dentary bone - no other cranial bones have been assigned to it with certainty. Only a middle part of the dentary is present, with an edentulous patch to the anterior and nine dental alveoli posteriorly. No teeth are preserved except a few fragments of root.
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The dentary is long and delicate, lacking significant muscle attachment points. The lower incisors are unicuspid, procumbent, sharp and delicate. Its dental formula is .
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Biarmosuchoides is a genus of biarmosuchian therapsid found in Dubovka I in Russia. It is known only from SGU 104B/2051, a left dentary.
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A Saurornitholestes dentary has been discovered in the Dinosaur Park Formation that bore tooth marks left by the bite of a young tyrannosaur, possibly Daspletosaurus.
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There are also three longitudinal rows of small teeth on each pterygoid bone, as well as a transverse row (which is not present in Marmoretta). The ectopterygoid resembles that of Sphenodon (the modern tuatara). The dentary has a small expansion at the tip, forming a "chin" similar to that of sphenodontians. The elongated, closely spaced dentary teeth are similar to those of the maxilla.
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Size of Chenanisaurus barbaricus compared to a human Chenanisaurus is quite a large abelisaurid, measuring , based on measurements of the holotype dentary. It is rivalled in size only by abelisaurids as Carnotaurus and Pycnonemosaurus. Nicholas R. Longrich and colleagues, the describers of Chenanisaurus, identified distinctive features distinguishing the animal from other abelisaurid species. The lower jaw is high, while the dentary is bent in side view.
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The fourth dentary tooth is raised in the lower jaw to form an effective canine. The foremost teeth of the lower jaw are much smaller and lower than the fourth tooth. At the tip of the jaw the first dentary tooth is procumbent, or directed forward. The teeth of the upper and lower jaws form an alternate pattern to allow the jaw to close tightly.
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A notch is present between the maxilla and premaxilla bones of the upper jaw, accommodating the fourth dentary tooth when the jaw is closed. The procumbent first dentary teeth fit between the first and second premaxillary teeth. This close fit allows the serrated edges of the teeth shear with one another. The articulation between the articular and quadrate bones at the jaw joint is well developed.
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The front teeth, including the first maxillary teeth, do not have serrations. Teeth in the middle of the dentary are more strongly recurved and possess serrated rear edges. At the rear of the dentary, the teeth are short and stout with serrations on both, mesial and distal, edges. Caihong probably has ten neck vertebrae, thirteen back vertebrae, five sacral vertebrae and twenty-sic tail vertebrae.
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Another derived, sauropod like feature was a bony plate that lined the tooth row laterally and became thicker towards the tip of the snout. This plate may have hindered the teeth to be displaced while defoliating plants. The dentary was deep. However, as in prosauropods, it became lower towards the tip of the snout, while in sauropods the dentary became deeper, forming a very deep symphysis.
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Huttenlocker et al. (2007) differentiated Plemmyradytes from other amphibamiforms by: (1) the reduced lateral exposure of the palatine (LEP); (2) a long and narrow supratemporal without a ventral flange; (3) a posteriorly extensive squamosal, long and slightly recurved teeth that decrease in size posteriorly; (4) a shallow dentary with a trough below the tooth row; and (5) smaller teeth on the dentary relative to the maxilla.
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The endocast was long, wide, and had a volume of . The dentary of the lower jaw expanded in height towards the front (by the mandibular symphysis, where the two halves of the lower jaw connected), where it was also flattened, and it had a downwards projection at the tip (which has been referred to as a "chin"). The lower side of the dentary was concave, the outer side was convex in upper view, and a groove ran along it, which supported foramina that nourished the teeth. The inner side of the dentary had a row of interdental plates, where each tooth had a foramen.
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The front-most part of the dentary was strongly deflected downwards at about a 30-degree angle, a unique feature for this genus. When each hemimandible is articulated with the other, they form a broadly U-shaped, toothless mandibular symphysis that projects upwards towards the front as in Erlikosaurus and Neimongosaurus. The expansive, toothless front region of the dentary spans on the right hemimandible of the holotype. Proportionally, the toothless part of the dentary is 20% of its tooth row, which is long. By comparison, the toothless region of Erlikosaurus was about 12% of the tooth row's length and was almost absent in Jianchangosaurus.
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Holotype dentary and only specimen of "Koutalisaurus kohlerorum", considered at different times a distinct taxon, specimen of P. isonensis, or indeterminate lambeosaurine specimen Near the village Abella de la Conca, in the 1990s, palaeontologist Marc Boada discovered a new site in the Talarn Formation, bearing dinosaur fossils. From this site, later named Les Llaus (LL), a right dentary, specimen designation IPS SRA 27, was excavated. In 1997, Casanovas-Cladellas and colleagues stated this dentary was discovered from SRA, the site where the original Pararhabdodon remains were found. The following year, they described the specimen and referred it to P. isonensis, and again stated it was from the same stratigraphic level.
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None of the teeth were particularly hypertrophied like the canine teeth of mammals (i.e., caniniform), but the first three dentary teeth were larger than the rest.
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Usually, the lower jaw remains of Talarurus do not preserve, however, MPC-D 100/1355 was found in association with a right dentary, very fragmented though.
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The dentary is long and shallow, and has a butt joint as the contact with the coronoid series, indicating the dentary is loosely attached to the jaw. Similar to some tetrapods such as Acanthostega and Tulerpeton, the dentary's lateral surface is ornamented on the dorsal side with a smooth section only on the ventral margin. Another lower jaw specimen (LDM 81/552) is the only known complete Ventastega dentary, and shows Ventastega had 89 marginal teeth on each side of the jaw that are all approximately the same size, although they decrease in height as you move distally. Ventastega also has a pair of fangs on each dentary that are situated close to where the two dentaries meet at the most anterior part of the lower jaw, similar to Panderichthyesand Ichthyostega.. On the precoronoid and intercornoid, Ventastega has fangs pairs set within the marginal row of teeth.
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The lower jaw is represented by low dentaries with parallel upper and lower edges. Preserved dentary teeth are variable in shape and serrated similarly to maxillary teeth.
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Under the 2003 interpretation of Eilenodon's jaws, the wear facets of maxillary teeth would point inwards and downwards, contacting the lateral wear facets of the dentary teeth.
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The holotype shows eighteen teeth in the right dentary, seventeen in the left dentary; such an asymmetry is not rare among large theropods. A row of foramina is present below and on the outer side of the tooth row. These openings are relatively large below the first four teeth; more to behind, they become smaller and their row curves downwards. From the ninth tooth onwards, the foramina merge into a groove.
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Krause et al., 2003, pp. 325-326 Krause and colleagues compared the dentary in detail to that of Sudamerica, the only other gondwanathere for which a substantial fragment of the jaw was known. Sudamerica has only four, not five, cheekteeth (all of which are molariform), a higher, narrower incisor with a root that extends further through the dentary, and a shorter diastema; in all these respects, TNM 02067 is more primitive.
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Skull of specimen AMNH 5618 The skull of Endothiodon is most quickly recognized by the prominent upturned beak. The premaxilla and palate of the upper jaw are vaulted and allows for the upturned and pointed lower jaw to fit into this region. On the lower jaw, lateral to the teeth, is a broad groove. Endothiodon lacks a lateral dentary shelf but has a bulbous swelling of the dentary.
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Later, a part of a dentary, the tooth-bearing bone of the front lower jaw, was found, which bears a just emerging tooth, and some tooth fragments were recovered from matrix sticking to other bones. The deep dentary is almost identical in shape to that of Stegosaurus, albeit much smaller. Similarly, the tooth is a typical stegosaurian tooth, small with a widened base and vertical grooves creating five ridges.
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The dentition of Yacarerani, like many other notosuchians, is heterodont, with different tooth morphologies in different parts of the jaws. Two teeth in the lower jaw project forward from the tip, resembling the incisors of a rabbit. Other teeth, situated posteriorly, are cusped and adapted for grinding or chopping food such as tubers or small arthropods. In the lower jaw, the dentary tooth rows merge posterior to the anterior dentary teeth.
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A seemingly complete tooth row of 24 teeth was found close to, but separated from, the left maxilla. This count corresponds to the tooth count of the , where the teeth are still anchored within the left and right (the only tooth-bearing bones of the lower jaw). Bajadasaurus thus likely had 44 teeth in total. The dentary was slender, similar to Suuwassea but unlike the deep dentary of Dicraeosaurus.
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A lateral projection extends from it to partially cover the mandibular fenestra. At the posterior end the surangular is closer to cylindrical. The angular is medially excavated by the mandibular fenestra, and forms a vertical contact zone with the dentary; at the posterior end, it is vertically expanded upwards to form a narrow blade. The dentary carries three teeth on the preserved portion, which closely resemble those on the maxilla.
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Robertia and other dicynodonts had a particularly specialized jaw. A forward-backward motion of the lower jaw allowed them to effectively breakdown vegetation. Robertia’s small, fragile teeth may not have played a direct role in chewing, despite their ability to run along the dentary table. Shredding from movement of the dentary along the caniniform tusks and up past the premaxilla and maxilla occurred as the lower jaw motioned propalinally.
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Firstly, the teeth in the rear dentary of the lower jaw were relatively tall (half the depth of the supporting bone at that point). Secondly, the three hindmost maxillary teeth were widely spaced. In 2018 however, the first trait was rejected, as it could not be reliably established where the dentary ended. Another autapomorphy was now proposed: the outer sides of the jaws are undulating because of the bulging tooth sockets.
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Hyperadapedons also lack the double-bladed dentary that the early genera have. The only absolute synapomorphy between all the rhynchosaurs is that the dentary is at least half the total length of the jaw. Stenaulorhynchinae, a subfamily of rhynchosaurs including Stenaulorhhynchus, has been proposed. Based on an analysis of morphological characteristics, one study defines it as including all taxa that are more closely related to Stenaulorhynchus stockleyi than Hyperodapedon gordoni.
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The , where the two halves of the lower jaw connected at the front, was particularly short. The rest of the lower jaw was fragile; the hind third was much thinner than the front, with a blade-like appearance. The front part of the dentary curved outwards to accommodate the large front teeth, and this area formed the mandibular part of the rosette. The dentary–like the snout—had many foramina.
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Like all sauropods, it was a large, quadrupedal herbivore with long neck and tail. The body length of the only specimen is estimated at 12 to 13 meters. The remains consists of the dentary (the tooth bearing bone of the mandible) including teeth as well as several parts of the postcranium. By now, only the dentary and the teeth were studied extensively; the remaining skeleton still awaits a proper description.
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Its twelve maxillary tooth positions is also suggestive of a juvenile condition, with adult coelurosaurs typically having 15 or more. The teeth are distinctive, because they have no serrations (in the premaxillary and in some dentary teeth), or bear very fine serrations (∼10/mm) only on the distal carinae (maxillary teeth and some dentary teeth). The authors noted, however, that the variability in the dentition may represent the juvenile condition.
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Upon its discovery, Himalayacetus was described as a pakicetid because the dentary has a small mandibular canal and a dentition similar to Pakicetus. assigned Himalaycetus to the ambulocetids.
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The coronoid process is a thin anterior projection of bone from the dentary, which serves as a site for the attachment of muscles that aid in chewing behavior.
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The surangular was long and sword-shaped, the angular was wing-like in shape, the prearticular was narrow and curved, and the splenial was thin and triangular in outline. The external mandibular fenestra, an opening at the outer side of the mandible, was larger than that of Erlikosaurus because the surangular was shallow from top to bottom. Frontmost dentary teeth, showing folded (lf) and accessory (ad) Segnosaurus had the fewest teeth in the dentary; 24 in each half determined from the number of sockets, as well as the largest teeth known among therizinosaurs. The dentary teeth were foliodont (leaf-shaped) and bore enlarged, relatively tall, sideways compressed crowns with a slight recurvature at the upper margin of the tips.
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Each of the dentary bones is very slender, only about 22 mm wide even at the slightly thickened 'chin' of the symphysis. While L. thaumastos has a small crest running along the lingual side of the dentary to thicken it, this feature is not present in L. maghrebensis. The splenial is a very thin sheet of bone in both species; it stretches much of the way along the lower jaws, but does not participate in the symphysis as the dentary does. The anterior end of the splenial differs between the two species; in L. thaumastos it is bifurcated, whereas in L. maghrebensis the anterior end of the splenial comes to a simple point.
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It has been suggested on the basis of the wide jugal foramen and dentary occlusion that Hispanochampsa was closely related to a contemporary Spanish species of Diplocynodon, D. tormis.
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About 22 teeth were present in a mostly unbroken row along the coronoids. The largest coronoid teeth were present at the front of the first coronoid, the middle of the second, and (to a lesser extent) about a third the way down the rear coronoid. These large teeth are the same size as the dentary teeth. In contrast, even the largest coronoid teeth of Ichthyostega are much smaller than the dentary teeth.
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Dentary with replacement teeth, found in 1851 and in 1857 by Owen referred to Megalosaurus, but now lost. 1800s illustration by J. Erxleben Type dentary and referred teeth. 1800s restoration by J. Erxleben In 1857, Joseph Leidy renamed Deinodon horridus (Leidy, 1856) into Megalosaurus horridus, the "frightening one", a genus based on teeth. In 1858, Friedrich August Quenstedt named Megalosaurus cloacinus, based on a probable Late Triassic theropod tooth found near Bebenhausen, specimen SMNH 52457.
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Skeletal reconstruction of Asilisaurus kongwe on display at the Burke Museum of Natural History and Culture in Seattle. Like the premaxilla, the front of the dentary is toothless and curves into a point. The tip bends down, in contrast to other silesaurids where it bends up. In addition, advanced silesaurids have a longitudinal groove at the lower edge of the inner portion of the dentary, while that of Asilisaurus is positioned higher.
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The jaws of the available specimen for examination are poorly preserved. The jaw that has been examined for Odontocyclops, only has preservation of the anterior portion of the jaw. From this available information it was determined that Odontocyclops lack denary teeth, but do contain a lateral dentary shelf. The presence of the lateral dentary shelf combined with the quadrates being similar in morphology to other dicynodonts suggest that Odontocyclops used a propalinal sliding feeding mechanism.
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In 1955, René Lavocat described a theropod dentary (MNHN.MAJ 1) with teeth from the Maevarano Formation in the same region where the original material was found. The teeth matched those first described by Depéret, but the strongly curved jaw bone was very different from both Megalosaurus and Dryptosaurus. Based on this dentary, Lavocat created the new genus Majungasaurus, using an older spelling of Mahajanga as well as the Greek word σαυρος (meaning "lizard").
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Skeletal restoration. Leptoceratops, like other ceratopsians, would have been a herbivore. The jaws were relatively short and deep, and the jaw muscles would have inserted over the large parietosquamosal frill, giving Leptoceratops a powerful bite. The teeth are unusual in that the dentary teeth have dual wear facets, with a vertical wear facet where the maxillary teeth sheared past the crown, and a horizontal wear facet where the maxillary teeth crushed against the dentary teeth.
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When looking at the different parts however, there are indications of at least six elements present in the lower jaw of the Mesosuchus: dentary, splenial, surangular, angular, prearticular, and articular.
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That is also the minimal number in the dentary. The teeth are relatively short, conical and moderately recurved. Their cross-section is oval. They are widely spaced at equal distances.
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Proa is distinguished from other basal hadrosauriforms (especially other iguanodontids) in having a predentary that reaches the rostral margin, with divergent lateral processes. It can also be diagnosed by a unique combination of characters: dentary tooth row convex dorsally in lateral view; dentary tooth row extending caudal to the base of the coronoid process; platform between the dentary tooth row and the base of the coronoid process; coronoid process expanded along rostral and caudal margins; maxilla lacks a rostrodorsal process; quadrate straight in lateral view; ilium with dorsal margin convex dorsally, non-pendant supraacetabular process, and postacetabular process that tapers without a break in slope along its dorsal margin; cranial pubic process concave along its dorsal margin but lacks expansion of distal end.
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The bottom margin of the jaw is slightly convex; in Sinornithoides, it is straight. The dentary and angular bones may have formed a flexible joint within the jaw - that is, an intramandibular joint. Unlike Xiaotingia, the dentary and maxilla terminate at the same position in the jaw. Also like other troodontids (with Sinusonasus being an exception), Liaoningvenator has a number of small, closely spaced teeth, with at least 15 in the upper jaw and 23 in the lower jaw.
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The first four alveoli of the dentary (corresponding to the tip of the upper jaw) were the largest, with the rest more regular in size. Small subtriangular were present between the alveoli.
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A species of genus Bettongia, small to medium sized mammals that are usually nocturnal and fungivorous. The dentary of Bettongia anhydra resembles that of the Potorous species and those of the bettong genus.
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It is a nomen dubium, a possible carcharodontosaurid, or a very large abelisaurid. Dentary of ?Megalosaurus cambrensis. Lithograph by Newton in 1899 In 1985, Zhao Xijin named two Megalosaurus species found in Tibet.
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Dentary MHNT.PAL.2012.6.1 of Razanandrongobe; splenial attachment marked as asp The lower jaw of Razanandrongobe was also tall and robust. Uniquely, the tip of the lower jaw was devoid of teeth, for a section of the dentary corresponding to the diameter of more than one tooth. The front of the jaw would have been fused; on the inside of the bone, there was a scar running along the rear 20% of the fused portion, representing the attachment of the splenial bone.
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Razanandrongobe had five teeth in each premaxilla, at least ten in each maxilla, and eight in each half of the dentary. Most of the tooth sockets were sub-circular, although the inner half of the sockets in the maxilla and the front of the dentary were rectangular. All of them were wider than they were long, and were nearly vertical. Larger sockets were separated by narrower distances than smaller teeth, with the separating surfaces being ornamented like the paradental shelves.
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It is cataloged as YPM 616\. As noted by Lull and Wright, this long slender partial jaw shares with Cope's specimen a prominent ridge running on its side. However, it is much larger: Cope's specimen had a dentary, or tooth-bearing bone of the lower jaw, that is long, whereas Marsh's dentary is estimated at long. A second mostly complete skeleton (AMNH 5886) was found in 1904 in Hell Creek Formation rocks at Crooked Creek in central Montana by Oscar Hunter, a rancher.
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It closely resembles that of Arizonasaurus, indicating that the two species are close relatives. The dentary bone is partially preserved for both left and right, and would have held thirteen teeth on each side, although only the nutrient foramina remain. Like that of most archosaurs from the Triassic, the dentary is unspecialised. The cervical vertebrae have large, flattened neural spines which make up most of their height and would have formed a sail-like structure in life, similar to other ctenosauriscids.
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As the dentary bone of the lower jaw continued to enlarge during the Triassic, the older quadrate-articular joint fell out of use. Some of the bones were lost, but the quadrate, the articular, and the angular bones became free-floating and associated with the stapes. This occurred at least twice in the mammaliformes. The multituberculates had jaw joints that consisted of only the dentary and squamosal bones, and the quadrate and articular bones were part of the middle ear.
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63136, one of the most complete dentaries found for any silesaurid. As in other sulcimentisaurians, the meckelian groove is positioned close to the lower edge of the jaw and the teeth are constricted at the root. The front tip of the dentary is pointed, toothless, and has a lateral groove akin to that of Silesaurus and Sacisaurus, along with several medial grooves. Further back, the dentary is relatively deep and develops a lateral ridge similar to one reported for Diodorus and Eucoelophysis.
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The pattern of pitting and holes on the outer surface of the dentary also resembles those taxa. The tooth row is edged by a medial groove connecting a series of replacement pits; above the groove the bone is inset similar to the case in Silesaurus, Eucoelophysis, and Technosaurus. Kwanasaurus is the only silesaurid to preserve data on the mandibular fenestra. This hole in the jaw was triangular, edged from below by a posteroventral process of the dentary which also overlapped a partial angular.
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The anterior ectotympanic limb is nestled in a post-dentary trough on the internal edge of the mandible. This groove occupies a similar location in other mammliaforms, however, it is narrower and much shorter in Vilevolodon, and does not extend posteriorly to the dentary condyle. Based upon CT scans and proximity of preservation, the Meckel's cartilage and the ectotympanic contact each other loosely. Luo et al reconstructed these two elements as contiguous, in a similar fashion to cynodonts and other mammaliaforms.
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These include MWC 2907 (a right dentary fragment from Westwater Canyon), BYU 11460 (a dentary fragment from Dry Mesa Quarry), MWC 1200 (a left maxilla fragment from near Uravan), and DMNH 10685 (numerous jaw fragments and teeth from Garden Park). Components of the last specimen were discussed in a 2018 study on the microstructure of Eilenodon teeth. Eilenodon remains have also been reported from a site in Carbon County, Wyoming. Eilenodon is much more rare than another Morrison rhynchocephalian, Opisthias.
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Currently, a single species is known, P. peregrina, hailing from the Colhuehuapian-dating deposits of the Sarmiento Formation, Chubut Province. The holotype, MACN-CH-869, is composed of a semi- complete mandible; isolated upper and lower teeth are also known. The jaw is short and deep, bearing an unfused subvertical dentary symphysis and dorsally positioned masseteric fossa. The incisors are rootless and extend lingually along the ventral border of the dentary up to the level of molariform 3, and the molariforms are hypsodont.
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Speculative restoration of P. walkeri, based on the related mosasaur Halisaurus Pluridens was a moderately large mosasaur at roughly 5 m (16.4 ft) in length if the proportions of the dentary and the rest of the animal matches that of Halisaurus. A feature that separates Pluridens not only from the rest of the Halisaurinae, but from the rest of the Mosasauridae at large is its unusually high tooth count, dentaries assigned to the genus preserve almost twice the amount of teeth found in most other mosasaur genera. Additionally, the dentary of Pluridens also has one of the narrowest profiles among the mosasaurs, with the only genus approaching a similarly narrow dentary being the mosasaurine Plotosaurus. This combination of features indicate a feeding niche and lifestyle unique among the mosasaurs.
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They are 10–13 meters in body length. They share thirteen unambiguous synapomorphies including dorsal vertebrae without pleurocoels, the presence of a ventrally directed prong on the squamosal, and a subtriangular-shaped dentary symphysis.
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Dentary tooth shape in Sphenodon' and its fossil relatives (Diapsida: Lepidosauria: Rhynchocephalia). In Koppe, T., Meyer, G., Alt, K.W., eds. Interdisciplinary Dental Morphology, Frontiers of Oral Biology (vol 13). Greifswald, Germany; Karger. 9–15.
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The maxillary and dentary teeth are elongated, only recurving near the top, with perpendicular denticles on both edges. Their bases are circular in cross- section; the top of the tooth crown is more flattened.
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Paratype and holotype possibly represent a single individual. The paratype is displayed in the Lingwu Geopark. Several specimens have been referred to the species. IVPP V23704 is a series of twenty-nine dentary teeth.
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Evidence of lactation is present in morganucodontans, via tooth replacement patterns.Panciroli E., Benson RBJ., and Walsh S. 2017. The dentary of Wareolestes rex (Megazostrodontidae): a new specimen from Scotland and implications for morganucodontan tooth replacement.
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The jaw joints were low. There were about twelve, rather large, maxillary or dentary teeth in each upper or lower jaw. The forelimbs were lightly built. The ilium was short and low, the pubis thin.
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Both are about 1.5 mm in diameter, but the first tooth may have been slightly smaller than the second. The third tooth, the largest of the cheekteeth, has the root slightly curved backward. This root is deeply anchored in the dentary, extending down through about three-fourths of the bone. The crown is preserved in the form of a stump of dentine, 2.3 mm (0.091 in) long and 1.9 mm (0.075 in) broad, that extends high above the dentary, indicating that the tooth was hypsodont (high-crowned).
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Excluding the pseudocaniniforms, the maxillary tooth size remains roughly constant but gradually decreases after the pseudocaniniforms in both species; all tooth sockets after the twelfth are replaced by a continuous trough. In total, K. guimarotae had at least 15 maxillary teeth, and K. langenbergensis 17 or 18. Meanwhile, the dentary exhibits 21 teeth in K. langenbergensis and at least 20 in K. guimarotae. Like the maxilla, distinct sockets for dentary teeth are replaced by a groove from the eleventh tooth backwards in K. langenbergensis.
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Like Protohadros and several other hadrosauriforms but unlike Probactrosaurus, only the front end of this process is thickened. As in Equijubus, Probactrosaurus, and various other iguanodonts, a small foramen is present on the side of the surangular, which is located behind the dentary. Similar to other iguanodonts, the teeth of Eolambia are arranged in tightly- spaced and interlocking rows. At any given time, each of the 32 maxillary tooth sockets holds three teeth, while each of the 30 dentary tooth sockets holds four teeth.
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Tsagandelta is currently known from one specimen, the holotype PSS-MAE 629. This specimen is composed of a left dentary fragment containing an almost intact second molar, the base of the third molar and the roots of the first premolar; various other tooth sockets are empty, and the dental formula is probably similar to that of Deltatheridium. Based on comparisons with the related Lotheridium, the preserved dentary indicates that Tsagandelta was slightly smaller than the former; Lotheridium is about the size of a modern marten.
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Further Observations upon Hyperodapedon gordoni. Quarterly Journal of the Geological Society, 43, 675-694. Hyperodapedon's closest relative is Rhynchosaurus, and they both share a synapomorphy that the dentary is half the length of the lower jaw.
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Recent cladistic analysis places Massaliasuchus as a member of Allodaposuchidae, a clade of basal eusuchians from the Late Cretaceous of southern Europe. The genus can be distinguished from Musturzabalsuchus in having 15 alveoli in the dentary.
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First of its fossils were cranial remains found in Portugal, and later more fossils were found in France and Spain. They are only known from very fragmentary fossils, elements of the skull, dentary, teeth and osteoderm.
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The teeth of the animal were small, conical, and serrated, and were distributed irregularly in its jaws. The tip of the dentary had no teeth, and evidence suggests that it was covered by a keratinous beak.
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The braincase lacks a recessus suboticus and a crista otosphenoidalis. The rear of the pterygoid has a secondary, rod-like, process. The front dentary teeth are closely packed. The rear of the surangular is extraordinarily deep.
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85-102 The holotype specimen, NMV P199075, a fifty-six millimetres long single left dentary of the lower jaw, containing ten teeth (three unerupted), was found by Mrs Nicole Evered, a long time participant of the dig. Two other jaws, specimens NMV P198962, a left dentary, and NMV P199087, a right dentary, found at the same site the same year have also been tentatively associated with, or referred to, the species. It was named Qantassaurus intrepidus by Patricia Vickers-Rich and Tom Rich, in honor of the Queensland and Northern Territory Aerial Services, which shipped fossils around the country as part of the Great Russian Dinosaurs Exhibit between 1993 and 1996, and sponsored expeditions to South America and Eastern Europe. QANTAS is an acronym, which is why a u does not follow the q in Qantassaurus.
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Species in genus Leptochilichthys have toothless maxillae. The maxillae are considered especially long There are teeth on the palate and dentary. Many long gill rakers are also present. This genus does not exhibit any shoulder sac apparatus.
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Descriptions, in New aphids in Cretaceous amber from Alberta (Insecta, Homoptera). The Canadian Entomologist 124:1027-1053 Another indeterminate specimen of the genus was found in amber in the Dinosaur Park Formation associated with a Prosaurolophus dentary.
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The primary head of the quadrate meets the prootic and squamosal. The quadrate and pterygoid are not fused to the braincase and the basipterygoid articulation is free.The dentary is not gracile and has anterior swelling.Parrish, J. Michael.
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Moreover, three additional specimens coming from the same locality are referred to the same species. These include UALVP 55804 (a partial pelvis), TMP 1982.019.0023 (a partial skull), and TMP 1992.036.575 (a right dentary and several left metatarsals).
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In about 1980 Leon Case found the midsection of a right dentary with teeth of a hadrosaur while walking along a beach in San Diego County.Hilton (Dinosaurs and Other Mesozoic Reptiles of California, 2003), pp. 233-36.
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Carinodens is like its close relative Globidens considered to have been a durophagous mosasaur. Because the anteriormost part of the dentary of Carinodens is relatively slender with small pointed tooth crowns, only the posteriormost five teeth actually functioned for crushing food. The anteriormost portion of the dentary was thus likely used for acquiring and handling food rather than crushing it, an idea already suggested by Dollo (1913) during the description of the type species. The maxilla of Carinodens is unknown, which hinders knowledge on the interaction between the lower and upper jaw.
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The holotype, DORCM G 913, was collected by Charles Willcox, an amateur paleontologist living at Swanage, from the Feather Quarry near Durlston Bay in a marine deposition of Cherty Freshwater Member of the Lulworth Formation, dating from the middle Berriasian. It consists of an about three inch long left dentary fragment with nine teeth. The holotype was once thought to be lost but was rediscovered in the seventies in the Dorset County Museum. Later several other teeth and specimen BMNH 48207, another dentary fragment from a somewhat smaller individual, were referred to the species.
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Of the skull only the anterior part of the right dentary was found. Near the area where it touches the contralateral element at the tip of the lower jaw (the symphysis) the bone is straight and only gently arched medially, as is seen in basal sauropods. More derived sauropods (eusauropods) have medially broadly arching symphyseal regione and anterior portions of the tooth row. The ventral (lower) edge of the dentary is damaged, but does not appear to be ventrally deflected at the symphysis as in some basal sauropodomorphs such as Plateosaurus.
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The side of the dentary is pitted, albeit much more densely so in K. langenbergensis. Near the back of the dentary in both species, the pits are replaced by longitudinal grooves. On the interior of the jaw, the splenial bears an oval foramen behind the level of the symphysis in both species, and the top of the bone bears a low and roughened crest in K. guimarotae. The tip of the angular is situated close to the midpoint of the bone in K. langenbergensis rather than being at the back as in K. guimarotae.
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The holotype, GAA 00225-1, is a nearly complete right premaxilla. Several other specimens have been referred including: GAA 00242, a right premaxilla; GAA 00239, a right premaxillary fragment; GAA 00207, a left maxillary fragment; GAA 00225-2, a right maxillary fragment; GAA 00240, a left maxillary fragment with two teeth and fragments of two other teeth; GAA 00246-1, a partial left dentary with eight teeth; GAA 00246-2, a partial right dentary with 12 teeth or parts of teeth and GAA 00244, a series of three dorsal vertebrae.
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Dentaries Assignment of two dentaries to a caseid is based on the shape of the symphyseal area. As in other caseids, the dorsal edge of the dentary bone curves ventrally near the symphysis, and forms an acute angle with the ventral edge of the bone. This results in a substantially more slender dentary bone near the symphysis than in the rest of the bone. As in other caseids, this is related to the presence of a well-developed anterior process of the splenial bone, one that contributes to a large portion of the symphysis medially.
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The outer (marginal) tooth row was present solely on the dentary bone, which was narrow and had alternating regions of light and absent texturing. It had at most 33 teeth, including a symphysial fang (an enlarged tooth near the chin) which was only slightly larger than the other dentary teeth. The inner tooth row stretched along four plate-like bones: the parasymphysial plate and three coronoid bones. The parasymphysial plate has a large tooth at its front edge, followed by a smaller tooth and a diastema (toothless area), similar to Ichthyostega.
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Holotype dentary and ilium In 1877, Marsh named two species of Nanosaurus in separate publications, based on partial remains from the Morrison Formation of Garden Park, Colorado. One paper described N. agilis, based on YPM 1913, with remains including impressions of a dentary, and postcranial bits including an ilium, thigh bones, shin bones, and a fibula. The other paper named N. rex, a second species which Marsh based on YPM 1915 (also called 1925 in Galton, 2007), a complete thigh bone. He regarded both species as small ("fox-sized") animals.
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The largest tooth of the maxilla was either in or near the fourth alveolus, and the height of the tooth crowns decreased hindwards. The first tooth of the maxilla pointed slightly forwards from its alveolus because the lower border of the prexamilla process (which projected backwards towards the maxilla) was upturned. The teeth of the dentary were much smaller than those of the maxilla. The third or fourth tooth in the dentary of Dilophosaurus and some coelophysoids was the largest there, and seems to have fit into the subnarial gap of the upper jaw.
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Magnamanus is a large ornithopod, with an estimated length of between nine and ten meters, and weight over three tons—a similar size to Iguanodon bernissartensis. The hand is broad and similar to other basal members of Iguanodontia, with a protruding thumb spine and a fifth finger. The descriptors established nine distinctive features for this taxon, all autapomorphies. The dentary contributes to the front coronoid process of the lower jaw so that the last dentary tooth is located on the slope of the protrusion, instead of on the basis of it.
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A narrow, deep ran at the inner side of the dentary, just above its lower margin, towards the front of the mandibular symphysis. Just behind the symphysis and below the Meckelian groove, a distinct foramen was present, similar to the condition in Urbacodon. On the outer side of the dentary, at the level of the Meckelian groove, there was a shallow groove with elongated pits. Unlike most troodontids, Xixiasaurus did not have on its teeth, and their (front and back edges) were instead smooth and sharp, as in Byronosaurus.
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The upper part was slightly rotated forward, probably permitting some degree of binocular vision. The teeth were long and slender, as opposed to the usually very short teeth seen in other abelisaurids. On each side of the upper jaws there were four premaxillary and twelve maxillary teeth, while the lower jaws were equipped with fifteen dentary teeth per side. In contrast to the robust-looking skull, the lower jaw was shallow and weakly constructed, with the dentary (the foremost jaw bone) connected to the hindmost jaw bones by only two contact points.
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The lower part of the rear edge of the dentary has a long prong, known as a ventral process. This differs from the situation in abelisaurids, which have a much shorter ventral process. On the other hand, the upper part of the rear edge of the dentary is very similar to that of abelisaurids such as Majungasaurus and Carnotaurus. This part of the bone possesses an array of four small structures, three of which line a socket which connects to the surangular bone at the back of the lower jaw.
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The holotype and only known specimen of Polyodontosaurus was collected in 1928 by Charles Mortram Sternberg, and includes only a left dentary, lacking any teeth. Sternberg presented the dentary to Charles Gilmore, who identified it as a lizard. Gilmore thus named the binomial Polyodontosaurus grandis for the new taxon. Sternberg revisited the material in 1951 and determined that it represented a carnivorous dinosaur based on the general morphology of the bone, as well as the anatomy of the Meckelian groove, multiple nutrient foramina, and separation of teeth into multiple sockets.
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The dentary also does not deepen substantially at the front end, and thus lacks one of the distinguishing traits of Eolambia dentaries. However, the other distinguishing trait, which is the expansion of the front end of the coronoid process, is present in the specimen. Although it is possible that this individual represents an unusual Eolambia specimen, McDonald and colleagues cautioned that it may represent a distinct hadrosauroid that differs in the morphology of the dentary from Eolambia (albeit one that is not suggested by any of the other materials at the quarry).
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Cross section of a rib from specimen FMNH PR 3847; LAGs marked by arrows Being known from a variety of juvenile and adult specimens, the changes Eolambia underwent as it grew are well-documented. The number of teeth in the maxilla increased with age, from 23 in a juvenile to 33 in an adult. A similar increase occurred in the dentary teeth, from 18–22 in juveniles to 25–30 in adults. While juveniles lack secondary ridges on the crowns of their dentary teeth, faint secondary ridges are present in adults.
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Stong jaw musculature combined with a relatively short and tall dentary would have resulted in a very powerful bite. The skull of the type specimen of Prognathodon saturator is nearly complete, only lacking the anterior portion of the premaxilla and the dentaries. Though most of the anterior marginal teeth are missing, the inclination of the preserved roots suggest that P. saturator had procumbent teeth, a trait also seen in P. solvayi. The dorsal margin of the dentary is concave, whilst the ventral margin of the maxilla is slightly convex.
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There were at least five teeth in each premaxilla, and at least nineteen in the maxilla and sixteen in the dentary of the lower jaw. However, the number of maxillary and dentary teeth were established with the incomplete skull of one of the first specimens found; the actual numbers might have ranged up to about two dozen, perhaps twenty-six for the lower jaw. The premaxillary teeth were somewhat longer and recurved. To the rear, they gradually approach the form of the maxillary teeth, beginning to show denticles.
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The teeth on the outer row, also known as "marginal teeth", are attached to the dentary bone and are sharp and curved. They are also slightly flattened in an anteroposterior (front-to-back) direction, although not to the extent seen in capitosaurs such as Mastodonsaurus. At the front of the jaw, the dentary tooth row also twists slightly outwards. The front of the jaw also possesses an enlarged tooth known as a parasymphyseal tusk, although this tooth is less than twice as wide as the rest of the marginal teeth.
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11: 142–144 A second species, J. fuyunensis, was described by Wu (1984) for a dentary from Xinjiang, China, but is dubious.Wu S. 1973. [A fossil of Jaxartosaurus is discovered in the Xinjiang]. Vertebrata PalAsiatica 11: 217–218.
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"New partial dentaries of amphitheriid mammalian Palaeoxonodon ooliticus from Scotland, and posterior dentary morphology in early cladotherians". Acta Palaeontologica Polonica. in press. doi:10.4202/app.00434.2017. It is found in the Forest Marble Formation and the Taynton Limestone Formation.
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Salentijn, L. Biology of Mineralized Tissues: Prenatal Skull Development, Columbia University College of Dental Medicine post-graduate dental lecture series, 2007 Mammalian jaw structures are also set apart by the dentary-squamosal jaw joint. In this form of jaw joint, the dentary forms a connection with a depression in the squamosal known as the glenoid cavity. In contrast, all other jawed vertebrates, including reptiles and nonmammalian synapsids, possess a jaw joint in which one of the smaller bones of the lower jaw, the articular, makes a connection with a bone of the cranium called the quadrate bone to form the articular-quadrate jaw joint. In forms transitional to mammals, the jaw joint is composed of a large, lower jaw bone (similar to the dentary found in mammals) that does not connect to the squamosal, but connects to the quadrate with a receding articular bone.
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In The Dinosauria: Second Edition (pp. 517-606).22 University of California Press. The type and only specimen of A. tigrinus consists of a fragmentary skull and fragmentary dentary. The remains of A. buceros are unknown and are possibly now lost.
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It contains premaxillary, maxillary, prevomerine, and palatine teeth. Most teeth monocuspid. The prevomerine and palatine teeth are the only exceptions and they are bicuspid. The front end of the tongue is attached to the gums directly behind the dentary teeth.
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Fossils have been found in the Upper Jurassic Morrison Formation of Wyoming (U.S.). The animal was reportedly about long. It seems to have been a rather specialized creature, judging by the dentary. Zofiabaataridae are believed to belong to the allodontid line.
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Harpymimus is a basal ornithomimosaurian theropod dinosaur from the Early Cretaceous Period of what is now Mongolia. Unlike later, more derived ornithomimosaurs, Harpymimus still possessed teeth, although they appear to have been restricted to the dentary of the lower jaw.
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A relatively small number of teeth in comparison to other mosasaurs (for an example, Prognathodon saturator preserves 14 teeth in the dentary, 12 in the maxilla and 6 in the pterygoid) is a characteristic present in all species of Prognathodon.
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The 3 premaxillary, 19 maxillary, and 14 dentary teeth are all thin, curved, and blade-like. There are serrations on the distal (rear) edge of all the teeth, and the maxillary teeth also have serrations on the mesial (front) edge.
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Some species have jaw bones completely fused, while others may have joints allowing for mobility of the dentary, quadrate, or maxilla. The snake skull shows the greatest degree of cranial kinesis, which allows the snake to swallow large prey items.
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Dentary and premaxilla, MHNT.PAL.2012.6.1–2, from the same individual of Razanandrongobe Between 1972 to 1974, the assistant director of technical services of the Sugar Company of Mahavavy had previously collected a dentary (lower jawbone) and a premaxilla from the area where the holotype of Razanandrongobe was discovered. Under the authorization of the Mines and Energy Directorate of Madagascar, these specimens were exported and stored in the collection of D. Descouens. After they were prepared, these fossils were discovered to pertain to Razanandrongobe; based on the fact that they fit together perfectly, they were further inferred to belong to the same individual.
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Although the dentary bones assigned are nearly complete anteriorly, their morphology cannot confirm the entire depth or height of the lower jaw at the symphysis. This is because the dentary contributes only to the dorsal half of the symphysis in caseids, and the splenial most likely contributed to the symphysis, as it formed the lower part of the symphyseal region of the mandible. The assignment of these dentaries to Arisierpeton is based mainly on dental features, and to some extent on the labial surface characteristics of the bone. The teeth of these dentaries are identical to those found on the maxillae.
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The retroarticular process of the mandible (a backwards projection) was long, and the surangular shelf was strongly horizontal. The dentary bone (the front part of the mandible where most of the teeth there were attached) had an up-curved rather than pointed chin. The chin had a large foramen at the tip, and a row of small foramina ran in rough parallel with the upper edge of the dentary. On the inner side, the mandibular symphysis (where the two halves of the lower jaw connected) was flat and smooth, and showed no sign of being fused with its opposite half.
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Restoration of Rhizodopsis The upper jaw had a marginal row of small teeth on the maxilla and premaxilla, medium- sized fangs on the ectopterygoid and dermopalatine bones, and large tusks on the vomers and premaxillae. On the lower jaw were marginal teeth on the dentary, with fangs on the three coronoids and a huge tusk at the symphysial tip of the dentary. Apparently, the left and right mandibles rotated inwards towards each other on biting. This may have been a kinetic mechanism to dig the marginal teeth more deeply into the prey, to help grip slippery or struggling items.
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The coronoid process (a site for jaw muscle attachment) is unusually short compared to that of other kingoriids. The dentary also has a short horizontal shelf about halfway up its side, representing a greatly reduced lateral dentary shelf (a site of attachment for the external lateral adductor, an important jaw muscle in dicynodont feeding). The reflected lamina of the angular is relatively short, surrounded by a concave lateral exposure on each side. The articular has a curved, convex upper surface that contacts the condyles of the quadrate and extends beyond them, facilitating palinal (backwards) motion of the lower jaw, typical of dicynodonts.
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In 1963, M.E. Malan observed an interesting pattern in the positioning of the maxillary and dentary teeth. The middle section, where the medial expansion of the maxilla is wideset, had a zig-zag arrangement of teeth while the first and last four teeth are aligned in a row that is parallel to the maxilla. In the dentary, a simpler arrangement with only a slight zig-zag arrangement. Comparing this feature to Captorhinus aguti, which also possessed a zig-zag pattern of teeth, they hypothesized that Mesosuchus could have had multiple teeth on at least the maxilla.
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The mandible specimen was found in the "Lutetian" fossil site of Issel in France. It has a symphysis that has a spoon-like shape that reaches the 8th alveoli and is the thickest in with at the 4th tooth, the splenial is one-half the length of the symphysis. The dentary has light started ornamentations and vermiculation, there are a row of vascular foramen that open backwards on the upper part of the dentary, and the lower half has longitudinal depressions on the lateral. There is a surface full of wrinkles on the lateral dorsal side, for muscle attachment to surangular.
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The species name multidentata alludes to the many teeth preserved in the jaw. The jaw, which is housed in the Field Museum and cataloged as FM PR 1820, curves strongly downward but was probably straight to begin with, having been deformed by the process of fossilization after the individual died. Rooted in the dentary bone along the outermost edge of the jaw are 88 small, pointed marginal teeth. An additional row of even smaller teeth runs along the coronoids, three bones positioned lengthwise along the lower boundary of the dentary on the inner surface of the lower jaw.
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Like the rest of the skull, the lower jaw of Alioramus was long and slender, another possible juvenile characteristic. As in Tarbosaurus, a ridge on the outer surface of the angular bone of the lower jaw articulated with the rear of the dentary bone, locking the two bones together and removing much of the flexibility seen in other tyrannosaurids. Other tyrannosaurids had four premaxillary teeth, D-shaped in cross section, on each side. Including 16 or 17 in each maxilla, and 18 in each dentary, Alioramus had 76 or 78 teeth, more than any other tyrannosaurid.
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The occiput was narrow, with the paroccipital processes pointing outwards horizontally, and the were lengthened, descending far below the (the lowermost bone of the occiput). Sereno and colleagues suggested that some of Baryonyx cranial bones had been misidentified by Charig and Milner, resulting in the occiput being reconstructed as too deep, and that the skull was instead probably as low, long and narrow as that of Suchomimus. The front of the dentary in the mandible sloped upwards towards the curve of the snout. The dentary was very long and shallow, with a prominent Meckelian groove on the inner side.
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In general, the 18 front-most teeth were relatively homodont (of the same type), though the crown of the second tooth was relatively shorter and more tapered; this may also have been true for the first tooth, but it was not preserved. The teeth further back in the row also decreased in relative height hindwards. By comparison, the front four to five dentary teeth of Erlikosaurus were conidont (cone-shaped) with a gradual transition to foliodont teeth. The dentary teeth were tightly packed, but not pressed closely together, with the tooth crowns approaching each other at mid-length.
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Most of the other hindmost tooth crowns are damaged so their complete features are unknown. The additional carina on tooth 23 appears to have been fully denticulated while the denticles were restricted to the basal side of the crown in tooth 22. Segnosaurus was unique among all known theropods in possessing triple carinae. The 14th alveolus on the right dentary of the holotype is walled over by seemingly pathological (due to injury or disease) bone growth but the teeth in that part of the dentary are damaged so it is not possible to determine how the teeth were affected by this.
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Previously it was thought that the dentary of Andreolepis did not contain true teeth, but instead harbored denticles. The lack of teeth and the recognition of initial denticle organisation suggested a basal phylogenetic position within the osteichthyes. It was even argued that the presumed dentary fossil of A. hedei is uninformative of dental evolution, as the fossil did not represent dental development, but rather development of the dermal skeleton. This would mean the tooth-like structures of Andreolepis neither match with teeth of chondrichthyans nor with those of osteichthyans and are more similar to the development of structures in dermal scales.
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The skull of the type specimen of Harpymimus is virtually complete, but badly crushed, obscuring some anatomical detail. There is evidence of a beak covering the upper jaw which, in concert with the dentary teeth, was likely employed for grasping and holding food. Its general appearance was much like that of later ornithomimosaurs (long-necked, long arms with sharp grasping claws, and long legs). The teeth of Harpymimus differ from those of another basal ornithomimosaur, Pelecanimimus polyodon, in that they are restricted to the dentary, are cylindrical and separated by interdental plates, and number at least ten and perhaps eleven per side.
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Dissorophus multicinctus skull in Lateral view including dentary Williston’s anatomical analysis on Dissorophus reveal that there are about thirty five teeth on the dentary. Additionally, DeMar's mentions that the entire lower jaw is covered by dermal pitting except for the region of coronoid process. He also mentions that the coronoid process extends anteriorly and serves as an attachment point for muscles and thus the most probable diet inferred would be a carnivore likely to prey on smaller animals such as insects and smaller animals. DeMar also comments on a distinctive feature that is only present in Dissorophus multicinctus and not any other dissorophids.
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The dentary was curved in dorsal view, so that the mandibles formed a U-shaped, broad snout. This feature is typical for sauropods – in Prosauropods, on the contrary, the dentary was straight, forming a V-shaped, tapered snout. Paul Upchurch and colleagues (2007) suppose that this differences can give hints about feeding habits: The prosauropods with their tapered snouts possibly where selective feeders, who ate only certain plant parts, whereas sauropods with their broad snouts where bulk feeders, adapted to consume large amounts of foliage. The tooth size increased towards the tip of the snout, like in sauropods.
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The outer face of the dentary also has a depression near the tooth row about midway down the length of the bone. This depression would have received the maxillary fang while the mouth was closed, similar to how the diastema at the front of the maxilla would have received the dentary fang. The surangular and angular (a pair of untoothed bones in the rear part of the lower jaw) are deep. The articular bone, which houses the jaw joint at the rear end of the lower jaw, is concave and opens towards the rear, similar to that of phytosaurs.
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Illustration of the "Newtonsaurus" dentary mold in internal and external views "Newtonsaurus" is an informally named genus erected for the theropod dinosaur species Zanclodon cambrensis, which was discovered in the Lilstock Formation in 1898. It was probably a ceratosaur, which lived in what is now the United Kingdom. The taxon was reassigned to Megalosaurus due to the taxonomic difficulties associated with Zanclodon. It is based on a mold of a dentary from Rhaetian-age beds in Wales (hence the species name), and is one of the relatively few dinosaurs known from the time near the Triassic–Jurassic boundary.
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In addition, Aymberedactylus shows a unique combination of traits: the shelf on the dentary symphysis is deep, the dorsal rim of the symphysis is concave, the jaw is relatively wide, the dentary fossa is short and shallow (which indicates a relatively weak bite), and the mandibular rami form a very large angle with the symphysis. These traits are a unique combination of basal and derived characteristics within Tapejaridae. The preserved specimen of Aymberedactylus would have had a wingspan of approximately , typical of tapejarids. Judging by how the bones in its skull were not yet entirely fused, it was likely a subadult.
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The lateral surface of the quadrate is flat and on the anterior border a cut for the quadratojugal can be identified, however, most of its articular borders are lost except a small dorsal area and a long bottom surface. A right dentary is represented by specimen AMNH FARB 30654, a partial element with a badly eroded dental battery. It preserves about 15 alveoli of which none is filled with teeth. The total dentary teeth count on Gilmoreosaurus was probably less than 30 and the tooth row is oriented to the lateral sides as seen in other hadrosauroids, unlike the more advanced hadrosaurids.
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The teeth in the upper jaw are concentrated in the front part and spaced far apart; their number is uncertain. The lower jaws have been well preserved. They are long and their symphysis is short. Twelve teeth are present in the dentary.
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The tooth count is five per premaxilla; the number is at least nine for the maxilla, and at least fourteen per dentary: no reliable estimates can be given of the last two totals because the back of the head has been lost.
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The holotype of Aztlanolagus agilis was deposited at the University of Texas at El Paso Biodiversity Collections. (Specimen No. UTEP:ES:1-1202). The specimen, collected by Richard A. Smartt, is a left dentary with premolars 3 and 4 and molars 1 and 2.
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The dentary is a very slender and long bone, holding up to about 45 teeth. There is also the presence of palatal teeth that are much smaller in size than the marginal teeth, and also being sharp, straight and with homodont structures.
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Polyodontosaurus is a potentially dubious genus of troodontid dinosaur named in 1932 by Gilmore for a left dentary from the Dinosaur Park Formation. It had been considered a synonym of Stenonychosaurus or Troodon for a significant time, before being declared a nomen dubium.
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The type specimen of Sudamerica ameghinoi was discovered in Punta Peligro, Argentina in deposits dating to the Lower Paleocene period. In 1999, a near complete lower jaw (dentary) was found. The position of gondwanatherians within the class Mammalia is not yet clear.
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The postdentary bones are reduced to form a free standing coronoid process. The reflected lamina is spade shaped and does not extend below the dentary The area between left and right dentaries remains relatively long and narrow just posterior to symphyseal region.
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Its primitive jaw joint is located between the quadrate and articular bones, and its derived, mammalian jaw joint is located between the squamosal and dentary bones.Prothero, Donald. Evolution: What the Fossils Say and Why It Matters, p. 278 (Columbia University Press, 2013).
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Alticonodon is currently a monotypic genus, represented exclusively by A. lindoei. Its is known from the Milk River Formation deposits of the early Campanian of Alberta, Canada. It is known from two specimens: a dentary fragment bearing two molars, and an isolated lower last molar.
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Large holes and cavities in the skull called adductor chambers and temporal openings would have provided room for large jaw-closing muscles. A ridge on the dentary bone of the lower jaw may have provided a surface for chewing or even supported a beak.
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Benson et al. (2013) discussed only BHN 2R.370 originally referred to Pliosaurus grandis, stating that P. carpenteri has a similar count of dentary and symphysial teeth, and thus the specimen cannot be identified to species level. However it was referred to Pliosaurus indet.
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There are no traces of rings on the vertebrae. The marginal teeth are slender and styliform. The portion of the dentary that bears teeth is deepened near the symphysis. It is known from a few, mostly complete specimens, P. 6841, P. 6838, and P. 6840.
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The referred elements represent slightly larger individuals. Additionally sixteen isolated teeth were referred: IPFUB GUI D 89-91: three teeth of the premaxilla, and IPFUB GUI D 174-186: thirteen teeth of the maxilla and dentary. These had in 1998 been described by Jens Zinke.
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Huehuecanauhtlus is known only from two individuals. The holotype IGM 6253 represented by fragmentary skull (partial left maxilla and dentary fragment) and postcranial skeleton including four cervical vertebrae, nine dorsal vertebrae, four dorsal neural spines, one dorsal diapophysis, five right dorsal ribs, seven left dorsal ribs, seven sacral neural spines, seven sacral diapophyses, one caudal diapophysis, three caudal vertebrae, two caudal neural spine, eight fragmentary ossified tendons, left and right partial ilium, and left and right partial pubis. The smaller paratype, IGM 6254, is represented by fragment of left dentary, two teeth, and one cervical prezygapophysis. Both specimens were collected at the Barranca Los Bonetes locality in Tuzantla, Michoacán.
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The squamosal appeared to have a concave formation on the surface at the upper end of the quadrate. In Cope's fossil the mandible was preserved almost perfectly and from this he recorded that the jaw was very similar to the Chelonidae and the dentary had a broad for above downward with a concave surface, marked by deep pits in the dentary. Cope concluded that these animals were most likely omnivores and consumed a diet of hard shelled crustacean creatures, due to the long symphysis of its lower jaw. Along with probably consisted of seaweed and jellyfish or scavenged on floating carcasses as well, like modern turtles.
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Several traits in 2008 identified as autapomorphies, later transpired to have been the result of damage. However, a unique combination of traits is present in the wide longitudinal groove on the outer side (shared with Torvosaurus), the small third dentary tooth and a vascular channel, below the row of interdental plates, that only is closed from the fifth tooth position onwards. The number of dentary teeth was probably thirteen or fourteen, though the preserved damaged specimens show at most eleven tooth sockets. The interdental plates have smooth inner sides, whereas those of the maxilla are vertically grooved; the same combination is shown by Piatnitzkysaurus.
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The sharp blades of the dentary and along the tusks provide cutting action. The front end of the jaws and the anterior notch aligned the vegetation in the mouth, and as the lower jaw moves backward, it pulled the plant matter past the caniniform tusks, cutting it into bite-size pieces. The food was further processed by the dentary blades and the edges of the tusks and crushed on the palatine pad. The horned beak may have allowed small dicynodonts such as Robertia to pick out individual leaves, seeds, and buds, however it is suggested that they preferred stems and rhizomes over leafy vegetation.
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The mandible of Taoheodon is mostly known from part of the dentary, with portions of the angular, surangular and splenial bones. The dentary is large and robust, with a rough, pitted surface texture at its front and along the top surface, corresponding to the horny beak typical of dicynodonts. The tip of the lower jaw is missing, so the exact shape of the beak is unknown; however, a low and wide curved ridge defines a clear edge between the side and front faces of the beak. Like other dicynodonts, the angular supports a prominent reflected lamina, which may have supported the eardrum in non-mammalian therapsids.
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Vitalia is an extinct genus of reptile from the Early Triassic (late Olenekian stage) of European Russia known from the type species V. grata. It is known from the holotype dentary PIN 4173/126 (SGU 104/3105) as well as two additional dentaries PIN 1043/627 and 1043/628, all housed at the Paleontological Institute, Russian Academy of Sciences. The type dentary was originally included in the hypodigm of Coelodontognathus donensis named by the notable Russian vertebrate paleontologist Vitaliy Georgiyevich Ochev in 1967. Ivakhnenko (1973) separated the specimen and gave it its own genus and species name in light of the new material, which he named in honor of Ochev.
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The teeth in the same area of the left dentary bear triple carinae, though this dentary has no external indications of pathology that could have led to this condition, thus it cannot be concluded nor ruled out that this feature is the result of a pathology. Segnosaurus replaced its teeth in waves running from back to front of the jaws, that encompassed two to three erupting crowns. Some of the fully erupted teeth have wear on the carinae of their hind sides, unlike what is seen in other therizinosaurs. The texture of the appears to have been broadly irregular and the roots of the teeth were almost circular.
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In all thalattosaurs found, the posterior end of the dentary bifurcates into two diverging processes (upper and lower). This can be distinguished from Clarazia in which these two process are almost equal in length whereas in T. borealis the ventral process is much longer than the upper.
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It also had long pennaceous feathers on its tibia and metatarsus. If Xiaotingia could fly short distances it might also have used its hind limbs as wings. Xiaotingia had a dentary tooth count probably less than 10 and teeth similar in morphology to those of basal avians.
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"Dentition and relationships of the Jurassic mammal Shuotherium" (PDF). Acta Palaeontologica Polonica. 47 (3): 479–86 The original holotype is composed of a partial dentary and seven teeth (two which are incomplete). The holotypes for other species of this genus are solely represented by isolated molars.
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Tianyuornis however, also possesses several autapomorphies such as a straight dentary, and teeth that were preserved in the maxilla and mandible. The possession of teeth reveals new and important morphological information of hongshanornithids, as well as confirms the controversial presence of teeth of the members of Hongshanornithidae.
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Each dentary had space for about 14 teeth. The maxillary tooth rows of Brachiosaurus and Giraffatitan ended well in front of the antorbital fenestra (the opening in front of the orbit), whereas they ended just in front of and below the fenestra in Camarasaurus and Shunosaurus.
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Mandibular teeth were present, along with a well-developed dentary table. The dorsal margin of the symphysis is upturned, forming a cutting edge at the front of the lower jaw. The jaw joint facilitated a fore and aft sliding motion, allowing the animal to process vegetation effectively.
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The suprangular or surangular is a jaw bone found in most land vertebrates, except mammals. Usually in the back of the jaw, on the upper edge, it is connected to all other jaw bones: dentary, angular, splenial and articular. It is often a muscle attachment site.
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The first two dentary teeth are large and procumbent; and the premaxillary and anterior maxillary teeth are much enlarged relative to the posterior maxillary teeth. The third cervical vertebra has a deep, rimmed, ovoid pleurocoels on the anterolateral surfaces of both the centrum and the neural arch.
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While teleost bones are well calcified, they are constructed from a scaffolding of struts, rather than the dense cancellous bones of holostean fish. In addition, the lower jaw of the teleost is reduced to just three bones; the dentary, the angular bone and the articular bone.
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The holotype is a partial left dentary known as NMV P208231. An age of approximately 123 million years makes this the earliest known monotreme. The lower molar is broadly similar in morphology to the m2 of Steropodon. The trigonid is compressed and the talonid has no basin.
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The holotype specimen is deposited at the University of Texas at El Paso Biodiverstiy Collections as UTEP:ES:120-2526. It is an adult, left dentary with the first incisor, fourth premolar and first through third molars. The specimen was collected from Big Manhole Cave in Eddy County, New Mexico.
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Stenaulorychus and Rhynchosaurus are close outgroups to Hyperdapedontinae during the middle Triassic. They share the synapomorphy of the dentary is well over half the length of the lower jaw. Rhynchosaurs were basal archosauromorphs that were herbivorous on dry land in Triassic Pangea. Some rare forms are Mesosuchus and Howesia.
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The generic name is derived from Xinmin, the district where the fossil was found, and Greek sauros, "lizard". The specific name is derived from Greek kataktes, "crusher", in reference to one of the taxon's autapomorphies - the presence of bulbous and laterally compressed crushing teeth in maxilla and posterior dentary.
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Ichthyoconodon has been found to be a eutriconodontan mammal, despite there only being two molar teeth. although some authors have been skeptical of this interpretation.Rose, K.D., Cifelli, R.L. & Lipka, T.R. (2001) Second triconodont dentary from the Early Cretaceous of Maryland. Journal of Vertebrate Paleontology Volume 21. pp. 628–632.
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In Procynosuchus and Dvinia the location of masseteric fossa high on the coronoid process is seen as an initial stage of differentiation of masseter (Botha et al., 2007). In Cynosaurus and Nanictosaurus the extension of masseteric fossa is to the base of the dentary (Botha et al., 2007).
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Barbosania was a medium-sized pterodactyloid with a skull length of 392 millimetres. Its body was 209.5 millimetres long. The skull is elongated with a slight upwards bend in the snout. Its lack of a rostral and dentary median sagittal crest allows a distinction from other related pterosaurs.
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Fishes of the World (5th ed.). Wiley. p. 348. A single row of comb-like teeth are found on the dentary and premaxilla but are absent on the palatine bone.Springer, V. (1962). A Review of the Blenniid Fishes of the Genus Ophioblennius Gill. Copeia, 1962(2), 426-433.
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Averianov and Sues also identified teeth and other material, earlier described by Lev Nesov, as a Urbacodon sp. from the nearby Turonian Bissekty Formation. The holotype dentary of U. itemirensis is 79.2 millimetres long (3.12 in) and has 32 tooth positions. It is rather straight in top view.
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The front teeth of the dentary have a base width, measured from the front to the rear, of about . Their crown height is about . The teeth have in total twelve to fourteen cusps on their edges. The cusp forming the tip of the tooth is off-set to behind.
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Another major difference between Tarbosaurus and its North American relatives was its more rigid mandible (lower jaw). While many theropods, including North American tyrannosaurids, had some degree of flexibility between the bones in the rear of the mandible and the dentary in the front, Tarbosaurus had a locking mechanism formed from a ridge on the surface of the angular, which articulated with a square process on the rear of the dentary. Some scientists have hypothesized that the more rigid skull of Tarbosaurus was an adaptation to hunting the massive titanosaurid sauropods found in the Nemegt Formation, which did not exist in most of North America during the Late Cretaceous. The differences in skull mechanics also affect tyrannosaurid phylogeny.
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The authors of the description of the neotype suggested that Platyognathus may be closely related to the clade containing Protosuchidae and Shantungosuchus because it possesses a dentary tooth that fits into a notch between the premaxilla and maxilla. Because Platyognathus is known from such incomplete material, there is yet to be an adequate cladistic analyses that can determine a phylogenetic position for Platyognathus within Protosuchia. An unnamed mesosuchian from the Salt Wash Member of the Late Jurassic Morrison Formation of western Colorado in the United States possesses several features that are also seen in Platyognathus. The dentition of the mesosuchian is similar to that of Platyognathus and like Platyognathus, the dentary is laterally expanded.
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In the same year that Gingerich and Sahni recognized the two species of Sivaladapis, Thomas and Verma placed S. narigii, S. palaeindicus, and the species belonging to the genus Indraloris in their own subfamily, Sivaladapinae, which was later promoted to the family level, Sivaladapidae. Gingerich and Sahni assigned S. nagrii as the type species for the genus. The holotype for S. nagrii is represented by a partial right dentary that preserves M1-M3 (GSI 18093) collected from the Middle Siwaliks Nagri formation near Haritalyangar, India. The holotype for S. palaeindicus is represented by a partial right dentary preserving P4 and M2-M3 (GSI D-224) collected from the Lower Siwaliks Chinji formation near Chinji, Pakistan.
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Indication of three semilunar pockets along a shallow groove between the dentary and the prearticular shows that the lower jaw has three coronoids. It is unique in that it has a very large adductor fossa, a convex ventral flange, and a prearticular of minute denticles dorsally and undulating parallel ridges ventrally.
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The mouth is inferior. H. anisitsi has three dark bands on its caudal fin, while dark lines are irregular or absent in the other three species. Among the other three species, H. graciosa has 5-6 rows of teeth in the dentary (vs. 6-7 in the other two species).
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The external mandibular fenestra is large. The dentary, lower jaw, teeth are quite pointed and have no front edge denticles; their rear edge is very straight. The holotype preserves a furcula and a basket of fifteen pairs of gastralia. The arms are weakly developed, with a slender humerus and ulna.
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Neotrirachodon is an extinct genus of cynodonts which existed in Russia during the Middle Triassic period. It contains the type and only species Neotrirachodon expectatus. It is known from a jaw fossil consisting of the left dentary with postcanines. It was recovered from the Donguz Formation, Orenburg Oblast of Russia.
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In addition, the surface characteristics of the labial side of the dentaries are similar to those of the maxillae, showing little sculpturing, and occasional small foramina. A well-developed, anteriorly extending Meckelian canal is formed by the dentary bone, below which it would be attached to the splenial by sutures.
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Behind the dentary was a moderately large mandibular fenestra. Individuals of Desmatosuchus were heavily armored. The carapace was made up of two rows of median scutes surrounded by two more rows of lateral scutes. The lateral scutes had well-developed spine-like processes which pointed out laterally and dorso-posteriorly.
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Only three teeth are preserved on the dentary, one of which contacts a maxillary tooth's inner surface with its outer surface. The denticles on this tooth's outer surface perfectly match up with those of the inner surface of the maxillary tooth, forming a chisel contact surface for grinding or cutting food.
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Scutarx is an aetosaurine suchian known from the Triassic Chinle Formation of Petrified Forest National Park of Arizona and the Cooper Canyon Formation of Texas. The type and only species, Scutarx deltatylus, was described in 2016 by William G. Parker. Known fossils include a mandible and a dentary from Arizona.
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Allosaurids have a general anatomy typical of other neotheropod dinosaurs, contributing to the difficulty in defining the family's membership. A typical 8m specimen of Allosaurus fragilis had a skull of about 0.85m. The premaxilla has five teeth and the maxilla usually around 16. The dentary also typically has 16 teeth.
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Allosaurus fragilis: A Revised Osteology. Utah Geological Survey Bulletin 109 (2nd ed.). Salt Lake City: Utah Geological Survey. The skull also exhibits features consistent with significant cranial kinesis: a synovial joint between the braincase and the frontals and a loose articulation between the dentary and the angular/surangular.Paul, Gregory S. (1988).
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Tubercules are no longer present from segments 1–11. The cephalopharyngeal skeleton is dark brown-black and 0.93–1.05 mm long. Mandibular sclerites are well-developed and present in pairs on either end of the body. Dentary sclerites are also paired and found separately near the margin of the mandibular sclerites.
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In 2007, David B. Norman and colleagues regarded this as unfounded. They instead found Tatisaurus to be a dubious basal thyreophoran, showing a single thyreophorean synapomorphy; a ventrally deflected mesial end of the dentary. If considered a thyreophoran, it would be one of the oldest known members of the group.
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One autapomorphy (unique characteristic) of Ratchasimasaurus is its elongated and flat ramus of the dentary. Ratchasimasaurus shows both primitive and derived characters for Iguanodontia, such as "a caudally inclined coronoid process and alveolar trough with a primitive crown impression, and a derived buccal shelf between the tooth row and the coronoid process".
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There is a strong posterior ridge along the quadrate's main axis. Above the two parts of the mandibular condyle, there is a well-defined facet for articulation with the quadratojugal. The anterior parts of the dentary are preserved, up to the first eight teeth. The lateral faces bear a series of vascular foramina.
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The largest found so far is estimated to have been long including the root when the animal was alive, making it the largest tooth of any carnivorous dinosaur yet found. The lower jaw was robust. Its front dentary bone bore thirteen teeth. Behind the tooth row, the lower jaw became notably taller.
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The dentary, the bone bearing the teeth, at the front curves sharply to the inside. This way both dentaries together had a profile fitting in the broad snout. The tooth row has a length of about . At the rear underside of the right lower jaw numerous ossicles, small bony scales, are visible.
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In 2016, a new specimen comprising a dentary and teeth was described as belonging to Maxakalisaurus. The phylogenetic analysis recovered Maxakalisaurus as an aeolosaurine along with Aeolosaurus and Gondwanatitan.França et al. (2016), New lower jaw and teeth referred to Maxakalisaurus topai (Titanosauria: Aeolosaurini) and their implications for the phylogeny of titanosaurid sauropods.
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Early mammal (above) vs. pelycosaur (below) jaw configuration with relevance to hearing It has been suggested that early theriodonts (including gorgonopsians) possessed an eardrum, unlike earlier pelycosaurs, because the connection between the quadrate bone (at the jaw hinge) and the pterygoid bone (at the palate) was beginning to reduce, allowing the quadrate to independently vibrate to a degree. This may have allowed the detection of air-borne sounds with a low amplitude of less than , but the eardrum would have been supported by cartilage or ligaments instead of bone. If correct, then the postdentary bones (which in early mammals form the middle ear bones) would have needed to become detached from the dentary (jawbone); the gorgonopsian fossil record seems to indicate the postdentary- dentary connection was reduced.
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General morphology of the American paddlefish Paddlefish ram suspension-feeding zooplankton in aquarium American paddlefish are among the largest and longest-lived freshwater fishes in North America. They have a shark-like body, average in length, weigh , and can live in excess of thirty years. For most populations the median age is five to eight years and the maximum age is fourteen to eighteen years. The age of American paddlefish is best determined by dentary studies, a process which usually occurs on fish harvested during snagging season, a popular sport fishing activity in certain parts of the U.S. The dentary is removed from the lower jawbone, cleaned of any remaining soft tissue, and cross-sectioned to expose the annual rings.
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Godefroit and colleagues assigned additional remains from the bonebed to their new genus, including three braincases, a cheekbone, two maxillae (the toothbearing bone of the upper jaw), another dentary, two shoulder blades, two sternal elements, two upper arm bones, and an ischium. It can be distinguished from other hadrosaurids by its slender dentary and the unique form of its upper arm, which had distinctive articulations and placements for muscle attachments. Godefroit and colleagues performed a phylogenetic analysis that suggests Wulagasaurus was the most basal saurolophine known (which would result in a long ghost lineage), and interpreted this as evidence that saurolophines and hadrosaurids in general originated in Asia, which has been supported by other finds since. As a hadrosaurid, Wulagasaurus would have been an herbivore.
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Just above this ridge, the dentary was pierced by a row of as in Jianchangosaurus and Alxasaurus, which became less regular by the region around the mandibular symphysis, where the two halves of the mandible met at the front. This row was instead directly in line with and on the side of the ridge in Erlikosaurus. The that ran along the inner side of the mandible, was placed further down than in Erlikosaurus and had a consistent depth until the thirteenth tooth position, whereafter it widened. The lower jaw elements behind the dentary (the , surangular, , and bones) were distinct from those of other therizinosaurs, being gracile and linear, and contributing to the hind part of the hemimandible being elongate and almost rectangular.
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Hindmost dentary teeth showing the third cutting edge (lc), unique to Segnosaurus among theropods Zanno and colleagues stated in 2016 that therizinosaurs were generally accepted to fall within the spectrum of omnivory and herbivory, with a trend towards intensified herbivory. While various anatomical features have been used to support this idea, tooth morphology had been considered relatively simplistic and with few unique specializations compared to other herbivorous dinosaurs. The few modifications include the increased symmetry in the teeth of Erlikosaurus and the enlargement of denticles in Segnosaurus. Zanno and collegaues identified novel, complex features in the dentary teeth of Segnosaurus, including the presence of additional carinae and folded carinae with denticulated front edges, which indicate Segnosaurus had a higher degree of oral food processing than other therizinosaurs.
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In 2004 and 2007, Kielan-Jaworowska and colleagues aligned the dentary with the multituberculate suborder "Plagiaulacida" because the p4 is rectangular in labial view, not curved as in the suborder Cimolodonta. This feature was also used to distinguish MACN Pv-RN 975 from the single p4 assigned to Argentodites, which was tentatively placed in Cimolodonta. Gurovich, Guillermo Rougier, and colleagues, on the other hand, maintain that the dentary is referable to Ferugliotherium and that the p4s of Argentodites and MACN Pv-RN 975 are very similar. The alveolus of MACN Pv-RN 975 fits the lower incisors attributed to Ferugliotherium in size and the blade-like premolar is of the size expected for an animal with molariforms the size of Ferugliotherium teeth.
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Mandibular symphysis Aymberedactylus can be identified as a tapejarine tapejarid from the holotypic jawbone due to its toothlessness, slightly downturned dentary symphysis which accounts for half of the total length of the jaw, and a small crest on the bottom of the dentary (which was incompletely preserved). Small neurovascular foramina on the symphysis indicates the likely presence of a horned sheath over the tip of the jaw, which is also seen in Tupandactylus. The preserved portion is long. It can be distinguished from other pterosaurs by a long retroarticular process (a process to which the depressor mandibulae muscle attaches, implying that Aymberedactylus had good control over the movement of its jaw bones) and a small fossa, or depression, with a roughened bone texture on the splenial bone.
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A. gomesii, A. wegeneri and A. tsangatsangana all have a mild concavity of the external alveolar margin of the premaxilla as viewed from the ventral surface; A. rattoides may also have this feature, although this part of its skull is not known, as the dentary suggests that this would be the case. A. rattoides also had the distinctive feature of a highly enlarged and forward-pointing first dentary tooth referred to as an incisiform, resembling the elongated incisors found in rodents (hence the specific epithet). All species of Araripesuchus had relatively large orbits and hence eyes. They also had thin osteoderms that covered the entire body, multiple rows of them across the back and paired dorsal ones along the tail.
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Only part of the supraoccipital is exposed, but it has a deeply concave posterior margin. The surangular, which is only exposed in the postorbital region, has no lateral ridge, and the angular is very small. A small fragment of splenial is exposed, but the dentary is barely visible and no teeth can be seen.
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The palate is broad and plate-like. Casea genus has a narrow interpterygoid vacuity that divides the posterior portions of the palate at the midline. The jaw is dominated by a large dentary and a strong medially directed process off the articular bone is present at the level of the articular facets for the quadrate.
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The orbit has a reniform, or kidney-like, shape caused by posterior extension of the maxilla toward the prefrontals. The pre-orbital skull length ratio is high, indicating a longer snout than other polycotylids. The postorbital bar is reduced. The dentary has many ridges and valleys, becoming especially prominent near the enlarged caniniform teeth.
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Although the monograph is comprehensive, the editors noted that it describes only material recovered from 1993 through 2001. A significant quantity of specimens, some very complete, were excavated in 2003 and 2005 and await preparation and description in future publications. The dentary was made the neotype specimen after a 2009 petition to the ICZN.
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In other words, jaw joints and ears do not define any except the most recent groups of mammals. Mammalian and non-mammalian jaws. In the mammal configuration, the quadrate and articular bones are much smaller and form part of the middle ear. Note that in mammals the lower jaw consists of only the dentary bone.
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Ornithischians shared a unique bone called the predentary (Figure 2). This unpaired bone was situated at the front of the lower jaw, where it extended the dentary (the main lower jaw bone). The predentary coincided with the premaxilla in the upper jaw. Together, they formed a beak-like apparatus used to clip off plant material.
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Dentary teeth of UMNH VP 14527 and UMNH VP 15259 The head anatomy of Falcarius is partially known. The skull was small and elongated. With its long neck, Falcarius could apparently reach about off the ground to munch leaves or fruit. The teeth numbered at least sixteen in the maxilla of the upper jaw.
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Dryolestidae was a widespread family of Mesozoic mammals. The clade is not based on a phylogenetic definition, but instead on the possession of unequal roots for the molars of the lower jaw. Additionally, the clade is distinguished by hypsodonty in lower molars, and uneven labio-lingual height for the alveolar borders of the dentary.
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Averianov and Sues viewed Urbacodon as more plesiomorphic than Troodon and Saurornithoides in having a straight dentary with fewer teeth, but did not attempt to place it on a cladogram. In 2010, a cladistic analysis showed it as a close relative of Byronosaurus and Xixiasaurus.Lü J.-C, Xu L., Liu Y.-Q., Zhang X.-L.
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Isocetus was considered a nomen dubium by Steeman (2010) but was treated as a distinct species by Bisconti et al. (2013) based on characters of the mandibular condyle and dentary. A complete thalassothere specimen from Belgium previously assigned to Isocetus depauwi by Abel (1938) is now the holotype of the species Parietobalaena campiniana.O. Abel. 1938.
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Norman, D. B. (2020). Scelidosaurus harrisonii (Dinosauria: Ornithischia) from the Early Jurassic of Dorset, England: biology and phylogenetic relationships. Zoological Journal of the Linnean Society. doi:10.1093/zoolinnean/zlaa061 This is because Emausaurus posesses a dorsal margin of the dentary sinuous in lateral view and neither elongated nor squat proportions of metacarpal 1 ‘medium’.
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The eyes are small and covered by a thin membrane. The mouth is terminal, with the upper jaw longer than the lower. There are no teeth on the premaxilla and one row of 11 tiny conical teeth on the dentary. Both upper and lower pharyngeal tooth plates are present, bearing 8 and 10 teeth respectively.
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Both Anatosuchus and Comahuesuchus have maxillary tooth rows in the upper jaw that extend out and over the dentary tooth rows of the lower jaw. Several recent phylogenetic analyses of notosuchians have placed Anatosuchus outside of Notosuchia altogether, and therefore outside Comahuesuchidae. If this is true, Comahuesuchus would be the only member of Comahuesuchidae.
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The absence of enlarged, specialized crushing teeth in the jaws of Oardasaurus and other barbateiids suggests that they were feeding on a varied diet of arthropods (such as insects, millipedes, and spiders), small vertebrates (fish, amphibians, turtle hatchlings, smaller lizards, and perhaps multituberculate mammals), and plants. A dentary referred to Barbatteius bears a furrow, probably produced by plant roots.
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Baeotherates is known from the holotype OMNH 55758, a dentary bone from the right mandible. It was collected within the Dolese Brothers Limestone Quarry of Richard's Spur in Comanche County, Oklahoma and found in the Garber Formation of the Sumner Group, which dates to the middle Sakmarian stage of the Early Permian, about 289 ± 0.68 million years ago.
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Rhabdodon priscus is known from a specimen from the Marnes Rouges Inférieures Formation. The material of Rhabdodon priscus includes a dentary and many other postcranial remains. More specifically, it is known from the Bellevue layer, which has produced many vertebrate fossils. Even though it produced many vertebrates, the formation only has a scarce record of plants and invertebrates.
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Ramírez-Velasco et al. (2012) diagnosed Huehuecanauhtlus by a unique combination of characters. For example, two teeth exposed on the occlusal plane of the rostral third and the posterior third of the dentary and maxilla, respectively. It had seven sacral vertebrae and tall neural spines of posterior vertebrae, being between 3.5 and 4 times taller than their corresponding centra.
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Reconstructions of the skull Left dentary and surangular bones Wiman in 1929 was uncertain about the affinities of Helopus and placed it in a Helopodidae of its own. Yang made this a Helopodinae, first within the Morosauridae, then within the Brachiosauridae. Romer in 1956 created a Euhelopodinae. In 1990, John Stanton McIntosh placed Euhelopus in the Camarasauridae.
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The mandible of Akidolestes cifellii is similar to that of Zhangheotherium and Maotherium. They all have a coronoid process and dentary condyle. At the same time, the structure and surface features of the teeth of Akidolestes are closer to spalacotheriids as compared with zhangheotheriids. Based on these overall dental characteristics, Akidolestes has been classified as a member of Spalacotheriidae.
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Each half of the mandibular symphysis (where the two halves of the mandible connect) was shaped like an upside-down teardrop. The pterygoid fossa on the inner side of the mandible was very large, and occupied most of the hind part of the dentary. The lower part of this fossa had a boundary, known as the pterygoideus shelf.
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The darter characine is a small, fusiform fish growing to a maximum length of . Like other characids, it has a mouth on the underside of the head with a poorly developed upper lip. There are no dentary teeth and the pectoral fins have a single, unbranched fin-ray which the fish uses to prop itself up on the substrate.
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The dentary is wedge-shaped elongated and preserves 31 alveoli. In a dorsal view, it is U-shaped and flattened at the back with an expansion lying across. The lateral and ventral surfaces in the symphyseal region bears a series of foramina that measure in diameter. Isolated foramina are connected internally by a complex neurovascular canal.
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The jaws are lined with many small pointed teeth. Like other sebecians, Pepesuchus has ziphodont teeth that are laterally compressed and serrated. 17 teeth are present in each maxilla, the most of any sebecian after Stolokrosuchus. There are also numerous dentary teeth in the lower jaw, with the foremost ones directed in a slight forward position.
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The referral of the additional femur and tibia has been questioned by later researchers. In 2003 Jaime Eduardo Powell tentatively referred them to cf. Argyrosaurus and in 2012 Philip Mannion and Alejandro Otero considered it an indeterminate titanosaur. The incomplete mandible attributed to A. wichmannianus is squared off at the front with each dentary bone being L shaped.
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Nimbacinus richi lived during the middle Miocene and has been found in deposits in Bullock Creek in the Northern Territory of Australia. Nimbacinus richi is distinguished from Nimbacinus dicksoni by a well-preserved holotype of a right dentary. The species was a carnivorous, quadrupedal marsupial in Australia. In appearance it resembled a dog with a long snout.
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The maxilla has an indentation behind the canine root, and in the same area possess several large foramina. These suggest that Abdalodon may have had whiskers. The posterior end of the maxilla bends medially, insetting the postcanines from the labial border of the snout. The dentary of Abdalodon diastematicus has a well defined masseteric fossa (a synapomorphy of cynodonts).
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The skull of Acynodon is extremely brevirostrine; it had a very short and broad snout compared to other known alligatorids. Its dentition was quite derived, with enlarged molariform teeth and a lack of maxillary and dentary caniniform teeth, presumably an adaptation to feed on slow prey with hard shells. The paravertebral osteoderms of Acynodon were distinctively double-keeled.
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The left dentary is preserved on the skull along with teeth, which, have shield-shaped crowns. The lacrimal bone closely resembles those of Dakotadon and Theiophytalia. Life restoration Vertebrae indicates a characteristic iguanodont body shape. Most of the body remains are gracile, such as the right humerus and scapula, the right tibia and femur are fragmented, having irregular surfaces.
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Most of the teeth have small carinae present on their surfaces. The dentary sypmhysis has no teeth present to either side of it for 11 mm, but forms a sharpish edge which may have been used with the premaxillary teeth 1-3 for cutting into prey. The largest teeth are found at the corners of the skull.
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Thliptosaurus skull with diagram isolating the mandible. The mandibular symphysis of the dentaries is long, creating a long, flattened shovel-like beak tip. The rest of the jaws is otherwise roughly v-shaped, as is typical for dicynodonts. The dentary has a tall plate on its sides that obscures the external mandibular fenestra, an unusual condition amongst dicynodonts.
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Furthermore, they are believed to have had homodont dentition. This, combined with its shovel like snout, indicate that Desmatosuchus fed by digging up soft vegetation. This method of feeding is further evidenced by its toothless premaxilla and dentary tip, which were covered in horny sheaths. These sheaths protected the bones and could be used for cutting or holding objects.
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Aerosaurus has been recognized as a basal member of the Synapsida, a clade that ultimately produced mammals. Relative to the skull, the body was much larger and the ribs were deeper. The tail was unusually long for a synapsid. Overall Varanopseid pelycosaurs measure about one meter long with fewer maxillary and dentary teeth compared to other Varanops.
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The mandible (lower jaw) was tipped by the predentary, a bone unique to ornithischians. This bone also supported a beak similar to the one found on the premaxilla. All the teeth in the lower jaw were found on the dentary bone. Snouts of Heterodontosaurus (A), Abrictosaurus (B), and Tianyulong (C) Heterodontosaurids are named for their strongly heterodont dentition.
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The front snout bone, the premaxilla, bears a crest with ridges and grooves that curve to the front. The groove on the dentary reaches the highest point of that bone. Both the snout tip and the tip of the lower jaws are slightly expanded. The deltopectoral crest is moderately twisted around the longitudinal axis of the humerus.
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It consists of a partial left upper jaw and lower jaw, including the maxilla, part of the praemaxilla, elements of the lacrimal and the dentary. Shuangmiaosaurus was a rather large euornithopod. In 2010 Gregory S. Paul estimated its length at 7.5 metres, its weight at 2.5 tonnes.Paul, G.S., 2010, The Princeton Field Guide to Dinosaurs, Princeton University Press p.
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Mouth is protractible, upwardly directed, with small teeth. Lower jaw has an upper expansion within mouth (high dentary bone). There are two separate dorsal fins, with all rays of first and 1-2 anterior rays of second dorsal fin being unsegmented. The anal fin is similar to the second dorsal fin, while the caudal fin is forked.
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The dentary (part of the lower jaw) carried twenty-eight teeth. Its small leaf-shaped and very finely serrated maxillary teeth indicate that it consumed plant material. The front-most five teeth of the lower jaw are much longer, straighter and more pointed though, and might indicate a partially omnivorous diet including meat, e.g. small animals such as lizards.
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The bowfin skull is made up of 28 fused bones, which compose the dermatocranium. The roof of the mouth is made up of 3 bones, the ectopterygoid, the palantine, and the vomer. The teeth are on two bones, the premaxillae and the maxillae. Another three bones make up the lower jaw the dentary, the angular, and the surangular.
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Gishlick, A. D. & Gauthier, J. A. 2007. On the manual morphology of Composognathus longipes and its bearing on the diagnosis of Compsognathidae. Zoological Journal of the Linnean Society, 149, 569–581. It is estimated that the number of teeth in the premaxilla is four, in the maxilla twelve, and in the dentary between twenty-five and thirty.
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Jinzhousaurus has a length of about 7 metres (23 ft) and its skull is about half a metre long. Its snout was elongated with large nares and lacking an antorbital fenestra. The back of the skull was uncommonly wide with a small crest on top. The dentary of the lower jaw has at least seventeen tooth positions.
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When the jaw is closed, the teeth of the upper jaw overlie those of the lower jaw and shear closely together. Stratiotosuchus has one large caniniform tooth in its premaxilla, and several large maxillary teeth behind it. An enlarged fourth dentary tooth in the lower jaw also forms a canine, and is visible when the jaw is closed.
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On the right side of the upper jaw, A. polydentatus has 13 teeth, and on the left it has 14 teeth. The bottom jaw is also asymmetric, with 14 teeth in the right dentary and 15 in the left. This is the first polydont aetiocetid, meaning that it had more teeth than the standard mammalian formula.
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The tip of the jaw, known to be toothless and possibly supporting a beak in other silesaurids, is missing and so its shape is unknown for Soumyasaurus. Soumyasaurus was described as "minute" by Sarıgül and colleagues, inferring a small body size from the length of the preserved dentary, certainly smaller in size than the contemporary Technosaurus.
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Tyrannosaurus was estimated to have weighed , and Hartman noted that it had a wider torso, though the two seemed similar in side view. He also pointed out that the Giganotosaurus dentary that was supposedly 8% larger than that of the holotype specimen would rather have been 6.5% larger, or could simply have belonged to a similarly sized animal with a more robust dentary. He conceded that with only one good Giganotosaurus specimen known, it is possible that larger individuals will be found, as it took most of a century to find "Sue" after Tyrannosaurus was discovered. In 2014, Nizar Ibrahim and colleagues estimated the length of Spinosaurus to have been over , by extrapolating from a new specimen scaled up to match the snout described by Dal Sasso and colleagues.
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Libognathus is known from a single holotype specimen including the left dentary bone and coronoid process of the lower jaw, as well as six teeth implanted in the jaw. Libognathus can be identified as a procolophonid by its wide molar-like teeth, each of which has a ridge running along its width and several projections or cusps around it. It is considered a member of the procolophonid subfamily Leptopleuroninae based on the presence of more conically-shaped teeth at the front of the jaw. Libognathus is distinguished from other procolophonids by the steep angle of the lower margin of the dentary (indicating a deeper lower jaw than in related procolophonids such as Hypsognathus and Leptopleuron) and a small hole or foramen on the jaw's outer surface below the fifth tooth.
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Baalsaurus (named after the dinosaur fossil site Baal in Argentina, which in turn is named after the ancient Phoenician god Baal) is a genus of titanosaurian sauropod dinosaur from the Late Cretaceous of Neuquén Province, Patagonia, Argentina. The type and only known species is B. mansillai, with the specific name honoring the discoverer Juan Eduardo Mansilla, a museum technician at the Geology and Paleontology Museum of the National University of Comahue. The holotype specimen, MUCPv-1460, is a mostly complete right dentary that was found in rocks of the upper Portezuelo Formation. The dentary is squared-off instead of curved when viewed from above or below, with the teeth crowded into the front of the jaw, making it similar to the jaw of Antarctosaurus, Brasilotitan, and to a lesser extent Bonitasaura.
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This mirrored the contours of the maxilla of the upper jaw, and the strong expansion of the rear skull; this was similar to Bistahieversor, Tyrannosaurus, and Tarbosaurus, but unlike other tyrannosauroids. The dentary was also deep at the rear end, indicating that the following part of the mandible was comparable to Tarbosaurus and Tyrannosaurus in depth, but not to other tyrannosaurids. Like other tyrannosaurids, the behind the dentary had a deep and well-developed shelf just in front of where the jaw articulated with the skull, and Lythronax was similar to Tyrannosaurus in that this shelf had a concave upper surface. Life restoration showing hypothetical feathers Though the postcranial skeleton of Lythronax is poorly known, the known remains of the pubis (part of the pelvis) and the hindlimb show features typical within Tyrannosauridae.
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Dentary A phylogenetic analysis found Australovenator to be an allosauroid carnosaurian, with similarities to Fukuiraptor and carcharodontosaurids. In the initial analysis, it was shown to be the sister taxon of the Carcharodontosauridae. More detailed studies found that it formed a clade with several other carcharodontosaurid-like allosaurs, the Neovenatoridae. Recent phylogenetic analysis suggests Australovenator is a tyrannosauroid, like with all other megaraptorans.
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Atherina hepsetusThe body is rather long, slender and moderately flattened. The mouth is protrusible, directed upward with small teeth; the head and body are scaly. The lower jaw has an upper expansion within the mouth (high dentary bone). Two separate dorsal fins, all rays of first and 1-2 anterior rays of second dorsal fin are unsegmented, with the remaining rays segmented.
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Orodromeus was a small fast bipedal herbivore that probably coexisted with dinosaurs such as Daspletosaurus and Einiosaurus. Its length was estimated by Horner & Weishampel at 2.5 metres. Orodromeus is distinguished by a palpebral that is at its back attached to the postorbital; a boss on the jugal; a non-fused wrist; and triangular maxillary and dentary teeth with a vertical occlusion.
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The unique feature of a shortened frontal in lambeosaurines is also found in Prosaurolophus, and the other horned hadrosaurines Brachylophosaurus, Maiasaura, and Saurolophus. Although they lack a shorter frontal, the genera Edmontosaurus and Shantungosaurus share with saurolophins an elongated dentary. Three-dimensional reconstruction of a P. maximus head Patches of preserved skin are known from two juvenile specimens, TMP 1998.50.1 and TMP 2016.37.
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There are two empty alveoli, so that the total tooth count on one side was at least 15. Three teeth were found isolated near the dentary. The teeth and alveoli are angled forward (procumbent) by ~60°, similar to eusauropods, but also to juveniles of Mussaurus. Tooth height and width decreases from the front to the back, and neighboring teeth overlapping each other.
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Restoration Leonerasaurus taquetrensis is known from one incomplete individual. Parts of a dentary and some teeth, neck and trunk vertebrae, a sacrum, parts of the pectoral (shoulder) and pelvis (hip) girdle as well as several limb bones were found. Much of the remains were found in articulation. It was only 2.40 meters long, 1 m high and weighing about 70 kg.
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The dentary of the lower jaw likewise bears an estimated twenty to twenty-five teeth. The nostrils are relatively retracted. They are also unique for a theropod in being obliquely oriented to the top in front view. Despite the length of the snout, the main opening in the side of the front skull, the antorbital fenestra, is short; shorter than high.
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Studies have shown that ear bones in mammal embryos are attached to the dentary, which is part of the jaw. These are ossified portions of cartilage—called Meckel's cartilage—that are attached to the jaw. As the embryo develops, the cartilage hardens to form bone. Later in development, the bone structure breaks loose from the jaw and migrates to the inner ear area.
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In birds and turtles, the lips are hard and keratinous, forming a solid beak. Clevosaurids like Clevosaurus are notable for the presence of bone "lips"; in these species the tooth-like jaw projections common to all sphenodontians form a beak-like edge around the jaws, protecting the teeth within.Jones MEH (2009). "Dentary tooth shape in Sphenodon and its fossil relatives (Diapsida: Lepidosauria: Rhynchocephalia)".
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There are approximately 30 closely spaced teeth on the maxilla and dentary, and a sutural pattern of the skull closely resembles that of the Late Carboniferous aïstopod Oestocephalus. There is no trace of limbs. However, unlike later members of the aïstopod lineage, the vertebrae still possess intercentra, and the pleurocentra are large. Lethiscus is the only representative of the family Lethiscidae.
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Dizzya is an extinct, monotypic genus of bat that occurred in the Chambi region, Tunisia, in the Middle Eocene. It was described based on a single upper molar, a lower dentary with two broken teeth, and a humerus. It is the smallest and, along with Witwatia sigei, the oldest representative of the Philisidae, an extinct family of bats related to the Vespertilionidae.
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The dentition of Abdalodon helps distinguish it from Procynosuchus, the genus to which it was originally attributed. Charassognathus however bears a similar dental formula to Abdalodon, which has been the basis behind grouping them into the clade Charassognathidae. Charrasognathus however lacks the substantial maxillary and dentary diastema found on Abdalodon, as well as the masseteric fossa, which distinguishes the two.
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Published by the Phoenix Valley Provincial Aviary of Taiwan. In Chinese, translated by Will Downs, Bilby Research Center, Northern Arizona University, January, 2001. The holotype fossil is that of a small perching bird, with a skull about 27 millimeters (1 inch) long. There are five pairs of tiny teeth in the premaxilla, and another five pairs in the anterior dentary.
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The dorsal margin of the maxilla is unusually concave unlike the convex condition in tyrannosaurids. The nares are large and elliptical, supporting its relation to proceratosauridae. The dentary gradually curves upwards as it approaches its front edge. Many teeth are preserved attached to the maxillae, with a roughly equal number of denticles on each side, similarly to those of tyrannosaurids.
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Another such fossa is present between the two parietals themselves. The dentary turns down very slightly at the tip; a precise tooth count is unknown due to the bone being hidden by the maxillary teeth in the fossils. The hyoid bones are long and slender, with slightly expanded ends. Qianosuchus had nine cervical, fifteen dorsal, two sacral and at least 50 caudal vertebrae.
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Eophis is an early genus of stem-snake (clade Ophidia) containing one species, Eophis underwoodi, from the Middle Jurassic (Bathonian) from the Forest Marble Formation of United Kingdom. It is known from a fragmentary dentary from Kirtlington Quarry. It was previously interpreted as an anguimorph lizard. The placement of Eophis as a stem snake was re-affirmed by subsequent analyses.
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Size compared to a human The holotype, and only known specimen, is fragmentary. From the skull are preserved both maxillae, premaxillae, nasals, prefrontals, palatines and quadrates, the left jugal, the right pterygoid, quadratojugal, surangular, articular, squamosal and lacrimal, and fragments of the dentary. There are also the first three cervical vertebrae, nine caudal vertebrae, some caudal scutes and fragments of cervical ribs.
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The wingspan of the individuals described in 2014 ranged from . The describing authors indicated some distinguishing traits, all of them autapomorphies, unique derived characters. The dentary, the front bone of the lower jaw, has a hook-shaped process. The ascending branch of the jugal bone, running to the lacrimal bone, is thin, inclined to the front, and expanded at the top.
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The ascending (or dorsal) process of the maxilla, which lies in front of the antorbital fenestra, is short and very thin. This process is also uniquely diagonally oriented when seen from above, with its rear edge set inwards from the front edge. The only preserved tooth is thin and serrated. The dentary fragment is incomplete, but seemingly slender and similar to the maxilla.
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The Mount Pulgnasco specimen represents an early rorqual that fed differently from modern species. Compared to the laterally bowed dentaries of the latter, its dentary is more straight, which should have made it impossible to perform the intermittent ram feeding seen in modern rorquals. Another primitive character is that the anterior border of the supraoccipital is triangular and pointed like in Miocene Cetotheriidae.
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In 2018, the British palaeontologist Thomas M. S. Arden and colleagues found that the Portuguese skeleton did not belong to Baryonyx, since the front of its dentary bone was not strongly upturned. Some additional spinosaurid remains from Iberia may belong to taxa other than Baryonyx, including Vallibonavenatrix from Morella, which appears to be closer to the African genus Spinosaurus and the Asian Ichthyovenator.
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Bitia hydroides is noted for its unusual dentition. In all other snakes, any enlarged teeth are located on the dentary or maxilla, with the inner, palatine teeth of the upper jaw being smaller. In Bitia hydroides, the palatine teeth are greatly enlarged. Not enough is known about this animal's feeding behavior or ecology to attempt to infer a function of this peculiar arrangement.
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Eosimias dawsonae is the newest of the Eosimias species. It is categorized by the type specimen IVPP V11999, which includes a left dentary fragment and roots of the alveoli. It was collected by Christopher Beard in 1995. Analysis of these remains has led to the conclusion it was the largest of the known species of Eosimias, yielding a body mass ranging from .
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L. barkeri differs from L. meachami in having one less row of teeth in both maxillary and dentary, however, the validity of its classification critiqued in 1959 by R. J. Seltin who thought the size difference between specimens may indicate that the tooth row disparity was an age related developmental difference.R. J. Seltin.1959. A review of the family Captorhinidae.
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The dorsal process of the stapes in Theriognathus is greatly reduced or entirely absent. The dentary is short, shaped like a banana, and continuously tapers anteriorly to a narrow edge. The dentarys’ lateral surface is smooth. The posterodorsal terminal end of the coronoid process is more rounded, and the dorsal extent terminates below the middle of the orbit in adults.
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Petrolacosaurus teeth were of moderate length, slightly recurved, and possessed no lateral compression. Located on the premaxilla of the upper jaw are two teeth, reminiscent of fangs. On the dentary were around 25 smaller teeth, all of different lengths. Placement in the jaw reveals that the teeth on the upper and lower jaw do not interlock but rather meet along a medial plane.
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The rear tip of the jaw is formed by the articular bone while the inside edge of the jaw possesses a long, plate-like angular bone and a thin prearticular bone directly above it. A mandibular foramen (hole) is present at the intersection point of the dentary, coronoid, and surangular, a position further forward than the mandibular foramen of Toxolophosaurus.
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It consists of the rear of a skull associated with a series of dentary teeth found in their original position. It is part of the collection of the Lingwu Museum. The paratype, LGP V001b, is a partial skeleton lacking the skull. It contains the rear vertebrae of the back, the sacrum, the pelvis, the first tail vertebra and elements of the right hindlimb.
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Assigned dentary Roxochampsa was originally described as a new species of Goniopholis, G. paulistanus, in 1936, based on two teeth (DGM 259-R and DGM 258-R) and a tibia (DGM 225-R), all from the Adamantina Formation of São Paulo state, Brazil.Roxo MGO. On a new species of fossil Crocodilia from Brazil, Goniopholis paulistanus sp. n. An. Acad. Bras.
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The incomplete mandible of the largest specimen (CMN 8880) is the same length. AMNH 5214 has 35 dental alveoli in the left dentary and 36 in the right, for a total of 71. The predentary bone of the tip of the mandibles has not yet been found. Like other ankylosaurs, Ankylosaurus had small, phylliform (leaf-shaped) teeth, which were compressed sideways.
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Modern humpback whales ram feeding. Unlike living rorquals, Plesiobalaenoptera was probably not capable of ram feeding. During ram feeding, modern whales swim toward their prey with open mouths and engulf them in an expandable throat. Plesiobalaenoptera has a postcoronoid fossa, or hole in the dentary bone of the lower jaw, which would have made this method of feeding difficult to perform.
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Finally, the lateral surface of the mandible dorsoventrally concave posteriorly, while other thalassophoneans show flat or weakly convex lateral surface of the postedentary bones. P. kevani also possesses a unique combination of characters, including: high dentary alveolar count including 22 postsymphysial alveoli and an estimated total count of 36–37; high count of symphysial dentary alveoli including at least 7, estimated as 14–15; subtrihedral teeth, possessing a suboval cross-section with slightly flattened labial surface bearing only thinly distributed enamel ridges; pronounced mediolateral expansion of caniniform regions of the premaxilla and maxilla; six closely spaced premaxillary alveoli; anisodont premaxillary dentition; and premaxilla–parietal suture located level with the anterior region of the orbit. CAMSM J.35990, a complete postcranial skeleton originally referred to Stretosaurus macromerus, and later to Pliosaurus sp., might also pertain to P. kevani.
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The teeth of the dentary were of similar shape and size, except for the first one, which was smaller. The teeth were compressed sideways, were oval in cross-section, and had serrations at the front and back borders, which is typical of theropods. The teeth were sigmoid- shaped when seen in front and back view. One tooth had nine to twelve serrations per mm (0.039 in).
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The tooth count for each dentary (tooth- bearing bone in the lower jaw) was at least 22. All the teeth were very thick and robust; those close to the rear of the jaws were short, rounded, and blunt. They appear to have been adapted for crushing, rather than piercing. When the mouth was closed, only the fourth tooth of the lower jaw would have been visible.
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Members of the genus Atractaspis share the following characters. Venom fangs enormously developed; a few teeth on the palatines, none on the pterygoids; mandibles edentulous anteriorly, with 2 or 3 very small teeth in the middle of the dentary bone. Postfrontal bone absent. Head small, not distinct from neck, covered with large symmetrical shields; nostril between 2 nasals; no loreal; eye minute, with round pupil.
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Currently about 245 fragmentary specimens are known, representing numerous individuals. In 1985, Peter Galton designated another lower jaw, a right dentary, as the neotype, BCM 2. The remains had been found in chalkstone infillings, breccia deposited in fissures in older rocks. The age of these deposits was once estimated as old as the late Carnian, but recent studies indicate that they date from the Rhaetian.
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Tail vertebrae Left dentary In 2012 Magnapaulia was assigned to the Lambeosaurinae. The 2012 study contained a cladistic analysis which found it to be closest to Velafrons, also from Mexico, with this sister species forming a separate southern clade, itself the sister group of a clade of more northern Asian and North-American forms, including Lambeosaurus, Corythosaurus, Hypacrosaurus and Olorotitan. The cladogram below follows this analysis.
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The premaxilla and dentary are larger than archaeopteryx, while also lacking teeth. The anterior of these bones shows evidence of vasculature and innervation, implying the presence of a beak. The lack of recovery of this structure indicates that the beak had a soft horny sheath. The softness of the beak along with the innervation suggest that the beak was sensitive, making it useful for searching for prey.
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There are two in situ lower incisiforms that are followed by two displaced lower teeth, the second of these teeth is transversally expanded and shows a saddle-like crown just like the palatal teeth. Additionally, there are three posterior lower teeth on the dentary with an unerupted, replacement tooth evident below the last lower tooth, which is evidence of at least a second wave of tooth replacement.
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Brindled madtoms are approximately long. The brindled madtom, like other Noturus species, has a caudally-fused adipose fin which extends from the caudal fin and runs nearly to the dorsal fin. The caudal fin spreads around the caudal peduncle, terminating just prior to the anal fin. The species has smooth skin without scales and possesses four pairs of barbels along the premaxilla and dentary.
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Suborder Tillodontia Retrieved July 2013. : Genus †Azygonyx (), dentary, postcranial fragments : Genus †Basalina (), poorly preserved jaw fragment with incomplete cheek tooth : Genus †Benaius (), left lower jaw : Genus †Dysnoetodon (), maxilla and lower jaw : Family †Esthonychidae () (Syn. Anchippodontidae, Tillotheriidae) :: Genus †Adapidium (), right lower jaw :: Subfamily †Esthonychinae () ::: Genus †Esthonyx (), lower mandibles, teeth :: Genus †Megalesthonyx (), left mandible, teeth, feet bones :: Subfamily †Trogosinae () (Syn. Anchippodus) ::: Genus †Tillodon (), skull ::: Genus †Trogosus () (Syn.
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Aquilarhinus (meaning "eagle snout" after the unusual beak morphology) is a genus of hadrosaurid ornithopod dinosaur from the Aguja Formation from Texas in the United States. The type and only species is Aquilarhinus palimentus. Due to its unusual dentary, it has been inferred to have had shovel-like beak morphology, different from the beaks of other hadrosaurs. It was originally classified as a Kritosaurus sp.
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They are carnivorous creatures and will eat almost anything they can get into their mouths. Typically they prey upon animals such as insects, mollusks, annelids, small fish, amphibians, earthworms, and spiders. The jaw of a mudpuppy also plays a significant role in its diet. The mudpuppy jaw is considered metaautostyly, like most amphibians, meaning the jaw is more stable and that the salamander has a dentary.
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Skull of Abdalodon In left lateral view. Photo courtesy of Christian Kammerer. The only existing specimen for Abdalodon is an incomplete, dorsoventrally crushed skull, In which the lower jaws are tightly occluded to the palate. Abdalodon diastematicus is characterized by the presence of diastema between the canines and postcanines of the dentary, and on the maxilla, an even longer diastema between the canines and postcanines.
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Carlastyanax aurocaudatus is a species of fish in the family Characidae native to the Río Cauca in Colombia.Thomaz, A.T., Arcila, D., Ortí, G. & Malabarba, L.R. (2015): Molecular phylogeny of the subfamily Stevardiinae Gill, 1858 (Characiformes: Characidae): classification and the evolution of reproductive traits. BMC Evolutionary Biology, (2015) 15: 146. C. aurocaudatus is distinguished by several diagnostic morphological features, especially the presence of a hooked third dentary tooth.
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Like other troodontids, the teeth are short-crowned, strongly recurved, and unevenly distributed. The teeth at the front of the jaws are more closely packed than the rear teeth, which also have fine serrations on their rear edges. These serrations are fine, as in Sinovenator, instead of robust as in derived troodontids. Unusually, the first several teeth in the dentary appear to be angled forwards, or procumbent.
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The morphology of O. turkae is difficult to determine due to the complete lack of post-cranial remains. The post-canine dentary is second only to that of Gigantopithecus in size, perhaps suggesting a large body size. It is unknown whether the species was sexually dimorphic as there are no known female fossils. The ape was probably a quadruped but there is no evidence to confirm this.
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Unlike the better-known embolomeres, the baphetid cheek and skull roof are sutured together. There is a strongly embayed spiracular ("otic") notch, but the stapes is distally broad, which seems to rule out a sensitive hearing apparatus. The palate is closed—a primitive character, but very different from the temnospondyls. The coronoids bear no teeth or denticles, while the dentary has a double tooth row.
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Paraplacosauriops was originally named Plestiodon quercyi by Filhol (1882) on the basis of dentary remains from fissure fill deposits in Quercy, France.Filhol, H. 1882. Description d'un genre nouveau de Reptile fossile et note sur une espèce de Reptile fossile du genre Plestiodon. Bulletin de la Société Philomathique de Paris, 6: 127. Hoffstetter (1944) referred P. quercyi to the glyptosaurine genus Placosaurus, which is likewise endemic to Europe.
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The dentary tooth row is slightly shorter than the tooth row of the maxilla. The teeth are all laterally compressed and serrated, however unlike later Archosauriformes they are only serrated on their distal (rear) margins. The teeth are also unlike early archosauriform teeth in that they are loosely implanted in deep sockets (thecodont), whereas the earliest archosauriforms had teeth fused to their bony sockets (ankylothecodont).
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Like other pylaecephalids, Eosimops had a roughly square skull that sported caniform tusks. These tusks have been interpreted as representing sexual dimorphism within the closely related genus Diictodon, so may have been used for sexual selection. At least one postcanine tooth was present on the dentary blade. Its skull shape is described as being similar to that of its fellow pylaecephalid Robertia, but likely attaining larger sizes.
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Most of the palate is obscured by overlapping bones. The palatine is very broad, while the transverse flange of the pterygoid is oriented forwards. What can be seen of the braincase indicates that Microleter had tubular paroccipital processes, rather than fan-shaped ones present in other parareptiles. The elongated dentary is ornamented with small pits, but its teeth are obscured and cannot be properly counted.
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The holotype, XMDFEC V0013, was found in the Majiacun Formation dating from the middle Santonian, about eighty-five million years old. It consists of a partial skull and lower jaw, including the right maxilla, the right jugal and the right dentary. The paratype is XMDFEC V0014, a partial skeleton lacking the skull, including five back vertebrae, ribs, a shoulder blade and the right ulna.
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This body length falls within the size range of the top predator of the Oxford Clay Sea, the pliosaurid Liopleurodon ferox. Two further specimens in the Museum of Jurassic Marine Life are referable to Plesiosuchus manselii: K181, isolated teeth, partial maxilla?, partial left mandible, ribs, vertebrae, femur; and K434, right dentary. The isolated Spanish tooth crown (MUJA-1004) described by Ruiz-Omeñaca et al.
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Notoceratops (meaning "southern horned face") is the name given to a dubious genus of ornithischian dinosaur based on an incomplete, toothless left dentary (now lost) from the Late Cretaceous of Patagonia (in Argentina), probably dating to the Campanian or Maastrichtian. It was probably a ceratopsianDodson, Peter; The Horned Dinosaurs (1996). and it was found in the Pehunche Formation or the Laguna Palacios Formation.Bonaparte, J. (1996).
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Labidosaurus hamatus fossil A lower jaw of Labidosaurus was described in 2011 that shows evidence of osteomyelitis, or an infection of the bone. It is the earliest known example of an infection in a land vertebrate. The infection probably developed because the pulp cavity of a broken dentary tooth was exposed to bacteria. Although another tooth would have replaced the broken one, regeneration would have been slow.
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However, Basilemys has a more complex triturating surface that includes well-defined pockets on the dentary. Basilemys also has tooth-like projections on the triturating surface of the maxilla. From the turtle species, Basilemys is described to be most similar to tortoises. Many paleontologists have described the behaviors of Basilemys to be similar to tortoises due to living in terrestrial habitats and the consumption of tough plants.
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These relatively small snakes rarely exceed 30 cm in length; only Trilepida macrolepis and Leptotyphlops occidentalis grow larger. The cranium and upper jaws are immobile and no teeth are in the upper jaw. The lower jaw consists of a much elongated quadrate bone, a tiny compound bone, and a relatively larger dentary bone. The body is cylindrical with a blunt head and a short tail.
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Depéret later reassigned the species to the North American genus Dryptosaurus, another poorly known taxon. Neotype specimen of M. crenatissimus (MNHN.MAJ 1), the right dentary of a subadult individual, Muséum national d'histoire naturelle, Paris. Numerous fragmentary remains from Mahajanga Province in northwestern Madagascar were recovered by French collectors over the next 100 years, many of which were deposited in the Muséum National d'Histoire Naturelle in Paris.
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Because of their extremely mammal-like appearance, tritylodontids were originally placed within Mammalia. Starting with the work of British paleontologist D. M. S. Watson in 1942, a close relationship was favored between tritylodontids and cynodonts. Watson and other paleontologists noted that tritylodontids lacked the dentary and squamosal jaw articulation that was characteristic of early mammals. Haughton and Brink (1954) were the first to classify tritylodontids within Cynodontia.
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Skull material for Mandasuchus is limited to maxillae and part of a dentary. The maxilla is low, with an elongated antorbital fenestra and at least 12 tooth sockets separated by discrete interdental plates. The antorbital fenestra is surrounded by an inset basin, the antorbital fossa, as with other archosaurs. However, Mandasuchus has a restricted and weakly differentiated antorbital fossa compared to other loricatans and Ticinosuchus.
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The type species comes from Park County in northwestern Wyoming, and is composed of teeth, cranial, and postcranial bones. The bone fragments were broken and scattered suggesting a taphonomic pathway that includes trampling before burial. The holotype specimen (UM 83874) from Wyoming, USA consists of upper and lower dentition with dentary bone. Post cranial remains include the scapula, ulna, radius, ankle bones, and others.
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Reconstructed skull, Field Museum of Natural History The most distinctive characteristic of Masiakasaurus is the forward-projecting, or procumbent, front teeth. The teeth are heterodont, meaning that they have different shapes along the jaw. The first four dentary teeth of the lower jaw project forward, with the first tooth angled only 10° above the horizontal. These teeth are long and spoon-shaped with hooked edges.
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All known specimens of Augustynolophus have been found only in California, which was a part of Laramidia, arguably one of the best known locations for dinosaur fossils. There are currently two known specimens of Augustynolophus. The holotype, LACM/CIT 2852, was unearthed in 1943. It consisted of the majority of the skull (including the dentary and predentary), vertebrae, and bones of the limb and hand.
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Teeth on the maxilla and dentary of both examined specimens show considerable wear. Crown apices are unusually smooth and polished, this breakage and subsequent polishing is likely due to prolonged contact with food. The tooth breakage is not severe and nearly horizontal, which is unlike typical predators with "cutting" teeth. The teeth may have been robust enough to prevent extensive breaking, or perhaps the curvature limited it.
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There were also a few larger-than average teeth further back on the maxilla, which were probably homologous with caniform teeth retained from the common ancestor between true sauropsid reptiles and synapsids (mammal ancestors). On the dentary, there are marginal teeth, displaying a primitive type of shallow implantation. The palatal arrangement bears close resemblance to Youngoides.Gardner, N. M., Holliday, C. M., & O’Keefe, F. R. (2010).
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The dentary bears a short lateral-line canal ending at or shortly behind mid-length, and altogether the lateral-line canals of the head are divided into at least two ossified tubes. All anostomids have an adipose fin; their dorsal fin contains one and 11, the anal fin one and 9, and the pelvic fins one and 8-9 hard and soft rays, respectively.
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The parietal is a good sized element forming nearly the entire intertemporal region along with the majority of the occiput. There is no parietal foramen present. The dentary is slender and moderate in length, it appears to have roughly fourteen teeth with a third of them being larger than the others. Overall the skull is similar to those of crocodiles however it is slightly deeper.
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A deep longitudinal groove known as an oral sulcus is visible below the marginal tooth row. This genus, Lapillopsis, was closely related to Manubrantlia. The inner row of conical teeth form out of the three coronoid bones which lie inwards from the dentary. This feature is practically unique to lapillopsids among early Triassic temnospondyls, as most other groups have much more reduced coronoid teeth.
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Theriodont jaws were more mammal-like than was the case of other therapsids, because their dentary was larger, which gave them more efficient chewing ability. Furthermore, several other bones that were on the lower jaw (found in reptiles), moved into the ears, allowing the theriodonts to hear better and their mouths to open wider. This made the theriodonts the most successful group of synapsids.
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The jaw transition is a good classification tool, as most other fossilized features that make a chronological progression from a reptile-like to a mammalian condition follow the progression of the jaw transition. The mandible, or lower jaw, consists of a single, tooth-bearing bone in mammals (the dentary), whereas the lower jaw of modern and prehistoric reptiles consists of a conglomeration of smaller bones (including the dentary, articular, and others). As they evolved in synapsids, these jaw bones were reduced in size and either lost or, in the case of the articular, gradually moved into the ear, forming one of the middle ear bones: while modern mammals possess the malleus, incus and stapes, basal synapsids (like all other tetrapods) possess only a stapes. The malleus is derived from the articular (a lower jaw bone), while the incus is derived from the quadrate (a cranial bone).
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Although the holotype was first described in 2009, the process of excavating the "Matilda site" is still ongoing and papers describing new elements of the holotype are still being published. Silhouette with known skeletal elements. Additional arm elements of the holotype were described in 2012, more leg elements were described in 2013, and a right dentary was described in 2015. Rapator was described by Huene for a first metacarpal from Australia.
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Characters that are typically stegosaurid are the inclined quadrate; the vertical plate on the dentary; the depression on the pterygoid flange of the quadrate; the bottom edge of the scapula exceeding the upper edge of the coracoid in length; and the double row of larger neck plates. A basal stegosaurid position is suggested by the horizontal front branch of the quadratojugal combined with a ventral process on the main body.
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Fusion of sutures (joints) in the braincase indicates the holotype specimen was a mature individual. A second specimen, consisting of a dentary bone from a supposedly larger individual, has been used to extrapolate a length of , a skull long, and a weight of . Some writers have considered the largest size estimates for both specimens exaggerated. Giganotosaurus has been compared to an oversized version of the well-known genus Allosaurus.
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This cutting edge allows parrotfish to scrape and feed on coral tissue and skeleton. The cutting edge on the teeth of parrotfish resembles a beak, which is the basis for the organism's common name. In addition to the cutting edge adaptation, parrotfish also have well-developed crossed joints that connect the dentary and articular bones of the lower jaw, which presents a mechanical advantage that makes the bite much stronger.
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The entire row is moved posteriorly so that the anterior portion of the premaxilla contains no teeth but the most posterior portion still holds two teeth. The teeth are also situated internally to the edge of the maxilla. It was first thought that the dentary contained three parallel rows of teeth. Instead of arranging the teeth in longitudinal rows, they are now known to fall into obliquely arranged Zahnreihen.
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The tip of the lower jaw would have been strengthened by being upturned at an angle of about 50°. Like the premaxilla, the outer surface of the dentary was textured, bearing a dense network of zigzagging canals for blood vessels (i.e., vascular canals). On the interior surface, immediately adjacent to the tooth row, there was a row of pits, which were enclosed by a groove towards the back of the jaw.
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Although most of the skull is poorly preserved, several elements are identifiable. The premaxilla is short and tall, while the rear part of the frontal is domed. The left dentary preserves fourteen teeth, a characteristically high number compared to other enantiornitheans. Although none of the teeth preserve complete crowns, there is a visible trend of the teeth becoming more buccolingually (side-to-side) flattened towards the back of the jaw.
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Aardonyx shows a transition toward the bulk-browsing form of feeding characteristic of sauropods. The jaws of Aardonyx are narrow and V-shaped with a pointed symphysis, a plesiomorphic characteristic shared with other basal sauropodomorphs. In sauropods, the jaws are broad and U-shaped to allow for a wider bite. The absence of a lateral ridge at the caudal end of the dentary is indicative of a loss of fleshy cheeks.
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Salamanders have three different sets of teeth: dentary, premaxillary, and vomerine teeth, which are named due to their location in the mouth. All the teeth, despite their different locations, are very similar. They are small and conical, meaning mudpuppies are homodonts due to their similar shape. The common mudpuppy never leaves its aquatic environment and therefore does not undergo morphogenesis, however many salamanders do and develop differentiated teeth.
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The anterior region palatal surface of the skull is obscured by the lower jaw, which tightly fixed to the palate. The transverse processes of the pterygoid sweep laterally and posteriorly. When first described the skull was considered to have a triangular interpterygoing vacuity, however upon later examination, the status of a pterygoid vacuity was left ambiguous. The dentary symphysis is covered with foramina, suggesting there may have been whiskers there.
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In Megaconus, these bones are still associated with the lower jaw, placed within a groove behind the dentary bone of the lower jaw. Megaconus is estimated to have weighed about . It probably had an outwardly similar appearance to multituberculates, a major group of Mesozoic mammals. However, its body is longer than those of multituberculates and most other Mesozoic mammaliaforms, having more back vertebrae (24) than other early mammals.
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The preserved portion of the jaw was smooth, shallow and relatively wide, curving upwards at the parasymphyseal (chin) region. The main bone of the jaw, the dentary, possessed a single row of long, curved teeth, known as marginal teeth. These teeth were weakly attached to the underlying bone, which allows them to fold backwards. This ability is also seen in certain snakes as well as oestocephalid aistopods, betraying Andersonerpeton's aistopod affinities.
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The lower jaw curved downwards towards its tip, and the jaw joint was located well below the level of the tooth row. There is no evidence for a beak. Each side of the upper jaw was lined with 20 teeth – four in the premaxilla, the front bone of the upper jaw, and 16 in the maxilla which followed behind. The dentary bone of the lower jaw likewise had 20 teeth.
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In contrast, several members of the Abelisauridae feature very short tooth crowns. In the holotype, each half of the , the tooth-bearing bone of the , was equipped with 15 teeth, which are, however, poorly preserved. Both specimens MWC 1 and UMNH VP 5278 show only 11 teeth in each dentary, which were, as shown by the latter specimen, slightly straighter and less sturdy than those of the upper jaw.
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The first remains of Asilisaurus were found in 2007 at "locality Z34", a bonebed near the town of Litumba Ndyosi in Tanzania. This bonebed is part of the Lifua Member of the Manda Beds, which preserves a middle Triassic lake ecosystem. At least 14 individuals were present at the site, including NMT RB9, the holotype dentary. Fossils likely belonging to Asilisaurus are known from throughout the Manda Beds.
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Asilisaurus has fewer teeth in the dentary (8-10) than other silesaurids, and the tooth row occupies a smaller portion of the bone than its relatives. The rear of the lower jaw is similar to other silesaurids, with a long retroarticular process and weakly defined surangular ridge. The middle portion of the lower jaw is not known, so there is ambiguity about the overall shape of the jaw.
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According to Knutsen (2012), Bardet et al. (1993) referred two additional mandibles to P. brachyspondylus based solely on a similar number of dentary and symphyseal teeth; BHN 2R.370, collected at the Moulin-Wibert quarry, from the Rasenia cymodoce ammonite zone of the Calcaires de Moulin- Wibert Formation of Nord-Pas-de-Calais, and MNHN cat.24.1 collected at Le Havre, Normandy, both from the early Kimmeridgian of France.
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A fossil species described in 1990 by Suzanne J. Hand, a researcher at the Riversleigh World Heritage Area. The author separated the species as a new genus, Petramops, and allied this to the Molossidae family of microchiropterans. The holotype, a partial dentary, was discovered at the Gotham City site at Riversleigh. The genus is masculine, and combines the Latin petrus for rock with mops, a common suffix of chiropteran genera.
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Desmatosuchus also had very thin vomers, which bounded the medial side of the internal nares. These internal nares were relatively large, roughly half the length of the entire palate. The lower jaw typically carried 5 or 6 teeth, and had a toothless beak on the end. The dentary was about half the length of the lower jaw, with the front portion being toothless and covered by a horny sheath.
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Phlaocyon yatkolai is an extinct species of canid mammal known from the early Hemingfordian () Runningwater Formation, Box Butte County, Nebraska (, paleocoordinates ). P. yatkolai, named after the collector late Daniel Yatkola, is known from a right dentary with teeth. It is a large species of Phlaocyon and it displays several derived characters in its dentition. These characters are, however, slightly less derived than in its sister taxon P. mariae.
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In top view, the dentaries do not form the box-shaped snout seen in diplodocids, but are more rounded with a J-shaped curvature, as typical for dicraeosaurids. The front of the dentary had a hook-like "chin" projecting downwards, as seen in other flagellicaudatans. The angular bone of the hind part of the lower jaw was very elongated and longer than the surangular bone, unlike in diplodocids.
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Gryphoceratops is known only from the holotype ROM 56635, a partial right dentary. The holotype was collected in the northwest corner of Dinosaur Provincial Park, from bonebed 55 of the Milk River Formation, dating to the late Santonian stage of the middle Late Cretaceous period, about 83.5 million years ago. Thus, Gryphoceratops represents the oldest known leptoceratopsid. However, a cladistic analysis found it to be one of the most advanced leptoceratopsids.
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It is one of several hadrosaurids from the Amur River region named since 2000. The type and only species to date is W. dongi, named in honor of Chinese paleontologist Dong Zhiming. In 2010 Gregory S. Paul estimated its size at 9 meters (30 ft) and 3 tonnes (3.3 short tons). specimens of Wulagasaurus Wulagasaurus is based on GMH W184, a partial dentary (toothbearing bone of the lower jaw).
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Eine Reptilfauna aus der ältesten Trias Nordrußlands [A reptilian fauna from the earliest Triassic of northern Russia]. Neues Jahrbuch für Mineralogie, Geologie und Paläontologie, Beilagen-Band, Abteilung B 84:1-23 The holotype, PIN 2252/387, consists of fifteen dorsal vertebrae, seventeen caudal vertebrae, two humeri, radius, ulna, ten femora, eleven tibiae, a fibula, ten unidentifiable bone fragments, a scapula-coracoid, a maxilla and dentary missing anterior end.
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The eye sockets are positioned far forward in the skull and face somewhat forward and upward. A wide area on the lower jaw called the lateral dentary shelf is another distinguishing feature of the genus. The temporal regions behind the eyes are large, and the back of the skull is wide and square-shaped. The holotype specimen of E. oweni is unusual in that it has two pairs of tusks.
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This fieldwork culminated in a 2007 monograph consisting of seven scientific papers on all aspects of the animal's biology, published in the Society of Vertebrate Paleontology Memoirs. The papers are in English, although each has an abstract written in Malagasy. In this volume, the dentary described by Lavocat was re- evaluated and determined to be diagnostic for this species. Therefore, the name Majungatholus was replaced by the older name Majungasaurus.
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Rhabdodontid fossils have been mainly found in Europe in formations dating to the Late Cretaceous. The defining characteristics of the clade Rhabdodontidae include the spade-shape of the teeth, the presence of three or more premaxillary teeth, the distinct difference between the two maxillary and dentary teeth ridge patterns, and the uniquely shaped femur, humerus, and ulna. Members of Rhabdodontidae have an adult body length of 1.6 to 6.0 meters.
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The lacrimal bone has a crest strongly projecting to above and sideways. In the lower jaw, the dentary is robust with the front tip higher than the middle section. In the pelvis, the ilium is short with a length less than half that of the femur (thighbone); in all other theropods the ilium is more than half as long. All these traits are unique within the clade Paraves.
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One of these slabs contained additional vertebrae and ribs while the other contained a partial skull and mandible. These additional slabs were collectively termed the paratype, USNM 214823. An isolated right jugal found at the site (USNM 437574) was also referred to the species. In the 1950s and 1960s, several additional bones (including vertebrae, osteoderms, a dentary, and a femur) were unearthed near Ashland, a little south of Doswell.
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The first part of the generic name Urbacodon is an acronym, honouring the Uzbek, Russian, British, American and Canadian scientists who participated in its discovery. This acronym was combined with a Greek ὀδών, odon, "tooth". The specific name refers to the provenance from Itemir. The name was based on the holotype ZIN PH 944/16, a single left dentary with preserved replacement teeth from the Cenomanian Dzharakuduk Formation.
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Batropetes is distinguished from Carrolla, another brachystelechid microsaur, by the presence of three cusps on the premaxillary and anterior dentary teeth. In Carrolla, there are only two cusps. Additional diagnostic features seen in Batropetes include a supraoccipital bone that is not fused to the otic capsule, the presence of a retroarticular process (a projection at the back of the lower jaw), and two proximal bones in the tarsus.
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The inner scleral ring diameter is 18 millimeters, and the outer diameter is around 35 millimeters. The articular and the prearticular cannot be distinguished, which might indicate they are fused. The splenial is bound by the dentary, which keeps it from being visible on the ventral edge of the mandible. The quadrate and the quadratojugal are appressed on the right side, and there is a quadratojugal foramen present.
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The Pseudaminae is a subfamily of ray-finned fishes, one of two subfamilies of the family Apogonidae, the cardinalfishes. They are characterised by having large caniform teeth which are placed on the on dentary and premaxillae, by having the lateral line absent or incomplete, by having no scales or if scales are present they are cycloid. One species, Gymnapogon urospilotus, is notable for its larvae being rather large and fast-swimming.
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Named after the scientist and writer Dr. Mario Teruggi by Romer. M. teruggi skulls on average are approximately 45 percent larger than the skulls of M. pascuali and had a more defined sagittal crest. The dentary is less sharp and had 15 maxillaries compared to the 12 M. pascuali had. M. ochagaviae is known to be the most common species from the Santa Maria Formation, Rio Grande do Sul, Brazil.
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Named after Mário Costa Barberena. It had a higher skull and mandible, slightly dorsally pointed dentary ventral border under the coronoid process, and less post canines compared to the other three species. M. major is known for having the largest skull out of the 4 species that can reach up to 204 mm. It had a distinctively narrow snout with the teeth being less curved compared to its sister taxa.
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The postdentary trough is a skeletal feature seen in Mesozoic mammals. It is found on the inside of the lower jaw (dentary), at the back behind the molar teeth. It is the hollow in which the postdentary bones and Meckel's cartilage sit. These bones form the middle ear in later mammal groups (see Evolution of mammalian auditory ossicles), they include the incus (quadrate), malleus (articular), ectotympanic (angular) and prearticular.
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Its length was about with a weight of . Araripesuchus can be distinguished by their laterally bulged edges of the snout, with the bulge being the most prominent around the area of an enlarged maxillary tooth. The snout and premaxilla are also smoother than that of most crocodyliforms, without foramina or the typical rugose texture. There are six valid species within this genus, all with slightly differing maxillary or dentary structure.
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The sixth species, A. rattoides, was found in the Kem Kem Beds of the Sahara in a similar location to the specimens of A. wegeneri found by Sereno and Larsson, and is known only from parts of dentary bones, up to the fourteenth alveolus. It was described in the same paper as Kaprosuchus, Laganosuchus and Anatosuchus; the four were therefore popularized by the authors as 'RatCroc', 'BoarCroc', 'PancakeCroc' and 'DuckCroc' respectively.
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Several characteristics are indicative of a rhamphothecae, such as an edentulous premaxilla with a thin, tapering lower edge, the successive loss of maxillary and dentary teeth, a mandibular concavity in the lower side, the displacement of the lower surface in the dentary, and a rostral projection of the mandibular symphysis. In Erlikosaurus, the presence of a keratinous beak on the maxilla and premaxilla can be inferred by the presence of numerous neurovascular foramina on the rostral and lateral surfaces in the skull, furthermore, it bears all the mentioned features above, however, it is unclear the extension of the beak. The preserved rhamphotheca in specimens of Gallimimus and Ornithomimus evidences that the keratin sheath covered the premaxilla and overlapped it on the lower side by a few millimeters. In some extant birds, the rhamphotheca is typically restricted to the premaxilla and maxilla, although in some cases it partially covers the nasal process in some birds.
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The fishes of the genus Filimanus have a body which is oblong to moderately deep and compressed. They have a well developed adipose eyelid and the diameter of the eye is longer than the length of the snout. They have a well developed lip on their lower jaws and the teeth on the dentary bone are restricted to its dorsal surface. There are narrow bands of villiform teeth on their jaws, palatine bone and ectopterygoids.
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Conversely, nectarivores rely on their tongue during feeding, resulting in less stress on the dentary. Research has revealed that there is no significant difference in the bite forces of insectivorous bats compared to frugivorous bats. However, observations have noted that insectivore bats have different feeding behaviors than frugivores, particularly that they do not engage in prolonged periods of unilateral feeding. Pertaining to dental characteristics, Ariteus flavescens has a metaconid on m1 and lacks a M3.
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Estimated size of Pelecanimimus, compared to a human. Pelecanimimus was a small ornithomimosaur, at about and 17-25 kg (37-55 lbs). Its skull was unusually long and narrow, with a maximum length of about 4.5 times its maximum height. It was highly unusual among ornithomimosaurs in its large number of teeth: it had about 220 very small teeth in total, with seven premaxillary teeth, about thirty maxillary, and seventy-five in the dentary.
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C. motatanensis has a caudal fin darkly pigmented throughout other than for a narrow pale distal margin, while C. orinoco has dark pigmentation on the caudal fin particularly on the distal portions of the fin. The body of Cetopsis species ranges from slender to stout. Unlike all other species, C. candiru has incisiform (vs. conical) teeth on the vomer and dentary, and also has a more slender body than all other species.
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Ambedus is a small diadectid known only from maxillae and dentary bones. It is considered the most primitive diadectid because unlike other forms it had a small, shallow lower jaw and many simple, conical teeth. It was also smaller than the later, rather bulky diadectids. Later diadectids have deep jaws with few teeth and forward-projecting incisiforms at the tips of the jaws for consuming plant material, and a corresponding greater girth.
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Though incompletely preserved, it is assumed that the occipital plate sloped back and upwards from the occipital condyles (as in some relatives). The orbito-temporal vascular system inside the skull of Catopsbaatar did not differ much from those of related genera. Catopsbaatar mandible was robust and very elongated. The diastema (gap between the front and cheek teeth) was concave, and extended for 20 percent of the dentary bone (the main bone of the lower jaw).
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Iguanodontids exhibit contact between maxillary and dentary teeth upon closure of the jaw. They have a thick layer of enamel over the lip-facing (labial) surface of the crown, a robust primary ridge beginning at the base of the crown, and a denticulate margin. Most members of the family have maxillary tooth crowns lanceolate in shape. The labial surface of the teeth has some grooves, while the tongue-facing (lingual) surface is smooth.
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However, there is no evidence of a paired, diverging tooth row like we see in T. alexandrae. The wide, button- like teeth on the dentary are characteristic of all three, Thalattosaurus, Clarazia, and Paralonectes. The posterior mandibular teeth of T. borealis differ from these genera, however, being set flush with the margin of the jaw. In both T. alexandrae and Clarazia the posterior, bulbous teeth are set slightly ventral and medial to the jaw margin.
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It is known from an incomplete skeleton of an adult (measuring 5.3 m) including maxilla, mandibles, teeth, tusks and other materials have been discovered. The Japanese species S. sendaicus described in 1924 from dentary materials from Pliocene deposits has been ascribed to the genus, as well as the species S. bumiajuensis (formerly Tetralophodon) from the late Pliocene of Java. One individual of S. hanjiangensis was a 30-year-old tall and weighed .
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The maxillary tooth row was in its entirety transversely rotated, its normal rear 90° everted towards the front. This was matched by an identical rotation of the dentary of the lower jaw. As a result, no other tetrapod had all of its teeth located as far to the front as Nigersaurus. Teeth at different growth stages, Museo di Storia Naturale di Venezia The slender teeth had slightly curved crowns, which were oval in cross-section.
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In Amphisbaenia, the extracolumella is particularly lengthened and firmly connects with a layer of skin over dentary bone of the lower jaw. This connection appears to facilitate detection of airborne vibrations in the facial area. The embedding in the skin often occurs at a specially enlarged labial scale. As a result, the amphisbaenian is able to detect substrate vibrations as it burrows through the ground while protecting the internal ear from damage.
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The maxillary tooth plates are easily seen in Hyperodapedon and there are seven cranial, six postcranial, and three dentition synapomorphy traits. Hyperodapedon had jaws that allowed them to have a precision-shear bite to break down the tough plants that they ate. The beak-like premaxilla and hind limbs were used for digging up food. Teeth along the maxilla and dentary had open roots which could not be replaced like other reptiles.
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It refers to the elongated shape of the skull, which resembles a horse skull. The specific name scutodens is a combination of the Latin words scutum (meaning shield) and dens (meaning tooth), and it references the shield-shaped dentary tooth crowns. UMNH VP 20208 was unearthed from the Yellow Cat Member of the Cedar Mountain Formation, Utah, at a site known as Andrew's Site, dating from the Valanginian stage in the Early Cretaceous period.
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Nankangia is an extinct genus of caenagnathoid oviraptorosaurian dinosaur known from the Upper Cretaceous Nanxiong Formation of Nankang County, Ganzhou City of Jiangxi Province, southeastern China. It contains a single species, Nankangia jiangxiensis. N. jiangxiensis coexisted with at least four other caenagnathoids, including an unnamed oviraptorid, Banji long, Ganzhousaurus nankangensis and Jiangxisaurus ganzhouensis. The relatively short dentary and non-downturned mandibular symphysis of Nankangia suggest that it may have been more herbivorous than carnivorous.
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The taphonomy (changes between death and fossilization) of the Irritator challengeri holotype specimen has been discussed by some researchers. The skull was found lying on its side. Preceding fossilization, several bones from the back of the braincase, as well as the dentary, splenial, coronoid, and right angular bones from the lower jaw, were lost. Other bones, mostly from the skull rear, had become and displaced towards alternate regions of the head before burial.
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Holotype partial dentary of Chenanisaurus barbaricus The most striking feature of the mandible is the extreme height, especially when compared with the relatively short teeth. This seems to indicate that the jaw is also very short, with a build even more extreme than seen in the related Carnotaurus. This suggests the jaws were built to withstand a high bite force. The jaw flexes forwardly downwards to terminate in a deep blunt point.
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Ikanogavialis had a dorsoventrally deep snout and a distinctive notch between the dentary and maxillary alveoli. The external nares projected anterodorsally from the rostrum. This can be seen as a plesiomorphic characteristic in crocodilians, but given that the earliest gavialoids possessed dorsally projecting external nares, this feature can be seen as having been a reversal from the gavialoid apomorphy back to the crocodilian plesiomorphy rather than having been directly obtained from an early crocodilian ancestor.
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It developed a short secondary bony palate, with crocodilian featuring pterygoids. The elongated choana is located behind the secondary palate, which is made by the premaxilla and maxilla. In modern crocodiles, the choana is between the vomers and the anterior processes of pterygoids. The dentary forms the largest part of the lower jaw with some shallow pits, which indicated that the animal probably has 15-18 teeth, fewer teeth in the far back.
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They are distantly related to the extant Sphenodon (tuatara of New Zealand) with which they shared a number of skeletal features including a large tooth row along the side of the palatine bone (part of the palate) and posterior process of the dentary bone (part of the lower jaw). The type species, G. bridensis, lived during Early Jurassic in Wales, UK.Evans, S.E. 1981. Caudal autonomy in a lower Jurassic Eosuchian. Copeia 1981: 883-884.
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S. nattereri has a laterally compressed, knife-shaped body. The dorsal profile of the head is sharply curved from the nape to the snout. The mouth is terminal, with the upper jaw longer than the lower. The dentary is as long as deep, bearing a row of 7-8 conical teeth on the posterior portion, and there are upper and lower pharyngeal tooth plates bearing 9-11 and 7-9 teeth respectively.
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In mammals, the articular bone evolves to form the malleus, one of the mammalian ossicles of the middle ear. This is an apomorphy of the mammalian clade, and is used to determine the fossil transition to mammals. It is analogous to, but not homologous to the articular process of the lower jaw. After the loss of the quadrate-articular joint, the squamosal and dentary bones form the new jaw joint in mammals.
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Unescoceratops is known only from the holotype specimen TMP 95.12.6, a partial left dentary. The fossil was collected in 1995 in the Black Coulee locality (formerly Deadhorse Coulee), near the Writing-on-Stone Provincial Park, from the Dinosaur Park Formation, dating to the late Campanian stage of the Late Cretaceous period, about 76.5-75 million years ago. The specimen was regarded as too incomplete to identify, and was shelved for several years.
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This complex primitive pattern has, however, been simplified to various degrees in the great majority of vertebrates, as bones have either fused or vanished entirely. In teleosts, only the dentary, articular, and angular bones remain. Cartilagenous fish, such as sharks, do not have any of the bones found in the lower jaw of other vertebrates. Instead, their lower jaw is composed of a cartilagenous structure homologous with the Meckel's cartilage of other groups.
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The dentary had three processes that extended backwards into other bones placed further back in the mandible. The articular bone at the back of the mandible was completely fused with the surangular and prearticular bones. The mandible extended hindwards beyond the cotyla (which connected with the condyle of the upper jaw), and this part was therefore similar to a retroarticular process as seen in other taxa. The surangular enclosed two mandibular fenestrae.
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The tooth margin alternates between concave and convex on the dentary. 19 teeth are in the dentaries, but there may be more that are not visible due to presence of the matrix it was mostly uncovered from. The eight caniniform teeth are procumbent, or tilt forward, and smooth but are striated near where they attach to the jaw. The skull was not prepared in such a way that allows for examination of the palate.
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The mandible of Limnoscelis was well-built, with large processes for jaw muscle attachment, indicating that it had a powerful bite. In addition to its premaxillary, maxillary, and dentary teeth, Limnoscelis had additional palatal teeth on transverse flanges of its pterygoid. These flanges consisted of an anterior row of smaller blunt denticles, and a posterior row of larger teeth, with neither having labyrinthodont infolding. The pterygoid of Limnoscelis articulated with the basisphenoid.
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Forward slide of the lower jaw was limited by the second morphological feature unique to dicynodonts, a pivot point created between the dentary groove and palatal notch upon closure of the jaw. The lower jaw would then move so that the articular condyle slid anterio-ventrally along the quadrate condyle, which would cause the mandible to pivot in such a way that the front of the mouth closed and the back opened.
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The most distinctive characteristic of its head was its strongly hooked snout, formed by a downturned premaxilla. The premaxilla contained up to nine teeth in adults, and the teeth in the snout tip were splayed out to the sides. The jaws of Proterosuchus contained numerous teeth, with up to 9 premaxillary, 31 maxillary, and 28 dentary teeth in each side. The teeth of Proterosuchus were recurved, labiolingually compressed, and serrated, as in most archosauriforms.
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P. meileyingensis has the shortest snout and neck frill of any species, making the skull nearly circular in profile. The orbit (eye socket) is roughly triangular, and there is a prominent flange on the lower edge of the dentary, a feature also seen in specimens of P. lujiatunensis, and to a lesser degree in P. mongoliensis, P. sattayaraki, and P. sibiricus. The complete type skull, probably adult, is 13.7 centimetres (5.5 in) long.
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The lower jaws were elongated and met at their tips in a shared epidentary bone, the core of the toothless lower beak. In the dentary bone, the tooth battery curved to the outside to meet the battery of the upper jaw. At the rear of the lower jaw, the articular bone was exceptionally wide, matching the general width of the jaw joint. T. horridus can be distinguished from T. prorsus by having a shallower snout.
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Mochlodon and Struthiosaurus, the latter found at the same site, are the only dinosaur genera named from Austrian finds. The type specimen PIUW 2349 was found in the Grünbach Formation of the Gosau Group dating from the Lower Campanian, about 80 million years old. It consists of a dentary, two vertebrae (presently lost), a parietal, a scapula, an ulna, a manual ungual, a femur and a tibia. Bunzel did not assign a holotype.
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In 2005 the dentary was chosen as the lectotype. Vertebrae of Mochlodon vorosi At the end of the nineteenth century Baron Franz Nopcsa noted the similarity of fossils found in Romania to both the French Rhabdodon and the Austrian Mochlodon. In 1899 he named some of these Mochlodon inkeyi, the specific name honouring Béla Inkey, but the same year changed the name into Rhabdodon inkeyi. In 1900 Nopcsa named some Romanian remains Mochlodon robustumF.
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Sternberg compared this dentary to one referred to Troodon by Russel in 1948, and decided that they belonged to the same family, and potentially the same genus. While similar, there were a few differences, that might be shown to relate to age or variation within the genus. Sternberg, therefore, referred Polyodontosaurus to the family Troodontidae, until further material could be found. The name Polyodontosaurus has been misspelled as "Polydontosaurus" by some authors.
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The rear portion of the holotype maxilla is characteristically complex and similar to that described for Plateosaurus. These complex traits include a posterolateral flange which likely shielded part of the jugal, a pair of deep dorsomedial grooves (likely articulating with the lacrimal and jugal), and a broad groove behind the medial flange which likely articulated with the palatine. DMNH EPV.63136, the most complete referred dentary Lower jaw bones referred to Kwanasaurus include DMNH EPV.
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The lower jaw tapered towards the front, and the dentary bone (the main part of the lower jaw) was robust. The front of the jaws were covered by a toothless keratinous beak (or rhamphotheca). The upper beak covered the front of the premaxilla bone and the lower beak covered the predentary, which are, respectively, the foremost bones of the upper and lower jaw in ornithischians. This is evidenced by the rough surfaces on these structures.
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Infernovenator is diagnosed by a unique combination of features: (1) 61 presacral vertebrae; (2) a triangular postfrontal that contacts the tabular; (3) a circumorbital series formed by the prefrontal, the postfrontal, the lacrimal, and the maxilla; and (4) an ossified septomaxilla. Features shared with the lysorophian Brachydectes and not with other recumbirostrans include: (1) postorbital absent and cheek emargination present; (2) bar-like tabular- squamosal complex; and (3) short and robust dentary.
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Restored E. rugosidens skeleton without back armour The skull of Edmontonia, up to half a metre long, is somewhat elongated with a protruding truncated snout. The snout carried a horny upper beak and the front snout bones, the premaxillae, were toothless. The cutting edge of the upper beak continued into the maxillary tooth rows, each containing fourteen to seventeen small teeth. In each dentary of the lower jaws, eighteen to twenty- one teeth were present.
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Estimated size compared to a human Zhuchengtyrannus was a large carnivorous theropod, and the holotype has been estimated to have been in length and up to in weight. The holotype dentary is slightly smaller than that of most specimens of Tyrannosaurus rex and slightly bigger than most of Tarbosaurus bataar, but significantly smaller than the corresponding bones of one of the largest Tyrannosaurus specimens ("Sue").Hone D, "So just how big was Zhuchengtyrannus?", archosaurmusings.wordpress.
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Front teeth are small and peg-like with an ovular cross section and were most likely used for grabbing food. In some species, the last premaxillary tooth was enlarged and canine-like. Back teeth are small and triangular with denticles on the front and back of the crown, used for mouth processing. In species in which the dentary has been found, mandibular teeth are similar in size and shape to those in the upper jaw.
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There are five or six premaxillary teeth and sixteen maxillary teeth, all of which are narrow and peg-shaped. The palate also has teeth, with rows on the ectopterygoid, palatine, and vomer. The bones of the skull roof are similar to those of gymnarthrids. There are two rows of teeth adjacent to one another in the lower jaw, with a marginal row on the dentary and an inner row on the coronoid.
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Pehuenchesaurus was described in 2005 by Alan Turner and Jorge Calvo based on MAU-PV-CRS-440, a nearly complete dentary (the main tooth-bearing bone of the lower jaw). This animal had a narrow, tall lower jaw, and differed from all other sebecosuchians by lacking serrations on its teeth. The first and fourth teeth were the largest, and the first tooth pointed forward slightly. The preserved jaw bone is about long.
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Fossils of Invertebrates like ostracodes and bivalves were used to determine these sediments as Upper Jurassic in age. A more precise dating could not be made. The holotype specimen (IVPP V14474) consists of a left dentary, one cervical and several dorsal and caudal vertebrae, both scapulae, some pelvic bones and the hind limbs. C. H. Ye mentioned this specimen in 1975 under the name Chinshakiangosaurus chunghoensis (after the Yangtze River and the village Zhonghe).
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The splenial bone uniquely reaches forward to about 2/3 the length of the tooth row. On the splenial, the anterior inferior alveolar foramen is also located partially on the dentary, and is uniquely located behind and above the anterior mylohyoid foramen. Meanwhile, the angular bone bears a process in front of the jaw joint. On the vertebrae, the zygosphere processes are separate, and located on a distinct foot, or pedicle, of the vertebral arch.
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The jaw in tetrapods is substantially simplified compared to fish. Most of the upper jaw bones (premaxilla, maxilla, jugal, quadratojugal, and quadrate) have been fused to the braincase, while the lower jaw bones (dentary, splenial, angular, surangular, and articular) have been fused together into a unit called the mandible. The jaw articulates via a hinge joint between the quadrate and articular. The jaws of tetrapods exhibit varying degrees of mobility between jaw bones.
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Life restoration of Moschops capensis Skull of Titanophoneus Apart from the Biarmosuchians, the dinocephalians are the least advanced therapsids, although still uniquely specialised in their own way. They retain a number of primitive characteristics (e.g. no secondary palate, small dentary) shared with their pelycosaur ancestors, although they are also more advanced in possessing therapsid adaptations like the expansion of the ilium and more erect limbs. They include carnivorous, herbivorous, and omnivorous forms.
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This is illustrated by a 419-million-year-old fossil, Entelognathus, from China, which is the only known placoderm with a type of bony jaw like that found in modern bony fishes. This includes a dentary bone, which is found in humans and other tetrapods. The jaws in other placoderms were simplified and consisted of a single bone. Placoderms were also the first fish to develop pelvic fins, the precursor to hindlimbs in tetrapods, as well as true teeth.
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The mandibles (lower jaws) are straight and slender, formed by the tooth-bearing dentary bones at the front and the splenial and angular bones at the back. The front tip of the mandibles curves very slightly downwards and inwards. The teeth of Jesairosaurus are pointed and very slightly curved, although they are also conical (particularly so in the maxilla) and only slightly flattened from the side. In addition, the teeth are subthecodont (also known as pleurothecodont).
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Photographs and illustrations of TNM 02067 in lingual (A), labial (B), and occlusal (C) views. Scale bar=5 mm TNM 02067 is a damaged, partial left dentary (lower jaw bone). It preserves much of the body of the bone, which is short and deep, but is broken along a vertical fracture behind the toothrow. There is another fracture in the front part of the jaw. The bone is 19.5 mm (0.77 in) long and 11.4 mm (0.45 in) deep.
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The large incisor is inclined forward, and its root--the only part of the tooth that is preserved--forms an angle of about 55° with the horizontal. At the tip of the alveolus, where the tooth projects out of the bone, it is 3.0 mm (0.12 in) high and 2.1 mm broad. The root extends through the dentary to a position below the third cheektooth. Only the roots of the first and second cheekteeth are preserved.
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Sinoconodon differs from all nonmammalian cynodonts in the presence of a promontorium, an enlarged anterior lamina, and the floor of the trigeminal ganglion. Sinoconodon shares several derived characters with other mammals. The most distinguished are the expansion of the brain vault in the parietal region, complete ossification of the medial wall of the orbit, a large dentary condyle, and a concave glenoid fossa in the squamosal. These characters suggest that Sinoconodon and other mammals form a monophyletic group.
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Life restoration Skull and dentary in various views The Majorcan giant dormouse (Hypnomys morpheus) is an extinct animal from the Balearic Islands of Majorca and Mallorca, Spain. It is considered an example of island gigantism. The closest extant relative is considered to be the genus Eliomys, which includes the garden dormouse,MC McKenna and SK Bell "Classification of Mammals Above the Species Level" 1997 Columbia University Press, New York . which was confirmed by a mitochondrial DNA analysis in 2020.
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The description of the species was published in 2000 by researchers Peter F. Murray, working at the Museum of Central Australia and Dirk Megirian of the Northern Territory Museum. The holotype is fossilised material excavated at "Top Site" at the Bullock Creek fossil area, a partial left dentary with a premolar and several molars that is dated to the mid-Miocene. The specific epithet commemorates Tom Rich, who introduced the authors to the site of their discovery.
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In appearance it resembled a dog with a long snout. Its molar teeth were specialized for carnivory; the cups and crest were reduced or elongated to give the molars a cutting blade. W. ridei is known from a right maxillary fragment (QMF 16851) containing molars one and two to the anterior section of the infraorbital foramen that was dorsal to the third molar. The left dentary fragment (QMF 16852) contains a partial second premolar and a full third molar.
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The toothed dentary bone had two rear prongs surrounding the mandibular fenestra. Unique to Turfanosuchus among gracilisuchids, the lower prong was much longer than the upper prong. This had the added effect of excluding the angular bone (which formed the rear lower edge of the jaw) from forming the lower border of the mandibular fenestra. The surangular, which forms the upper rear portion of the jaw (and the upper border of the mandibular fenestra), was large.
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It sits high on the coronoid process, and is where the masseter muscle would have attached to the dentary. The postdentary bones, which are of particular importance since they form the ear bones in mammals, are absent or severely damaged. The nasal bone is relatively flat, and is separated from the maxilla at the anterior end of the snout by the septomaxilla (a therapsid synapomorphy). The lacrimal bone is smaller and narrower than is typical for early cynodonts.
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Procynosuchidae is an extinct family of therapsids which, along with Dviniidae, were the earliest cynodonts. They appeared around 260 million years ago, and were most abundant during the latest Permian time (251 mya), shortly before the Permian-Triassic extinction event. Despite being the basal member of the cynodont clade, they already showed some of the advanced mammalian characteristics, but Procynosuchids bore resemblance to the Therocephalians. Procynosuchid eyes are forward-facing, and the dentary was larger than the Therocephalians.
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Unusually, the teeth also have a maze-like internal structure, formally known as labyrinthine infolding. This type of structure is known in large "labyrinthodont" tetrapods and their tetrapodomorph ancestors, but unknown in any other aistopod. Lingually from the dentary tooth row (i.e. towards the tongue), the upper surface of the mandible has five plate-like bones: a parasymphyseal plate at the chin, an adsymphyseal bone directly behind it, and a string of three coronoid bones directly behind the adsymphyseal.
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Skull cast The skull of Postosuchus was constructed narrow in front and extended wide and deep behind. It was 55 cm in length and 21 cm broad and deep. There are many fenestrae (openings) present in the bones that lighten the skull, providing space for the muscles. Like more derived archosaurs, the lower jaw had mandibular fenestrae (openings at the lower jaw), formed by the junction of the dentary with other jaw bones (surangular and angular).
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In many mammals, including humans, the squamosal fuses with the periotic bone and the auditory bulla to form the temporal bone, then referred to as the squama temporalis. In mammals, the quadrate bone evolves to form the incus, one of the ossicles of the mammalian ear. Similarly, the articular bone evolves to form the malleus. The squamosal bone migrates and lengthens to become a new point of articulation with the lower jaw (at the dentary bone).
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Jianchangosaurus possesses 27 maxillary teeth and approximately 25 to 28 dentary teeth. The crowns on its teeth diminish in size as they progress toward the posterior of the skull. The teeth on the upper jaw, exhibit the conventional dental morphology - in which the surface of the tooth facing the outside of the mouth is convex. The teeth on the lower jaw possess the reversed morphology, where the surface of the tooth facing the outside is concave.
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The alveoli were elliptical to almost circular, and all were larger than the bases of the teeth they contained, which may therefore have been loosely held in the jaws. Though the number of alveoli in the dentary would seem to indicate that the teeth were very crowded, they were rather far apart, due to the larger size of their alveoli. The jaws contained replacement teeth at various stages of eruption. The interdental plates between the teeth were very low.
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Notosyodon is an extinct genus of non-mammalian therapsids. The holotype PIN 2505/1, consists of a partial skull preserving the orbital, occipital, and basicranial regions. Other remains include PIN 2505/2, a right lower incisor, and PIN 2505/3, a left upper postcanine, found associated with the holotype and PIN 2608/1, the anterior half of a left dentary found on the right bank of the Donguz River, near Dolmatovskii Farm, Sol-Iletsk District, Orenburg Region, Russia.
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The maxillary teeth are inset medially and project below the internal naris. There is also an occlusion between the vomerine teeth and dentary teeth with saddle-shaped vomers that overhang the dorsal side of the premaxillary symphysis. Looking at the spine, the length of the axis neural spine is greater than the length of axis centrum. It also has a craniocaudally narrow neural spine of the third cervical and a prominent midventral groove on the first two caudal centra.
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The jaw function and adaptive radiation of the dicynodont mammal-like reptiles of the Karoo Basin of South Africa. Zoological Journal of the Linnean Society 122:349–384. Unlike other members of the infraorder, the front of the lower jaw is not flattened, but curved and tapering anteriorly. Cox suggests this feature, as well as the strong jaw musculature, indicated by the large lateral wing on the dentary, may point towards grubbing in the dirt for food.
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Other herbivorous groups like ornithomimids, therizinosaurs, pachycephalosaurs, small ornithopods, nodosaurids and ankylosaurids were also represented. Small predatory dinosaurs like oviraptorosaurs, troodonts and dromaeosaurs hunted smaller prey than the huge tyrannosaurids; Daspletosaurus and Gorgosaurus, which were two orders of magnitude larger in mass. Intervening predatory niches may have been filled by young tyrannosaurids. A Saurornitholestes dentary has been discovered in the Dinosaur Park Formation that bore tooth marks left by the bite of a young tyrannosaur, possibly Gorgosaurus.
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In addition, a unique combination of in themselves not unique traits is present. The temporal opening on the skull roof is round and much smaller than the temporal opening of the skull side. The rear branch of the praemaxilla touches the lacrimal bone and features a prominent opening at this point, on the rear underside. The upper rear branch of the dentary covers the outer side opening of the lower jaw and has a concave lower rim.
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In 2009, a study by J. R. Foster was published that estimated the body masses of mammals from the Late Jurassic Morrison Formation by using the ratio of dentary length to body mass of modern marsupials as a reference. Foster concludes that Fruitafossor was the least massive of the formation at 6g, much lower than the average Morrison mammal of 48.5g.Foster, J.R. 2009. Preliminary body mass estimates for mammalian genera of the Morrison Formation (Upper Jurassic, North America).
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The fossils found are currently in the Oklahoma Museum of Natural History (OMNH). Two specimens held in the OMNH that have been part of the diagnostic process of these species are OMNH 52366, an almost complete right maxilla, and OMNH 52367, a partial right dentary. It is uncertain if the two elements belong to the same individual.Modesto 1996 Another commonly mentioned captorhinid, Labidosaurus hamatus, was found in a Lower Permian geologic group in Texas, called the Clear Fork Group.
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Since the comments were written by Boyle himself, and since they cite information he received specifically from Purnell, they are as legitimate a source of information as the article itself. Edmontosaurus dentary with teeth, typical of hadrosauridae Mallon et al. (2013) examined herbivore coexistence on the island continent of Laramidia, during the Late Cretaceous. It was concluded that hadrosaurids could reach low-growing trees and shrubs that were out of the reach of ceratopsids, ankylosaurs, and other small herbivores.
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Lycophocyon is an extinct genus of caniformian carnivoran from Middle Eocene (early Duchesnean and possibly late Uintan NALMA) deposits of San Diego County, California. Lycophocyon is known from the holotype UCMP 85202, a partial left and right dentary. Paratypes include UCMP 170713, SDSNH 107658, SDSNH 107659, SDSNH 107442, SDSNH 107443 and SDSNH 107444, partial dentaries, mandibles and other cranial remains, and SDSNH 107446 and SDSNH 107447, cranial and postcranial fragments. Many additional specimens are also known.
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The supraoccipital bone, which forms the top portion of the back of the skull, is flat and nearly vertical, as is the case in Probactrosaurus and other hadrosauroids. Dentary of Eolambia As with the premaxilla, the predentary of Eolambia bore denticles. There is a prominent dorsomedial process, a tab-like structure also seen in Probactrosaurus and other hadrosauriforms. Several additional tab-like denticles were present on either side of the dorsomedial process, which are likewise present in Probactrosaurus.
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In lateral view, the lower jaw has a long, dentary that provides most of the lateral surface. Near the coronoid, the dorsal rim swells and thickens, as in other biarmosuchians. Four large incisiform teeth are present on either side of the lower jaw, while an additional small one is present adjacent to the midline. This small incisiform is much shorter than the rest and appears to be a replacement tooth that is not yet fully erupted.
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The dentary (lower jaw bone) itself is robust and short. The length axis of the p4 makes an angle of about 58° with the length axis of the jawbone. The bone is concave on the lingual, but convex on the labial side. There is a diastema (gap) between the p4 and the incisor that would have been in front of it, as in the jaw of Sudamerica. Gurovich estimated the length of the diastema as 2.5 mm.
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There are also small peripheral cuspules present on the anterior and posterior borders of the crown. Roots of the upper postcanines are long, transversely flattened near the crown and taper away to a short point distally. The maximum known transverse diameter of the maxillary postcanines is 13mm. A characteristic feature of the mandible is the sharp angle formed by the junction of the lower margin of the dentary and the anterior surface of the dental symphysis.
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A major synapomorphy shared by the specimen and Sphenosuchus is the swelling of the anterior end of the dentary. Parrish and his team constructed 27 parsimonious trees and in every one the new specimen was placed as the sister group to Sphenosuchus. The specimen was rather incomplete therefore if more of the fossil is to be found this could be subject to revision. Also there is a slight issue with the synapomorphy that relates the two so closely.
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Unlike other Sternarchogiton species it has long, conical teeth (numbering 5 plus 2-3 replacements) on the premaxillary of the upper jaw; there is one row of teeth (numbering 10 plus 3 replacements) on the dentary bone of the lower jaw. Both upper and lower pharyngeal tooth plates are present, bearing 6 and 4-5 teeth respectively. The long anal fin contains 189-210 soft rays. The pectoral fins are broad and pointed, with 12-14 rays.
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Leptopleuron was a small, lizard-like animal of 270 mm that possessed a long tail as well as gastralia in contrast to Sclerosaurus, and a slight triangular depression on its jugal. As a reptile, five metatarsals were observed with lengths of roughly 8 mm with unknown values for some. In terms of its dentary, towards the posterior end, the ramus is notably deep. Its sacral ribs do not attach to the vertebrae after reconstruction of the fossil.
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This squamosal-dentary jaw articulation is the same joint exhibited by mammals, and the inclusion of this joint in Probainognathus indicates that it is a precursor to mammals. Along with this osteological feature, the jaw of Probainognathus is suggested to have had mammal-like soft tissue advancements, as well. The jaw muscles in Probainognathus were thought to have been positioned farther forward, with the masseter splitting into two separate muscles: the superficial masseter and the deep masseter.Ridley, Mark.
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Close up of the skull According to Pu et al. 2013, Jianchangosaurus can be distinguished based on the presence of 27 tightly packed maxillary teeth; the dorsal border of the antorbital fenestra is formed by the maxilla, nasal, and lacrimal, but with the majority of the border formed by the nasal; there is no participation of jugal in the margin of the antorbital fenestra; a short diastema is present in the anterior tip of the dentary; dentary teeth have a concave labial surface and a convex lingual surface (this condition is present for all except six anterior teeth); the lack of prominent hypapophyses in the anterior dorsal vertebrae; the anterior caudal centra have an oval cross section and the articular facet is as tall as it is wide; the presence of weakly curved manual unguals with weak flexor tubercles positioned ventral to the articular facet; the ilium is shallow and elongated; the ridge bounding the cuppedicus fossa is confluent with acetabular rim; and there is extensive contact between the pubic apron.
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Holotype skull The holotype, AR-1/10, represents a disarticulated partial skeleton spread over an area of seven by three meters. It consists of a nearly complete skull, isolated left and right nasals, a dentary fragment, 15 isolated teeth, an atlas, five cervical vertebrae, two cervical ribs, possibly the first and seven more posterior dorsal vertebrae, a section of synsacrum, three isolated dorsal ribs, seven dorsal rib fragments, three caudal vertebrae, four chevrons, a coracoid with a small portion of the scapula, a scapular blade fragment, two xiphosternal plates, both partial humeri, right articulated ilium, ischium and pubis, left articulated ischium and pubis, and 70 osteoderms. The second partial skeleton AR-1/31, designed as the paratype, consists of a partial left jaw with dentary and surangular and isolated angular, ten teeth, five cervical, nine dorsal, three or four dorsosacral, one caudosacral and 14 caudal vertebrae, a sacrum, two sacral rib fragments, both ischia with fused pubes, two left ilium fragments, complete right ilium, femur, tibia and fibula, a calcaneum, four metatarsals, eight phalanges, nine unguals, and 90 osteoderms.
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Lü and colleagues assigned Xixiasaurus to the family Troodontidae based on its high tooth-count, constriction between the crowns and roots of the teeth, close packing of teeth near the tip of the dentary, and distinct groove for the neurovascular foramina on the dentary. They found Xixiasaurus to be most closely related to Byronosaurus of Mongolia, and suggested the two may have formed a clade with Urbacodon from Uzbekistan consisting of troodontids with unserrated teeth, which radiated across Asia (while noting that serrations had been lost independently in different groups of theropods). A 2012 phylogenetic analysis by the paleontologist Alan H. Turner and colleagues instead found Xixiasaurus to belong in a clade with Sinovenator and Mei (both also from China), due to sharing a maxillary process of the premaxilla that separated the maxilla from the nasal behind the narial opening. In 2016, the palaeontologists Alexander Averianov and Hans-Dieter Sues did not identify a clade formed of troodontids with unserrated teeth, but found them to be successive sister taxa to a more derived (or "advanced") clade of troodontids with serrated teeth.
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In the lineage most closely related to mammals, the jaws of Hadrocodium (about 195M years ago in the very early Jurassic) suggest that it may have been the first to have a nearly fully mammalian middle ear: it lacks the trough at the rear of the lower jaw, over which the eardrum stretched in therapsids and earlier mammaliformes. The absence of this trough suggests that Hadrocodium’s ear was part of the cranium, as it is in mammals, and that the former articular and quadrate had migrated to the middle ear and become the malleus and incus. Hadrocodium’s dentary has a "bay" at the rear which mammals lack, a hint that the dentary bone retained the same shape as if the articular and quadrate had remained part of the jaw joint. However, several studies have cast doubt on whether Hadrocodium did indeed possess a definitive mammalian middle ear; Hadrocodium likely had an ossified connection between the middle ear and the jaw, which is not visible in the fossil evidence due to limited preservation.
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The skull of the Brasilitherium is about in length. The dentary bone in the skull is more slender than in previous ancestors, as well as a slightly smaller skull in general. The genus Brasilodon is different from Brasilitherium due to the lower post canines as well as the pre orbital. Although more studies and more fossils are needed to truly confirm, paleontologists seem to believe that Brasilodon and Brasilitherium are not sister groups and that Brasilitherium is more closely related to mammaliaformes.
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Fish of the genus Henonemus have an opercle with two odontodes (though H. triacanthopomus differs from other Henonemus in that there are three or four odontodes in specimens greater than 80 millimetres or 3.1 in SL) and the teeth of the most posterior row on the premaxilla and the dentary proximally turned to the midline then abruptly bent laterally in the distal half, and arranged in a compact band. They may grow about 4.1-9.4 centimetres (1.6-3.7 in) SL.
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The dentition is the number and type of teeth that an animal possesses. The mammalian jaw is composed of a lower jaw known as the mandible (dentary bone) that houses the lower molars, and an upper jaw commonly referred to as the maxilla that contains the upper molars. The dentition of the Jamaican fig-eating bat is specialized for its frugivorous diet. The first and second upper molars of the maxilla have a broad surface that is used for shearing fruit.
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Loricaria species are recognized by the presence of elongate, slender filaments on the lips and a low number of bicuspid premaxillary teeth (usually three to four per side) that are about twice the length of the dentary teeth. Sexual dimorphism includes hypertrophied development of the pectoral fin spines, blunt odontodes on the pelvic and anal fin spines, and tooth crowns becoming shortened and rounded in mature males. For the four species characterized, karyotypic diversity ranges from 2n = 62 to 2n = 68.
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A species described by Adam Yates, published in 2015, emerging from a study of the left dentary of a thylacinid obtained at the Curramulka fossil site in South Australia. The holotype had been examined by Neville Pledge, who remarked on the possibility of a new species in 1992. The specific epithet combines the name of the region it was discovered, the Yorke Peninsula, and the Latin ellus, a diminutive suffix that denotes a species that was smaller than Thylacinus cynocephalus.
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The edges of the teeth in the front of the jaw likely were not serrated, or at least only at the crown tips. This is usually the case in eusauropods. Teeth further back in the dentary are nearly all damaged, but a not erupted tooth has large denticles similar to basal sauropodomorphs. This pattern of teeth without denticles in front, and teeth with denticles in the back of the lower jaw is also seen in juveniles of Mussaurus and Melanorosaurus.
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In K. guimarotae, the two halves of the dentary diverge from each other at an angle of 20° near the front, then 40° near the back. It also bears two convexities on the bottom of the jaw, one at the third and fourth teeth and another at the eighth to tenth teeth. The latter convexity is replaced by a concavity in K. langenbergensis. In both species, the top margin of the jaw behind the tooth row slopes upwards in a straight line.
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The premaxilla has a smaller posterior process than in Placochelys, only reaching the naris while that of Placochelys reaches the orbit. Most of the other cranial bones are entirely fused, giving Glyphoderma a very strong skull. The temporal fenestrae are about twice as large as the orbits, at 37.3 mm long rather than 25.9 mm. There are two blunt teeth in the posterior part of the lower jaw, but most of the dentary lacks teeth entirely as in the other placochelyids.
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SEM comparison of dentary teeth of Oromycter and Arisierpeton Most of the premaxillary teeth on all the known specimens are damaged near their tips but show clear evidence of tapering crownward. However, all of the preserved teeth also show that they are somewhat spatulate towards the tip of the crown and are unlikely to have had a pointed apex. Most maxillary teeth are damaged in some way. Unfortunately, the preserved maxillary tooth rows are too short to determine if heterodonty was present.
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Life reconstruction of Angolasaurus alongside its contemporary, Angolachelys Angolasaurus was a small mosasaur, with a total length of about 4 meters (13 feet). It shared much of a body plan with its relative Platecarpus, but with a slightly longer skull relative to body length. Its skull housed 11 maxillary teeth, 4 premaxillary teeth, and 12 dentary teeth. The phylogenetic relationship of Angolasaurus indicates that individuals of this genus possessed a tail fluke, more forward-lying nostrils, and keeled scales for hydrodynamic efficiency.
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The skull of Plateosaurus is small and narrow, rectangular in side view, and nearly three times as long as it is high. There is an almost rectangular lateral temporal foramen at the back. The large, round orbit (eye socket), the sub-triangular antorbital fenestra and the oval naris (nostril) are of almost equal size. The jaws carried many small, leaf-shaped, socketed teeth: 5 to 6 per premaxilla, 24 to 30 per maxilla, and 21 to 28 per dentary (lower jaw).
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A non-directional exploitation of morphospace from smaller ancestors with a smaller size restriction is responsible for a large body size in Hyperodapedon. Hyperodapedon have a single row of teeth in mandible bites between their two rows of teeth fixed to a plate which is formed by a union of the maxilla with the palatine. Other key traits are the two maxillary grooves and a single dentary blade, along with missing the infraorbital foramen. The supraoccipital and opisthotics are fused together.
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Fossils of Arganasuchus were first reported by Jean-Michel Dutuit in 1979, who referred a maxilla, dentary, femur, and fibula to Ticinosuchus. These fossils were found in the lower part of unit T5 (the Irohalene Member) of the Timezgadiouine Formation. This geological formation, which is found in the Argana Basin of Morocco, may have been deposited in the Carnian stage of the Late Triassic period. Arganasuchus dutuiti was named and described in 2007 by Nour-Eddine Jalil and Karin Peyer.
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Brochiloricaria is morphologically very similar to Loricaria and can be distinguished from the latter only by its teeth characteristics; in Brochiloricaria, the teeth are very long and of equal size on both jaws, while in Loricaria the premaxillary teeth are almost two times longer than dentary teeth. However, dentition may not be a reliable characteristic to differentiate to genera, so Brochiloricaria may actually be a synonym of Loricaria. Both species of Brochiloricaria reach almost 30 centimetres (12 in) in length.
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All diagnostic traits of Mesosuchus come from the diagnosis of Mesosuchus browni, as it is the only known species. Most of the autapomorphies used to identify Mesosuchus browni pertain to the skull due to the relatively large amount of skull material known. It was a small rhynchosaurian diapsid with multiple rows of maxillary and dentary teeth, with each row consisting of only a small number of teeth. The two premaxillary teeth are approximately twice the size of the maxillary teeth.
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The pattern of grooves and ridges on the crest grows more prominent. The snout tip also starts to straighten in side view, no longer curving upwards. The groove in the dentary deepens and lengthens, as well. No change, however, takes place in the number of teeth, the degree of fusion in the symphysis of the lower jaws, or the shape of the postcranial skeleton, as far as can be ascertained, given the fact that the elements behind the skull were not found articulated.
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The skull has been suggested to be about 10 centimeters long; one axis and dentary comparison to zhelestids and rabbits would make it somewhat smaller at 7.5 centimeters, though this has since been contested.Alexander O. Averianov, J. David Archibald & Eric G. Ekdale, New material of the Late Cretaceous deltatheroidan mammal Sulestes from Uzbekistan and phylogenetic reassessment of the metatherian-eutherian dichotomy, Overall, the available proportions seem to indicate an animal comparable in size to the largest of modern mustelids and mid-sized felines.
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Compared to archaic people, anatomically modern humans have smaller, differently shaped teeth. This results in a smaller, more receded dentary, making the rest of the jaw-line stand out, giving an often quite prominent chin. The central part of the mandible forming the chin carries a triangularly shaped area forming the apex of the chin called the mental trigon, not found in archaic humans. Particularly in living populations, the use of fire and tools requires fewer jaw muscles, giving slender, more gracile jaws.
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I1, the smallest tooth, is sitting on the anteriormost portion of the dentary, with its alveolus left open towards the mandibular symphysis and located as close to the alveolus of I2 as it can. I2, I3, and C1 are very similar, considerably larger than I1. The lower premolars are double-rooted, buccolingually compressed teeth, except the deciduous P1 which is single-rooted. P3 is the second largest cheek tooth, P4 the largest; both are very similar, dominated by the central cusp.
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Russian Academy of Sciences, Palaeontological Institute, Special Issue: 1-50. However, it was later discovered that N. valifanoi was actually a new misidentified specimen of Gobipteryx minuta. The mistake was, at least in part, due to a misidentification of the maxilla and dentary bones of the skull. In 1994, an expedition to the Gobi Desert was conducted by the American Museum of Natural History and the Mongolian Academy of Sciences, where a well preserved Gobiptetyx minuta skull was found in the Nemegt Basin.
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In addition, the original remains of Labrosaurus did not include teeth, and an additional species, Labrosaurus ferox (now considered synonymous with Allosaurus fragillis), was based on a dentary bone bearing teeth of different morphology to those of L. sulcatus. Thus, Rauhut concluded there was no basis for attributing the Tendaguru teeth to Labrosaurus. He tentatively referred all of them except MB R 1084 to Ceratosaurus (under the name Ceratosaurus? stechowi), on the basis of anatomical similarities with teeth from that genus.
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Lydekker noted that Sarcolestes was similar in dental morphology to Priodontognathus, and that together they might be shown to be related to scelidosaurids. However, he also noted that together they may represent their own group within Theropoda. In 1901, Franz Nopcsa found that Sarcolestes was in fact herbivorous, and classified it in Stegosauridae with genera such as Polacanthus, Stegosaurus, Hylaeosaurus, Stenopelix and various others. Peter Galton concluded that Sarcolestes represents a genus within Nodosauridae, with a dentary similar to that of Sauropelta.
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E. platyops skull Unlike the sea turtles Toxochelys and Eochelone, Euclastes has a secondary palate. However, the secondary palate of Euclastes is not as extensive as it is in Ctenochelys and Angolachelys. The genus can be distinguished by later sea turtles based on its broad, low skull; broad, flat palate; wide, flat dentary bone with an elongated symphysis; and low tomial ridge on the beak. The widened palate and dentaries give Eochelone wide, flat jaws suitable for crushing hard-shelled organisms.
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While some of the tusks at the tip are missing, most of the rest of the teeth in the jaw are still present. There are new tusks forming in the sockets, indicating that Brachysuchus regrew teeth all its life. There is a large foramen between the dentary, the angular and the prearticular that passes right through the jaw (visible on the picture). The teeth themselves are asymmetrical in cross-section, with the outer side more convex than the inner side.
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Peramuroides is a genus of extinct mammal from the Early Cretaceous of southern England. The type and only species is Peramuroides tenuiscus, described in 2012 by Brian Davis for dentary fragments and teeth from the Berriasian Lulworth Formation. The genus name references closely related Peramus, while the species name is based on the Latin word for "thin". Peramuroides is closely related to coexisting genera Peramus and Kouriogenys, and along with other genera these make up the family Peramuridae, a group of extinct zatherians.
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Adult T. rex skeleton (the specimen AMNH 5027) at American Museum of Natural History. In 2016, analysis of limb proportions by Persons and Currie suggested Nanotyrannus specimens to have differing cursoriality levels, potentially separating it from T. rex. However, paleontologist Manabu Sakomoto has commented that this conclusion may be impacted by low sample size, and the discrepancy does not necessarily reflect taxonomic distinction. In 2016, Joshua Schmerge argued for Nanotyrannus' validity based on skull features, including a dentary groove in BMRP 2002.4.
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Olshevsky, G., 1991, A Revision of the Parainfraclass Archosauria Cope, 1869, Excluding the Advanced Crocodylia. Mesozoic Meanderings 2, iv + 196 pp Protognathosaurus is known only from a fragmentary lower jaw, holotype CV 00732 (= ChM V732) found in a layer of the Shaximiao Formation dating from the Bathonian-Callovian. The fragment consists of the front left dentary and shows eighteen tooth positions, some still containing sharp replacement teeth, after which the genus was named. Most researchers consider Protognathosaurus to be a nomen dubium.
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The parietals of Allkaruen were long, being 60% of the length of the frontals; the frontals themselves were broad, flat, and extensively pneumatized. The lower jaw was about 3.5 times the length of the section of the skull that is preserved, and it is curved upwards at its tip. The dentary bore four or five tooth sockets in its front half, and in the latter half they were replaced by a groove; this combination is unique among pterosaurs. Allkaruen was a small pterosaur.
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The lower jaw (dentary) of Z. shqiperorum is relatively shorter than the equivalent in Z. robustus, although it is much larger. Ossified tendons are known from the juvenile specimen, showing that they were circular or elliptical in cross section and have fine striations in Z. shqiperorum. Cervical, dorsal and caudal vertebrae are known from Z. shqiperorum, although the former two are only represented by juvenile material. A complete articulated sacrum is known for Z. shqiperorum, with three vertebrae and at least two sacrodorsals.
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The skull and dentary exhibit extreme thickening (pachyostosis) somewhat similar to that in Megaloceros, unlike Megaloceros, the vomer is largely unaffected. The pachyostosis is among the most extreme of any known mammal. The upper canines are absent (there are no sockets for them present on the Aïn Bénian skull) and the lower fourth premolar (P4) is molarised. The preserved proximal portion of the antler is straight and cylindrical in cross section, and orientated anteriorly, laterally and slightly dorsally, the antler becomes flattened distally.
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In lateral view, the dentary shows a prominent ridge running diagonally across the bone. Apart from Chinshakiangosaurus, this feature is only known from prosauropods, where it is interpreted as the insertion point of a fleshy cheek. Such cheeks would have prohibited food falling out of the mouth and may be a hint that the food underwent some degree of oral processing before it was swallowed. If Chinshakiangosaurus indeed was a basal sauropod, this would be the first evidence of cheeks in this group.
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The front of interpterygoid spacing is elongated front to back and narrow from the mid to the sides. Its parabasisphenoid was gently keeled, and the sides of the lower jaw are bowed from the mid to the sides. The mandibular symphysial region is expanded to the sides, nearly equal in width and length. The bottom surface of the dentary close to the mandibular symphysis, to which the splenials contribute on the mid bottom side, shows diverging bars and a midline longitudinal crest.
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One of the main ways Eilenodon can be differentiated from Toxolophosaurus and its other relatives is the fact that the dentary (lower jaw bone) forms almost the entire length of the lower jaw. Nevertheless, the top half of the back part of the jaw is formed by other bones. The coronoid bone characteristically forms most of the outer edge of the tall coronoid process, which attaches to jaw muscles. The surangular bone forms the upper part of the back of the jaw.
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The teeth of Isaberrysaura are heterodont, with recurved premaxillary teeth and lanceolate maxillary and dentary teeth. In extant iguanid lizards, similar dentition is correlated with omnivorous diets, indicating that Isaberrysaura might too have been omnivorous. Isaberrysaura is also estimated to have measured around long, making it of moderate size. The skull in particular is very unusual; it is estimated to be 52 cm long and 20 cm wide across the orbits, and it is almost as high as it is wide.
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This contrasts with the rest of the teeth, which are generally cone-shaped. The single tooth in front of the maxillary fang, as well four immediately behind it are very small. These small teeth are followed by six somewhat larger maxillary teeth and a final small tooth. Five teeth are also present in each premaxilla (a pair of bones at the tip of the snout), with the third tooth being a caniniform tooth similar to that of the maxilla and dentary.
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They also have the secondary palate that other primitive therapsids lacked, except the therocephalians, who were the closest relatives of cynodonts. (However, the secondary palate of cynodonts primarily comprises the maxillae and palatines as in mammals, whereas the secondary palate of the therocephalians primarily comprises the maxillae and the vomer.) The dentary was the largest bone in their lower jaw. The cynodonts probably had some form of warm-blooded metabolism. This has led to many reconstructions of cynodonts as having fur.
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Reconstruction of Cynognathus crateronotus The dentary was equipped with differentiated teeth that show this animal could effectively process its food before swallowing. The presence of a secondary palate in the mouth indicates that Cynognathus would have been able to breathe and swallow simultaneously. The possible lack of belly ribs, in the stomach region, suggests the presence of an efficient diaphragm: an important muscle for mammalian breathing. Pits and canals on the bone of the snout indicate concentrations of nerves and blood vessels.
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The teeth are oval-shaped with a moderately pinched upper end and have coarse denticles, these denticles have three diminutive pointed structures. It appears to be that the dentary teeth were more flattened with a pinched lower end as indicated by nine isolated teeth. In all teeth, a ridge-like structure is located at the center. An isolated and partial right jugal is represented by AMNH FARB 30657, which has lost most of the anterior area in the rostral joint.
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Paracanthopoma parva is a species of catfishes (order Siluriformes) of the family Trichomycteridae. P. parva grows to about 2.7 centimetres (1.1 in) SL and is endemic to Brazil where it occurs in the Amazon and Essequibo River basins. Paracanthopoma parva has been found on the gills of another species of giant catfish, Brachyplatystoma vaillanti. Species within the genus Paracanthopoma have the longest and most robust snout, and the longest and strongest dentary teeth among blood-feeding candirus, which fit their drilling needs.
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There is a distinct notch by the internal nostrils formed of the palatine, pterygoid, and vomer bones; this is a synapomorphy of Aetiocetus + Chonecetus. Synapomorphies of the aetiocetids present in Aetiocetus are: the coronoid process of the dentary, or lower jaw, is well developed; the zygomatic arch is expanded anteriorly and posteriorly but is narrow at the middle. Aetiocetus also shares several traits with all mysticetes. The mandibular symphysis, or the connection between both lower jaw bones, is not fused.
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The genus attracted much interest and became part of a scientific debate about the maximum sizes of theropod dinosaurs. Giganotosaurus was one of the largest known terrestrial carnivores, but the exact size has been hard to determine due to the incompleteness of the remains found so far. Estimates for the most complete specimen range from a length of , a skull in length, and a weight of . The dentary bone that belonged to a supposedly larger individual has been used to extrapolate a length of .
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A part of the jugal is expanded, forming a shelf projecting almost across the tooth row vertically, perhaps protecting the teeth. The mandibles have no teeth preserved, and only one dental alveolus, right at the posterior end of the dentary bone. It is estimated that the whole mandible was about 135-140 mm long. A ridge extends along the external side of the mandible, which may have been for the attachment of soft cheek tissue to prevent plant matter escaping while being chewed as in Notosuchus.
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Therizinosaurids had more specialized skulls compared to primitive members such as Falcarius, which had a generalist, beak-less snout. They had relatively elongated snouts and the tip was covered with a rhamphotheca (keratinous beak) used during feeding. Although the extension of the beak on the dorsal surface of the snout is unknown, it is estimated that it slightly overlapped the nasal cavity as in some modern-day birds. The dentary (lower jaw) also developed a rhamphotheca, seen on the edentulous (without teeth) anterior-most end.
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The four genera were grouped into the one genus Endothiodon. With originally nine species of Endothiodon, Cox was able to narrow it down to just three species based on skull size and robustness of the lower jaw. A fourth species of Endothiodon was found in India that was unique compared to the other three species. It had a small size, a single longitudinal ridge on the snout, an elongated pineal foramen situated on a low boss located midway on the intertemporal bar, and a slender dentary symphysis.
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The teeth come together and act as scissors, which allow the jaw muscles to act at one point at a time, shearing the plant material. In both animals the fleshy tongue is used to hold the plant material in place as the teeth cut through it. In Iguana iguana the pterygoid teeth aid in stabilizing the food, whereas the dentary of Uromastyx moves back to accomplish the same task. The difference in dental morphology between these two taxa is due to distinct tooth replacement strategies.
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The tooth immediately anterior to this un-erupted tooth has a similar superficial morphology as those on the premaxilla, with vertical fluting lingually on the enamel surface. Unfortunately, most of the teeth have lost their crown tips, making it difficult to determine if they were also tricuspid. However, the arrangement of the fluting suggests that there also was a central cone in these teeth and possibly two accessory cusps, or at least incipient accessory cusps. The anterior teeth of the dentary lean forward, as in all caseids.
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Sinoconodon rigneyiPaleofile.com (net, info) . is an ancient mammaliamorph or early mammal (depending on systematic approach) that appears in the fossil record of the Lufeng Formation of China in the Sinemurian stage of the Early Jurassic period, about 193 million years ago. While in many traits very similar to non-mammalian synapsids, it possessed a special, secondarily evolved jaw joint between the dentary and the squamosal bones, which had replaced the primitive tetrapod one between the articular and quadrate bones, a trait commonly used to define mammals.
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Labidiosuchus is characterized by a unique combination of characters, including four autapomorphies (unique characteristics) such as the presence of small teeth on the medial side of the anterior portion of the dentary. Labidiosuchus had a proportionally large number of the teeth (at least eight on each side of the jaw), packed tightly, some located lateral to each other. The first pair of teeth is procumbent and larger than all others. Its mandible is strongly anterodorsally projected and there is a symphyseal platform that holds the teeth.
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Many isolated teeth found throughout Cretaceous Nigeria can be assigned to Goronyosaurus, because of its unique tooth anatomy. Such isolated teeth display a similar polymorphic tapering, with crowns that become blunter towards the back of the tooth row. These fit the morphology of Goronyosaurus to the exclusion of all other mosasaurs, except in the fact that such isolated teeth lack the fluted grooves of Goronyosaurus. Teeth from the front of the dentary are slightly more robust than those more posterior, but still curve gently back.
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This arrangement gives the dentary a very mammal-like or ictidosaur appearance, but the coronoid process is by contrast typically scaloposaurid. It reaches far back and high through the temporal vacuity, but as a long slender extension, somewhat square terminally. There are three large incisors, one short canine only slightly larger than the incisors, and it would appear that the cheek teeth normally count one more than in the upper jaw. The lower teeth are narrower than the upper teeth, but are still distinctly transversely ovate.
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Arboroharamiya is the largest known haramiyidan, estimated to have weighed about 354 g. It has several features in common with living mammals, including a lower jaw formed by a single bone, the dentary, and hands and feet that each have four fingers with three bones each and one finger with two bones. Arboroharamiya is unlike any modern mammal in having a lower jaw that can move up, down, and backward, but not forward. It has a rodent-like dentition with enlarged incisors and molars and no canines.
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The maxilla preserves 14 alveoli, the presence of two concave surfaces suggest an elliptical and elongate antorbital fossa. Based on comparisons with Camptosaurus and Dakotadon, the two isolated teeth are clasiffied as dentary and maxillary, having a shield-shaped crown and lozenge-shaped crown respectively. The scapular bone is almost complete; a denticle is preserved on the predentary, various vertebrae indicate a very iguanodontian-like body shape, specially dorsal vertebrae. The two right metatarsals are classified as metatarsals III and IV based on Camptosaurus and Iguanodon.
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Lariosaurus balsami Lariosaurus valceresii For a nothosaur, Lariosaurus was primitive, possessing a short neck and small flippers in comparison to its relatives. This would have made it a relatively poor swimmer, and it is presumed to have spent much time on dry land, or hunting in shallows. It had a large postorbital region of the skull with the temporal fossae noticeably larger than the orbits. The premaxillary and anterior dentary teeth are strongly elongated, like fangs, and could have acted as a 'fish trap'.
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He also pointed out that since Irritator challengeris holotype lacked the tip of its snout, it would not be possible to know if Spinosauruss dentary could complement it or not. Based on comparisons with Spinosaurus, Kellner resolved Irritator as a spinosaurid and synonymized Irritatoridae with that family. Irritator was then assigned to the Baryonychidae along with Angaturama, Baryonyx, Suchomimus, and Spinosaurus by Oliver W.M. Rauhut in 2003. Thomas Holtz and colleagues in 2004 considered the Baryonychidae synonymous with Spinosauridae, and moved these genera to the latter family.
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Restoration of Agujaceratops mariscalensis Size comparison of Agujaceratops mariscalensis to a human Juvenile Agujaceratops skeleton as reproduced by Triebold Paleontology in Woodland Park, Colorado, USA In 1938, three dinosaur bone beds were excavated, and ceratopsian material was collected from Big Bend National Park (Texas) by William Strain. This material was studied by Lehman in 1989 and named Chasmosaurus mariscalensis. It is known only from the holotype UTEP P.37.7.086 a partial adult skull which includes a braincase, left supraorbital horncore, left maxilla and a right dentary.
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The typical cranial anatomy of a bird. Pmx= premaxilla, M= maxilla, D= dentary, V= vomer, Pal= palatine, Pt= Pterygoid, Lc= Lacrimal The skull consists of five major bones: the frontal (top of head), parietal (back of head), premaxillary and nasal (top beak), and the mandible (bottom beak). The skull of a normal bird usually weighs about 1% of the bird's total body weight. The eye occupies a considerable amount of the skull and is surrounded by a sclerotic eye-ring, a ring of tiny bones.
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Otherwise, the rear part of the skull is rather simple, without any pronounced crests or bosses, although the lacrimal and postorbital bones did have rugose patches in some genera. Aerosteon and Murusraptor possessed a pneumatic quadrate, as in a few allosauroids (Sinraptor, Mapusaurus) and tyrannosauroids. The dentary, which is only known in Australovenator, is long and graceful, with the first tooth smaller than the rest (as in tyrannosauroids). The mandible as a whole has only a single meckelian foramen, as in carcharodontosaurians, tyrannosaurids, and ornithomimids.
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The teeth more to the rear are at least 1.3 times longer than their tooth-sockets are wide. The rear laniary is at least 1.4 times and perhaps 2.4 times longer than the tooth to its rear (which could be an only partially erupted replacement tooth). The longest laniaries are at least 1.5 times taller than the vertical thickness of the front tooth-bearing lower jaw bone, the dentary, at its tallest point. The right lower jaw has a preserved length of fourteen centimetres.
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The front branch of the pterygoid bone makes a right angle to the outer side. The ectopterygoid bone is positioned behind the pterygoid and has a recurved outer side branch in the direction of the jugal as well as a rear branch. Teeth in the maxilla and the dentary bone possess multiple cusps, sometimes as high as six or seven, while erupted teeth with three cusps are absent. The first, second and third maxillary teeth are recurved, with the curvature gradually diminishing along the series.
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Magosternarchus species are immediately recognizable by their large jaws, allowing for a wide gape, and their numerous, large, conical teeth. Both the premaxilla and the dentary bone are elongated, the former bearing two to three rows of teeth (numbering 9-14 in the outermost row) and the latter bearing three rows of teeth (numbering 15-19 in the outermost row). The deeply concave dorsal margin of the opercle also serves to distinguish this genus. The eyes are small and placed towards the top of the head.
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There are several diagnostic features that characterize this specimen as a Biseridens. Related to its heterodont dentition, Biseridens is distinct from other anomodonts because of a differentiated tooth row that includes two rows of teeth on both the jaws, precanine teeth on the dentary and premaxilla, and a broad spread of teeth on the pterygoid and palatine. There are also denticles on the vomer, palatine, and pterygoid. The postcanies possess oval cross sections and have grinding surfaces, and the canines have a basal diameter of 10mm.
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Although both Lydekker (1888) and Vignaud (1995) referred the specimen to the teleosaurid species Machimosaurus mosae, Young et al. (2012) showed that its distinct from Machimosaurus that possess external mandibular fenestrae and an anterior transverse expansion of the mandibular symphysis, whereas NHMUK PV R1089 lacks both features. Furthermore, both species of Machimosaurus lack the prearticular, which is present in NHMUK PV R1089. Additionally, NHMUK PV R1089 exhibits extreme reduction in dentition (13 dentary alveoli compared to 19–25 in Machimosaurus) that is otherwise observed in geosaurine metriorhynchids.
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The long posterior process of the premaxilla almost contacts the anterior process of the lacrimal bone (possible autapomorphy). The ventral process of the lacrimal bone has a slender posterior projection extending along anterodorsal margin of the jugal bone. The jugal is dorsoventrally deep and has a prominent lateral ridge; and the alveolar margin of the dentary is downturned at the symphysis. The postorbital with anterolateral overhang over the orbit; and the prefrontal is large and occupies about 50% of the dorsal margin of the orbit.
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For example, in 2013, Krumlauf and his team configured mutant animals with a double-mutant cluster of HoxA-HoxB genes in their neural crest cells. In these mutant animals, they observed a bone that resembled the dentary along with an attachment of neo-muscle. This helped Krumlauf to determine the HoxB genes are able to enhance a phenotype that was directly caused by the deletion of a HoxA cluster. This helped the research group to assess the cooperation between different clusters of Hox genes.
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The name Brachygnathosuchus (Greek for "short jawed crocodile") refers to its characteristically broad, stout mandible, unusual among crocodilians. The holotype specimen was referred to Crocodilia on the basis of a partial right ramus of the lower jaw consisting of a portion of a very large dentary bone. The bone differs from those of other related fossil and modern crocodilians and was originally said to resemble that of a dinosaur. An eroded osteoderm also associated with the specimen provides further evidence for its classification as a crocodilian.
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The redear sunfish (family Centrarchidae) has thick pharyngeal teeth composed of hard, movable plates, which it uses to crush the exoskeletons of prey. The pharyngeal jaws of the moray eel (family Muraenidae) possess their own set of teeth. The dentary of the ghost knifefish species Sternarchogiton nattereri (family Apteronotidae) has upper and lower pharyngeal tooth plates bearing 9-11 and 7-9 teeth, respectively. The mouth cone ("everted pharynx") of a possible new species of Meiopriapulus, a marine worm in the Priapulida, bears pharyngeal teeth.
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The dentary of the lower jaw was found to be the biggest of all the mandibular parts. There also looked to be approximately 40–50 teeth found on each mandible (both the premaxilla and maxilla), producing marginal teeth. With these teeth Dendrerpeton can both catch its larger prey, and was also found to feed on insects which was determined through examination of fossils and presence of insects in the coal forests. The elements of the skull which are on the surface and exposed have s all over.
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In 1978, the remains of thirty four fossilized musk oxen were discovered by C.S. Bartlett Jr. in a salvage excavation. The spring of 1980, Jerry McDonald discovered the third most complete musk oxen skeleton ever found with a total of 49 bones circa 1983. Fossilized components of a giant short faced bear (arctodus simus) were discovered in 1999 in the form of a canine, and supplementing dentary found a year later nearby. These are the only known carnivorous megafauna that have been found in the Saltville Valley.
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The dentary of P. sattayaraki has a flange similar to that found in P. mongoliensis, P. sibiricus, P. lujiatunensis and P. meileyingensis, although it is less pronounced than in those species. The material appears to be roughly the same size as P. sinensis. The frontal bone of P. neimongoliensis is distinctly narrow compared to that of other species, resulting in a narrower skull overall. The ischium bone of the pelvis is also longer than the femur, which differs from other species in which these bones are known.
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500 is another Gorgosaurus with preserved face bite injuries but also has a thoroughly healed fracture in the right fibula. Also present was a healed fracture in the dentary and what the authors describing the specimen referred to as "a mushroom-like hyperostosis of a right pedal phalanx." Ralph Molnar has speculated that this may be the same kind of pathology afflicting an unidentified ornithomimid discovered with a similar mushroom shaped growth on a toe bone. TMP91.36.500 is also preserved in a characteristic death pose.
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Kollikodon is an australosphenidan species, often classified as a monotreme but more recently recovered as an outgroup. It is known only from an opalised dentary fragment, with one premolar and two molars in situ, as well as a referred maxillary fragment containing the last premolar and all four molars. The fossils were found in the Griman Creek Formation at Lightning Ridge, New South Wales, Australia, as was Steropodon. Kollikodon lived in the Late Cretaceous period, during the Cenomanian age (99-96 million years ago).
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As a result of its small size and heightened vulnerability to predation, this species of crocodile has a heavily armoured neck, back, and tail and also has osteoderms on its belly and underside of neck. Osteolaemus has a blunt short snout, as long as it is wide, similar to that of a Cuvier's dwarf caiman, probably a result of occupying a similar ecological niche. The dentition consists of four premaxillary teeth, 12 to 13 on the maxilla, and 14 to 15 on the dentary bone. O. t.
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The jaws of early synapsids, including the ancestors of mammals, were similar to those of other tetrapods of the time, with a lower jaw consisting of a tooth-bearing dentary bone and several smaller posterior bones. The jaw joint consisted of the articular bone in the lower jaw and the quadrate in the upper jaw. The early pelycosaurs (late Carboniferous and early Permian) likely did not have tympanic membranes (external eardrums). Additionally, their massive stapes bones supported the braincase, with the lower ends resting on the quadrates.
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New dinosaur species may give clues to evolutionary origin of megaraptorid clade ScienceDaily July 20, 2016 Coria & Currie established some distinguishing traits of Murusraptor. The front branch of the lacrimal is longer than the descending branch is high. In the lower jaw, the surangular shows a bone shelf at its outer side, under the groove between the front surangular opening and the notch for the upper rear branch of the dentary, contributing to the side joint. The sacral ribs are hollow and tube- like.
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Out of these, two of the teeth in each socket are replacement teeth like those of Probactrosaurus; the others are active teeth. Every active tooth has one wear facet. Like Probactrosaurus, Gongpoquansaurus, Protohadros, and other hadrosauroids, each maxillary tooth crown has only one ridge, which is slightly offset towards the midline of the mouth. Meanwhile, each dentary tooth crown characteristically bears a primary ridge, and an accessory ridge closer to the midline of the mouth, a condition which is also present in Protohadros and other hadrosauroids.
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A mandibular fragment corresponding to the dentary symphysis was found in natural occluding position. The specimen was collected at the sediments of the Adamantina Formation during the construction of the new railroad station of Buenopolis city of São Paulo. A second species, S. montealtensis has also been described from the Late Cretaceous of Brazil. It was named by Marco Brandalise de Andrade and Reinaldo J. Bertini in 2008, on the basis of MPMA 15-001/90, a nearly complete skull and mandible preserved in occlusion.
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The dentary bone of the lower jaw has ten teeth on either side, with two diastemata separating them. The forward-most teeth are suited for capturing food, while the back teeth are adapted for food processing. The palatine bone in the roof of the mouth connects to the maxilla bone of the snout by a region of bone called the cuneiform process. Caipirasuchus also has large pterygoid and ectopterygoid bones and a well-developed hole in front of the eye sockets called the antorbital fenestra.
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Restoration Based on the remains, the animal is estimated to have been approximately in length. Its skull measures in length and is wide. The bony secondary palate is poorly developed in Silvisaurus, the dentary includes at least twenty-five teeth, the basal tubera of the basioccipital are bulbous, and each premaxilla holds eight to nine teeth. The presence of teeth at the front of the jaw suggests that this may have been a relatively primitive nodosaur, since most later forms had a toothless beak instead.
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Most archosauriforms possess a hole known as a mandibular fenestra where the dentary, angular, and surangular meet. However, it cannot be determined if Vancleavea also possessed this hole. It is plausible that it was lost through evolution (as is the case with the antorbital and supratemporal fenestrae), but there is also the possibility that it was too small to be noticeable in the preserved Vancleavea skull. A small and sometimes overlooked mandibular fenestra is present in Proterosuchus, one of the first archosauriforms to evolve.
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The largest specimen of T. marauna measures long. Like other members of its family, this fish is knife- shaped with a long anal fin extending the length of its body, an electroreceptive appendage on its back, and no dorsal or pelvic fins. The head is long and low, with a rounded snout and a straight dorsal profile. The teeth are elongated and conical, numbering around 15 on the premaxillary bone (at the front of the upper jaw) and around 30 on the dentary bone (the lower jaw).
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D. rugosa is a fairly stout elongated cylindrical fish growing to a total length of about . The snout is fleshy with a number of papillae and tapers towards the front, overhanging the lower jaw. There are two pairs of nostrils, one pair at the tip of the snout and the other pair between the eyes, which are large and circular and covered with skin. There are no premaxillary teeth and the maxillary and dentary teeth are tiny and arranged in a number of irregular rows.
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Fossils of the early whale genus Saghacetus ("Sagha whale", originally named "Zeuglodon osiris") were first collected at Qasr al Sagha by German explorer Georg August Schweinfurth in January 1886 (a well-preserved dentary).Saghacetus is common in the middle of Qasr el Sagha, but there are few other specimens of archaeocetes whales; the only exception being the enigmatic "Prozeuglodon stromeri", named in 1828 based on specimens from 1904, but never adequately described before their destruction during the bombing of Munich in World War II.
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They each connected to a thick yet complex stapes which possessed a conspicuous footplate, stapedial foramen, and a dorsal process. A knob on the outer edge of the stapes likely connected to a characteristic spur on the quadrate. What can be seen of the lower jaw indicates that it was primarily formed by the dentary in its front half, and the low, elongated surangular and angular in its rear half. The coronoid had a low peak and the tall articular had a small retroarticular process.
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This assignment was based on five characteristics, all present in Eolambia: the presence of denticles on the premaxilla; the quadrate's narrow joint with the lower jaw; the narrow dentary teeth; the presence of a single edge, or carina, on each dentary tooth; and the angled deltopectoral crest on the humerus. Caudal vertebrae of Eolambia; note the tall neural spines Within the Hadrosauridae, Kirkland further considered Eolambia to either be a basal member of the Lambeosaurinae, or the sister group of Lambeosaurinae. He identified five characteristics shared with the Lambeosaurinae, as defined across various studies: the absence of a foramen on the premaxilla; the (at least partial) enclosure of the nostril by the premaxilla; the development of a shelf on the maxilla; the very tall neural spines of the caudal vertebrae; the robustness of the humerus; and the large "boot" of the ischium in adults. Kirkland found that two additional traits separated the crestless Eolambia from other, crested lambeosaurines, which were considered as being related to the development of the crest: the elevation of the nasal cavity above the eye socket, and the shortening of the parietal.
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Giganotosaurus ( ) is a genus of theropod dinosaur that lived in what is now Argentina, during the early Cenomanian age of the Late Cretaceous period, approximately 98 to 97 million years ago. The holotype specimen was discovered in the Candeleros Formation of Patagonia in 1993, and is almost 70% complete. The animal was named Giganotosaurus carolinii in 1995; the genus name translates as "giant southern lizard" and the specific name honors the discoverer, Rubén D. Carolini. A dentary bone, a tooth and some tracks, discovered before the holotype, were later assigned to this animal.
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The teeth of C. fraasi are unicuspid and the teeth of C. belgicus are tricuspid. Carinodens fossils from Jordan, consisting of an almost complete skull with at least 24 teeth still occupying their natural locations, a complete neck vertebral series as well as several back vertebrae, and front paddles were reported by Kaddumi (2009). In addition to the dentary, maxillary, and premaxillary teeth, several small pterygoid teeth were also recovered from the same specimen. Kaddumi (2009) fully described the remains and referred them to a new species of Carinodens.
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The size of the teeth varies greatly along the length of the jaws, lending Dimetrodon its name, which means "two measures of tooth" in reference to sets of small and large teeth. One or two pairs of caniniforms (large pointed canine-like teeth) extend from the maxilla. Large incisor teeth are also present at the tips of the upper and lower jaws, rooted in the premaxillae and dentary bones. Small teeth are present around the maxillary "step" and behind the caniniforms, becoming smaller further back in the jaw.
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At least two different tooth morphologies are observed among therizinosaurids; the first is represented by relatively homodont, oval to lanceolate-shaped teeth with moderate coarse denticles (serrations) on the crowns (upper exposed part). This type of dentition is better represented by the complete, three-dimensional holotype skull of Erlikosaurus which features the mentioned characters. Two isolated teeth are known from the therizinosaurids Nothronychus and they are lanceolate-shaped, symmetrical, have moderate denticles, and strongly resemble those of Erlikosaurus. Furthermore, they seem to derive from the dentary based on comparisons with Erlikosaurus.
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The preserved holotype dentary tip of Neimongosaurus preserves an erupted tooth that is lanceolate-shaped with small coarse serrations, falling within this type of dentition. Another type of dental morphology is the one seen on the highly specialized Segnosaurus. In this taxon, the teeth are very heterodont, leaf-shaped with relatively less denticles that are prominently developed being bigger than in the previous therizinosaurids. These denticles are composed of numerous folded carinae (cutting edges) with denticulated front edges, creating a roughened and shredding surface near the base of the tooth crowns.
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Itilochelys rasstrigin is known only from three fossils, the holotype, specimen number "ZIN PH 1/118" and two referred specimens, numbers "ZIN PH 2/118" and "ZIN PH 3/118" . The type specimen is composed of a grouping of cervical vertebrae I-III, partial skull, and disarticulated lower jaw. Specimen ZIN PH 2/118 is an isolated section of dentary while ZIN PH 3/118 is a right humerus. The fossils were all recovered by A. A. Yarkov from fossiliferous outcrops of the Beryozovaya beds exposed at the Rasstrigin 2 locality.
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52); however, the species has no accepted common name. This species is suspected of being paedophagous, because it shares attributes of its dentition, a heavy dentary or lower jaw, and thickened oral mucous membrane in which the teeth are buried, all characteristics found especially in other known paedophagous cichlids (Oliver 2012: 45). However, this diet has not been confirmed since neither behavioral observation nor analysis of its stomach contents has been possible. It has been found only at two widely separated localities in Malawi, Thumbi Island West at Cape Maclear and Nkhata Bay.
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Endothiodon and Emydops skulls Endothiodon was first discovered by Richard Owen in 1876 in the Karoo region of Beaufort Group, South Africa based on a skull and mandible. The genus was described based on the anterior portion of a snout and the corresponding part of the dentary, creating an upturned beak. Several more specimens have since been collected, many of them in the Beaufort Group in South Africa, it is here that the first partial skeleton was discovered by Broom in 1915. In the 1970s a skull and lower jaw was discovered in Brazil.
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Ferrodraco ("Iron Dragon" after the ironstone the fossil was found in) is an extinct genus of ornithocheirid pterosaur known from the Late Cretaceous Winton Formation of Queensland, Australia, containing the single species F. lentoni. The species was named after the former mayor of Winton, Graham Thomas ‘Butch’ Lenton. It is the most complete pterosaur fossil from Australia, being known from the holotype specimen AODF 876, consisting primarily of the anterior portion of the skull and dentary, cervical vertebral centra and a partial wing. Its wingspan was estimated to be about .
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The choanal septum is also ridged on the ventral surface. An autapomorphic single parachoanal fossa rostrolateral to the parachoanal fenestrae is present at the base of the pterygoid wing. In the lower jaw of Aplestosuchus, the outer sculpture of the mandible is limited to the dentary, and the occipital surface of the mandibular symphysis lack a peg. Additionally, the ridged border of the angular is not covering the rostral edge of the mandibular fenestra, and a row of foramina is present between the mandibular fenestra and the ectopterygoid-jugal suture.
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This is another distinguishing characteristic of Yonghesuchus, as other early archosauriforms have shorter and wider basisphenoid bones. Moreover, the entrance of the internal carotid artery, which passes through a foramen in the basisphenoid to supply blood to the brain, is in a different position than related genera. Its position is more similar to that of Dorosuchus (a euparkeriid) and more derived archosauriforms. In the lower jaw, the dentary bone has two projections at its posterior end where it attaches to the mandible, the higher one being markedly longer than the lower one.
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Labidiosuchus is known only from the holotype specimen DGM 1480-R, an incomplete lower jaw with the anterior part of the dentary complete, lacking most of the right mandibular ramus and the end of the left mandibular ramus. It is housed at the Earth Science Museum of the Departamento Nacional da Produção Mineral. A cast is housed at the Departamento de Geologia, Universidade Federal do Rio de Janeiro. It was found in Serra do Veadinho site, Municipality of Peirópolis of Minas Gerais State, from a site in which Itasuchus, yet another enigmatic mesoeucrocodylian, was found.
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The specimen consists of an incomplete but partly articulated skull and a number of cervical vertebrae exposed in ventral view on a small slab of pink-grey limestone. The skull includes a fragmentary right maxilla (with teeth), the co-ossified frontals and parietals, right jugal, postorbitofrontals, supratemporals, squamosals, quadrates, the right dentary and fragmentary postdentary bones; the occipital region of the skull is hidden beneath a calcareous deposit. Some elements, such as the jugals, are preserved only as impressions. The skull is small, measuring only 60-70 millimeters in length.
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Teeth were present only in the maxillae (upper cheeks) and dentaries (main bone of the lower jaw). They grew in columns, with an observed maximum of six in each, and the number of columns varied based on the animal's size. There were 51 to 53 columns per maxilla and 48 to 49 per dentary (teeth of the upper jaw being slightly narrower than those in the lower jaw). Life restoration E. regalis had thirteen neck vertebrae, eighteen back vertebrae, nine hip vertebrae, and an unknown number of tail vertebrae.
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Dentition The skull is in good preservation and is nearly complete, missing only the ventral lacrimal, the posterior jugal, the postorbital, the anterior edge of the quadrate, and the anterior surangular bones. Jianchangosaurus possesses 27 maxillary teeth and approximately 25 to 28 dentary teeth. The researchers observed, however, that at front of the upper jaw the premaxilla is edentulous and they hypothesized that it was covered by a rhamphotheca. This is also supported by the presence of a series of foramina along the buccal margin on the lateral surface of the premaxilla.
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The right jaw is better preserved than the left; at least 13 teeth were present in the right maxilla (the main tooth- bearing bone of the upper jaw), and 17 to 18 teeth were present in the right dentary, which held teeth in lower jaw. There was an unusually tall bony process on the coronoid, a bone of the lower jaw. Impressions of part of the brain and other cranial nervous tissue were found in the braincase. The backbone is incomplete, but 51 neck, 17 back, four sacral, and 12 tail vertebrae were preserved.
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The skull would have been slender and triangular, with large, fang-like teeth at the front, and smaller teeth towards the back. It had six teeth in each premaxilla of the upper jaw, and may have had 14 teeth in the maxilla and 19 in the dentary of the lower jaw. Most of the neck vertebrae were compressed sideways, and bore a longitudinal crest or keel along the sides. The family Elasmosauridae was based on the genus Elasmosaurus, the first recognized member of this group of long-necked plesiosaurs.
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The dentary projects somewhat posteriorly, forming the edge of the external mandibular fenestra. Both angular and surangular extend to the top of the coronid process, and the surangular forms much of the jaw articulation. The articular has a glenoid for the quadrate condyles; it is saddle-shaped, with no anterior or posterior lip, although there is a prominent attachment crest posteroventral to the jaw joint. The teeth have subconical crowns that curve in towards the centre of the mouth; all are fairly small and not very worn, indicating relatively little use.
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Skeleton of Probactrosaurus, the taxon just outside Hadrosauromorpha Probactrosaurus was selected as the outgroup to Hadrosauromorpha because of numerous differences that Norman (2014) thought to be significant. The tooth crowns in the dentary are asymmetrical and have multiple vertical ridges; there is a foramen in the surangular; and the quadrate bone has a more prominent depression for the articulation of the jugal. None of these features are found in the skulls of the more derived hadrosauromorphans. The premaxilla contacts the prefrontal, and the jugal contact with the ectopterygoid bone of the palate is reduced.
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Colosteids were unique compared to most stegocephalians in the fact that a pair of palatal fangs were present on the premaxillary bones at the tip of the snout. In conjunction with the forward position of these fangs, the dentary bones of the lower jaw developed a notch on either side near the symphysis (chin). The symphysis itself is formed by a rough area of bone on the left and right dentaries. This rough patch is formed by a complex system of ridges, which have been described as "brassicate" (textured like a cauliflower).
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This genus is characterized by a short skull, and has fewer teeth than any other mosasaur (around 10 teeth in each dentary).Burnham (1991) recently reported an unclassified species of Plioplatecarpus from the Lower Demopolis Formation in Alabama that has a lower number of teeth in its jaws. LACM 128319 preserves matter within the sclerotic ring that may possibly be the retina of the eye. Small structures in the retina, each around 2 µm long and observed by scanning electron microspectroscopy, may represent retinal melanosomes preserved in their original positions.
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However, the short mouth, blunted edges of the lower jaw, and the lack of a tough palatal surface against which the jaw could grind downplay the significance of this apparent shearing component. The morphology of the jaw hinge prevents the anterior end of the lower jaw from meeting the palate, only allowing palatal contact with the more posterior portion of the dentary. While there is little possibility of any transverse movement in the lower jaw, a crushing function is possible, and consistent with the feeding mechanism observed in other Emydopoids.Cox, C. B. 1998.
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In fact, despite the name meaning "grass-eating beast" it is likely that Poebrotherium was either a browser or a mixed-feeder, and grass may have played a minimal role in the diet of Poebrotherium. Milan Natural History Museum Right dentary dentition of a juvenile P. wilsoni from the White River Badlands. Unlike its modern cousins, which are either adapted for desert or alpine conditions, Poebrotherium took the place of a gazelle or deer in the White River Fauna ecosystem. This trait was taken to an extreme in later camels, notably Stenomylus.
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In the lower jaw, a ridge on the outer surface of the angular bone articulated with the rear of the dentary bone, creating a locking mechanism unique to Tarbosaurus and Alioramus. Other tyrannosaurids lacked this ridge and had more flexibility in the lower jaw. Restoration of an adult and subadult Tarbosaurus next to a human Tyrannosaurids varied little in body form, and Tarbosaurus was no exception. The head was supported by an S-shaped neck, while the rest of the vertebral column, including the long tail, was held horizontally.
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The specific name honours Kenneth Carpenter for his work on dinosaurs in general and iguandonts in particular. David Norman, in 2013, considered Paul's description of Mantellodon to be inadequate, identical to that given by Paul of Darwinsaurus and entirely incorrect, noting that no dentary is preserved in the holotype specimen, and that the preserved forelimb elements "are gracile, carpals are not preserved, the metacarpals are elongate and slender, and a thumb spike is not preserved". Norman considered the holotype specimen of Mantellodon carpenteri to be referable to the species Mantellisaurus atherfieldensis.
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Taxonomy, phylogeny, biostratigraphy, biochronology, paleobiogeography, and evolution of the Late Triassic Aetosauria (Archosauria: Crurotarsi) Zentralblatt für Geologie und Paläontologie Teil I 1998 Heft 11–12:1539-1587Long RA, Murry PA. 1995. Late Triassic (Carnian and Norian) tetrapods from the southwestern United States. New Mexico Museum of Natural History and Science Bulletin 4:1-254 recent work has found it generically distinct from Stagonolepis proper. This is because more material from the same species has been discovered, including a dentary bone, a possible maxilla, and further vertebrae from the neck and trunk.
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Tesis (Grado) Universidad Nacional de Córdoba, Córdoba. Additionally, the authors suggested that a lateral rim on the dentary as well as numerous aligned neurovascular foramina are evidence of soft cheek-like muscular tissue. The function of the trunk was likely used for searching for food by sniffing the ground in a manner similar to extant suids and peccaries, while the cheeks would aid in mastication by preventing food loss. A re-description of the skull material has since lent evidence toward minimal soft-tissue enhancement to the snout of Notosuchus.
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A very striking feature of P. sibiricus is the number of 'horns' around the eyes, with three prominences on each postorbital, and one in front of each eye, on the palpebral bones. Similar horns found on the postorbital of P. sinensis are not as pronounced but may be homologous. The jugal has extremely prominent 'horns' and may contact the premaxilla, both features also seen in the possibly related P. sinensis. There is a flange on the dentary of the lower jaw, similar to P. mongoliensis, P. meileyingensis, and P. sattayaraki.
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The jugal in Sahitisuchus is very large and ornamented, and as previously observed only in Bretesuchus, its rear ramus is higher than the anterior process and expands laterally. As in Bretesuchus and Sebecus, it has a rough longitudinal ridge on the lateroventral edge of angular bone and dentary, that ends near the mandibular symphysis level. Cervical vertebra The frontal bone is broad and triangular and ornamented similarly to the maxilla. As in many basal mesoeucrocodylian taxa, which includes some sebecosuchians like Lorosuchus, Sebecus, Zulmasuchus, Iberosuchus and Pepesuchus, a longitudinal frontal crest is present.
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Occlusion refers to the closing of the dinosaur's mouth, where the teeth from the upper and lower parts of the jaw meet. If the occlusion causes teeth from the maxillary or premaxillary bones to cover the teeth of the dentary and predentary, the dinosaur is said to have an overbite, the most common condition in this group. The opposite condition is considered to be an underbite, which is rare in theropod dinosaurs. The majority of dinosaurs had teeth that were similarly shaped throughout their jaws but varied in size.
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C. aguti from above Although a subfamily of Captorhinidae, Moradisaurinae, also possessed multiple-tooth-rows, the best-known type species Captorhinus aguti clearly acquired multiple-rowed-teeth independently. In contrast to the teeth rows in moradisaurines, the C. aguti rows are oriented obliquely to the margins, where each row is followed posterolaterally by the next one.Fox 1966 The toothed areas of the maxilla and dentary are broader in C. aguti than in single-tooth-rowed captorhinids. The vertebral structure in C. aguti is that commonly possessed by primitive reptiles.
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Rhabdodontids have a simple dentition with leaf-shaped teeth used for a powerful scissors-like shearing. These teeth are well-suited to a diet of tough and fibrous plants, examples of which include monocts and grass. Each tooth has a ridge on it that is offset from the midline of the tooth. These ridges also have a specific pattern which is unique to Rhabodontids: their dentary teeth have a central primary ridge with multiple equally spaced secondary ridges, and their maxillary teeth have no primary ridge and have similarly-sized secondary ridges.
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All non-mammalian amniotes use this system including lizards, crocodilians, dinosaurs (and their descendants the birds) and therapsids; so the only ossicle in their middle ears is the stapes. The mammalian jaw joint is composed of different skull bones, including the dentary (the lower jaw bone which carries the teeth) and the squamosal (another small skull bone). In mammals, the quadrate and articular bones have evolved into the incus and malleus bones in the middle ear. The mammalian middle ear contains three tiny bones known as the ossicles: malleus, incus, and stapes.
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Mature Azendohsaurus madagaskarensis have at least 44 pairs of palatal teeth, in addition to the 4 teeth in each premaxilla and 11–13 in the maxilla each, along with a maximum of 17 teeth in the dentary. Palatal teeth are not uncommon in herbivorous reptiles, but in Azendohsaurus they are almost identical in shape to those along the jaw margins, but a bit stouter. Other archosauromorphs with palatal teeth have a much simpler palatal dentition of small, domed teeth. Teraterpeton is the only other archosauromorph with similarly well developed palatal teeth.
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Mantell, G.A., 1848, "On the structure of the jaws and teeth of the Iguanodon", Philosophical Transactions of the Royal Society of London 138: 183-202 By present conventions, the type species is written as Regnosaurus northamptoni. Regnosaurus is known only from the holotype BMNH 2422, a right mandibular (lower jaw) fragment, consisting of a third of the dentary and a part of the splenial, found in the Tunbridge Wells Sand Formation. The specimen is six inches long and shows fifteen tooth sockets. Also some replacement teeth are visible.
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In front of this orbit, the lacrimal bone has a long and robust horn-like process, oriented sideways at its base and gradually curving upwards at its tip. The generally recurved teeth are more slender and tightly packed in the front of the jaws, such as in the praemaxilla and the anterior part of the dentary in the lower jaw. Further back the teeth become larger and widely spaced. The tooth row in the upper jaw is exceptionally long, reaching to a position below the front of the eye socket.
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Spalacotherium is a genus of extinct mammal from the Early Cretaceous of Europe. The type species Spalacotherium tricuspidens was originally named by Richard Owen in 1854, and its material includes maxillary and dentary fragments and many teeth from the Berriasian Lulworth Formation of southern England. Referred species include S. taylori, S. evansae and S. hookeri also from the Lulworth deposits, and S. henkeli from Barremian deposits of Galve, Spain. The Lulworth taxon Peralestes longirostris, named by Owen in 1871, is a junior synonym of the type species S. tricuspidens.
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It has been moved to the new genus Uteodon. Cast of a skull from Bone Cabin Quarry West, Wyoming While Marsh was describing Camptosaurus species in North America, numerous species from Europe were also referred to the genus in the late 19th and early 20th centuries: C. inkeyi, C. hoggii, C. leedsi, C. prestwichi, and C. valdensis. C. inkeyi (Nopcsa, 1900) consists of fragmentary material, a dentary and articular from Upper Cretaceous rocks of the Haţeg Basin in Romania. It is almost certainly a rhabdodontid and is no longer considered valid (nomen dubium).
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Chiromyoides is a small plesiadapid primatomorph that is known for its unusually robust upper and lower incisors, deep dentary, and comparatively small cheek teeth. Species of Chiromyoides are known from the middle Tiffanian through late Clarkforkian North American Land Mammal Ages (NALMA) of western North America, and from late Paleocene deposits in the Paris Basin, France. The unique dental morphology of Chiromyoides has led several authors to propose a specialized ecological role for the genus. Gingerich (1976) hypothesized that Chiromyoides was a specialist on seeds, while Szalay and Delson (1979) and Beard et al.
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Since the bones are well-preserved and had no gnaw marks, the carcass appears to have been undisturbed by scavengers (suggesting that it was quickly covered by sediment). The disarticulation of the bones may have been the result of soft-tissue decomposition. Parts of the skeleton seem to have weathered to different degrees, perhaps because water levels changed or the sediments shifted (exposing parts of the skeleton). The girdle and limb bones, the dentary, and a rib were broken before fossilisation, perhaps from trampling by large animals while buried.
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They have carinae, or sharp edges, that are weakly serrated. Serrations are more evident along the rear edge the posterior teeth in the back of the jaw, which are also recurved and laterally compressed (flattened from the side), resembling the less unusual teeth of other carnivorous dinosaurs. The margin of the dentary curves downward so that the alveoli (tooth sockets) of the front teeth are directed forward. In fact, the alveolus of the first tooth is actually situated lower than the bottom edge of the rest of the lower jaw.
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One autapomorphy (unique trait) was used to diagnose the taxon as a new species: a very elongated edentulous section on the dentary, which was medially (inwardly) extended. No teeth were preserved, but there are 35 tooth positions. Several other European hadrosaur dentaries were compared based on published data, and the specimen was found to be unique compared to all of them. Though the specimen proved too fragmentary to be used for phylogenetic analysis, it was determined to be a hadrosaurid of some kind, more derived than Pararhabdodon, considered the sister taxon to Hadrosauridae.
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Material from these quarries was described in 2012 by Kirkland along with Andrew McDonald, John Bird, and Peter Dodson, who also provided an updated diagnosis for Eolambia based on this material. One specimen discovered at the Cifelli #2 quarry, a right dentary catalogued as CEUM 34447, is unusual compared to other Eolambia specimens, including both adults and juveniles. While the ratio between the mid-point depth and overall length of the dentaries in other individuals generally ranges from 0.19 to 0.24, the same value in CEUM 34447 is 0.31, making it unusually deep.
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There is a rounded mental foramen (an opening in the labial side of the jawbone), with a diameter of 0.7 mm, located about 0.8 mm below the dorsal margin of the bone and 1.5 mm in front of the p4. Although the incisor itself is not preserved, its alveolus (the housing of the root) is in part. As in Sudamerica, it extends far into the dentary, passing below p4. The alveolus is 1.5 mm wide below the front root of p4 and 1.4 mm at the back of the jaw fragment.
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In terms of jaw morphology, a full prenarial crest is a distinctive anatomical feature for Nicrosaurus kapffi. In both the upper and lower jaw, the dentition has five morphologically separated arrays of teeth: tip-of-snout set, premaxilla set, maxilla set, tip-of-mandible set, and dentary set. Moving posteriorly in all of these sets, except the tip-of-the- snout and tip-of-mandible sets, tooth morphology starts out relatively simple and undifferentiated and gradually changes, resulting in a morphocline. The upper dentition is considered to be tripartite.
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The teeth are closely packed but between the front twenty-four teeth and the rear eight teeth, a distinctive gap is present, a diastema. This is a unique trait but was not formally designated as an autapomorphy because it might be the result of individual variation. Urbacodon resembles Byronosaurus and Mei but differs from most other Troodontidae in that its teeth lack serrations. Urbacodon is distinguished from Byronosaurus by a less vascularized lateral dentary groove and more bulbous anterior tooth crowns, and from Mei by considerably larger size.
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Casts of the holotype, IVPP FV 1794, are held at the Institute of Vertebrate Paleontology and Paleoanthropology. ZCDM V0031 was collected in the Xingezhuang Formation from the Wangshi Group at Zangjiazhuang quarry, Zhucheng City, dating to the Campanian stage, at least 73.5 million years ago. A second tyrannosaurid dentary (ZCDM V0030) and maxilla (ZCDM V0032) have also been collected at Zangjiazhuang quarry. Even though they were not associated with one another, both specimens are different from other tyrannosaurids, including Zhuchengtyrannus, implying the existence of at least one additional tyrannosaurid from the quarry.
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Both Rhynchonkos and caecilians possess a primitive combination of palatal bones, including the ectopterygoid. The two taxa also have rows of teeth on the palate in addition to the marginal rows on the maxilla and premaxilla. Carroll and Currie also mentioned that Rhynchonkos and caecilians have a pleurosphenoid that joins the otic-occipital portion of the braincase with the sphenethmoid, a characteristic which they considered unique among amphibians. The adjacent tooth rows on the coronoid and the dentary of Rhynchonkos were also considered a characteristic that linked it with caecilians.
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They had a shorter ribcage and larger lungs which allowed more efficient respiration. Their lower jaw comprised a single bone -- the dentary (as opposed to the multiple bones in the jaws of their ancestors, or seven different bones found in reptilian lower jaws). The other bones which once made up the jaw had reduced, and in later mammals would become incorporated into the middle ear, enhancing their hearing. Probably the most important change in the evolution of the first mammals was that their ancestors, the cynodonts, had become warm- blooded.
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The 2006 publication, however, established that the majority of specimens were adult, and that Europasaurus was an island dwarf. The number of individual sauropod bones had increased to 650 and include variously articulated individuals; the material was found within an area of squared. From these specimens, the holotype was selected, a disarticulated but associated individual (DFMMh/FV 291). The holotype includes multiple cranial bones (premaxilla, maxilla and quadratojugal), a partial braincase, multiple mandible bones (dentary, surangular and angular), large amounts of teeth, cervical vertebrae, sacral vertebrae and ribs from the neck and torso.
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In 1996, a newly described partial skull known as IVPP V8266 that was referable to Platyognathus was designated as a neotype. It was collected in 1984 from the Lower Lufeng in Yunnan. The authors of the paper that described the neotype agreed with the previous studies that the material described in 1965 does not belong to Platyognathus because CUP 2083 lacks many of the features of the holotype. In CUP 2083, the mandibular symphysis is unfused, there is a single caniniform tooth in the dentary, and there is no groove along the symphysis.
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It is different from Guanlong in lacking a medial crest on the premaxilla, nasals and frontal bones. It also lacks high external nostrils, and a short anterior maxillary process. It has a shorter premaxillary body, but with a larger maxillary fenestra, a rodlike jugal, closely spaced fine serrations on the distal tooth carinae of the maxilla and dentary. The cervical vertebral centra are elongated with two pneumatic foramina, the neural spines are short and elongated towards the posterior in the dorsal vertebrae, and the pubic shaft is curved at the end.
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To date, the only material of Pelagiarctos that has been found includes a handful of partial mandibles. The mandibles themselves are approximately the same size as those of the contemporaneous pinniped Allodesmus kernensis, but differ in that the cheek teeth have two roots (instead of one, as in Allodesmus) and that the dentary itself is much thicker. They are also highly vascularized and covered in unusually large mental foramina, indicating that Pelagiarctos may have had somewhat fleshy lips. The cheek teeth resemble those of several terrestrial carnivores, specifically borophagine dogs and hyaenids.
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The opisthotics, which sat at both sides of the basioccipital, had extensions pointing backwards and upwards, the paroccipital processes. These processes were elongated and slender in Acamptonectes and Ophthalmosaurus icenicus, but short and stout in other ophthalmosaurids. The dentary, the tooth-bearing bone of the lower jaw, was elongated, straight, and had a blunt front tip, contrasting with the downturned and beak-like tips of some platypterygiines. The splenial bones expanded hindwards in depth to form the lower border of the mandible and much of its midline surface.
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Each side of the mouth bore 24 teeth, relatively evenly spaced save for the sixth and seventh, the dental alveoli of which have merged. Each side of these jaws is gently bowed outwards horizontally, curving more strongly towards the symphysis of the two dentary bones from the seventh alveolus forwards. The symphysis itself is relatively small and weak compared to other crocodyliforms, suggesting a very weak bite, although the bones are fully fused. The jaws are also bowed slightly, curving downwards from the articular facet and then back upwards to the symphysis of the jaws.
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In most snakes, teeth are located on the dentary of the lower jaw, the maxilla, the palatine bone and the lateral pterygoid plate. The latter form an "inner row" of teeth that can move separately from the rest of the jaws and are used to help "walk" the jaws over prey. Several snake lineages have evolved venom which is typically delivered by specialized teeth called fangs located on the maxilla. Most snakes can be placed into one of four groups, based on their teeth, which correlate strongly with venom and lineage.
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Many of the remains discovered were then be sent to the collections of the Museum of Paleontology at the University of California, Berkeley (UCMP), where they are still housed. The description of the specimens did not come until 1965, when the American paleontologist Wann Langston Jr. published his monograph Fossil Crocodylians from Colombia, in which he made a detailed analysis of several fossils of crocodylomorphs in Colombia, including the remains of other species as Purussaurus neivensis, Mourasuchus atopus, Gryposuchus colombianus and Charactosuchus fieldsi (plus a possible dyrosaurid) As for the sebecid material he designated the dentary UCMP 37877 as the holotype of a new species a fragmentary taxon, which he called Sebecus huilensis; thus extending the time range of this genus and the family, hitherto known only from remains of the Eocene of Argentina. Langston gave the taxon a new species considering that besides being larger, as the dentary fragment is 68% larger than the Argentine species, S. icaeorhinus, it was also proportionally thinner, and had with more recurved teeth being laterally compressed. Additionally Langston referred a series of zyphodont teeth in the area found this species, with some teeth referred to as similar but classified generally to Sebecus sp.
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Australovenator is based on a theropod specimen (AODF 604), affectionately nicknamed "Banjo" after Banjo Paterson, which was found intermingled with the remains of the sauropod Diamantinasaurus matildae at the "Matilda site" (AODL 85). The parts of the holotype as it was initially described, which are held at the Australian Age of Dinosaurs Museum of Natural History, consists of a left dentary, teeth, partial forelimbs and hindlimbs, a partial right ilium, ribs, and gastralia. Australovenator was described in 2009 by paleontologist Scott Hocknull of the Queensland Museum, and colleagues. The type species is A. wintonensis, in reference to nearby Winton.
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The lower jaw is articulated to the skull, which is between the squamosal and the dentary which isn't seen in other cyandonts. When looking the jaw of Brasilitherium, one could say that it is closely related to Thrinaxodon, but paleontologists have concluded that they are not closely related, but simply have convergent evolution. The skull shows quadrangular upper post canines and asymmetrical lower post canines. Post- canines are constantly getting replaced in this taxon and they are replaced in an alternate sequence, meaning they are not getting replaced next to each other at the same time.
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ODAN-A-22, as well as the dentary PSMUBB.ODAN-A-24 - to this family. The family is diagnosed by the above traits as well as the presence of lappets of the parietals (shared by teiioids and lacertids), the constriction of the frontals to between the eye sockets, the widening of the squamosal bones at the rear; and the absence of a prearticular crest as well as the presence of a pterygoideus process on the prearticular bone of the lower jaw. It is unclear how closely related barbatteiids are to Meyasaurus, due to a lack of comparable bones beyond the skull.
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Sereno countered that it would be difficult to determine a size range for a species based on few, incomplete specimens, and both paleontologists agreed that other aspects of these dinosaurs were more important than settling the "size contest". In 1998, the paleontologist Jorge O. Calvo and Coria assigned a partial left dentary bone (part of the lower jaw) containing some teeth (MUCPv-95) to Giganotosaurus. It had been collected by Calvo near Los Candeleros in 1988 (found in 1987), who described it briefly in 1989, while noting it may have belonged to a new theropod taxon.
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The differences that make the two genera distinguishable and the species distinguishable from other dicynodonts are seen in the dentary. The ventral profile slopes upward and forward from the splenial to the tip of the beak, the front and side margins of the beak are sharp, and the symphysis tapers to a squared-off anterior margin as opposed to being parallel sided. The most distinctive feature that defined the new genus at the time was the lack of a pineal opening. This led Hotton to the determination that the fossils belonged to a new Dicynodont species, Kombuisia frerensis.
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More recently, new material belonging to T. jacobsi has been found, including a nearly complete left side of the skull that clearly shows that it belongs to the genus Trilophosaurus and is not a procolophonid. Since Variodens is thought to be closely related to T. jacobsi, it too is probably a trilophosaur rather than a procolophonid. Whiteside & Duffin (2017) agreed with Robinson's original interpretation of V. inopinatus as a trilophosaur, noting that tooth implantation of the specimen (fragment of a left dentary) described by the authors is ankylothecodont, as described for Trilophosaurus by Heckert et al. (2006).
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A second row of openings runs parallel to the lower jaw edge and ends at the thirteenth tooth position, which is exceptionally far. At the inside of the dentary, the Meckelian groove at the level of the third tooth extends to the front into two superimposed narrow slits. The rear of the lower jaw shows a unique combination of a kinked suture between the angular and the surangular, and the basal trait of the surangular reaching the rear jaw edge. The rather small foramen surangulare posterior is not overhung by a thick bone shelf, which is rare among large theropods.
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These areas probably had a horny covering in life. The broad groove running along the tooth row on the dentary was probably also covered by a horny layer. It is possible that these regions allowed for occlusion where the upper teeth met the groove lateral to the lower teeth and the lower teeth met one of the regions of the palatine. This is still under scrutiny as the palatine region is short in comparison to the lower tooth row and the second horn covered area on the palatine does not oppose any structure in the lower jaw.
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Its perinarial fossa was a common characteristic among mesoeucrocodylians, and it also lacked a notch in the upper jaw to receive an enlarged lower caniniform tooth; both characteristics were likely plesiomorphic for the group Notosuchia. Razanandrongobe had forward-facing bony nostrils like sphagesaurids (Caipirasuchus shown) In Razanandrongobe, the incisive foramen was larger than most mesoeucrocodylians, while the robust palate on the maxilla was more typical. The upturning of the dentary was most like Baurusuchidae and Kaprosuchus, but Uruguaysuchus and Peirosauridae also had dentaries that tapered upwards in an arch. Unlike Uruguaysuchus, the tooth sockets were not fused.
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The very small size of the Whitakersaurus fossil suggests that it may have been a juvenile, although the characteristic 'hatchling dentition' that would normally be found here is only present for the last two teeth. It is also not that much smaller than many other sphenodontians. It has fewer dentary teeth than many of its relatives, and fewer of them are pleurodont. Whitakersaurus is significant because, as well as being the most complete rhynchocephalian from the Chinle Group, it has many primitive features indicating it is a relatively basal sphenodont, but also a few more derived features.
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Rotating CT scan of the right dentary of the holotype The four individuals were found in localities at the base of the Morrison Formation's Brushy Basin Member, in crevasse splay sandstones deposited in floodplains. The Fruita localities preserved a contemporaneous fauna including snails, clams, crayfish, various insects (represented by trace fossils), the lungfish Ceratodus, ray–finned fish, the turtle Glyptops, rhynchocephalian reptiles Eilenodon and Opisthias, several genera of lizards, a mesosuchian crocodylomorph, and the mammals Fruitafossor, Glirodon, and Priacodon. Disarticulated dinosaur fossils are common in the area. Fruitadens was probably bipedal and cursorial, and is suggested to have been omnivorous.
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The longest is metatarsal III with a length of ; it is placed more anteriorly than the other metatarsals. Metatarsal I is more posterior and its upper part is transversely reduced to a splint. Some distinguishing traits of Jeholosaurus include: enlarged laterodorsal nasal foramina; a quadratojugal fenestra more than 25% maximum quadratojugal length; a quadratojugal less than 30% of skull height; a predentary with almost 150% of premaxillary body length; a dentary extending posteriorly almost to the posterior border of the angular; and the claw of the third toe being longer than the other third toe phalanges.
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The (tooth-bearing bone at the front of the lower jaw) was short compared to the rest of the lower jaw, as in other ceratosaurians. The front end of the dentary was down-turned and had a convex inner margin, similar to the related Masiakasaurus. The angular bone of the lower jaw was positioned significantly forwards in relation to the hind end of the mandible, similar to other ceratosaurians. Juveniles had nine teeth in each side of the upper jaw and twelve in each side of the lower; they were gradually lost as they grew, disappearing by adulthood.
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All of the teeth were either completely flattened or weakly pointed, and many of the teeth bore a constriction between the root and the crown. Unlike other ichthyosauriforms with molariform teeth, all of the tooth crowns were "swollen" to a similar extent. On the maxilla (upper jawbone) and dentary (lower jawbone), the teeth were arranged in three rows, with the outermost row having the most and largest teeth; the maxillae had seven, five, and probably one teeth each, while the dentaries had ten, seven, and four teeth each. Among ichthyosauriforms, only Cartorhynchus and Xinminosaurus have multiple rows of teeth.
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The specific name honours Ricardo Farias, on whose land the initial discovery was made. The genus was originally known from an almost complete postcranial skeleton lacking a skull as the holotype, and many referred specimens however in 2003 it was found that a dentary was referable to the species, so more specimens are probably this taxon. Its skeleton was found near those of Piatnitzkysaurus and Volkheimeria in the Callovian to Oxfordian aged Patagonian deposits of the Cañadón Asfalto Formation. Patagosaurus is almost completely known with many articulated specimens found covering almost all of the skeleton, including parts of the skull.
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Life restoration with size compared to a human The holotype of Sinotyrannus is KZV-001, a disarticulated partial skeleton including the front portion of the skull, three dorsal vertebrae, the incomplete ilia, three articulated manual phalanges (including an ungual), and other fragmentary bones. In 2010 Gregory S. Paul estimated its length at 9 meters (30 ft) and its weight at 2.5 tonnes (2.75 short tons). In 2016 it was given a smaller size of 7.5 meters (24.6 ft) and 1.2 tonnes (1.3 short tons). The preserved cranial elements include the premaxillae, dentary, and anterior portions of the maxillae and nasals.
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Skeleton of B. isis at Wadi El Hitan Basilosaurus isis fossil, Nantes History Museum in France Wadi El Hitan, Arabic وادي الحيتان , "Valley of the Whales", is an Egyptian sandstone formation where many early-whale skeletons were discovered. German botanist Georg August Schweinfurth discovered the first archaeocete whale in Egypt (Zeuglodon osiris, now Saghacetus osiris) in 1879. He visited the Qasr el Sagha Formation in 1884 and 1886 and missed the now famous Wadi El Hitan by a few kilometers. German paleontologist Wilhelm Barnim Dames described the material, including the type specimen of Z. osiris, a well-preserved dentary.
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By contrast, the long and slender dentary bones of the lower jaw curved slightly upwards towards the front. Unlike modern crocodilians, the eye of Terrestrisuchus was supported by a ring of bony ossicles, the sclerotic ring. Skeletal restoration showing known remains The body was relatively short and shallow, and the spine was topped by paired rows of osteoderms running down from its neck down its back. These osteoderms are described as "leaf-shaped", being relatively longer than wide with a prominent spur at the front that slides under and interlocks with the scute in front of it.
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Wannchampsus was described in 2014 by Thomas Adams. The type species is W. kirpachi, in honor of Wesley Kirpach, "who was instrumental in the discovery and excavations of the type specimen". W. kirpachi holotype and paratype fossilized skulls The skulls are described as "low and broad", and are small; SMU 76604 is estimated at long, and SMU 76605 is estimated at long. The lower jaw lacks external mandibular fenestrae, and the third tooth of the maxilla (main tooth-bearing bone of the upper jaw) and the fourth tooth of the dentary (tooth-bearing bone of the lower jaw) are enlarged.
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Oromycter was a small caseid characterized by its dentition, which lacked the distinct leaf-like serrations of other caseids and instead possessed broad, spatulate and roughened cutting edges. Its teeth were also more thoroughly attached to the bone of the skull and jaw than in other members of Caseidae. The first and second teeth of the premaxilla show distinct wear facets which suggest that they occluded with the first and second teeth of the dentary, possibly to facilitate the cropping of vegetation. Its lacrimal bone, while clearly caseid in form, appears more primitive than in any other known caseid.
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It is bordered below by a number of splenial bones, while the angle of the jaw is formed by a lower angular bone and a suprangular bone just above it. The inner surface of the jaw is lined by a prearticular bone, while the articular bone forms the articulation with the skull proper. Finally a set of three narrow coronoid bones lie above the prearticular bone. As the name implies, the majority of the teeth are attached to the dentary, but there are commonly also teeth on the coronoid bones, and sometimes on the prearticular as well.
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Omphalosaurus are moderately large and plump marine reptiles and are best known for their highly specialized dentition compared to other Ichthyosaurs. The teeth are button-like, with a dome shape when viewed laterally and almost circular crowns that have an irregular enamel surface akin to the texture of an orange peel. Individual teeth do not exceed 12mm in diameter and are arranged in tooth plates exclusively on the premaxilla, which sit at 90º from each other, and dentary. Based on O. nevadanus’ well preserved and smooth palatine, it’s unlikely that Omphalosaurus had palatine teeth akin to Placodonts.
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Robertia is an extinct genus of small herbivorous dicynodonts from the Middle to Late Permian of South Africa, between 260 and 265 million years ago. It is a monospecific genus, consisting of the type-species R. broomiana, which was classified by Lieuwe Dirk Boonstra in 1948 and named in honor of Robert Broom for his study of South African mammal-like reptiles. Robertia had characteristic caniniform tusks and few, small teeth on the maxillary and dentary table. Its beak and the propalinal movement of the jaw, as with other dicynodonts, allowed for efficient cutting of plant matter.
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The name Euteleostomi was coined as a monophyletic alternative that unambiguously includes the living tetrapods and is widely used in bioinformatics. The term Euteleostomi comes from Eu-teleostomi, where "Eu-" comes from the Greek εὖ meaning well or good, so the clade can be defined as the living teleostomes. Euteleostomes originally all had endochondral bone, fins with lepidotrichs (fin rays), jaws lined by maxillary, premaxillary, and dentary bones composed of dermal bone, and lungs. Many of these characters have since been lost by descendant groups, however, such as lepidotrichs lost in tetrapods, and bone lost among the chondrostean fishes.
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There were three premaxillary teeth. In the Early Jurassic Abrictosaurus, Heterodontosaurus, and Lycorhinus, the first two premaxillary teeth were small and conical, while the much larger third tooth resembled the canines of carnivoran mammals and is often called the caniniform or 'tusk'. A lower caniniform, larger than the upper, took the first position in the dentary and was accommodated by the arched diastema of the upper jaw when the mouth was closed. These caniniforms were serrated on both the anterior and posterior edges in Heterodontosaurus and Lycorhinus, while those of Abrictosaurus bore serrations only on the anterior edge.
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Nasal and frontal bones are paired and contact each other in a W-shape suture with no overlap between the two bones, and several bones are lost (lacrimal, postorbital and jugal) or highly reduced (supratemporal and squamosal). The main cranial differences, besides sizes, between Anelytropsis and Dibamus is the presence of epipterygoid and postfrontal in the Central American genus. The mandible of Dibamidae bears less than 10 teeth and is composed of only three bones, the dentary, the coronoid and the compound bone. A remnant of the splenial bone is only present in one species of Dibamus, Dibamus novaeguineae.
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The type and only species of the genus is Sirindhorna khoratensis. The taxon is known from the holotype specimen NRRU3001-166, an articulated braincase, as well as a number of disarticulated referred specimens. The material known from these referred specimens consists of three more partial braincases, one with an articulated postorbital, one right premaxilla, a left and right maxilla, a right jugal, surangular, and quadrate, one predentary, a right and left dentary, and assorted teeth. The generic name is dedication to Princess Maha Chakri Sirindhorn for her contribution to the support and encouragement of palaeontology in Thailand.
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He did however allow Louis Agassiz at Harvard to examine his specimens, and the Swiss professor replied that these were neither teeth of a juvenile nor those of Zeuglodon, but of a separate genus just as Gibbes had first proposed.; described Prozeuglodon atrox (="Proto-Basilosaurus") based on a nearly complete skull, a dentary, and three associated vertebrae presented to him by the Geological Museum of Cairo. , however, realized that Andrews' specimen was a juvenile, and, he assumed, the same species as Zeuglodon isis, described by Andrews 1906. Kellogg also realized that the generic name Zeuglodon was invalid and therefore recombined it Prozeuglodon isis.
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Although the name Majungasaurus crenatissimus was older than Majungatholus atopus, the authors judged the type dentary of Majungasaurus too fragmentary to confidently assign to the same species as the skull. Further fieldwork over the next decade turned up a series of less complete skulls, as well as dozens of partial skeletons of individuals ranging from juveniles to adults. Project members also collected hundreds of isolated bones and thousands of shed Majungasaurus teeth. Taken together, these remains represent nearly all the bones of the skeleton, although most of the forelimbs, most of the pelvis and the tip of the tail are still unknown.
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As in other oviraptorids, it had a pair of tooth-like projections on the palate that were directed downwards (a feature that has been called "pseudo- teeth"). Nemegtomaia had small foramina (openings) on the sides of the suture (joint) between the premaxillae at the front of the snout, which may have been nutrient openings (and which indicate the presence of a keratinous bill). The lower jaw was short and deep, with a convex lower surface, and reached 153 mm (6 in) in length. The dentary bone of the lower jaw reached 50 mm (2 in) at its highest point.
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The postcanines of the upper and lower jaw fit tightly together as an adaptation to processing plant material. An autapomorphy or unique feature of Bauriidae is the expansion of the dentary bone of the lower jaw inward toward the jaw midline, forming a wide shelf of bone to either side of the tooth row. A similar expansion of the maxilla in the upper jaw is also seen in bauriids, although it is not unique to the group as the feature has also evolved in a group of cynodont therapsids called gomphodonts (which, like bauriids, were herbivorous).
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Kouriogenys is a genus of extinct mammal from the Early Cretaceous of southern England. The type and only species was originally described as Spalacotherium minus by Richard Owen in 1871 for a dentary with teeth from the Berriasian Lulworth Formation, although it was given its own genus in 2012 by Brian Davis. The genus name is taken from the Ancient Greek "youthful" and "jaw" in reference to the replacement method of the premolars. Kouriogenys is closely related to coexisting genera Peramus and Peramuroides, and along with other genera these make up the family Peramuridae, a group of extinct zatherians.
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There were around six to eight denticles per mm (0.039 in), a much larger number than in large-bodied theropods like Torvosaurus and Tyrannosaurus. Some of the teeth were fluted, with six to eight ridges along the length of their inner sides and fine-grained (outermost layer of teeth), while others bore no flutes; their presence is probably related to position or ontogeny (development during growth). The inner side of each tooth row had a bony wall. The number of teeth was large compared to most other theropods, with six to seven teeth in each premaxilla and thirty-two in each dentary.
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Bones in a skeleton of C. bauri at the American Museum of Natural History, now interpreted as those of a crocodylomorph The teeth of Coelophysis were typical of predatory dinosaurs, blade-like, recurved, sharp and jagged with fine serrations on both the anterior and posterior edges. Its dentition shows that it was carnivorous, probably preying on the small, lizard-like animals that were discovered with it. It may also have hunted in packs to tackle larger prey.Coelophysis bauri has approximately 26 teeth on the maxillary bone of the upper jaw and 27 teeth on the dentary bone of the lower jaw.
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They also named the new family Istiodactylidae, with Istiodactylus as the sole member. Hooley's 1913 long- jawed skull reconstruction Additional Istiodactylus specimens were later found on the Isle of Wight, including IWCMS 2003.40, a dentary fragment that may belong to a juvenile, and isolated teeth found through screen washing from 2002 and onwards. During the early 21st century, new types of istiodactylids were reported from China. In 2006, Brian Andres and Ji Qiang named a second species of Istiodactylus, I. sinensis, from the Jiufotang Formation of China (from Greek sino, pertaining to China), based on a partial skeleton.
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Although Head had specifically redefined the Hadrosauridae, based on shared characteristics, to include Protohadros, Horner and colleagues adapted a taxon-based definition that excluded Protohadros and thus Eolambia. They also identified additional characteristics differentiating Eolambia from hadrosaurids: there are coarse denticles on the teeth of the dentary, and the coronoid process is weakly expanded. Quadrate of Eolambia Variance in recovered phylogenetic positions for Eolambia persisted in following years. In the 2009 description of Levnesovia, Hans-Dieter Sues and Alexander Averianov found that Protohadros occupied an intermediate position relative to Altirhinus and Probactrosaurus, being the sister group of Fukuisaurus.
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Multituberculate mastication is thought to have operated in a two stroke cycle: first, food held in place by the last upper premolar was sliced by the bladelike lower pre-molars as the dentary moved orthally (upward). Then the lower jaw moved palinally, grinding the food between the molar cusp rows. allodontid multituberculates The structure of the pelvis in the Multituberculata suggests that they gave birth to tiny helpless, underdeveloped young, similar to modern marsupials, such as kangaroos. At least two lineages developed hypsodonty, in which tooth enamel extends up beyond the gumline: lambdopsalid taeniolabidoideans and sudamericid gondwanatheres.
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292 even though the dentary bone itself was exceptionally long at the back, reaching a point below the middle of the eye socket.Cristiano dal Sasso & Simone Maganuco, 2011, Scipionyx samniticus (Theropoda: Compsognathidae) from the Lower Cretaceous of Italy — Osteology, ontogenetic assessment, phylogeny, soft tissue anatomy, taphonomy and palaeobiology, Memorie della Società Italiana de Scienze Naturali e del Museo Civico di Storia Naturale di Milano XXXVII(I): 1-281 Teeth did not extend as far back as the orbits, and neither tooth row spanned much more than one-third of the skull.Osborn (1903), p. 460; Norman (1990), p.
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The crowns of the maxillary and dentary teeth have denticles on their edges and a swollen basis The ascending branches of the paired premaxillae notched the combined nasal bones, whereas the opposite was usual in ornithischians. The frontal bones were covered by a halo of fine ridges; these indicate the presence of ceratinous plates, as with modern turtles. At the front of the braincase, paired hatchet-shaped ossified orbitosphenoids formed the floor of the olfactory lobes of the brain. The skull of the neotype was damaged by a paleoichthyologist resulting in the detachment of triangular plates from the palate.
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A further plate composed of four pairs of bones forms the roof of the mouth; these include the vomer and palatine bones. The base of the cranium is formed from a ring of bones surrounding the foramen magnum and a median bone lying further forward; these are homologous with the occipital bone and parts of the sphenoid in mammals. Finally, the lower jaw is composed of multiple bones, only the most anterior of which (the dentary) is homologous with the mammalian mandible. In living tetrapods, a great many of the original bones have either disappeared or fused into one another in various arrangements.
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Like other euharamiyidans. the ear bones of Vilevolodon had not achieved full separation from the mandible. As the transition of the middle ear away from the dentary via the modification of the quadrate and articular bones into and incus and malleus respectively is a hallmark for mammalian recognition, the preservation of an ear structure in the Vilevolodon holotype is not only crucial to its placement as a euharamiyidan, but has important phylogenetic implications as well. The holotype features a malleus connected anterior to Meckels's cartilage, and the ectotympanic features an anterior limb and a straight reflected lamina.
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Saghacetus is an extinct genus of basilosaurid early whale, fossils of which have been found in the Upper Eocene (middle Priabonian, ) Qasr el Sagha Formation, Egypt (, paleocoordinates ).. Retrieved May 2013.. Retrieved July 2013. Mandible from , the type specimen In 1879, German botanist Georg August Schweinfurth spent many years exploring Africa and eventually discovered the first archaeocete whale in Egypt. He visited Qasr el Sagha in 1884 and 1886 and missed the now famous "Zeuglodon Valley" with a few kilometres. German palaeontologist Wilhelm Barnim Dames described the material,; ; including a well-preserved dentary which is the type specimen of Zeuglodon osiris.
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The supraoccipital bone at the top of the braincase is trapezoidal when seen from behind (unlike Herrerasaurus's triangular supraoccipital) and has a blade-like crest on top. The occipital condyle is also thicker, the basioccipital has a V-shaped (rather than U-shaped) contact with the parabasisphenoid, and the paroccipital processes are larger in Gnathovorax compared to Herrerasaurus. Otherwise the braincase is similar between the two taxa. The dentary lacks sauropodomorph qualities and instead likely possessed a sliding joint at the chin similar to other herrerasaurids, although preservation is not good enough to fully confirm this.
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However, referred material discovered in 2003 proposed an alternative orientation of the lower jaw. This newer interpretation proposes that the upper edge of the jaws were rotated inwards, shifting the rectangular wear facets of the back of the jaw into a position more similar to the triangular shape in the front of the jaws. Eilenodon's dentary teeth differ from those of Toxolophosaurus by being more closely packed and somewhat simpler, only slightly concave from the front and having only two dental ridges per tooth. In addition, as an individual rhynchcephalian matures, additional teeth grow from the back of its jaws.
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In 1992 David Weishampel and Ronald Heinrich reviewed the systematics and phylogenetics of Hypsilophodontidae. Hypsilophodontidae was supported as a monophyletic clade that encompassed "thescelosaurids", Hypsilophodon and Yandusaurus. The family was diagnosed by the absence of ridges that end as denticles in teeth (reversed in Hypsilophodon); presence of a single central ridge on dentary teeth; ossified sternal plates on torso ribs; and a straight and unexpanded shape of the prepubis. Their resulting cladogram is reproduced below: The following cladogram of hypsilophodont relationships depicts the paraphyletic hypotheses; the "natural Hypsilophodontidae" hypothesis has been falling out of favor since the mid- late 1990s.
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Right maxilla of AMNH FARB 30653 (reversed) in lateral view. Maxillary foramina indicated by arrows A complete skull articulated is not known from the multiple specimens, however, numerous elements are known such as the right maxilla, dentary, jugal, squamosal and two lacrimals, quadrate and a complete predentary. In a lateral view, the right maxilla of specimen AMNH FARB 30653 is triangular in shape with various foramina on the surface. On the inner side 26 alveolar foramen are preserved and 22 alveoli are filled with teeth but the total count may be unknown due to incompleteness, the surface of this side is rather flat.
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The upper toothless border of the dentary and a significant portion of the articular border for the predentary are missing, but given that both of these borders have minor lengths—about less than the 25% of the length of the dental battery—they indicate that the toothless area between the tooth row and the predentary was rather reduced—another trait present in hadrosauroids but lost in hadrosaurids. The predentary is represented by a complete element of specimen AMNH FARB 6369, which has a U-shaped form. Numerous and pointed denticles are preserved on the dorsal surface of the predentary, giving a serrated texture.
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It may have consisted of connective tissue and skin, rather than muscle fibers, which meant that the tongue was used to move food that had accumulated between the teeth and the cheek, back to the tongue side of the cheek so that it could be further broken down by the teeth. The ornithischian cheek is absent or only weakly developed in Lesothosaurus, which supports its placement as a sister group to Genasauria. In Genasauria, the mandibular symphysis is shaped like a spout and forms at an acute angle. The mandibular symphysis is the point of fusion between the two lateral dentary bones.
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Several features were used to unite these groups: a deep snout, a ziphodont dentition, a curved tooth row, an enlarged canine-like dentary tooth that fits into a deep notch in the upper jaw, and a groove on the lower jaw. Many phylogenetic analyses within the past decades have supported a close relationship between the two families. Baurusuchids and sebecosuchids are both early members of the clade Metasuchia, which includes the subgroups Notosuchia (mainly terrestrial crocodyliforms) and Neosuchia (larger, often semiaquatic crocodyliforms, including living crocodylians). Sebecosuchians, which include both baurusuchids and sebecosuchids, were found to be closely related to notosuchians in several studies.
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The large sizes attained by some saurocephalids which exceed two meters in length, may indicate they were capable of handling larger prey items such as smaller marine reptiles and sharks. To process large prey, they would cut them into smaller more manageable pieces using their powerful large jaws and sharp teeth. A close modern analogue of saurocephalids and to the matter saurodontids, would be barracudas (Sphyraena barracuda) known to ambush, ram, and stun their prey using the strong anterior projection of the dentary. Although not as notably elongate, the overall body outline of barracudas is similar to saurocephalids.
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The fossiliferous Siwalik deposits of India and Pakistan have been known to paleontologists for decades, producing a plethora of vertebrate fossils since the early 20th Century. In 1932, British paleontologist Guy E. Pilgrim described what he identified as a procyonid carnivore partial dentary collected from Lower Siwalik deposits of Pakistan, naming it Sivanasua palaeindica. In his description, he identified a maximum of two lower molars, which informed his identification of the fossil as having procyonid affinities. Shortly after Pilgrim's description, G.E. Lewis of the Yale Peabody Museum recovered a single lower molar from the Nargi horizon in Middle Siwalik deposits of India.
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The Soumyasaurus holotype was found in association with other specimens in an assemblage catalogued under TTU P-11254, including a specimen of Vancleavea (TTU P-11254a), indeterminate archosauromorph remains (TTU P-11254c-e), and remains indeterminate beyond Sauria (TTU P-11254f-i). This is similar to another assemblage at the Post Quarry where the holotype premaxilla and dentary of Technosaurus was discovered with posterior jaw bones now known to be from Shuvosaurus. It is apparent that the remains labelled TTU P-11254 were brought together in association by similar taphonomic agents, which are inconsistent with previous suggestions of a rapid flooding event.
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When he first named the species, Argentine paleontologist José Bonaparte mentioned several features that distinguish it from all other traversodontids. The tooth rows of the upper jaw are more parallel to each other in I. sudamericanus than they are in Exaeretodon, and they are also inset closer to the inside of the mouth. There are also more postcanine teeth oriented toward middle of the subtemporal fenestrae (two holes in the bottom of the skull) and ascending rama of the dentary (projections of the lower jaw that extend up to the skull). The ascending rama are also wider and taller in the I. sudamericanus specimen.
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Skeletal diagram The braincase of Piatnitzkysaurus has been reviewed in detail by Oliver Rauhut; the review constitutes one of the few detailed accounts of braincase morphology in basal theropods. Piatnitzkysaurusis the only member of Piatnitzkysauridae with cranial material preserved, for which two maxillae, a frontal, a braincase, and a partial dentary are known. Piatnitzkysaurus is among the most basal members of the tetanurans and is important for understanding not only Middle Jurassic theropod evolution in the Southern Hemisphere, but also for knowledge of character evolution at the base of tetanurae. The braincase of the holotype of Piatnitzkysaurus floresi (PVL 4073) is rather well preserved and shows no signs of deformation.
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The only known fossil specimen of N. wangi is notable for having a large number of teeth compared to more advanced oviraptorosaurs, but the teeth in the back of the upper jaw (maxilla) are still reduced in number compared to most other non-avialan theropods. The reduced number of maxillary teeth in Ningyuansaurus is shared with the scansoriopterygids and other basal oviraptorosaurs such as Incisivosaurus. Though the skull is poorly preserved, the specimen preserved at least 14 teeth in the lower jaw (dentary) and 10 teeth in the upper jaw, four in the premaxilla and six in the maxilla. The teeth were closely packed together and lacked serrations.
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However, a later reexamination of fossils from the Guimarota Formation had found skull material that included a dentary similar to the one seen in the holotype of L. mitracostatus. These remains, being more complete than those of the holotype, showed that L. mitracostatus was really a crocodylomorph rather than an anguimorph. Furthermore, it was shown to be a genus distinct from Lisboasaurus, which had by then been shown to be a crocodylomorph as well. Several teeth referable to Lusitanisuchus were also found from Porto Dinheiro, Lourinhã in strata deposited during the Berriasian stage of the Early Cretaceous, extending the temporal range of this taxon by about 15 Ma.
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The holotype specimen, BP/1/5243, consists of both premaxillae, a fragment of the maxilla, two dentary fragments, a partial surangular bone, a partial angular bone, a partial prearticular bone, an articular bone, and several teeth. Dracovenator has a kink in its upper jaws, between the maxilla and the premaxilla. The back end of the lower jaw features an array of lumps and bumps, a condition seen in Dilophosaurus, but to a much smaller extent. Munyikwa and Raath (1999) reassigned paratype BP/1/5278, which was originally assigned to Syntarsus rhodesiensis, to Dracovenator, a juvenile specimen which consists of bones from the front of the skull, teeth, and jaw bones.
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The dentary, which houses the lower teeth, also takes up around two-thirds of the total length of the lower jaw. The upper jaws possess twenty-two functional teeth on the right side and twenty-three teeth on the left; four of the frontmost pairs are located on the premaxilla while the rest are located on the maxilla. Unlike in pliosaurs such as Liopleurodon or Pliosaurus, the maxillary teeth in Megacephalosaurus do not reduce in size towards the base of the skull and are all consistently large. A pair of small pits measuring less than long is present just before the frontmost pair of functional teeth.
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Life restoration of Bellubrunnus showing forward-curving wingtips The holotype specimen of Bellubrunnus represents a small individual, with a wingspan of less than a foot, and is one of the smallest pterosaur fossils known. Nearly every bone is preserved in BSP–1993–XVIII–2, although no soft tissues have been found, neither as impressions nor as organic remains. The entire skeleton is complete except for missing parts of the right foot and tail tip. Because the skeleton is preserved in ventral view, many details of the skull ("sk" in the skeletal diagram) are obscured by the lower jaws (dentary, "dt" + angular, "ar" in the skull diagram).
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A species of Thylacinus, it was somewhat larger than the recent Tasmanian tiger Thylacinus cynocephalus, and similar weight to another late Miocene species Thylacinus potens, both of which are estimated to have been in a range of 17.8 and 15.9 kilograms. The type material was exceptionally fragmented in its sandstone deposition at Alcoota, requiring the assembly of the dentary for examination and comparison. The first reconstruction of the specimen was modified by the describing author. Murray's reconstruction is of one larger and more robust dentition and palate than T. cynocephalus, but resembling the gracile and elongated snout, more so than the species T. potens.
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Both specimens were collected approximately four metres from one another, from the same mixed faunal bonebed that occurs in the upper part of the Hell Creek Formation of Montana, dating to the latest Maastrichtian stage of the Late Cretaceous, immediately prior to the Cretaceous–Paleogene extinction event. The holotype specimen was collected on August 28, 2009 by commercial fossil hunters, one of whom also collected the dentary several years later, and who were later able to provide detailed geographic data from GPS and photographs of the specimen in situ in the ground on the day of discovery. Both specimens were subsequently purchased by the Royal Ontario Museum from a private collector.
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Stratigraphy and taphonomy of the type locality, with quarry map (B) The holotype of Hippodraco, UMNH VP 20208, was discovered in 2004 by Andrew R. C. Milner. It is a fragmentary specimen including a fragmented skull and dentary teeth, vertebrae (dorsal, caudal and cervical), a right humerus, a right scapula, a left ischium, a right tibia, a right femur, and left metatarsals. It was later named in 2010 by Andrew T. McDonald, James I. Kirkland, Andrew R. C. Milner, Scott K. Madsen, Donald D. DeBlieux, Jennifer Cavin and Lukas Panzarin. The generic name Hippodraco is a combination of the Greek word hippos ("horse") and the Latin word draco ("dragon").
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Pyrenasaurus is an extinct genus of lizard that includes only one species, the type species Pyrenasaurus evansae, which lived around the Pyrenees mountains during the Late Eocene. P. evansae was named in 2014 on the basis of three dentaries (bones that form the lower jaw), one from the Phosphorites du Quercy in Quercy, France and two from the Sossís fossil locality in Catalonia, Spain. The paucity of known material makes its relationships uncertain; it is either a true skink in the family Scincidae or a close relative of skinks in the larger group Scincoidea. Pyrenasaurus is very small for a lizard, with a dentary length of only .
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Thliptosaurus was found to be a member of the clade Emydopoidea in the family Kingoriidae, closely related to the genera Kombuisia and Dicynodontoides. Thliptosaurus shares with other kingoriids a dentary plate that occludes and obscures the mandibular fenestra, an arcing anterior process of the lacrimal that contacts the nasal, cutting off the maxilla from contacting the prefrontal bone, and an absence of the postfrontal bone (also shared with other kistecephalians). It shares an extremely reduced pineal foramen with the kingoriid Kombuisia frerensis and cistecephalid Kawingasaurus. However, it is distinguished from these genera by having a moderately broad intertemporal bar, intermediate in width between that of Kombuisia and Kawingasaurus.
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As in Tyrannosaurus, the shelf of the palate was well developed. The jugal bone (or "cheek" bone) was robust, and had a broad postorbital process (which projected upwards from the jugal to contact the postorbital bone), unlike other tyrannosaurs except Bistahieversor, Tyrannosaurus and Tarbosaurus. The front border of the postorbital process had a strong process which indicates that Lythronax had a large subocular flange (a projection into the lower part of the orbit), dissimilar to the smaller ones of other tyrannosaurids. Each ramus of the dentary (half of the tooth-bearing portion of the lower jaw) was strongly concave towards the outer side (bowing inwards along the length of the skull).
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The teeth of both the upper and lower jaws are small and cone-shaped, some having slightly serrated edges, and are only differentiated by slight differences in length (some other synapsids have teeth that vary greatly and shape across their jaws). The three forward- most dentary teeth are angled slightly outward as in more derived synapsids such as Dimetrodon and Sphenacodon. Several features, including straight- margined maxillae and simple conical teeth, are also seen in the earliest reptiles. Twenty-three presacral (neck and back) vertebrae are preserved in the holotype, although several may be missing because the typical number of presacral vertebrae in early synapsids is 27.
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Another dentary, SGU 104/3105, originally referred to C. donensis was reassigned to its own genus and species Vitalia grata by Ivakhnenko, 1973. The fossils have been found at the Donskaya Luka Locality near the village of Sirotinskaya and the Don River in Ilovlinsky District, Volgograd Oblast, from the Lipovskaya Formation of the Gamskii Horizon. Like Coelodontognathus, Vitalia which is known from the same locality was also first identified as a procolophonid and later reclassified as a trilophosaurid. Coelodontognathus and Vitalia are similar to procolophonids in that they have wide teeth but differs from them in that they have tooth roots set deep into the jaws.
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The tomial crest was straight for its entire length, and a notch indented the sharp tip of the mandible. The mandible was spear-shaped in side view, due to its lower margin slanting downwards and back from its tip for the front third of its length (the jaw was also deepest at a point one third from the tip). The symphyseal part (where the two halves of the lower jaw connected) of the dentary was very robust. The lower margin formed an angle at the level of the front margin of the nasal foramen, which indicates how far back the rhamphotheca of the beak extended.
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In the Early Cretaceous Echinodon, there may have been two upper caniniforms, which were on the maxilla rather than the premaxilla, and Fruitadens from the Late Jurassic may have had two lower caniniforms on each dentary. Evolution of key masticatory specialisations in heterodontosaurids, according to Sereno, 2012 Like the characteristic tusks, the cheek teeth of derived heterodontosaurids were also unique among early ornithischians. Small ridges, or denticles, lined the edges of ornithischian cheek teeth in order to crop vegetation. These denticles extend only a third of the way down the tooth crown from the tip in all heterodontosaurids; in other ornithischians, the denticles extend further down towards the root.
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Partial skull in left side, front, and upper views Spinops is known from the holotype NHMUK R16307, a partial parietal bone, preserving most of the midline bar. Referred material include NHMUK R16308, a partial parietal bone, partial dentary and unidentifiable limb fragments, NHMUK R16306, an incomplete skull, preserving only the dorsal portion of the skull, and NHMUK R16309, a partial right squamosal. None of this material was found in articulation, however it was all closely associated in the same bone bed, in the northwestern region ("Steveville Badlands") of the Dinosaur Provincial Park. Fossils of Spinops were first found in 1916, and were housed in the Natural History Museum in London.
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However, Kelmayisaurus is diagnosable by the form and presence of a deeply inset accessory groove on the lateral side of the dentary, the main toothbearing bone of the lower jaw. Some of its features are like those of carcharodontosaurians, but they are also seen in large megalosauroids like Megalosaurus and Torvosaurus. In 2011, a redescription of the holotype by Stephen L. Brusatte, Roger B. J. Benson and Xing Xu found Kelmayisaurus to be valid genus of Carcharodontosauridae with a single autapomorphy. A phylogenetic analysis of Tetanurae recovered K. petrolicus as a basal carcharodontosaurid in a trichotomy with Eocarcharia and a clade comprising more derived carcharodontosaurids.
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They may have resembled basal cynodonts such as the Procynosuchidae, and they may have descended from a procynosuchid-like ancestor, but the galesaurids were more advanced than the basal Cynodontia. It is clear that, like many other epicynodontians, many galesaurids had a complete secondary palate, which allowed them to swallow food while breathing, and the dentary bone was enlarged relative to those of their ancestors. Their temporal fenestrae are much larger than those of the procynosuchids, but not as large as in more advanced epicynodontians. Their snouts are broad, rather than tall, and they may have walked erect, with the legs beneath the body like most other cynodontians.
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Restoration of C. aguti While there are several forms of Captorhinus, there are three main species that are the best known. The previously mentioned Captorhinus aguti is the type species of Captorhinus, but there is also a fair amount of material collected on Captorhinus magnus and Captorhinus laticeps.Canoville 2010 The most distinguishable trait of Captorhinus is its namesake: the hooking of the snout from prominent ventral angulation of the premaxillary process. Other notable characteristics include the dorsally positioned alary process of the jugal on the medial surface and flushed with the orbital margin, the retroarticular process longer anteroposteriorly than broad, and the anteriormost dentary tooth strongly procumbent.
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Harry Govier Seeley named this genus in 1879 for a disarticulated partial postcranial skeleton that had been uncovered at Reach, Cambridgeshire, composed of a left dentary fragment, numerous vertebrae from the neck, back, and sacrum, parts of the pectoral girdle, humerus fragments, part of the left femur, left tibia, foot bones, ribs, and other fragments. He regarded it as possibly juvenile, due to its small size, with a length of about five feet. The type species is Anoplosaurus curtonotus. The generic name, derived from the Greek hoplo~, a word element used in combinations, with the meaning of "armed", refers to the fact no armour plates had been discovered.
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The first fossils consisted of only a partial tooth- bearing dentary fragment and some associated teeth. This material was discovered by J. M. Dutuit in 1965 and described in 1972, who believed it to belong to a herbivorous ornithischian dinosaur, as well as one of the oldest dinosaurs yet discovered. He named the genus "Azendoh lizard", after the nearby Azendoh village located only 1.5 km to the west of where the fossils were discovered. Dutuit's description of Azendohsaurus as an ornithischian was soon challenged by palaeontologist Richard Thulborn two years later in 1974, who was the first to suggest that Azendohsaurus was a "prosauropod" instead.
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However, no functional studies have been performed on the palatal teeth so it is unknown exactly what they were used for, although their similar shape to the marginal teeth suggests they were used for processing similar food. A pterygoid from a younger individual of A. madagaskarensis has fewer rows of palatal teeth that are smaller in size than those of the larger, mature individuals, indicating that Azendohsaurus increased both the number and size of its palatal teeth as it grew into adulthood. Younger individuals also had fewer dentary teeth than adults, although the difference was much less extreme compared to the palatal teeth (16 compared to the 17 of mature specimens).
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The description of A. altai in 2009 confirmed the placement of the genus within the Tyrannosaurinae. A. remotus skull diagram, known portions in white Endocranial cast of Alioramus altai Tarbosaurus and Alioramus shared several skull features, including a locking mechanism in the lower jaw between the dentary and angular bones, and both lacked the prong of the nasal bones which connected to the lacrimal bones in all other tyrannosaurids except adult Daspletosaurus. The two genera may be closely related, representing an Asian branch of the Tyrannosauridae. Some specimens of Tarbosaurus have a row of bumps on the nasal bones like those of Alioramus, although much lower.
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Based on the closer packing and smaller size of the dentary teeth compared to those in the corresponding length of the premaxilla, the difference between the number of teeth in the upper and lower jaws appears to have been more pronounced than in other theropods. The terminal rosette in the upper jaw of the holotype had thirteen (tooth sockets), six on the left and seven on the right side, showing tooth count asymmetry. The first four upper teeth were large (with the second and third the largest), while the fourth and fifth progressively decreased in size. The diameter of the largest was twice that of the smallest.
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A 2019 a paper questioned the referral of MCD 4919 to P. isonensis. The specimen was found to have a differing compared to the maxilla of the holotype, which would conflict with belonging to the same species. As the specimen was still recognized as having tsintaosaurin characteristics, the authors still considered it to likely belong to a close relative of P. isonensis. A selection of dentary material from the Basturs Poble bonebed The same 2013 study also evaluated Blasisaurus canudoi, from the Blasi 1 locality of the underlying Arén Formation, and Arenysaurus ardevoli, from the Blasi 3 locality of the La Posa Formation, another part of the Tremp Group.
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Megalosaurus femur From the family's inception, many specimens found in the field have been wrongly classified as megalosaurids. For example, most large carnivores found for about a century after the naming of Megalosaurus bucklandii were placed in Megalosauridae. Megalosaurus was the first paleontological finding of its kind when William Buckland discovered a giant femur and named it in 1824, predating even the term Dinosauria. When initially defined, the species M. bucklandii was anatomically based on various dissociated bones found in quarries around the village of Stonesfield, UK. Some of these early findings included a right dentary with a well-preserved tooth, ribs, pelvic bones, and sacral vertebrae.
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Diagram showing known remains Zhuchengtyrannus was first described and named by David W. E. Hone, Kebai Wang, Corwin Sullivan, Xijin Zhao, Shuqing Chen, Dunjin Li, Shuan Ji, Qiang Ji and Xing Xu in 2011 and the type species is Zhuchengtyrannus magnus. The generic name is derived from the word Zhucheng, which refers to the type locality, and tyrant in reference to its phylogenetic position as a tyrannosaurid. The specific name magnus meaning "great" in Latin refers to the relatively large size of Zhuchengtyrannus. Zhuchengtyrannus is known solely from the holotype ZCDM V0031, a nearly complete right maxilla and associated left dentary (lower jaw, both with teeth) housed at Zhucheng Dinosaur Museum.
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Like all spinosaurids, Cristatusauruss (bony nostrils) were positioned further back on the skull that in typical theropods. Two bony processes extended across the underside of the snout, in a convex structure that formed the animal's secondary palate. This condition is observed in all extant crocodilians, but not in most theropod dinosaurs; however, it was a common trait among spinosaurids. Type premaxillae from reversed left side (A), bottom (B), and top (C) views Cristatusauruss dental (tooth sockets) were closely spaced, those in the maxilla and dentary were flattened somewhat sideways; while the ones in the premaxillae were large and mostly circular, with the frontmost alveoli being the largest.
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Dentary sclerites located next to the mandible are pointed down, and are lightly pigmented towards the back of the fly. Small sclerites are present between the mandibular ones, and an additional sclerite is found on the posterior end near the hypostome (a structure found near the mouth which allows an animal to anchor itself firmly on another to suck, as in the tick's hypostome). The third instar stage is 4.10–9.42 mm long and 0.76–2.13 mm wide. The integument is translucent, the body's overall shape comes to resemble a mix between a cone, and cylinder (with the front end of the insect becoming more pointed).
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In 2017, Magnuviator was found to be an iguanomorph, most closely related to the Asian Temujiniidae (which contains Saichangurvel and Temujinia). Three characteristics allow Magnuviator to be recognized as a member of the Iguanomorpha: the parietal eye being located at the frontal- parietal suture; the boss on the prefrontal; and the angular process in front of the jaw joint. Like the Temujiniidae, the splenial anterior inferior alveolar foramen is shared between the splenial and the dentary in Magnuviator, and it also has a thin pubic symphysis. However, unlike the Temujiniidae but like most other iguanomorphs, Magnuviator also has an upwards-directed process of the squamosal.
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It was named based on a partial left dentary from Alberta, Canada. Gryphoceratops represents the oldest known leptoceratopsid and probably the smallest adult- sized ceratopsian known from North America. Leptoceratopsids are known from Eastern North America by a partial maxilla dated to the early Campanian of North Carolina, whilst the European material referred to Leptoceratopsidae consists of isolated teeth and vertebrae from the early Campanian of Sweden. The former represents the first known ceratopsian from Eastern North America, and its specialised maxillary anatomy supports the hypothesis that Appalachia was isolated from Western Europe and Laramidia for an extended period during the Late Cretaceous, resulting in an endemic Late Cretaceous fauna.
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These species range in size from about 2.7-3.8 centimetres (1.1-1.5 in) SL. C. cuestae and C. tocantinensis were described to be differentiated by counts of premaxillary and dentary teeth. However, they also differ in color pattern, as the unbranched caudal fin rays of C. britskii and C. tocantinensis lack the striped pattern present in C. cuestae. Corumbataia species exhibit sexual dimorphism. Males differ from females by presenting a developed urogenital papillae posterior to the anus, a skin fold at the dorsal portion of the pelvic fin spine, and a much longer pelvic fin spine that extends over the first anal fin ray.
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Andersonia leptura is a species of catfish (order Siluriformes) of the family Amphiliidae, and is the only species of the genus Andersonia. This fish grows to about 50.0 cm (19.7 in) in total length; it is found in the Omo, Niger, and Upper Nile Rivers and the Lake Chad basin, and is also known from Lake Debo. Although previously considered to be toothless on the lower jaw, dentition has been found on the premaxilla and the dentary. The teeth are embedded in the mucous sheath that covers the head and extends into the oral cavity, which makes the teeth difficult to see with the naked eye.
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The quadrate and the maxillary and palatopterygoid arches are more or less movable to allow for the distension required by the passage of prey, often much exceeding the size of the mouth. For the same reason, the rami of the lower jaw, which consist of dentary, splenial, angular, and articular elements, with the addition of a coronoid in the boas and a few other small families, are connected at the symphysis by a very extensible elastic ligament. The hyoid apparatus is reduced to a pair of cartilaginous filaments situated below the trachea, and united in front. There are various modifications according to the genera.
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Necromantis has a strong negative tilting of the head, a characteristic thought to correlate with nasal-emission echolocation in bats, as seen in forms like megadermatids and phyllostomids, though it is not clear if Necromantis had a nose-leaf, too. Its powerful jaws, combined with the specialised dentition, strongly suggest that Necromantis was a carnivore, feeding primarily on other vertebrates. The shearing teeth and strong masseters suggest that it was more specialised to grind and crush flesh and bone than were other bat species. In particular, the angular process of the dentary implies that crushing force was much more important than the width of gape, unlike modern predatory bats.
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Later, in 2017, another team re- evaluated the specimen, and determined through investigating the fossils at a microscopic level (in a process called histology) that this was correct, although they doubted the significance of some of the characters identified in the former study. Though the quality of bone preservation is generally poor, the holotype skeleton is estimated to be 60% complete. It consists of a left maxilla and dentary, parietal, various isolated skull elements, thirteen cervical vertebrae, six dorsal vertebrae, two sacral vertebrae, a series of 35 caudal vertebrae, a left scapula, lower portions of both humeri, most elements of the lower forelimbs, an ischium, left ilium, and most of the hindlimbs.
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They found the holotype specimen to have been equal to Tyrannosaurus in size at (marginally smaller than "Sue"), but that the larger dentary might have represented an animal of , if geometrically similar to the holotype specimen. By using multivariate regression equations, these authors also suggested an alternative weight of for the holotype and for the larger specimen, and that the latter was therefore the largest known terrestrial carnivore. Frankfurt Hauptbahnhof. In 2005, the paleontologist Cristiano Dal Sasso and colleagues described new skull material (a snout) of Spinosaurus (the original fossils of which were also destroyed during World War II), and concluded this dinosaur would have been long with a weight , exceeding the maximum size of all other theropods.
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This would make Spinosaurus the largest known carnivorous dinosaur. In 2019, the paleontologist W. Scott Persons and colleagues described a Tyrannosaurus specimen (nicknamed "Scotty"), and estimated it to be more massive than other giant theropods, but cautioned that the femoral proportions of the carcharodontosaurids Giganotosaurus and Tyrannotitan indicated a body mass larger than other adult Tyrannosaurus. They noted that these theropods were known by far fewer specimens than Tyrannosaurus, and that future finds may reveal specimens larger than "Scotty", as indicated by the large Giganotosaurus dentary. While "Scotty" had the greatest femoral circumference, the femoral length of Giganotosaurus was about 10% longer, but the authors stated it was a difficult to compare proportions between large theropod clades.
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American Museum Novitates, 3717 . pp. 1-53. ISSN 0003-0082 Dryptosaurus may have used both its arms and its jaws and as weapons when hunting, capturing and processing prey. The type specimen is a fragmentary skeleton belonging to a single adult individual. ANSP 9995 consists of a fragmentary right maxilla, a fragmentary right dentary, a fragmentary right surangular, lateral teeth, 11 middle-distal caudal vertebrae, both the left and right humeri, three manual phalanges from the left hand (I-1, II-2, and an ungual), the shafts of the left and right pubic bones, a fragmentary right ischium, the left femur, the left tibia, the left fibula, the left astragalus, and a midshaft fragment of metatarsal III.
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It bears ten teeth. In the 1998 description a part of the splenial was mistaken for a supradentarium and the angular was misidentified as the surangular because in the fossil it had been displaced upwards, creating the false impression an external mandibular fenestra, an opening in the outer side of the jaw, would be present. Scipionyx has five teeth in the premaxilla, seven in the maxilla and ten in the dentary of the lower jaw for a total of twenty-two per side and a grand total for the head of forty-four. The number of five premaxillary teeth is surprising, as a total of four is normal for compsognathids: otherwise, only some Carnosauria have five.
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Restoration based on Torvosaurus, a close relative The type specimen of Wiehenvenator consists of an assortment of bones found in the Ornatenton Formation dating from the middle Callovian. They include parts of the skull (right premaxilla, right maxilla, right lacrimal bone, right postorbital and possible front branch of the right quadratojugal), the anterior parts of a right lower jaw (dentary), six teeth, three tail vertebrae, a pair of fused median segments of rear gastralia, one complete rib and four rib fragments, a finger phalanx, both fibulae, a right astragalus and a right calcaneum. All these bones were seen as belonging to a single individual. Two additional tail vertebrae may also belong to it.
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Genyodectes ("jaw bite", from the Greek words genys ("jaw") and dektes ("bite")) is a genus of ceratosaurian theropod dinosaur from the Lower Cretaceous (Aptian) of South America. The holotype material (MLP 26–39, Museo de La Plata, La Plata, Argentina) was collected from the Cerro Barcino Formation, Cañadón Grande, Departamento Paso de Indios in the Chubut Province of Argentina and consists of an incomplete snout, including the premaxillae, portions of both maxillas, the right and left dentary, many teeth, a fragment of the left splenial, and parts of the supradentaries. These elements are generally poorly preserved and some are in articulation. The premaxilla of Genyodectes possesses relatively large and protruding teeth, similar to those of Ceratosaurus.
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It is believed that pits represent vestigial dental alveoli that once held an additional pair of teeth in ancestral species but devolved in Megacephalosaurus. Almost all pliosaurs normally have five pairs of premaxillary teeth and this feature of reduction to four pairs is fairly unique among pliosaurs; it has only been documented elsewhere in Kronosaurus, Brachauchenius and Acostasaurus, indicating that the reduction to four pairs of premaxillary teeth may have been a novel adaptation introduced by Cretaceous pliosaurs. The lower jaws bear twenty-three pairs of functional teeth. Only the five frontmost pairs are relatively large, all teeth subsequent of them get progressively smaller as they progress towards the base of the dentary in a smooth transition.
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As far as can be determined, all of the dentary teeth conform to this pattern, although one tooth at tooth position 8 in GAA 00246-1, although slightly damaged at the tip, does appear to have both anterior and posterior cusps. In all cases the teeth are more slender than in the dentaries of Oromycter and have more modest lingual shoulders at the base of the crown. Overall, it appears that the dentition in Arisierpeton shows some modifications in tooth shape and crown outline from the primitive amniote condition seen in the basal caseid Eocasea and in eothyridid caseasaurians. The teeth show little or no recurvature, but instead have some medial or lingual curvature apically.
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Protoceratopsids may have had cheeks to hold food in their mouths. They have very well-defined maxillary and dentary ridges where the muscles in the cheek would have connected, and a number of foramina dotted the maxilla which allowed branches from the trigimenal nerve to reach the tissues attached to the maxilla, indicating that such tissues were likely muscular. The end of the upper jaw was likely not fleshy but instead covered by a horn-like material, and the upper and lower jaws curved in towards each other. Compared to more derived ceratopsians, protoceratopsids had a deep and wide oral cavity, though more narrow than in predecessors like Psittacosaurus, which may have aided in breathing or thermoregulation.
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Known material Acheroraptor was first described and named by David C. Evans, Derek W. Larson and Philip J. Currie in 2013 and the type species is Acheroraptor temertyorum. The generic name is derived from the Greek Ἀχέρων, Acheron, "underworld", in reference to the provenance from the Hell Creek Formation, and the Latin raptor, "thief". The specific name honours James and Louise Temerty, the chairman of Northland Power and the ROM Board of Governors and his wife, who have supported the museum for many years. Acheroraptor is known from the holotype ROM 63777, a complete right maxilla with several maxillary teeth (some isolated), and from a referred dentary (lower jaw) ROM 63778, both housed at the Royal Ontario Museum, Canada.
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He also synonymized Gryposaurus with Kritosaurus, a move supported by Charles Gilmore. This synonymy was used through the 1920s (William Parks's designation of a Canadian species as Kritosaurus incurvimanus, now considered a synonym of Gryposaurus notabilis) and became standard after the publication of Richard Swann Lull and Nelda Wright's 1942 monograph on North American hadrosaurids. From this time until 1990, Kritosaurus would be composed of at least the type species K. navajovius, K. incurvimanus, and K. notabilis, the former type species of Gryposaurus. The poorly known species Hadrosaurus breviceps (Marsh, 1889), known from a dentary from the Campanian-age Judith River Formation of Montana, was also assigned to Kritosaurus by Lull and Wright, but this is no longer accepted.
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X. bamaolinensis preserves a type 2 suture while X. kohi has a type 1 suture. X. suni's suture differs between specimens while X. xinyiensis seems to have a type 2 suture. The dentary is also narrow and shorter than the snout, with robust, pointed teeth in the front of its jaws and broad crushing teeth in the back of its jaws, suggesting that it fed on hard-shelled prey, although these adaptations are not as extreme as those of Concavispina, which had exclusively short and blunt teeth. This genus also has a uniquely upward-curving maxilla, a wide proximal end of the humerus, and a radius with a convex lateral edge and concave medial edge.
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Subsequent research seemed to confirm this hypothesis, and the genus Megalosaurus and species M. bucklandii became generally regarded as limited to the taxon having produced the lectotype, the dentary of the lower jaw. Furthermore, several researchers failed to find any characteristics in that jaw that could be used to distinguish Megalosaurus from its relatives, which would mean the genus were a nomen dubium. However, a comprehensive study by Roger Benson and colleagues in 2008, and several related analyses published in subsequent years, overturned the previous consensus by identifying several autapomorphies, or unique distinguishing characteristics, in the lower jaw that could be used to separate Megalosaurus from other megalosaurids. Various distinguishing traits of the lower jaw have been established.
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In 1990, Ralph Molnar chose the famous dentary (front part of the lower jaw), OUM J13505, as such a lectotype.Molnar, R.E.; Seriozha M.K. & Dong Z. (1990). "Carnosauria" In: Because he was unaccustomed to the deep dinosaurian pelvis, much taller than with typical reptiles, Buckland misidentified several bones, interpreting the pubic bone as a fibula and mistaking the ischium for a clavicle. Buckland identified the organism as being a giant animal belonging to the Sauria – the Lizards, at the time seen as including the crocodiles – and he placed it in the new genus Megalosaurus, repeating an estimate by Cuvier that the largest pieces he described, indicated an animal twelve metres long in life.
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The dentary (tooth-bearing lower jaw bone) was squared off at the front edge, as in Giganotosaurus, and shallow, while the rest of the jaw behind it became very deep. Acrocanthosaurus and Giganotosaurus shared a thick horizontal ridge on the outside surface of the surangular bone of the lower jaw, underneath the articulation with the skull. Skeletal diagram The most notable feature of Acrocanthosaurus was its row of tall neural spines, located on the vertebrae of the neck, back, hips and upper tail, which could be more than 2.5 times the height of the vertebrae from which they extended. Other dinosaurs also had high spines on the back, sometimes much higher than those of Acrocanthosaurus.
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However, later study of the type specimen showed that tooth sockets were present in the preserved parts of the jaw, and comparison with related forms showed that it did have teeth. The discovery of a more well preserved specimen confirmed the presence of teeth in at least the maxilla (middle of the upper jaw) and dentary (lower jaw). The snout appears to have lacked feathers, though whether it was only covered in skin or some parts bore a beak is currently unknown. The describers of Hongshanornis noted a unique bone in the end of the lower jaw which they equated with the beak-bearing "predentary bone" similar to the one found in ornithischian dinosaurs.
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It also has a long, sheet-like process of the maxilla that extends back to the anterolateral part of the maxilla–frontal contact medial to the external naris, and terminates just anterior to midlength of the orbital. Finally, the suture between the premaxilla and parietal bone is located around orbital midlength. P. westburyensis also possesses a unique combination of characters, including: low dentary alveolar count including only 18 postsymphysial alveoli; teeth fully trihedral in cross-section, possessing a flat, anteroposteriorly broad labial surface lacking enamel ridges; relatively slight mediolateral expansion of premaxilla and maxillary caniniform region; six premaxillary alveoli; lack of anisodont premaxillary dentition; lack of diastema between maxillary and premaxillary alveolar rows; and cervical centra lacking ventral ridge.
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The presence of the enlarged pseudo fangs on the premaxilla in Eusthenodon, supported its phylogenetic position within the Tristichopteridae clade as similar dentition patterns are found in other closely related derived tristichopterids. The number of small pointed teeth along the tooth row further supports dentition trends over time as in more derived genera, a greater number of teeth are found relative to more primitive species such as Eusthenopteron. Despite possessing sets of premaxillary pseudo fangs, Eusthenodon and other large, phylogenetically derived tristichopterids exhibit elaborate anterior dentition and distinctive enlarged dentary fangs. The faintly concave denticulated field of the parasphenoid bone is raised in primitive tristichopterids while it is notably recessed in Eusthenodon.
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They are positioned closer to the midlines of the upper and lower jaws than are the incisors due to an inward expansion of the maxilla and dentary bones. Microgomphodon is very similar in appearance to Bauria, but differs in having a small hole called a pineal foramen at the top of the skull behind the eye sockets, a complete postorbital bar enclosing the eye sockets from behind, fewer postcanine teeth, and canines located farther back along the upper jaw. Additionally, the two taxa can be distinguished by many subtle differences relating to the shape of the skull. For example, Microgomphodon has a deeper snout, slightly larger eyes, and a sharper angle to the zygomatic arches than does Bauria.
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Oral jaw from side and above of Piaractus brachypomus, a close relative of piranhas In vertebrates, the lower jaw (mandible or jawbone)The mandible is also in some sources still referred to as the inferior maxillary bone, though this is an outdated term which goes back to at least the 1858 first edition of Gray's Anatomy, if not earlier. is a bone forming the skull with the cranium. In lobe-finned fishes and the early fossil tetrapods, the bone homologous to the mandible of mammals is merely the largest of several bones in the lower jaw. It is referred to as the dentary bone, and forms the body of the outer surface of the jaw.
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More recent work looking at the morphometrics of the feet in hesperornithiformes and modern sea birds has thrown this interpretation into question, making webbed toes equally as likely as lobed toes for this group. Like many other Mesozoic birds such as Ichthyornis, Hesperornis had teeth as well as a beak. In the hesperornithiform lineage they were of a different arrangement than in any other known bird (or in non-avian theropod dinosaurs), with the teeth sitting in a longitudinal groove rather than in individual sockets, in a notable case of convergent evolution with mosasaurs. The teeth of Hesperornis were present along nearly the entire lower jaw (dentary) and the back of the upper jaw (maxilla).
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Nonetheless, Omphalosaurus teeth could potentially number in the hundreds, and are concentrated along the skull midline. Each species has varying degrees of tooth organization, but O. nevadanus has the most neatly organized teeth, which most closely resemble distinct rows despite some unevenness. Attempts have been made to count the number of rows of teeth for the other species, but they are mostly irregularly patterned on the occlusal surface. The upper tooth plates form a convex surface, while the lower plate is concave. They were previously thought to have short, broad jaws and powerful bite forces, but recent reconstruction indicates that the dentary symphysis is elongated and connects at an approximately 15º angle, giving the jaw a long “V” shape.
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Finally, its quadrate distal articular surface is not separated into two condyles by a sulcus, and has only a very shallow depression at the centre. Like other geosaurins, P. manselii have large robust teeth, with moderate to strong mediolateral compression. Other notable characters of P. manselii are the presence of a separation between premaxilla and nasal approximately subequal to the midline length of the premaxilla, carinae formed by a keel and true microscopic denticles, and a long mandibular symphysis to which 9 out of 13 dentary teeth are adjacent. In dorsal view, the lateral margins of the prefrontals have an inflexion point directed posteriorly at an angle of approximately 70 degrees from the anteroposterior axis of the skull.
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The dentary of Pluridens was likely elongated relative to the rest of the head to allow for the massive battery of teeth. Due to force exerted by the lower jaw when biting against the upper jaw would decrease with the distance from the joint, the anterior teeth would have been ineffectual for biting and crushing. During jaw adduction, however, the speed of the anterior teeth could allow Pluridens to swiftly catch and penetrate small soft prey and a large number of teeth would ensure that it did not loose hold of the prey. The tooth crowns are broad and short which indicates that they were used for crushing, perhaps of thinshelled invertebrates.
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A. jimmadseni skull with diagram highlighting individual bones The skull and teeth of Allosaurus were modestly proportioned for a theropod of its size. Paleontologist Gregory S. Paul gives a length of for a skull belonging to an individual he estimates at long. Each premaxilla (the bones that formed the tip of the snout) held five teeth with D-shaped cross-sections, and each maxilla (the main tooth-bearing bones in the upper jaw) had between 14 and 17 teeth; the number of teeth does not exactly correspond to the size of the bone. Each dentary (the tooth-bearing bone of the lower jaw) had between 14 and 17 teeth, with an average count of 16.
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Dicynodonts were specialized herbivores that employed a unique “cheek pivot system” of mastication that created powerful shearing action upon closure of the jaw and subsequently ground mouth contents through a system of interlocking ridges and grooves formed from the palate and dentary. Two morphological features, present already in Eodicynodon, made this motion possible. The first was a double convex jaw joint, wherein both the quadrate and articular formed convex condyles. As the jaw closed, the articular condyle of the lower jaw slid anterio-dorsally along the quadrate condyle, resulting in closure of the mouth from back to front as the posterior end of the mandible was elevated dorsally relative to the anterior end.
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The teeth were set obliquely along the length of the jaws, and overlapped each other slightly from front to back. On each side, the most complete specimen (UALVP 2) had three teeth in the premaxilla, sixteen in the maxilla (both part of the upper jaw), and seventeen in the dentary of the lower jaw. The teeth in the premaxilla were separated from those behind in the maxilla by a short diastema (space), and the two rows in the premaxilla were separated by a toothless gap at the front. The teeth in the front part of the upper jaw (premaxilla) and front lower jaw were similar; these had taller, more pointed and recurved crowns, and a "heel" at the back.
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The teeth were typical of abelisaurids in having short crowns, although Majungasaurus bore seventeen teeth in both the maxilla of the upper jaw and the dentary of the lower jaw, more than in any other abelisaurid except Rugops. Life restoration The postcranial skeleton of Majungasaurus closely resembles those of Carnotaurus and Aucasaurus, the only other abelisaurid genera for which complete skeletal material is known. Majungasaurus was bipedal, with a long tail to balance out the head and torso, putting the center of gravity over the hips. Although the cervical (neck) vertebrae had numerous cavities and excavations (pleurocoels) to reduce their weight, they were robust, with exaggerated muscle attachment sites and ribs that interlocked for strength.
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Skull diagram of Azendohsaurus madagaskarensis The skull of A. madagaskarensis is almost completely known, and is robustly built with a short and boxy shape and a deep snout. The premaxillae are gently curved at the front of the upper jaw, forming a blunt, round snout tip, while the lower jaws have a deep, down- turned tip like those of sauropods. The bony nostrils are fused into a single (confluent) opening that faces forwards at the front of the snout, similar to those of rhynchosaurs. The skull has a number of traits convergent with sauropodomorphs, including the downward curving dentary, a robust dorsal process of the maxilla, and several features of the teeth.
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In 2006, the stratigraphy of the region was re- evaluated, and the dentary's location was corrected to the LL locality, away from and below the SRA locality. The same 2006 study, by Albert Prieto-Márquez and colleagues, noted that no dentary had been found at the SRA locality to compare to the LL specimen, and so they restricted P. isonensis to material known from its original locality. Additionally, they named a genus and species for IPS SRA 27, Koutalisaurus kohlerorum. The generic name is derived from the Greek word koutali, meaning spoon, in reference to the shape the jaw of the animal would've had, and the specific name honours Terry and Mary Kohler, for their support of vertebrate paleontology.
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No material had, as yet, been discovered from the SRA locality permitting comparison with Pararhabdodon. However, traits uniting P. isonensis with T. spinorhinus were found. As both taxa from the Talarn Formation uniquely shared traits with the Asian genus, the authors decided to treat the two as one species, as maintaining them as provisionally separate would in their eyes be misleading to non-specialists, who would likely not distinguish the two taxa were kept separate to be conservative and not due to strong evidence for two hadrosaurs in the area. Prieto-Márquez returned again to the dentary in 2013, in a study alongside colleagues providing a review and investigation of hadrosaurs from all over Europe.
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Pelecanimimus possessed per side seventy-five dentary teeth in the lower jaw, as well as an additional thirty- seven teeth in the upper jaw (maxilla and premaxilla). The small teeth of Harpymimus were probably used only for grabbing and holding food items, unlike those of many other theropods, which were adapted to cutting or piercing prey. Of all the known ornithomimosaurs, only Harpymimus and Pelecanimimus retained teeth, a trait which is primitive (plesiomorphic) for the clade Ornithomimosauria. Other basal traits are the very short first metacarpal in the hand and a third metatarsal that, though pinched at the top, is at that point not excluded form the front surface of the metatarsus, so that the foot is not arctometatarsalian.
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Even in those multituberculates that do have small prisms, the prism sheath is closed, but the sheath is incomplete in Gondwanatherium and possibly Ferugliotherium. Krause and colleagues wrote that these two teeth resemble multituberculate deciduous anterior upper premolars, particularly second and third premolars (P2 and P3), and used this as one of their arguments for identifying Ferugliotherium as a multituberculate. However, as with the dentary MACN Pv-RN 975, the two upper premolars were excluded from Ferugliotherium and identified as multituberculates by Kielan-Jaworowska and colleagues after the discovery of the jaw of Sudamerica. Gurovich continues to identify them as Ferugliotherium on the basis of their size and provenance and other similarities between Ferugliotherium and multituberculates.
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The holotype's smaller size, smoother surface, and lack of co-ossified (fused) sutures all indicate that it belongs to a juvenile individual; while MNHN GDF 365 probably represents an adult. The tip of Cristatusauruss premaxilla was short and expanded, while the rear end was narrowed near the suture with the maxilla; this rosette-like snout shape was characteristic of spinosaurids. The front of the upper jaw was concave on the bottom, shaped to interlock with what would have been the convex and also enlarged tip of the mandible's dentary bone. A thin sagittal crest ran lengthwise on top of the premaxillae, a condition present in Baryonyx and Suchomimus, and very prominent in Angaturama (a possible synonym of Irritator).
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Patagosuchus is known solely from its holotype, MANE-PV 1, which consists of some associated bones belonging to a single individual. The remains include a fragmentary left dentary and splenial, the right maxilla and right jugal bone, a back vertebra, a back osteoderm and the right humerus. MANE-PV 1 was discovered at the Baal Quarry, in the Loma de La Lata area, near the northern coast of Lago Los Barreales, 12 km south of Añelo City, southeastern Neuquén Province of Patagonia. It was collected from the Portezuelo Formation which is the older of the two formations in the Río Neuquén Subgroup, of the Neuquén Group, dating to the late Turonian to early Coniacian of the early Late Cretaceous.
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The ear is prominent from the fur, and characteristic notches are seen at the outer margin of each lobe. The new species was distinguished from Falsistrellus tasmaniensis as being generally larger, specifically the comparative size of skull measurements, the proportionally longer dentary, and slightly bigger glans penis. The skull is robust, and an average of 19.2 millimetres at its greatest length (range: 18.2–20.1 mm). External lengths were 61.7 mm for snout to anus (range: 55.4–66.6 mm); forearm 45–56 mm; the tail is 46.2 mm on average (40.1–53.2 mm); tibia 22.1 mm (20.2–23.6 mm); ear 16.7 mm (14.0–18.3 mm); tragus 9.2 mm (7.7–10.6 mm) and pes length 10.2 mm (8.2–11.6 mm).
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Busbey also ruled out the Peruvian fossil belonging to S. huilensis, based on its unique anatomy, less spaced teeth and a wider nose. Langston, along with the Argentine paleontologist Zulma Gasparini, reported new remains of the species in a contribution on fossil crocodylomorphs of Colombia for the book Vertebrate Paleontology of the Neotropics: The Miocene Fauna of La Venta (1997). In this case it would be new specimens of teeth, a somewhat fuller premaxilla, an anterior fragment of dentary, and two vertebrae: a sacral and a caudal, which also were unknown to this group. The specimens discovered on this occasion were deposited in the Geological Museum of Ingeominas (previous name of Colombian Geological Service).
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The head of Liaodactylus is slender and long, with a skull length of and a jaw length of . Out of this, the snout is 49.1% of total skull length, and the nasoantorbital fenestra (the fusion of the nostril and the antorbital fenestra, seen in all members of the Monofenestrata) is 31% of skull length. In more derived ctenochasmatids, the nasoantorbital fenestra is much smaller relative to the skull, being only 10-12% of skull length in Pterodaustro; the snout is also longer, being over 85% of skull length in Pterodaustro. Also shorter than other ctenochasmatids is the dentary symphysis, the fused portion of the lower jaw, which is only 30.5% of jaw length.
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The differences which distinguish the genus Chindongo from other mbuna genera in Lake Malawi are the possession of bicuspid teeth in the front parts of the outer rows of both the upper and lower mandibles, the vomer is moderately to steeply sloped and has a narrow rostral tip has an angle of between 53° and 68° with the parasphenoid, they have a small mouth in which the lower jaw is slightly shorter than the upper jaw, there is a wide tooth bearing area on the anterior portions of both the premaxillary bone and dentary which have three or more rows of teeth (normally 5–6 rows) and a pattern of vertical bars on their flanks throughout their development.
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In the lower jaw, the dentary has an opening in its side. The formula for the phalanges of the hand is 1-2-3-0-0 or 2-3-3-0-0 — or 0-1-2-3-0/0-2-2-3-0 if the three fingers of the hand are interpreted as the second, third and fourth. The upper phalanges of the second and third (or third and fourth) finger are elongated with more than 75% of the length of the corresponding metacarpal. The lower leg is relatively long with the tibiotarsus having 137% of the length of the thighbone. The skull of Hexing is relatively large with a length of 136 millimetres.
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Cargninia is an extinct genus of basal lepidosaur from the Late Triassic period. It lived during the late Triassic period (Carnian to Norian stage) in what is now Faxinal do Soturno, Rio Grande do Sul, southern Brazil, in the geopark Paleorrota. It is known from the holotype UFRGS PV 1027 T, a partial dentary, recovered from the middle section of the Caturrita Formation. Cargninia was named by José Fernando Bonaparte, César Leandro Schultz, Marina Bento Soares and Agustín G. Martinelli in 2010 and the type species is Cargninia enigmatica. The generic name honors Daniel Cargnin priest, a Brazilian fossil collector, and the specific name means “enigmatic” in reference to the basal position within the Lepidosauria.
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Because of this, the jaw of Probainognathus remains distinct from that of mammals due mostly to the presence of the articular and the quadrate. Once the dentary-squamosal articulation becomes more established, the former bones involved in jaw articulation, the articular and quadrate, can become integrated into the inner ear as the malleus and incus, respectively. This has not yet happened in the case of Probainognathus, but the reduced size of the quadrate, as well as its loose association with the squamosal and proximity to the stapes indicates the quadrate to incus process is underway. This combination of evidence further solidifies Probainognathus’ phylogenetic placement on the line to Mammalia, and provides a sound evolutionary connection between reptiles and mammals.
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Traditionally, membership in Mammalia is diagnosed by the presence of a single dominant jaw joint, in which the dentary contacts the squamosal. However, taxonomists debate whether established names, such as Mammalia, should correspond to the clade which is closest to the traditional definition or, alternatively, should be restricted to the 'crown- group' (which includes only descendants of the most recent common ancestor shared by all living member species and excludes any fossil forms which diverged at an earlier stage, even if they meet the traditional criteria). Supporters of the crown-group approach refer to the broader grouping as the Mammaliformes or Mammaliaformes, whereas traditionalists describe the entire assemblage as "mammals". For a summary of the argument and issues, see Benton 2005: 289.
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Calvo and Coria found the dentary to be identical to that of the holotype, though 8% larger at 62 cm (24 in). Though the rear part of it is incomplete, they proposed that the skull of the holotype specimen would have been long, and estimated the skull of the larger specimen to have been long, the longest skull of any theropod. In 1999, Calvo referred an incomplete tooth, (MUCPv-52), to Giganotosaurus; this specimen was discovered near Lake Ezequiel Ramos Mexia in 1987 by A. Delgado, and is therefore the first known fossil of the genus. Calvo further suggested that some theropod trackways and isolated tracks (which he made the basis of the ichnotaxon Abelichnus astigarrae in 1991) belonged to Giganotosaurus, based on their large size.
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Laelaps trihedrodon was coined by Cope in 1877 for a partial dentary (now missing) from the Morrison Formation of Colorado. Five damaged partial tooth crowns (AMNH 5780) mistakenly thought to have belonged to the L. trihedrodon holotype share many features in common with Allosaurus and probably belong to that genus. However some of the Allosaurus-like characters of the teeth are primitive to theropods as a whole and may have been present in other large- bodied Morrison Formation theropod species. "Laelaps" macropus was coined by Cope for a partial hind limb found in the Navesink Formation that Joseph Leidy had referred earlier to the ornithomimid Coelosaurus, distinguishing it from Dryptosaurus by its longer toes.Cope, E.D., On the genus Laelaps, American Journal of Science, 1868; 2: 415-417.
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Ambondro is more closely related to monotremes than to therian mammals while Amphilestes and Amphitherium are more closely related to the therians; as fossils of all three genera are dated about in the Middle Jurassic, this is a reasonable estimate for the appearance of the crown group. T. S. Kemp has provided a more traditional definition: "Synapsids that possess a dentary–squamosal jaw articulation and occlusion between upper and lower molars with a transverse component to the movement" or, equivalently in Kemp's view, the clade originating with the last common ancestor of Sinoconodon and living mammals. The earliest known synapsid satisfying Kemp's definitions is Tikitherium, dated , so the appearance of mammals in this broader sense can be given this Late Triassic date.
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The basal New Egypt is a massive clayey, glauconitic marl that closely resembles the Navasink Formation into which it grades below. Ammonites and other invertebrates found at the Spheno Run site correlate well with the middle Severn Formation of Maryland. Spheno Run has so far produced a remarkable number of vertebrate specimens, especially from marine reptiles, including: carapace elements from at least two species of turtles, Peritresius ornatus and Taphrosphys sulcatus; various bone elements from at least two species of mosasaurs including a sizable fragment of dentary bone from Prognathodon rapax and numerous shed teeth from Mosasaurus maximus. Vertebrate remains also include material from sharks, particularly teeth and unusually large vertebral centra from an individual lamniform shark Squalicorax pristodontus, bony fish, and, rarely, dinosaurs.
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They also noted another difference from spinosaurids in that the bony nostrils were not retracted up the length of the snout. Within the Crocodylomorpha, Dal Sasso and colleagues confirmed previous observations that the palate of Razanandrongobe differed from "sphenosuchians", in addition to having a more robust dentary with a shorter toothless portion and a less conspicuous splenial. In particular, the extent of the splenial was probably similar to many other notosuchians, but was not as extreme as the Peirosauridae where the bone contributes to half of the jaw. The fused bony nostrils were most similar in morphology and orientation to the Sphagesauridae; they differed from the Peirosauridae in their complete fusion, and from the Sebecidae in their orientation forwards and not upwards.
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A pseudotooth bird's lower right dentary piece (specimen YPM 4617) from near Charleston, South Carolina (United States) – apparently dredged up from near the source of the Stono River – was provisionally assigned to P. longirostris as it closely matches the holotype in size and appearance. At first the South Carolina fossil was believed to be from the Early Miocene Hawthorne Formation, but in fact no Hawthorne Formation sediments were known in the Charleston region when the fossil was found. Consequently, modern authors consider a Chattian (Late Oligocene) age more likely and suggest the fossil came from the Cooper or Chandler Bridge Formation. Some fossil remains from the Middle Miocene Bahía Inglesa Formation of Chile were prematurely affiliated with P. longirostris in error; they are, if anything, of Pelagornis.
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Behind this expansion, the upper jaw had a notch bearing significantly smaller teeth, into which the also expanded tips of the dentaries (tooth bearing bones of the mandible) fit into, with a notch behind the expansion of the dentary. The maxillae (main upper jaw bones) were long and formed a low branch under the nostrils that connected to the rear of the premaxillae. The teeth at the frontmost part of the maxillae were small, becoming significantly larger soon after and then gradually decreasing in size towards the back of the jaw. left Lengthwise atop their skulls ran a thin and shallow sagittal crest that was usually tallest near or above the eyes, either becoming shorter or disappearing entirely towards the front of the head.
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All five of these bones are covered with tiny tooth-like bumps known as denticles. Larger fangs, similar to the marginal teeth, were also present on some of these bones; the first and second coronoids each have two of these fangs at their front outer corner and the parasympheseal has a single large fang in the middle. Additional denticles may have been present on the dentary, which has a small number of small bumps on the outer surface of the parasymphyseal region. If these were true denticles, then this is a surprisingly "primitive" feature present in Andersonerpeton, as this feature is typically considered to have been lost very early in the evolution of tetrapods (specifically, after the evolution of Elginerpeton).
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Unlike the V-shaped mandibular symphysis of Luoyanggia, Nankangia and other oviraptorosaurs have a U-shaped mandibular symphysis. Although Nankangia and Jiangxisaurus possess similar lower jaws, the medial margin of the humerus is more curved medially in Nankangia than it is in Jiangxisaurus. Based on its phylogenetic position, Nankangia displays five other possible autapomorphies, including an anteriorly projecting acromion, separated anterior and greater trochanters, dorsoventral extension of the pubic peduncle that is deeper than the ischial peduncle, and the lack of a downturned symphyseal portion of the dentary. The latter trait is shared with the coeval Ganzhousaurus and Jiangxisaurus, suggesting a primarily herbivorous diet, whereas Banji and another unnamed oviraptorid from the same formation may have been more carnivorous, as they bear a downturned mandibular symphysis.
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Macrorhineura is an extinct genus of rhineurid amphisbaenian or worm lizard, including the type and only species Macrorhineura skinneri, named in 1970 on the basis of the front half of a skull from the Early Miocene Sharps Formation in Wounded Knee, South Dakota. Although the skull is incomplete, features such as a pointed, shovel-shaped snout indicate that it belongs to the family Rhineuridae. Within Rhineuridae, Macrorhineura is most closely related to Ototriton and Hyporhina, two genera from the Eocene and Oligocene of Colorado and Wyoming, based on the shared feature of equally sized dentary teeth in the lower jaw. Together they form a clade or evolutionary grouping of mid- continental rhineurids, which became isolated from a more western clade of rhineurids that includes Dyticonastis and Spathorhynchus.
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Although both specimens lack cranial material, Button and colleagues reported an isolated dentary tooth referred to Suzhousaurus that was collected in the Yujingzi Basin near the area of the two specimens, which was described in detail by the same team and You Hailu in 2017. In 2018, You with colleagues proposed the Mazongshan Fauna, which is composed by dinosaur taxa found on the Xiagou and Zhonggou formations, and provided more historical data from the Suzhousaurus specimens: FRDC-GSJB-99 was discovered around 1999 being found in mid gray- variegated beds of the Xiagou Formation dating to the early–mid-Aptian stage, and FRDC-GSJB-2004-001 was found in 2004 at the upper red beds in the Zhonggou Formation dating to the Early Albian.
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Phlaocyon minor is an extinct species of canid mammal known from the Miocene- Oligocene (Arikareean NALMA, more than ) of the United States (Wyoming, South Dakota, Nebraska, Wyoming, and Texas.) The type specimen of P. minor is a partial maxilla, a partial dentary, and limb fragments found in Oglala Lakota County, South Dakota (: paleocoordinates ). referred half a dozen other specimens to P. minor, including a nearly complete skull and a mandible from Wyoming. P. minor is the most basal member of Phlaocyon but it can still be distinguished from more primitive borophagines such as Archaeocyon, Rhizocyon, and Cynarctoides. Characters placing it in Phlaocyon includes robust and shortened premolars, a quadrate first upper molar, and widened talonid on the first lower molar.
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Basal forms like Abrictosaurus had cheek teeth in both maxilla and dentary that were generally similar to other ornithischians: widely spaced, each having a low crown and a strongly-developed ridge (cingulum) separating the crown from the root. In more derived forms like Lycorhinus and Heterodontosaurus, the teeth were chisel-shaped, with much higher crowns and no cingula, so that there was no difference in width between the crowns and the roots. These derived cheek teeth were overlapping, so that their crowns formed a continuous surface on which food could be chewed. The tooth rows were slightly inset from the side of the mouth, leaving a space outside the teeth that may have been bounded by a muscular cheek, which would have been necessary for chewing.
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Restored heads of eight species, to scale Skulls of P. mongoliensis are flat on top, especially over the back of the skull, with a triangular depression, the antorbital fossa, on the outside surface of the maxilla (an upper jaw bone). A flange is present on the lower edge of the dentary (the tooth-bearing bone of the lower jaw), although it is not as prominent as in P. meileyingensis or P. major (=P. lujiatunensis). P. mongoliensis is among the largest known species. The skull of the type specimen, which is probably a juvenile, is 15.2 centimetres (6 in) long, and the associated femur is 16.2 centimetres (6.4 in) in length. Other specimens are larger, with the largest documented femur measuring about 21 centimetres (8.25 in) long.
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Lower jaw of the holotype specimen, with beak on the right The diet of oviraptorids has been interpreted in various ways since the time Oviraptor was wrongly thought to have been a predator of eggs. It has been suggested that oviraptorosaurs as a whole were herbivores, which is supported by the gastroliths (stomach stones) found in Caudipteryx, and the wear facets in the teeth of Incisivosaurus. In 2010 Longrich and colleagues found that oviraptorid jaws had features similar to those seen in herbivorous tetrapods (four-limbed animals), especially those of dicynodonts, an extinct group of synapsid stem- mammals. Oviraptorids and dicynodonts share features such as short, deep, and toothless mandibles; elongated dentary symphyses; elongated mandibular fenestrae; and a downwards-projecting bar in the palate.
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Tooth of the related genus Spinosaurus, Museo di Storia Naturale A. Stoppani, Lombardy Fowler in 2007 put forward the possibility of spinosaurids having evolved from ceratosaurian ancestors, given that baryonychine teeth have ridges on their crowns reminiscent to those seen on the premaxillary and dentary teeth of Ceratosaurus. In 2008, Buffetaut rejected this proposal, citing that the D-shaped cross section of said Ceratosaurus teeth is not present in those of baryonychines. The main difference between MB R 1084 and all other known spinosaurid teeth, as Buffetaut noted, was in the large size of the denticles borne by the carinae. This led him to hypothesize in 2008 that spinosaurid dental evolution was largely characterized by the shrinking and eventual loss of serrations.
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Brown and Erich Maren Schlaikjer compared the finds, and, though they allowed that both specimens were from the same general locality and geological formation, they considered the specimen sufficiently distinct from the holotype to warrant erecting a new species, and described the fossils as Styracosaurus parksi, named in honor of William Parks. Among the differences between the specimens cited by Brown and Schlaikjer were a cheekbone quite different from that of S. albertensis, and smaller tail vertebrae. S. parksi also had a more robust jaw, a shorter dentary, and the frill differed in shape from that of the type species. However, much of the skull consisted of plaster reconstruction, and the original 1937 paper did not illustrate the actual skull bones.
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The skull of Shringasaurus is not completely known, but what's preserved indicates that the skull was small and boxy, with a short, deep snout with rounded jaw tips and bony nostrils fused into a single, confluent opening at the front of the snout. This is broadly similar to the completely known skull of Azendohsaurus, however the lower jaw of Shringasaurus has a more conspicuous taper towards the tip compared to the deep, down-turned dentary of Azendohsaurus. The horns of Shringasaurus closely resemble those seen in ceratopsid dinosaurs, despite being totally unrelated to each other. The horns are attached to the frontal bones on the roof of the skull over the eyes, and sit across almost the entire breadth of the skull.
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By the Late Permian many other groups of tetrapods had entered that niche, and increased competition among herbivores likely resulted in the eventual extinction of diadectids. Alveusdectes may have been able to persist because the fauna of north China seems to have been isolated from other Laurasian faunas during the Late Permian, meaning that fewer herbivores were competing for the same ecological space. Alveusdectes differs from other diadectids in having a pair of large holes at the back of its skull called suborbital fenestrae, which would have been attachment points for large jaw muscles. Other defining features include a large fourth tooth in the dentary bone of the lower jaw and an elongate Meckelian fenestra positioned near the back of the jaw.
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In eilenodonts, the mandibular teeth of the dentary become worn down on two sides due to contact with the maxillary and palatine teeth on the roof of the mouth. This creates two wear facets (worn away areas) in all but the most posterior teeth, converging in a 90 degree angle to form a blade-like ridge. The labial wear facet (worn-away area on the side facing the lips) was originally believed to have been positioned practically vertically while the apical (upward-facing) wear facet would have been positioned nearly horizontally, making the tooth row rectangular in cross-section. Towards the front of the jaw the wear facets shift inwards to a more diagonal position, making the tooth row triangular in cross-section.
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The sediments were laid down in the floodplain of a river, which transported the fossils, but only a short distance, judging by the randomly assorted, disarticulated, but well-preserved bones within the bonebed, including fragile skull elements. Only a small section of the bonebed has been uncovered, but 90% of the remains found so far belong to lambeosaurines like Amurosaurus, mostly juveniles, with the rest belonging to other taxa, such as the hadrosaurine Kerberosaurus. Theropod teeth are also abundant, and there are many toothmarks on the bones, made by predators or scavengers. Restored skull The holotype, or original specimen, consists of only a maxilla (upper jaw bone), and a dentary (lower jaw bone), both from the left side of the same individual.
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Both species of Laganosuchus are known only from their lower jaws, those of L. thaumastos almost complete save for the left retroarticular process and those of L. maghrebensis only from a fragment of the dentary bone. L. thaumastos had a total jaw length of 838 mm and a jaw length from tip to articular facet of 750 mm, of which 490 mm actually bore teeth. Across the jaws, the total width of the lower jaw ranged from around 140 mm at the symphysis to 240 mm at the articular facets, widening fairly evenly all the way along. All the teeth were simple straight spikes, with the first pair the largest and the rest of the teeth decreasing in size towards the back of the mouth.
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Further back, there were at least 22 teeth per upper jaw side in the maxilla, while the entire lower jaw side carried 32 teeth in the dentary bone. Closeup of front of the snout and dentition The upper jaw had a prominent kink just behind the rosette, protruding downwards; this convexly curved part of the maxilla had the longest teeth of the entire skull. The internal bone shelves of the maxillae met each other in the midline of the skull over a long distance, forming a closed secondary palate that stiffened the snout, and setting off the internal nostrils and palatal complex (including the pterygoid, palatine and ectopterygoid) towards the back of the skull. The nostrils, unlike in most theropods, were retracted further back on the skull and behind the premaxillary teeth.
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Given the incompleteness of Razanandrongobe, Maganuco and colleagues did not assign Razanandrongobe to a specific group in 2006. Subsequently, the discovery of additional specimens allowed Dal Sasso and colleagues to refine the phylogenetic placement of Razanandrongobe in 2017. The new specimens allowed them to unequivocally identify it as a crocodylomorph and not a theropod, with all similarities having been convergently acquired. Unlike theropods, it has forward-facing and fused bony nostrils that do not contact the maxilla anywhere and are not divided by any bony process; a dentary taller and more robust than any theropod; a splenial which would have been a conspicuous part of the lower jaw, being even visible from the side; a well-developed bony palate on the maxilla; and the previously-noted thickening of the tooth crowns.
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Cranial remains Mosaiceratops lived in the upper Cretaceous in what is now the Henan Province of China. The holotype is represented by an incomplete and disarticulated skeleton including pelvis bones and leg bones (femur, tibia, fibula, ischium, ilium, some phalanges and metatarsals, calcaneum and astragalus), 24 vertebrae (3 cervicals, 3 dorsals and 18 caudals), a dorsal rib, a humerus, a radius and the anterior part of an articulated skull with a disarticulated postorbital bone and squamosal. The articulates skull preserves the rostral bone, premaxilla, maxilla, jugal bone, quadratojugal, dentary, surangular, angular bone, the anterior section of the prefrontal bone, and the anterior part of the nasal bone. The name Mosaiceratops means "mosaic horned face", which refers to the mosaic of features normally found on basal neoceratopsians, psittacosaurids and other basal ceratopsians.
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The examination of specimens of T. minor with those of E. lerichei yielded many similarities between the two species, including the foramen aerum as well as other features such as a long nasal process between the premaxillae, dentary alveoli arranged in pairs, and a W-shaped basioccipital tuberosity. E. minor differs from E. lerichei on the basis of a noticeably wider nasal and prefrontals positioned anteriorly further up the skull than the lacrimals. Other material present from the Aquia Formation of Maryland and Virginia, which dates back to the early Paleocene, tends to be more complete. Some specimens found from these localities are known from nearly complete skulls that provide a more detailed view of the phylogenetic position of Eosuchus, and further aid in distinguishing E. minor from other gavialoids.
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Zhanghenglong is probably a non-hadrosaurid hadrosauroid based on a series of plesiomorphic features present in this taxon. The new genus and species significantly differs from other known members of Hadrosauroidea in having two distinct autapomorphies (strongly deflected posteroventrally posterior third of the maxilla relative to the anterior two thirds of it and dentary teeth with crowns of both median and distally offset primary ridges) and a unique combination of features. Despite the confluence of some plesiomorphic features typical of non- hadrosaurid hadrosauroids, Zhanghenglong possesses some derived characters seen in hadrosaurids, as well as two transitional features that are intermediate between the corresponding plesiomorphic and derived characters of hadrosauroids. This taxon may therefore represent a relatively derived non- hadrosaurid hadrosauroid, and is thought to be one of the closest relatives to Hadrosauridae.
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In 1945, after examining casts of T. formosus and S. validus teeth, the American palaeontologist Charles M. Sternberg demonstrated differences between the two, and instead suggested that Troodon was a theropod dinosaur, and that the dome-headed dinosaurs should be placed in their own family. Though Stegoceras was the first member of this family to be named, Sternberg named the group Pachycephalosauridae after the second genus, as he found that name (meaning "thick head lizard") more descriptive. He also considered T. sternbergi and T. edmontonensis members of Stegoceras, found S. brevis valid, and named a new species, S. lambei, based on a specimen formerly referred to S. validus. The split from Troodon was supported by Russell in 1948, who described a theropod dentary with teeth almost identical to those of T. formosus.
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The first mammaliaforms evolved from the cynodonts during the early Norian age of the Late Triassic, about 225 mya. During the evolutionary succession from early therapsid to cynodont to eucynodont to mammal, the main lower jaw bone, the dentary, replaced the adjacent bones. Thus, the lower jaw gradually became just one large bone, with several of the smaller jaw bones migrating into the inner ear and allowing sophisticated hearing. Repenomamus was the largest mammal of the Mesozoic Whether through climate change, vegetation change, ecological competition, or a combination of factors, most of the remaining large cynodonts (belonging to the Traversodontidae) and dicynodonts (of the family Kannemeyeriidae) had disappeared by the Rhaetian age, even before the Triassic–Jurassic extinction event that killed off most of the large non-dinosaurian archosaurs.
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Teeth of Revueltosaurus callenderi collected in Petrified Forest National Park R. callenderi was named by Adrian P. Hunt in 1989 and it is the type species of the genus. The generic name honors its type locality, Revuelto Creek, Quay County of New Mexico. Revuelto is derived from Spanish revuelta, "revolution", in reference to the importance of the Late Triassic period for terrestrial vertebrate evolution. The specific name honours the director of the New Mexico Museum of Natural History Jonathan F. Callender. R. callenderi was originally described as a basal ornithischian on the basis of 32 teeth: the holotype NMMNH P-4957 a nearly complete premaxillary (incisiform) tooth, the paratypes (NMMNH P-4958-9, a nearly complete maxillary or dentary tooth crown with root and a nearly complete premaxillary tooth crown) and 28 referred specimens.
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Maxilla of specimen ZLJT01 Over the years, paleontologists referred additional specimens to D. sinensis which are now assigned to Sinosaurus. Dong (2003) referred specimen LDM-LCA10 which consists of a skull and an incomplete skeleton. In 2012, Xing referred two individuals, ZLJ0003 which consists of a partial skull and an incomplete skeleton, and ZLJT01 which is a juvenile individual that consists of a premaxillary fragment, an incomplete maxilla, a maxillary fragment, a lacrimal, both frontals, both parietals, an incomplete braincase, an incomplete dentary, an atlantal intercentrum, two dorsal rib fragments, and a partial proximal caudal neural arch, to Sinosaurus. The holotype, IVPP V34, was found in the Lower Lufeng Formation, and consists of two maxillary (upper jaw) fragments, four maxillary teeth, and a lower jaw fragment with three teeth.
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Restoration of H. okladnikovi by a nest Harpymimus was for the first time extensively described in a dissertation by Yoshitsugu Kobayashi in 2004.Kobayashi, Y., 2004, Asian ornithomimosaurs. PhD Thesis, Southern Methodist University. 340 pp In a 2005 article, Kobayashi and Barsbold diagnosed Harpymimus based on a number of anatomical characteristics, including eleven teeth in the front of the lower jaw (dentary), the transition between anterior and posterior tail vertebrae taking place at the eighteenth caudal, a triangular-shaped depression above the dorsal surface of a ridge on the shoulder blade (scapula) above the shoulder joint, a low ridge above a distinctive depression along back edge of the shoulder blade, and a small but deep collateral ligament fossa on the lateral condyle of metacarpal III (a hand bone).
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The dentary of the holotype Eolambia specimen CEUM 9758 In 1979 Peter Galton and James A. Jensen described a fragmentary right femur, BYU 2000, belonging to a hadrosaurian dinosaur discovered in sediments belonging to the Cedar Mountain Formation in Arches National Park, Utah. Though poor material, it was important for it (alongside a second North American femur described in the paper) was the first hadrosaur specimen from the Lower Cretaceous anywhere in the world. Galton and Jensen hypothesized more complete remains of a hadrosaur may be found from the formation in the future. Various hadrosauroid teeth had also been found in quarries of small vertebrates in the western region of the San Rafael Swell, near Castle Dale in Emery County, Utah; they were described in 1991 by J. Michael Parrish.
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Specimen CEUM 34447, an unusually deep dentary which may or may not pertain to Eolambia Additional excavations since 1998 have revealed additional skeletal elements belonging to Eolambia. It is now the most completely-known iguanodont from between the Cenomanian and Santonian stages. Nearly every single skeletal element belonging to the taxon is represented by multiple fossils across existing collections. At least twelve individuals, including at least eight juveniles, were discovered in a quarry south of the town of Emery, including parts from both the skull and the rest of the body. The quarry is known as the Cifelli #2 Eolambia caroljonesa Quarry, or more formally CEUM locality 42em432v. Another quarry south of the town of Emery – the Willow Springs 8 quarry, or CEUM locality 42Em576v – preserves at least four juveniles.
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Obamadon is known from two lower jaw fragments, each less than a centimeter in length. One was found in the collections of the University of California Museum of Paleontology after having been collected from the Hell Creek Formation in Montana, and the other collected from the Lance Formation in Wyoming. When it was first named in 2012, Obamadon was identified as a member of the extinct group Polyglyphanodontia on the basis of a V-shaped connection between the two halves of the lower jaw, a slot-and-ridge type connection between the dentary bone of the lower jaw and another missing bone called the splenial bone, and teeth that are implanted within the jaw bone. Its jaw is thin and straight, unlike the curved jaws of most other polyglyphanodontians.
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Both the angular and the prearticular bones have thin posterior rami that entirely overlap the articular laterally and medially, leaving only the top and bottom faces of the articular open. L. thaumastos has the first two teeth in each dentary tilted forwards, and these would probably have projected out from the mouth below matching teeth in the premaxilla. Between each alveolus, the dorsal margin of the alveolar row forms a ridge that slopes downwards labially in concave depressions between the alveoli, probably indicating strongly interdigitating teeth that fitted together to form a kind of 'fish trap'. Most of the teeth are broken or missing, but a few were being replaced when the specimen died and have so been preserved in their crypts; they are straight, perfectly symmetrical spikes with no ornamentation, carinae or recurvature.
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In L. maghrebensis, however, the fourth tooth in the dentary is slightly larger than the first and there is no procumbency of the first dental alveoli, so its front teeth would not have projected forwards in the same fashion. Both species of Laganosuchus would have been between 4 and 6 metres in total length, a comparatively large proprtion of which would have been the large flattened head. It is possible that they had gular sacs beneath their throats, just as their relative Stomatosuchus may have done, but there is no fossil evidence either to support or disprove this theory. The jaws would have been unable to be opened or closed at speed or with much power due to their length relative to all the possible muscles that could be used to close them.
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Teeth from the maxilla (a-d) and lower jaw (e-g) All specimens of Matheronodon have been found at the locality of Velaux-La Bastide Neuve, in the Aix-en-Provence basin, Bouches-du-Rhône, France. The sandstones at this locality, which was discovered by Xavier Valentin in 1992, are part of the Begudian regional stage (which correlates to the late Campanian epoch, about 74 to 72 million years ago). After their discovery, the fossils were stored in the paleontology and archaeology collections of the municipality of Velaux, and labelled as belonging to the Musée du Moulin Seigneurial/Velaux-La Bastide Neuve (MMS/VBN). The type specimen is MMS/VBN-02-102, a right maxilla; associated with it are maxillary teeth (-93-34, -09-149a, -09-150, and -12-22) and dentary teeth: (-02-11, -09-43c, and -12-A002).
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In 2000, Michael Benton noted the existence of a robust morph in the population, seen by him as a possible second species or, more likely, an instance of sexual dimorphism. Benton also indicated some unique derived traits, or autapomorphies, for the species: a long basipterygoid process on the braincase; a dentary that is short in relation to the total length of the lower jaw; an ilium that has a back end that is subquadrate instead of rounded.M.J. Benton, L. Juul, G.W. Storrs and P.M. Galton, 2000, "Anatomy and systematics of the prosauropod dinosaur Thecodontosaurus antiquus from the upper Triassic of southwest England", Journal of Vertebrate Paleontology 20(1): 77-108 The small size has been explained as an instance of insular dwarfism.Whiteside, D.I. and Marshall, J.E.A. (2008) "The age, fauna and palaeoenvironment of the Late Triassic fissure deposits of Tytherington, South Gloucestershire, UK".
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The dentary superficially resembles that of various other mammalian groups with enlarged incisors, such as rodents, lagomorphs, hyraxes, wombats, the aye-aye, and the extinct apatemyids, tillodonts, and taeniodonts--all of which are known only from the Cenozoic, less than 66 million years ago. Krause and colleagues could not exclude the possibility that TNM 02067 represents an early member of such a group or an otherwise unknown major group of mammals. However, only two groups of Mesozoic mammals resemble TNM 02067: gondwanatheres; and multituberculates in the superfamilies Djadochtatherioidea and Taeniolabidoidea. Djadochtatherioids and taeniolabidoids occur in the late Cretaceous through Paleogene of the northern continents (Laurasia), and gondwanatheres, an enigmatic group of uncertain evolutionary affinities, are known from the late Cretaceous through Paleogene of Gondwana, with forms such as Gondwanatherium, Sudamerica (both from Argentina), Lavanify (Madagascar), and Bharattherium (India).Gurovich and Beck, 2009, pp.
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Lower jaw of Erlikosaurus (bottom) and Segnosaurus (top) Erlikosaurus lived alongside a larger species of therizinosaurid in the Bayan Shireh Formation, Segnosaurus. In 2016, Zanno and colleagues re-examined the lower jaws and dentition of Segnosaurus making direct comparisons with those of Erlikosaurus in the process. They identified rather complex features in the dentary teeth of Segnosaurus, which are represented by the presence of numerous carinae (cutting edges) and folded carinae with denticulated front edges, and the enlargement of denticles (serrations). These traits together create a roughened, shredding surface near the base of the tooth crowns that was unique to Segnosaurus and suggest it consumed unique food resources or used highly specialized feeding strategies, with the addition of a higher degree of oral food processing than the sympatric—related species that lived in the same area at the same time—Erlikosaurus.
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The possible presence of denticles on the dentary next to the tooth row is particularly significant, as these are present in many tetrapodomorph fish but completely lacking in all but the earliest four- limbed vertebrates, with Elginerpeton believed to have been the last known animal to have possessed such a feature. Overall, Andersonerpeton seems to bridge a gap between stem-tetrapods and aistopods. This classification scheme contrasts with traditional interpretations of aistopods forming a group called Lepospondyli with animals like Diplocaulus and microsaurs, which are almost always considered true crown-tetrapods. However, the idea that aistopods branched off from the tetrapodomorph family tree much earlier than other lepospondyls has been supported by some analyses, such as a 2017 study on the braincase of Lethiscus, which was considered to have been the most "primitive" aistopod prior to the naming of Andersonerpeton.
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All ankylosaurs that possess these characteristics - a narrow predentary; a nearly horizontal quadrate that is not fused and is oriented 30 degrees from the skull roof; the presence of mandibular condyles that are three times wider than long; premaxillary and dentary teeth that are near a symphysis with the front of the lower jaw (the predentary); a sacrum arched on top; an acromion process above the midpoint of the scapula to coracoid attachment; a straight ischium with a straight dorsal margin; relatively long, slender limbs; sacral shield armour; and the presence of erect pelvic osteoderms with flat bases - form a clade of basal nodosaurids, the Struthiosaurinae. That set of cranial and postcranial features are only present on genera considered to be in the clade. The features above distinguish Struthiosaurinae from other clades and genera found by other analysis'.
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Restoration of two specimens The American paleontologist O. C. Marsh named Sphenacodon (from Greek ' "wedge" + ' "point" + ' (-odon) "tooth") in 1878, based on part of a lower jaw (dentary) bone found in the redbeds of northern New Mexico by fossil collector David Baldwin. In his very short description of the jaw, Marsh cited the back teeth as characteristic ("crowns are much compressed, and have very sharp cutting edges without crenulations") and assessed the animal as "about six feet in length, and carnivorous in habit," although the rest of the skeleton was not known. He did not provide an illustration of the specimen. Marsh gave the genus the Latin specific name ferox "fierce" and erected the new family Sphenacodontidae, placed under the primitive reptilian order "Rhynchocephala" (=Rhynchocephalia), then including nearly all groups of early reptiles in addition to the living tuatara.
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28, No. 4 (Dec. 12, 2008), pp. 1130-1143. Is known from a nearly complete skull with mandible of a post- hatchling individual (the specimen IGM 3497, in the Instituto de Geologia, of the Universidad Nacional Autónoma de Mexico), and is one of the smallest skulls between the sphenodontians, with an estimated total length of 11.3 millimetres, a bit smaller than the hatchling individuals observed in the modern tuatara (Sphenodon); features like the oblique mandibular symphysis suggests that the holotype is from an individual in a relatively mature stage of ontogenic development. Zapatadon is diagnosed by their hatchling tooth series located in a depression in the anterior part of the dentary bone, the prefrontal bone surrounding the dorsal process of the maxilla and the broad jugal that extends over the maxillary suborbital process, been almost excluded of the orbit.
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Iberosuchus has ziphodont teeth that have a laterally compressed tooth crown that had a distally curved apex; anterior-posteriorly elongated dorsal osteoderms that have a keel running through the central median; rugose ornamentations with no pits and cupules; osteoderm lack anterolateral process; the skull is vermiculated; spoon-like premaxilla palatal shelf or mandibular symphysis; notch between premaxilla and maxilla or large 4th mandibular tooth; deep rostrum or mandible. It also had traits that it shared with other metasuchians, the dentary had lateral depressions and had a prolongation that extends dorsally behind the tooth row; the splenials are robust, had a big slot-like foramen intermandibularis oralis; had anteriorposteriorly elongated glanoid fossa on articular. Though only known by skull fragments and osteoderms, many artistic reconstructions use its close relatives such as Sebecus which has post cranial remains found as a reference.
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There are 3 fossils of the premaxilla excavated from Aumelas, one consisting a close to complete right element, a fragmentary right element, and one with both elements pressed up against one another; they all display a very vermiculated surface texture and contain a concave dent where the dentary tooth lay. Premaxilla foramen is also visible on right element fossil's palatal view and the nares are anterior pointing, the lateral surface has very distinct ornamentation composed of bony ridges that make up the nares lateral margin. The premaxilla contains five alveoli, they increase in diameter towards the distal end and the fourth one being the largest, the last is the same size as the third and does not line up with other alveoli. There are two deep pits lingually right next to the third and fourth alveoli.
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Mammals are unique in having evolved a three-ossicle middle-ear independently of the various single-ossicle middle ears of other land vertebrates, all during the Triassic period of geological history. Functionally, the mammalian middle ear is very similar to the single-ossicle ear of non-mammals, except that it responds to sounds of higher frequency, because these are better taken up by the inner ear (which also responds to higher frequencies than those of non-mammals). The malleus, or "hammer", evolved from the articular bone of the lower jaw, and the incus, or "anvil", from the quadrate. In other vertebrates, these bones form the primary jaw joint, but the expansion of the dentary bone in mammals led to the evolution of an entirely new jaw joint, freeing up the old joint to become part of the ear.
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Bolt and Lombard were able to classify Sigournea as an early member of Tetrapoda based on the presence of bone surfaces covered in pits and ridges, a single row of dentary teeth, a jaw joint that faces upward, and an open groove for a lateral line along the outer surface of the jaw, and on the absence of teeth on the prearticular bone or enlarged fangs on the coronoids. Sigournea differs from other stem tetrapods in having several holes within a depression called the exomeckelian fenestra on the inner surface of the jaw. The closest relatives of Sigournea within Tetrapoda are unknown. Bolt and Lombard did not include it in a phylogenetic analysis in their 2006 description because they thought the single known jawbone did not possess enough unique anatomical characteristics to elucidate its evolutionary relationships.
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A 2013 study by Lü and colleagues found that oviraptorids appear to have retained their hind limb proportions throughout ontogeny (growth), which is also a pattern mainly seen in herbivorous animals. In 2017, the Canadian palaeontologist Gregory F. Funston and colleagues suggested that the parrot- like jaws of oviraptorids may indicate a frugivorous diet that incorporated nuts and seeds. Diagrams showing the hands of specimen MPC-D 107/15 and 107/16 In 1977 Barsbold suggested that oviraptorids fed on molluscs, but Longrich and colleagues rejected the idea that they practised shell-crushing altogether, since such animals tend to have teeth with broad crushing surfaces. Instead, the shape of the dentary bones in the lower jaws of oviraptorids suggests they had a sharp-edged beak used for shearing tough food, not for cracking hard food items such as bivalves or eggs.
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Other specimens were referred: MgD-Ij116, a skull and lower jaws of a juvenile; MgD-Ij 118, fragmentary postcrania and lower jaws of a juvenile; MgD-Ij119, a dentary and three neural arches; MgD-IjI20, two dentaries and loose teeth; MgD-JjI21, a maxilla fragment with four teeth of a juvenile; and MgD-JjI22, teeth. They were then named as a separate genus, Breviceratops, by Sergei Mikhailovich Kurzanov in 1990, the generic name combining the Latin brevis, "short", with a reference to the Ceratopsia.Kurzanov, S., 1990, "A new Late Cretaceous protoceratopsid genus from Mongolia", Palaeontological Journal, 24: 85-91 Kurzanov also referred an additional number of fossils from Khermin Tsav, the type locality of Bagaceratops, to the new genus. The Khermin Tsav specimens closely resemble Bagaceratops, which has led to the proposal that Breviceratops and Bagaceratops are synonymous.
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During the early part of the development of the teeth, the roots would have been open, and the only connection that would have been facilitated would have been the cementum between the tooth and the alveolar bone, the periodontal ligament and the cementum made anchorage trabeculae would have mediated this connection. This complex, called the tripartite periodontium, during the life of Stereosternum, would have acted as a mechanism for keeping the teeth within the jaw, working against the lateral forces that could easily pull teeth out of the socket, given the size of these teeth. The teeth also have multiple different types of dentine and there are different orientations of the dentine tubules along the tooth, including mixed composition in the dentary wall. These adaptations helped to increase the tooth's resistance to tension forces, especially the lateral forces.
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In 1999, a postorbital, , tooth, vertebral remains, (hand bones), and a phalanx from the Sala de los Infantes deposit in Burgos Province, Spain, were attributed to an immature Baryonyx (though some of these elements are unknown in the holotype) by the Spanish palaeontologist Carolina Fuentes Vidarte and colleagues. Dinosaur tracks near Burgos have also been suggested to belong to Baryonyx or a similar theropod. In 2011, a specimen (ML1190) from the Papo Seco Formation in Boca do Chapim, Portugal, with a fragmentary dentary, teeth, vertebrae, ribs, hip bones, a scapula, and a phalanx bone, was attributed to Baryonyx by the Portuguese palaeontologist Octávio Mateus and colleagues, the most complete Iberian remains of the animal. The skeletal elements of this specimen are also represented in the more complete holotype (which was of similar size), except for the mid-neck vertebrae.
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The carinae of the hind edges were also very modified, and bifurcated (split in two) near the cervix, where they formed a flattened triangular, raised facet, which projected from the tooth crown and contacted or approached the folded carinae on the front edge of the crowns behind them (this arrangement is present in teeth 2–12). Such split carinae are known from other tetanuran theropods, where they are considered abnormalities caused by trauma, aberrant tooth replacement, or genetic factors. Though the condition in Segnosaurus was similar, it was uniformly expressed across the teeth of both dentaries, and does not appear to have been an abnormality, but served to roughen the contacts between tooth bases. The 22nd and 23rd dentary teeth of Segnosaurus were significantly smaller than the rest, almost conidont, and had an additional third carina with denticles on their inner sides.
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The specific name refers to the Ashile Formation, the old name for the layers where Shanag was found, used by Henry Fairfield Osborn. The holotype of Shanag, IGM 100/1119, was discovered in the Öösh Formation, the stratification of which is uncertain but probably dating to the Berriasian-Barremian. Shanag bears a strong resemblance to basal Chinese dromaeosaurids such as Microraptor and Sinornithosaurus, suggesting a close similarity between the fauna of the Öösh deposits, dated tentatively to 130 million years ago, and the Jehol Biota of China (such as the animals found in the roughly contemporary Yixian Formation), during the Early Cretaceous. The holotype specimen, about six centimetres long, is composed of an associated uncompressed upper and lower jaw fragment, containing a nearly complete right maxilla with teeth, a partial right dentary with teeth and an attached partial splenial.
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The holotype was first discovered and collected in 2002 during the field expedition conducted by the Mongolian Academy of Sciences and the American Museum of Natural History, the specimen only preserved a partial left dentary. It was discovered on the outcrops at the Tsagan Tsonj locality in the Bayan Shireh Formation, the age is estimated to be around 102 million to 86 million years ago, between the Cenomanian and Santonian stages of the Late Cretaceous epoch. The generic name, Tsagandelta, is derived from the Mongolian цагаан (tsagaan, meaning white) and the Greek δέλτᾰ (delta, meaning crest or point-shaped) in reference to the withish sediments at the Tsagan Tsonj locality and the prominent dentition of the Deltatheroida. The specific name, dashzevegi, is in honor to the Mongolian paleontologist Demberlyin Dashzeveg who did notable research on early mammals.
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The only known element of Soumyasaurus is a small (less than 3 cm long), poorly preserved left dentary, missing its anterior end and containing some teeth with an estimated tooth count of at least 15. Soumyasaurus is mostly characterised by its teeth, which are fused to the jaw bone by a rim fibrous bone at their bases (ankylothecodont), a characteristic trait of silesaurids. Unlike the typically leaf-shaped teeth of other silesaurids, the teeth of Soumyasaurus are smooth and conical, resembling those of Asilisaurus, and are readily distinguishable from the uniquely triangular, possibly tricuspid teeth of the contemporary silesaurid Technosaurus. Unfortunately, it is unknown if Soumyasaurus had small serrations like Asilisaurus, as these portions of the teeth are either missing or badly damaged, and is only distinguished from it by the lower position of the Meckelian groove on the inside of the jaw.
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They are: the type specimen DFMMh/FV 200, the partial skeleton of an adult with a skull; DFMMh/FV 605, the complete skull of a juvenile; DFMMh/FV 261, an isolated angular; DFMMh/FV 790.12, an isolated left dentary; DFMMh/FV 279, an isolated femur; DFMMh/FV 790.11, an isolated metatarsal; and DFMMh/FV 325, a partial skeleton including osteoderms, vertebrae, and ribs. Stereomicroscopy was used to examine the specimens, which were described in a 2017 paper published by Daniela Schwarz, Maik Raddatz, and Oliver Wings. The genus name Knoetschkesuchus combines the family name of Nils Knötschke, a researcher at the DFMMh who was responsible for the collection, curation, and preparation of Langenberg Quarry specimens, with the common crocodilian suffix suchus, from the Greek souchos ("crocodile"). Meanwhile, the species name langenbergensis is in reference to the provenance of this species from the Langenberg Quarry.
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The skeletons were discovered during eight seasons of fieldwork (2004–2012 field seasons) in the Slottsmøya Member, that have yielded other skeletal remains of marine reptiles, including the plesiosauroids Colymbosaurus svalbardensis, Djupedalia and Spitrasaurus, and the ichthyosaurs Cryopterygius and Palvennia. P. funkei was first described and named by Espen M. Knutsen, Patrick S. Druckenmiller and Jørn H. Hurum in 2012. The specific name honors Bjørn Funke, the discoverer of the holotype, and his wife May-Liss Knudsen Funke for volunteering in the paleontological collections at the Museum. Low resolution pdf The holotype of P. funkei is represented by the anterior portions of the upper and lower jaws (including premaxillary and dentary teeth), one nearly complete cervical centrum and two partial cervical centra, three pectoral centra with neural arches, fifteen dorsal centra and eight neural arches, a complete right coracoid, numerous rib fragments and gastralia, and a complete right forelimb.
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A nasal-premaxilla contact and similar dentary and maxillary tooth counts also seem to suggest that there may be a close relationship between the genus and later tomistomines, although these features represent more primitive conditions that changed later in gavialoid history. Despite this, it is currently accepted that a close relationship between Eosuchus and tomistomines is not the case, and that the similarities between the two may just be superficial and that these characteristics are plesiomorphic to all gavialoids, being lost in more derived members such as the modern Gavialis. Eosuchus lerichei and E. minor were included in the study on the phylogenetic relationships of putative fossil gavialoids published by Lee & Yates (2018). The authors considered it most likely that Eosuchus was not a gavialoid, or even a crocodylian, but rather a member of the clade of non-crocodylian eusuchians that also included the genera Argochampsa, Eogavialis, Eothoracosaurus and Thoracosaurus.
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Cotylorhynchus (background), Ophiacodon and Varanops The 'pelycosaurs' existed during the Early Permian, Middle Permian, Late Permian, and to the Early Triassic. 'Mammal-like Reptiles' or pelycosaur is based on the morphology of their dentary and marginal teeth. However, there is a significant negative correlation between skeletal completeness and the diversity of 'pelycosaurs' suggests many species were named using poor specimens. The majority of pelycosaur species named during the 1930s to the 1960 were based on size and location rather than character based morphology to suggest that there is a great deal of missing fossil record. Basal synapsids or ‘pelycosaurs’ form the beginning portion of the mammalian stem lineage from ‘reptile-like’ to the more mammal derived traits we find in therapsids. ‘Pelycosaurs dominated the terrestrial ecosystem from the Carboniferous to the Early Permian creating animals 3-6.5 meters long, herbivores, macropredators and a diversity of smaller bodied vertebrate.
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Echinerpeton is known from six specimens, five housed in the Museum of Comparative Zoology and a sixth in the Redpath Museum: the holotype MCZ 4090, which consists of a partial postcranial skeleton and some jaw fragments; MCZ 4091, which includes vertebrae and an interclavicle; MCZ 4092, a left maxilla or upper jaw bone; MCZ 4093, a partial right maxilla; MCZ 4094, including three neural arches or vertebral spines; and RM 10057, consisting of a right maxilla, neural arch, rib, and a phalanx or finger bone. Since all other specimens besides the holotype are isolated bone fragments, their assignment to the same species is not certain. The maxillae are distinct in having straight lower margins, distinct from the often curved jaws of ophiacodontids and sphenacodontids but similar to the straight jaws of some other synapsids like Archaeothyris, Haptodus, and Varanops. The dentary or lower jaw bone has a slight upward curve.
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The holotype dentary of Labrosaurus ferox, which may have been injured by the bite of another A. fragilis It has been speculated since the 1970s that Allosaurus preyed on sauropods and other large dinosaurs by hunting in groups. Such a depiction is common in semitechnical and popular dinosaur literature. Robert T. Bakker has extended social behavior to parental care, and has interpreted shed allosaur teeth and chewed bones of large prey animals as evidence that adult allosaurs brought food to lairs for their young to eat until they were grown, and prevented other carnivores from scavenging on the food. However, there is actually little evidence of gregarious behavior in theropods, and social interactions with members of the same species would have included antagonistic encounters, as shown by injuries to gastralia and bite wounds to skulls (the pathologic lower jaw named Labrosaurus ferox is one such possible example).
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Originally named as Globidens aegyptiacus by Zdansky (1935),Zdansky, O. 1935. The occurrence of mosasaurs in Egypt and in Africa in general. Bulletin de l’Institut d’Egypte 17:83-94 the species was first recognised as sufficiently distinct to be separated into its own genus by Lingham-Soliar (1991), who named it Igdamanosaurus after the village of Igdaman (sometimes called In Dama), which was near to where the type specimen was found. Though undoubtedly similar to Globidens in its dental adaptations and similar to G. alabamaensis in possessing unusually small foramina for exits of the mandibular nerve on the lower lateral surface of the dentary, Lingham-Soliar (1991) noted that the vertical striae present in Igdamanosaurus would suggest that it represented a completely new type of durophagous mosasaur that was derived from a Platecarpus-like ancestor rather than a Clidastes-like one and thus classified it as part of the Plioplatecarpinae.
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Baryonychinae was distinguished by the small size and larger number of teeth in the dentary behind the terminal rosette, the deeply keeled front dorsal vertebrae, and by having serrated teeth. Spinosaurinae was distinguished by their straight tooth crowns without serrations, small first tooth in the premaxilla, increased spacing of teeth in the jaws, and possibly by having their nostrils placed further back and the presence of a deep neural spine sail. They also united the spinosaurids and their closest relatives in the superfamily Spinosauroidea, but in 2010, the British palaeontologist Roger Benson considered this a junior synonym of Megalosauroidea (an older name). In a 2007 conference abstract, the American palaeontologist Denver W. Fowler suggested that since Suchosaurus is the first named genus in its group, the clade names Spinosauroidea, Spinosauridae, and Baryonychinae should be replaced by Suchosauroidea, Suchosauridae, and Suchosaurinae, regardless of whether or not the name Baryonyx is retained.
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Guyanancistus niger possesses a long pectoral-fin spine and white spots that differentiate it from G. nassauensis. Guyanancistrus nassauensis is morphologically discriminated from all congeners by a small adult size (largest specimen observed 61 mm SL; adult size likely reached around 40 mm SL), by a reduced number of anal-fin rays (4 branched rays vs 5, apart from exceptional specimens), and by a wide oval mouth with both large dentary and premaxillary tooth cups (in % of head length, respectively: 24.2–31.9, mean 27.6, vs 23.6 or less except in Guyanancistrus niger, and 25.4–31.4, mean 28.1, vs 24.5 or less). Only G. niger has dentaries nearly as large (22.5–26.3, mean 25.0% of HL) but its premaxillaries are shorter (21.7–23.6, mean 22.6% of HL). Guyanancistus longispinis possesses a long pectoral-fin spine and roundish yellow spots that differentiate it from G. nassauensis.
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The single known species, elesitaiensis, is named after Elesitai, a village found in this region, near which the fossil remains of Alxasaurus were located. Five Alxasaurus specimens were recovered from the Bayin-Gobi Formation of Inner Mongolia, which dates to the Albian stage of the Early Cretaceous Period, or about 113 million to 100 million years ago. The holotype specimen, IVPP 88402 (large individual), which is considered to exemplify the genus and species, is the largest and most complete of the five, consisting of the right dentary (lower jaw) with some teeth, 5 cervical vertebrae, 28 caudal vertebrae, 5 sacral vertebrae, 9 ribs, 15 chevrons, an isolated scapula, both coracoids, both humeri, isolated radius, both ulnae, a virtually complete manus, both ilia, both ischia and both femora. The other four specimens are the paratypes IVPP 88301, IVPP 88402 (small individual), IVPP 88501 (immature individual) and IVPP 88510.
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A phylogenetic analysis was conducted by Shen and colleagues, who modified the Theropod Working Group dataset to add Daliansaurus and Sinusonasus. They used the analysis to identify traits that allowed Daliansaurus to be placed in the Troodontidae, concurring with previous assessments: the teeth are numerous and closely packed; the bar of the premaxilla separating the nostrils is flattened; there is a groove on the side of the dentary in the lower jaw; the neural spines are replaced by shallow grooves towards the end of the tail; and the metatarsals are asymmetrical, with the fourth being more robust than the second. The analysis also found that Daliansaurus formed a distinct evolutionary radiation along with other troodontids in the Yixian Formation: Mei, Sinovenator, and Sinusonasus. This group, which was named the Sinovenatorinae, was united by a synapomorphy not observable for Daliansaurus, the possession of a wide and flattened fourth metatarsal.
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Morphologically, the sides of the snout are parallel (unlike the spoon-tipped snouts of Gnathosaurus), most of the mandible is composed mainly of the dentary, and the well-developed retroarticular process is formed by the angular bone like in other ctenochasmatids. There are many long, needle-like, outward-projecting, tightly packed, equally-spaced teeth in the jaws of Liaodactylus, totalling to 152 teeth across both jaws. This is more than Gnathosaurus (128-136), about the same as Gegepterus (150), but much less than Ctenochasma (200-552) and Pterodaustro (almost a thousand). The teeth become shorter towards the back of the jaws, eventually becoming short, peg-like structures at the back of the tooth row; the back of the tooth row corresponding to the front 1/3 of the nasoantorbital fenestra, which is unusual among ctenochasmatids (where the teeth usually stop entirely before the fenestra).
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Isbrueckerichthys is composed of small- to medium-sized species up to 90.2 millimetres (3.55 in) SL. These fish have a dorsal fin with one spine and seven branched rays, and a caudal peduncle ovoid in cross- section. I. alipionis is the only species in which the teeth of the dentary and premaxilla are without a lateral cusp. I. epakmos is the only species in which mature males have a clump of hypertrophied odontodes only on the anterior portion of snout; in the other species, odontodes are also present on the lateral margins of the head. The most distinctive features of I. epakmos are the anterior portion of head ornamented with a large and rugose soft fleshy area and the presence of a clump of hypertrophied odontodes located only on anterior portion of snout, usually short and thick, directed forward or slightly upward on adult males.
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The fossils were left undescribed and neglected until 2015, when Jeffrey Wilson and Ronan Allain cleaned the holotype and described the remaining fossils that Lavocat never described in 1954. A second specimen, consisting of a partial vertebra measuring up to tall if complete (also found in Aoufous) has also been assigned to R. garasbae. A second species was named by de Lapparent in 1960, Rebbachisaurus tamesnensis. The type specimen, collected by Lapparent in the Gall locality, Irhazer Shale, supposedly composed of two humeri and two femora, and a second specimen composed of four isolated teeth, a dentary fragment with three teeth, over 100 vertebrae, six chevrons, 12 ribs, 5 scapulae, an ilium, two ischia, and numerous limb elements, but however, the material of this taxon was collected from multiple localities across the Sahara, such as several sites in the Elrhaz Formation of Niger, and is not referrable to Rebbachisaurus.de Lapparent A. F. (1960) "The dinosaurs of the “Continental Intercalaire” of the central Sahara".
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They brought the skull to the Denver Museum of Natural History, where they further prepared it and made a reconstruction of it based on casts of the individual bones, with the skulls of Giraffatitan and Camarasaurus acting as templates for the missing bones. In 1998, Carpenter and Tidwell described the Felch Quarry skull, and formally assigned it to Brachiosaurus sp. (of uncertain species), since it is impossible to determine whether it belonged to the species B. altithorax itself (as there is no overlapping material between the two specimens). They based the skull's assignment to Brachiosaurus on its similarity to that of B. brancai, later known as Giraffatitan. In 2019, American paleontologists Michael D. D'Emic and Matthew T. Carrano re-examined the Felch Quarry skull after having it further prepared and CT-scanned (while consulting historical illustrations that showed earlier states of the bones), and concluded that a quadrate bone and dentary tooth considered part of the skull by Carpenter and Tidwell did not belong to it.
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Ji and Ji (1996) identified many features that set Sinosauropteryx apart from other birds and dinosaurs. They found that it was a small primitive bird with a relatively high skull, blunt rostrum and a slightly high premaxilla; that the antorbital fenestra was elliptical but not enlarged, the dentary was robust, the surangular was narrow and elongated, and the dentition is extremely well developed and acute; that there are over 50 extremely elongated caudals, constituting 60% of the body length, and the forelimb is extremely short with a short and thick humerus; the pubis was elongated and extremely inflated at its distal end and the ischium is broad; the hind limb was long and robust, the tibia is only slightly longer than the femur, the tarsals are separated, and the metatarsals are relatively robust with unfused proximal ends; the feathers are short, small, and uniform; many ornament the top of the skull, cervical, and dorsal regions, in addition to the dorsal and ventral caudal region.
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Clack and Ahlberg noted several distinctive features of Occidens, including a straight row of teeth along the coronoid bones on the inner surface of the lower jaw, an open groove for a lateral line sense organ on the jaw's outer surface, and a stepped shape to the connection between the dentary and angular bones. The jaw bone is deep, resembling those of Crassigyrinus and whatcheeriids (which both occur in Romer's gap) in overall appearance. In most phylogenetic trees produced by Clack and Ahlberg's 2004 analysis, Occidens fell near whatcheeriids and the Devonian taxon Tulerpeton, being more derived than all other Devonian taxa and more basal than Crassigyrinus and the post-Romer's Gap taxa Greererpeton and Megalocephalus. A 2008 phylogenetic analysis by paleontologists Marcello Ruta and John Bolt found Occidens to be the closest relative of Sigournea multidentata, a species from the end of the gap found in Iowa, but could not determine where these two taxa fit relative to other Early Carboniferous tetrapods.
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Holotype rostrum of Protosphyraena nitida (from Hay, 1903) Holotype of Protosphyraena nitida (from Hay, 1903); portions of dentary, splenial, pectoral fin In its general body plan, Protosphyraena resembled a modern sailfish, though it was smaller with a shorter rostrum, was somewhat less hydrodynamic, and adults possessed large blade-like teeth (adults of living swordfish species are toothless). Complete skeletons of Protosphyraena are relatively rare, but in parts of the Niobrara Chalk, the Mooreville Chalk Formation of Alabama, and other geological formations, fragmentary specimens are quite common and most often include isolated teeth, the distinctive rostrum, and fragments of the long saw-edged pectoral fin first described by Mantell. Usually, portions of the skull and postcranial skeleton are found separately. This preservational bias can be explained by the fact that the skeleton of Protosphyraena was less ossified than that of most bony fishes and tended to be torn apart by scavengers or decay before burial and fossilization (Everhart, 2005; p. 93).
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The symphyseal shelf at the front of the dentary may have given some ability for crushing, but as this was a relatively small area, it was probably not the main function of the jaws. The fact that most oviraptorids have been found in sediments that are interpreted as having been xeric and arid or semi-arid environments also argues against them having been specialised eaters of shellfish and eggs, as it is unlikely there would have been enough of these items under such conditions to support them. Longrich and colleagues pointed out that the robust forelimbs and enlargement of a single finger in heyuannine oviraptorids is similar to that seen in modern animals that eat ants and termites, such as anteaters and pangolins, but the morpholology of heyuannine jaws does not support them being insectivorous. The researchers found that the function of heyuannine forelimbs was unclear, but suggested that they could have been used for scratching, tearing, or digging, though not prey capture.
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Foulke contacted paleontologist Joseph Leidy, and together they recovered 8 teeth from the maxillar and dentary areas, dental battery fragments, left maxilla fragments, 3 partial dorsal vertebrae, 13 caudal centra including an almost complete middle caudal vertebra and other fragments, partial right coracoid, left humerus, left radius, left ulna, left ilium, right ischium, right partial pubis, the left hindlimb composed by the femur, tibia, fibula with metatarsals II and IV and the first pedal phalanx from the third digit. Foulke and Leidy studied the fossils together, and in 1858, Leidy formally described and named Hadrosaurus foulkii in honor of his collaborator. Hadrosaurus is derived from the Greek , , meaning "bulky" or "large", and , , meaning "lizard". Leidy recognized that these bones were from a dinosaur by their similarity to those of Iguanodon, discovered in England some decades before, but at the time, the skeleton of Hadrosaurus was one of the most complete dinosaur skeletons known.
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Life restoration of Teraterpeton, another allokotosaur of previously uncertain placement Azendohsaurus was first misidentified as an ornithischian dinosaur by Dutuit, based on shared characteristics of its teeth such as the leaf-like shape and the number of denticles. It was later believed to be a sauropodomorph instead by other researchers, assigned to the defunct infraorder "Prosauropoda" (then believed to be a distinct monophyletic group related to sauropods, now known to be a paraphyletic grade) based on the morphology of its lower jaw, maxilla and teeth, such as the downward curving dentary and absence of a predentary bone, one of the characteristic traits of ornithischians. These misidentifications were caused by the convergence in jaw and tooth shape between it and the herbivorous dinosaurs while its true phylogenetic relationships could not be realised due to the absence of other bones of the skull and skeleton. The non- dinosaurian identity of Azendohsaurus was first hinted at after the discovery of additional skeletal material recovered from the type locality.
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If the dentary and premolars (whose identification has been similarly controversial; see below) do not belong to Ferugliotherium, then, Gurovich and Beck argue, the Los Alamitos Formation would contain two mammals (Ferugliotherium and a multituberculate) similar in size and morphology, and therefore presumably occupying similar ecological niches—and one of those would be represented only by molariforms and incisors and the other only by premolars and a jaw fragment among the available fossils. Furthermore, they noted that the transition from blade-like to molariform premolars had actually been observed in the fossil record of the extinct sthenurine kangaroos, and that the first molariform in Sudamerica and Gondwanatherium is laterally compressed, suggesting that it may have derived from a blade-like tooth. Gurovich and Beck attributed the difference in shape between the MACN Pv-RN 975 and Argentodites p4s to the extensive wear of the former, and suggested that the two are similar enough that they probably represent at least closely related species.
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In 1984, the premaxilla specimens MNHN GDF 365 and 366 were first described in detail by Taquet, where he referred them to an unnamed new theropod within the family Spinosauridae, because of shared characteristics with the holotype dentary of Spinosaurus aegyptiacus. At the time Taquet believed these specimens belonged to the creature's lower jaw, since no theropod was known then with over five teeth in the premaxilla, while Cristatusaurus had seven. This was later proven incorrect in 1996 by Brazilian paleontologists Alexander Kellner and Diogenes Campos, in light of the discoveries of other spinosaurids preserving upper jaw tips with over five teeth. Referred claw, Muséum national d'Histoire naturelle, Paris In a 1986 publication, British paleontologists Alan Charig and Angela Milner considered Taquet's jaw elements nearly indistinguishable from those of the spinosaurid Baryonyx walkeri; which they were describing on the basis of a partial skeleton from the Barremian of the Weald Clay Formation, England.
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Little is known about the mandible due to its compression during fossilisation, but the angular had a lateral process just below the facet for attachment which, along with the long articular facet enabling a sliding motion, probably allowed Chimaerasuchus to move its lower jaw back and forth in a chewing motion to grind plant matter. The absence of a posterior buttress on the articular facet indicates that the pterygoideus muscle could have generated horizontal force enabling this chewing to take place. The two roughly conical teeth in each premaxilla would have been used for nipping off plant material or possibly for defence, while the molariform, polycuspid teeth in the maxillae (at least four in each) could have ground up the food. Although the dentary teeth are not known, it is very likely that there was one conical pair at the front which fitted in the gap between premaxilla and maxilla, while the remainder worked with the maxillary teeth to grind, indicating that Chimaerasuchus was almost certainly a herbivore.
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Hadrocodium, whose fossils date from approximately 195 million years ago, in the early Jurassic, provides the first clear evidence of a jaw joint formed solely by the squamosal and dentary bones; there is no space in the jaw for the articular, a bone involved in the jaws of all early synapsids. Fossil of Thrinaxodon at the National Museum of Natural History The earliest clear evidence of hair or fur is in fossils of Castorocauda and Megaconus, from 164 million years ago in the mid-Jurassic. In the 1950s, it was suggested that the foramina (passages) in the maxillae and premaxillae (bones in the front of the upper jaw) of cynodonts were channels which supplied blood vessels and nerves to vibrissae (whiskers) and so were evidence of hair or fur; it was soon pointed out, however, that foramina do not necessarily show that an animal had vibrissae, as the modern lizard Tupinambis has foramina that are almost identical to those found in the nonmammalian cynodont Thrinaxodon. Popular sources, nevertheless, continue to attribute whiskers to Thrinaxodon.
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However, in 2007 these were described by paleontologist Martin Kundrát and colleagues and tentatively identified as therizinosaurids based on anatomical features such as the tooth-less premaxilla with a downturned edge, dentary with a lateral shelf, teeth with leaf-shaped crowns, humerus with a prominent deltopectoral crest, ilium with an expanded anterior end, and the elongated, sharply-pointed manual unguals. Most eggs have an average size of and given these dimensions, they likely were laid by a medium- sized female. Although several egg clutches were found, one was found containing 7 eggs of which 3 of them were preserving the embryos. In 2019, Hartman and colleagues were the first authors to include these embryos in a phylogenetic analysis and as expected, the embryos were recovered as therizinosaurids. In a 2013 conference abstract, paleontologist Yoshitsugu Kobayashi and colleagues reported an exceptional nesting ground site of theropod dinosaurs at the Javkhlant Formation, which contained at least 17 egg clutches from the same layer within an area of 22 m by 52 m.
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Teeth of Eolambia In Kirkland's initial description of Eolambia, he considered it to be a member of the Hadrosauridae, as defined by David B. Weishampel, David B. Norman, and Dan Grigorescu in 1993. Weishampel and colleagues used seven unifying characteristics to define the Hadrosauridae: the upward expansion of the ascending process of the maxilla; the absence of the paraquadrate foramen, which separates the quadrate and quadratojugal; the location of the angular on the inner surface of the lower jaw; the absence of the surangular foramen on the surangular; the narrow teeth of the maxilla; the presence of three or more teeth in each dentary tooth position; and the reduction of the top margin of the scapular blade. The first, fifth, sixth, and seventh of these traits were recognized in Eolambia, with the rest being unknown due to missing material. Kirkland further assigned Eolambia to the Euhadrosauria, defined by Weishampel and colleagues to include the common ancestor of Hadrosaurinae (now the Saurolophinae) and Lambeosaurinae – the two primary branches of hadrosaurids – and all of its descendants.
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A large hole may be present between the frontal bones and the basisphenoid (Psammophis, Coelopeltis); the maxillary may be much abbreviated and movable vertically, as in the Viperidae; the pterygoids may taper and converge posteriorly, without any connection with the quadrate, as in the Amblycephalidae; the supratemporal may be much reduced, and wedged in between the adjacent bones of the cranium; the quadrate may be short or extremely large; the prefrontals may join in a median suture in front of the frontals; the dentary may be freely movable, and detached from the articular posteriorly. The deviation from the normal type is much greater still when we consider the degraded wormlike members of the families Typhlopidae and Glauconiidae, in which the skull is very compact and the maxillary much reduced. In the former this bone is loosely attached to the lower aspect of the cranium; in the latter it borders the mouth, and is suturally joined to the premaxillary and the prefrontal. In both the transverse bone and the supratemporal are absent, but the coronoid element is present in the mandible.
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About 88% of amphibian species are classified in the order Anura. These include over 7,100 species in 55 families, of which the Craugastoridae (850 spp.), Hylidae (724 spp.), Microhylidae (688 spp.), and Bufonidae (621 spp.) are the richest in species. European fire-bellied toad (Bombina bombina) The Anura include all modern frogs and any fossil species that fit within the anuran definition. The characteristics of anuran adults include: 9 or fewer presacral vertebrae, the presence of a urostyle formed of fused vertebrae, no tail, a long and forward- sloping ilium, shorter fore limbs than hind limbs, radius and ulna fused, tibia and fibula fused, elongated ankle bones, absence of a prefrontal bone, presence of a hyoid plate, a lower jaw without teeth (with the exception of Gastrotheca guentheri) consisting of three pairs of bones (angulosplenial, dentary, and mentomeckelian, with the last pair being absent in Pipoidea),Duellman, William E. an unsupported tongue, lymph spaces underneath the skin, and a muscle, the protractor lentis, attached to the lens of the eye.
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Peirosaurus is known from the holotype DGM 433-R, fragmentary skull (left premaxilla bearing five teeth, isolated maxillary and dentary teeth and left palpebral bone) and partial postcranial skeleton including radius, ulna, left pubis and ischium, some presacral and a single caudal vertebrae, ribs, haemal arches and dermal plates. It was collected by Llewellyn Ivor Price in 1947-1949 at the Price Quarry 3, Peirópolis Site near Uberaba, in the Serra de Galga Member of the Marília Formation (Bauru Group), dating to the late Maastrichtian stage of the Late Cretaceous, about 68-66 million years ago. A partial skull and several postcranial elements such as vertebrae and dermal plates from the Bajo de la Carpa Formation in Argentina and another partial skull and several unprepared postcranial elements from the Anacleto Formation, Argentina, were assigned to Peirosaurus by Gasparini, Chiappe and Fernandez (1991) and Praderio, Martinelli and Candeiro (2008), respectively. However, more recently Agustín G. Martinelli, Joseph J.W. Sertich, Alberto C. Garrido and Ángel M. Praderio concluded that the traits which used to unite the holotype (from Brazil) and the referred material from Argentina are shared with other peirosaurids and some other mesoeucrocodylians.
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A number of characteristics allow Jianianhualong to be identified as a member of the Troodontidae. These include the long forward-projecting branch and flange of the lacrimal bonw; the foramina on the nasal bone; the smooth transition between the eye socket and the backward-projecting branch of the frontal bone; the ridge on the forward- projecting branch of the jugal bone; the triangular dentary bearing a widening groove; the robust forward-projecting branch of the surangular bone; the relatively large number of unevenly-distributed teeth; the flattened chevrons with blunt forward projections and bifurcated backward projections; and the broad and flat "pubic apron" formed by the pubic bones. Within the troodontids, Jianianhualong displays a unique combination of characteristics from both basal and derived troodontids, organized in distinct regions of its body. The forelimbs and pelvis largely resemble basal troodontids such as Sinovenator: the short deltopectoral crest on the humerus; the long hand, metacarpal II, and phalanx III-2 on the hand; the small ilium; the ridge on the pubic apron; and the short ischium with two projections and an obturator process near the bottom of the bone.
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Carcharodontosaurids are characterized by the following morphological characters : Dorsoventral depth of anterior maxillary interdental plates more than twice anteroposterior width, squared, sub-rectangular anterior portion of the dentary, teeth with wrinkled enamel surfaces, presence of four premaxillary alveoli and a premaxillary body taller than long in lateral aspect, opisthocoelous cervical vertebrae with neural spines more than 1.9 times the height of the centrum, large, textured rugosities on the lacrimal and postorbital formed by roofing and forming broad orbital shelves, and a proximomedially inclined femoral head. With the discovery of Mapusaurus in 2006, Rodolfo Coria and Phil Currie erected a subfamily of Carcharodontosauridae, the Giganotosaurinae, to contain the most advanced South American species, which they found to be more closely related to each other than to the African and European forms. Coria and Currie did not formally refer Tyrannotitan to this subfamily, pending a more detailed description of that genus, but noted that based on characteristics of the femur, it may be a gigantosaurin as well. Size comparison of seven carcharodontosaurids In 1998 Paul Sereno defined Carcharodontosauridae as a clade, consisting of Carcharodontosaurus and all species closer to it than to either Allosaurus, Sinraptor, Monolophosaurus, or Cryolophosaurus.
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The specific name refers to its origin in Soria. The fossils, with catalogue numbers MNS 2000/132, 2001/122, 2002/95, 2003/69, 2004/54, were found in the Golmayo Formation which dates from the Hauterivian - Barremian, about 130 million years old. It consists of a partial skeleton with skull and lower jaws. Have been preserved: parts of the maxilla, a piece of premaxilla, a left dentary piece, a piece of the right surangular, pieces of the hyoid apparatus, loose edges of alveolar ridge, sixty two loose teeth from the upper jaw, thirty-six loose teeth from the lower jaw, a proatlas, a centrum of a cervical vertebra, a neck rib, four dorsal vertebrae, thirty-six pieces of the sacrum, thirty-two caudal vertebrae, six ribs, three complete chevrons, pieces of chevrons, ossified tendons, the right shoulder blade (scapula), both coracoids, both humeri, the right-hand radius, the left ulna, the right hand thumb, the right hand, a piece of left iliac, the processus praepubici of the two pubic bones, a piece of the right femur, a part of the right tibia, and the second and fourth metatarsals of the right leg.
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The genus is named after Timurleng, founder of the Timurid Empire in Central Asia. The specific name euotica is Greek for “well-eared”, because detailed CAT-scans showed that Timurlengia had long inner ear canals, for hearing low-frequency sounds. The species was based on the holotype, specimen ZIN PH 1146/16, consisting of the braincase. Other bones, not belonging to a single individual, and described in 2012, were referred to the species. These included the specimens ZIN PH 854/16: the right half of a braincase; ZIN PH 676/16: a right maxilla; ZIN PH 2330/16: a left frontal bone; ZIN PH 2296/16: a left quadrate; ZIN PH 15/16: a piece of a right dentary; ZIN PH 1239/16: a right articular with angular; ZIN PH 671/16: a front neck vertebra; USNM 538131: a rear neck vertebra; USNM 538132: the neural arch of front back vertebra; CCMGE 432/12457: a middle back vertebra; ZIN PH 951/16: a front tail vertebra; ZIN PH 120/16: a middle tail vertebra; ZIN PH 120/16: a rear tail vertebra; ZINPH 619/16; and USNM 538167: a toe claw.
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