121 Sentences With "denticle" | Random Sentence Generator

The rather thin columella is weakly sigmoid and ends in a rounded denticle.

The pointed, denticle-covered snout distinguishes this species from the rest of the genus. The maximum known disc width is .

BMC Evolutionary Biology 12: 245. . The radula of Pontohedyle milaschewitchii shows that the lateral radula tooth (rlp) is with a denticle (arrowhead).

All of the crowns also bear small, denticle-like serrations on the front and rear edges, which is also seen in Probactrosaurus.

The base of the shell is rounded. The umbilicus has a crenulate margin. The columella has an acute, prominent denticle. The inner lip is grooved.

The morphology of the chelicerae is similar across all ages, with the same arrangement and number of denticles, but there were also some noticeable differences. Particularly, the principal denticles grew in size relative to the intermediate denticles, being 1.5 times the size of the intermediate denticles in juveniles, but up to 3.5 times the size of the intermediate denticles in adults. Furthermore, the terminal denticle was far larger and more robust in adult specimens than in juveniles. Perhaps most extreme of all, the second intermediate denticle is not different in size from the other intermediate denticles in juveniles, but it is massively elongated in adults, where it is more than twice the length of any principal denticle.

The umbilical margin is subcrenulate. The top of the columella is plicate. The columella lacks a denticle and has three tubercles at its base. The inner lip is subsulcate.

Species of Hindeodus are divided into two groups based on the morphology of the posterior portion of the elements. Species such as H.parvus and H.eurypyge grow posteriorly and look rectangular from a lateral perspective. Elements grow by the addition of new denticles to the posterior margin. After one denticle fully grows, a bulge begins to form on the lower posterior margin of the element, and gradually grows upward until the denticle fully develops.

Holtz, Thomas R., Brinkman, Daniel L., Chandler, Chistine L. (1998) Denticle Morphometrics and a Possibly Omnivorous Feeding Habit for the Theropod Dinosaur Troodon. Gaia number 15. December 1998. pp. 159-166.

The vomer also bears two vomerine rows: a transversal denticle row and a longitudinal denticle row that runs along the inner margin of the choana. The palatines and ectopterygoids are broader than other temnospondyls, barring other capitosaurids. Stanocephalosaurus has a long, triangular skull, which is much longer than broad, with an elongated preorbital region continuously narrowing anteriorly to an obtuse rounded snout, though this varies in species (S. amenasensis tend to have much narrower snouts than S. birdi).

This animal shows an increased expansion of the pterygoids and palatines, as well as narrow posterior nostrils. The vomer also bears two vomerine rows: a transversal denticle row and a longitudinal denticle row that runs along the inner margin of the choana. The palatines and ectopterygoids are broader than in other temnospondyls, which is somewhat common within mastodonsaurids. Stanocephalosaurus also has a long, triangular skull which is much longer than broad, and has an elongated preorbital region continuously narrowing anteriorly to an obtuse rounded snout.

The minute shell is similar in form to Phasianella. The aperture is ovate. The columella has a heavy callus, bearing near the base a strong curved denticle projecting into the aperture. The outer lip is simple.

Placoid scales are structurally homologous with vertebrate teeth ("denticle" translates to "small tooth"), having a central pulp cavity supplied with blood vessels, surrounded by a conical layer of dentine, all of which sits on top of a rectangular basal plate that rests on the dermis. The outermost layer is composed of vitrodentine, a largely inorganic enamel-like substance. Placoid scales cannot grow in size, but rather more scales are added as the fish increases in size. Similar scales can also be found under the head of the denticle herring.

The umbilicus is deeply channelled. The aperture is rounded-quadrate. The columella is deeply sinuous, callous, terminating in an acute denticle. The outer lip is sulcate within, subcinereus or ashen-reddish, with scattered obscure spots on the upper whorls.

In 1967, Obruchev placed this genus within Hadrosteidae, on the basis of how the two genera have similar denticle ("teeth") patterns of the inferognathals, though, Denison (1978) contests this placement, preferring to leave the taxon as arthrodira incertae sedis.

The oblique aperture is subcircular. The outer and basal lips are rounded and finely crenulate within. The columella is slightly concave, bearing a small denticle at its base and above near the insertion. The parietal wall is nearly smooth.

The whorls are rather convex, the body whorl scarcely angled. The margin of the umbilicus is dentate. The columella is very oblique, not solute above and terminates below in a simple denticle. The lip is thickened and corrugated within.

Also in contrast to those two species, young leopard whiprays across have still not developed the dorsal denticle band. Sexual maturity is attained at across for males. Known parasites of this species include the tapeworms Parachristianella indonesiensis and P. baverstocki.

Newborns measure about across, comparable to H. uarnak and larger than H. leoparda. Also like H. uarnak but unlike H. leoparda, by a disc width of juvenile rays have a well-developed dorsal denticle band. Males reach sexual maturity at across.

Klein, Adam G. Common Sawsharks. Checkerboard Books, 2005 Fins are fully scaled but the snout is only partially covered. The ventral scales are usually leaf like with no accessory points or ridges. P. nudipinnis shows the largest difference in denticle structures.

No diagnostic differences in external morphology or spicules could be detected between the collected populations apart from eyes externally visible or not. Comparative SEM-examination of the available radulae revealed two types of the typically hook-shaped radula: a lateral tooth without a denticle (Pontohedyle verrucosa) or with a denticle (Pontohedyle milaschewitchii). Pontohedyle slugs have a well-adapted body plan that can be conserved for millions of years in a worldwide evolutionary success story. Pontohedyle presents a stunning example of extreme morphological stasis and uniformity over long evolutionary timeframes, probably constrained by their simplified bodyplan and by the requirements of the meiofaunal habitat.

The base is nearly flat. The oblique aperture is smooth within. The oblique columella is sinuous and bidentate. The umbilicus is surrounded by a white callus, bearing inside a strong spiral rib which terminates in a denticle about the middle of the columella.

The denticle (tiny teeth) of radula have the formula ∞ 1, (1 + 1 + 1), 1 ∞. The central denticles are small and elongated. The lateral tooth is rather large, straight, without a cusp. The numerous lateral teeth are denticulate, and arranged in very oblique series.

The basal lip has a broad, prominent knob. The lower palatal tooth is a prominent, crescentic lamella, with strong lateral buttresses. The upper palatal lip often has a small tuberculate denticle. The periostracum is brownish in color, occasionally speckled with greenish yellow.

The species is smaller and lower-spired than the other Dominican Helicina species, and always has a dull brown colour, a paler aperture and a hairy periostracum; ‘covered with a velvety epidermis’, weakly keeled, with a columellar denticle. Its size is 5-8.5 mm.

The central rachidian is heart-shaped, narrow free end surmounted by small, slightly serrated denticle. The other rachidians have trilobed cusps, which gradually enlarge outwards. There is a single lateral with one cusp trilobed at its base. The many marginals are unicuspidate, and not serrated.

December 1998. pp. 159–166. The jaws met in a broad, U-shaped symphysis similar to that of an iguana, a lizard species adapted to a plant-eating lifestyle. Additionally, the teeth of Stenonychosaurus bore large serrations, each of which is called a denticle.

The specialization of the ears may indicate that troodontids hunted in a manner similar to owls, using their hearing to locate small prey. Although most paleontologists believe that they were predatory carnivores, the many small, coarsely serrated teeth, large denticle size, and U-shaped jaws of some species (particularly Troodon) suggest that some species may have been omnivorous or herbivorous. Some suggest that the large denticle size is reminiscent of the teeth of extant iguanine lizards. In contrast, a few species, such as Byronosaurus, had large numbers of needle-like teeth, which seem best-suited for picking up small prey, such as birds, lizards and small mammals.

They found five genes – even- skipped, hairy, odd-skipped, paired and runt – where mutations caused the deletion of a particular region of every alternate segment. For example, in even-skipped, the denticle bands of alternate segments are missing, which results in an embryo having half the number of denticle bands. Later work identified more pair-rule genes in the Drosophila early embryo – fushi tarazu, odd-paired and sloppy paired. Once the pair-rule genes had been identified at the molecular level it was found that each gene is expressed in alternate parasegments – regions in the embryo that are closely related to segments, but are slightly out of register.

The oblique aperture is subrhomboidal. The outer lip is descending, very lightly convex, and forms an acute angle with the faintly arched basal lip. Both are strengthened inside by a thin callus. The oblique columella is straight with a distinct tubercle above, and a small denticle at the base.

The white columella is arcuate and wide but not dentate below. The base of the shell has a minute internal denticle. Some specimens are almost entirely red; others are white, with red spots at the periphery. There is some variation in form, also, and in the prominence of the spiral riblets.

The hind tibiae are apically widened, with both dorsomesal and ventral carinae that are strong. Its first tarsomere does not have an apical denticle ventrally. On its abdomen, ventrite 5 is emarginate, as long as the 4th sternite. Its first ventrite has a patch of short erect setae basally, which are somewhat scaly.

This rim is followed by a band of opaque white which is deposited thi. It is not more than I2 mm broad, and does not extend to the upper angle of aperture. Within this the aperture is very brilliantly iridescent and green. The pearly columella is vertical, ending in an acute, compressed denticle.

They show about 14 axial ribs. The spiral sculpture consists of 3 cords in the upperwhorls and 16-20 in the body whorl. The aperture is elongate-ovate, measuring about half the total length. The outer lip is marked by transverse striations and is incrassate with a strong denticle close to the posterior sinus.

The outermost lateral is so much concealed by the large uncini, that its shape could not be traced. It seems to have a simple cusp, without the sharp denticle of the preceding species. The proximal uncini are strongly hooked and simple. The median ones seem to be serrated and the exterior one again simple.

These are narrower than the interspaces in which there are very fine, prosocline lamellae. A considerably thicker compound cord is seen above the suture on the spire and at the periphery of body whorl. The aperture is subquadrangular, with a moderate denticle at the base of the columella. The outer lip has a cutting edge.

The interstices are about as wide as the lirae. The body whorl is somewhat gibbous and descends toward the aperture, which in adult specimens is somewhat contracted and subtrigonal. The outer lip shows a few deeply entering lirae within, the upper one terminating in a small denticle. The short columella is concave and smooth.

The parietal callus is appressed and devoid of a parietal denticle. It continues into a columellar callus which has a rounded edge, slightly raised over the siphonal canal and bearing a few tubercles. The colour of the shell has a brownish hue over a white background. The subsutural and median cords are articulated with darker brown.

This species is a plain ochre to dark grayish brown above, becoming lighter towards the disc margins, on the thorns, and past the sting, and white below. Reaching across and long, the dwarf black stingray is less than a third as wide as the wide black stingray. The two species also differ in denticle coverage and meristic counts.

This ray can also be distinguished from its similar relatives by an enlarged, pearl-like dermal denticle at the center of the back, which is followed by a few thorns. The International Union for Conservation of Nature (IUCN) has assessed the honeycomb whipray as Vulnerable, as it faces heavy fishing pressure and habitat degradation across much of its range.

They are encircled by lirae, usually 5 or 6 in number on the penultimate whorl, but very variable. The body whorl shows a prominent rib at the periphery, convex beneath. The aperture is quadrangular, delicately ribbed within and iridescent, green predominating. The columella is arcuate above, then straight and oblique, terminating near the base in a slight denticle.

The 6 to 7 whorls are rather rounded with a convex base, the last one is scarcely angled. The margin of the narrow umbilicus is dentate. The columella is very oblique, not solute above and terminates below in a simple, small denticle. The outer lip is thickened within with five folds but near the edge with numerous wrinkles.

The first (i), second (2), third (3) and fourth (4) laterals are about equal in shape. The first one is subtriangular, with a slightly concave inner and convex outer margin, thickened at its upper part, the second is very similar, the third is narrower and the fourth is more subquadrangularly elongate; the fifth (5) or last lateral is club-shaped, thickened above, without cusp. Of the uncini (U) the proximal one has a short, broad cusp, with a small denticle near the base of the distal margin; the second is more elongate, also with a small denticle; the subsequent ones are much more elongate, No denticles can be detected, perhaps because the cusps lie so close together, as to cover each other in part.Schepman 1908-1913, The Prosobranchia of the Siboga Expedition; Leyden,E.

The number of maxillary teeth were twenty per side, lower than the number with Stegosaurus. Carpenter described them as similar to the teeth of Stegosaurus, though somewhat larger. Peter Malcolm Galton in 2007 established some differences: there are rough vertical ridges present on the upper part of the crown, one per denticle; the fine grooves on the tooth surface are weakly developed.

Its cusp is large, longer than the base, with about 4 to 6 denticles on each side of the median denticle. The first lateral has a subquadrate body. Its cusp has very small denticles, at its proximal, more conspicuous ones at its distal margin. The second lateral has a similar body, with larger cusp and more numerous denticles at its distal margin.

The outer lip is four or five-lirate within, the upper fold somewhat enlarged and subdentiform. The basal margin and marginal rib of the umbilicus is finely plicate. The columella is oblique, nearly straight, its edge reflexed and plicate-dentate, terminating below in a small square denticle, inserted above upon the side of the umbilicus. The umbilicus is rather wide and funnel-shaped.

Tadpoles are large and bronze colored, with large, irregular gold flecks, and can grow up to 37 mm long, and metamorphs are 17–19 mm. Larvae are well-equipped for grazing, with an inferior oral disc consisting of a beak and 6-7/7-10 denticle rows. They tend to live in fast-flowing streams in rock piles, and are nocturnal.

The petiolar and postpetiolar shapes of Viti Levu workers are more similar to those of Koro workers than those of Taveuni and Vanua Levu. Some of the Viti Levu workers have an unarmed propodeum like those of the outlying islands, whereas others have a propodeum armed with an acute denticle equal or less than the size of the propodeal lobe.

A weak, parietal denticle may be present in Balea perversa, but not in Balea sarsii. All these characters are, however, variable; especially the shell dimensions. The most reliable character to use in separating the two species is the form of the apical whorls: in Balea perversa this part of the shell is almost cylindrical, but in Balea sarsii it is conical.

Specimens with a perfectly formed outer lip show a low denticle below the notch well within the aperture. The parietal callus is moderately thickened adjoining notch. The sculpture consists of axial ribs, barely overridden by fine spiral threads, and of microscopic frosted spirals. Brachycythara is a genus of small, biconic turrids having a very rapidly enlarging axially sculptured protoconch, non- varicose outer lip, and no anterior canal.

Two much shorter rows of smaller tubercles, slightly converging backward, are found alongside the central row behind the shoulders. Numerous small dermal denticles are also found between the eyes and on the tail behind the spine. The dorsal coloration varies from plain reddish-brown to dark gray, and the underside is light. The extent of denticle coverage and number of oral papillae can vary among individuals.

The caudal fin has a strong lower lobe and a long upper lobe with a prominent notch near the tip. The body is covered by small, non- overlapping dermal denticles; each denticle has radial ridges converging to a round central pit. The body is dark brown above and black below, with light margins on the fins. Small, light-emitting photophores are scattered over the body.

The solid shell has a depressed-conical shape. The outer surface is sharply, spirally striate and closely obliquely striated . The shell has a more or less developed callous ridge or funicle revolving on the inner side of the whorl within the umbilicus, and terminating at the columella, the edge of which is reflexed over it. The sinuous columella terminates in a point or denticle at its base.

Ventral view of repeating denticle bands on the cuticle of a 22-hour-old embryo. The head is on the left. Drosophila embryogenesis, the process by which Drosophila (fruit fly) embryos form, is a favorite model system for genetics and developmental biology. The study of its embryogenesis unlocked the century-long puzzle of how development was controlled, creating the field of evolutionary developmental biology.

The aperture is rounded-subquadrate. Its right margin is incomplete, its columellar margin is curved, with a denticle in the basal part. It is slightly reflected over the umbilicus. The interior of the shell is nacreous, (the nacreous texture of the inner layers is clearly visible on some of the exterior parts, where the outer layer has been removed by accidents during the youth of the animal).

The first to eight denticles of originally twelve or thirteen are also preserved. The enlarged anterior denticle and the curvature present in the anterior margin of the coxal neck suggest an assignment to Acutiramus rather than other genera in Pterygotidae. However, B. horrida has not been formally synonymized with Acutiramus due to the lack of more diagnostic material, and therefore remains as a dubious name.

Close-up from above of the caudal fin denticle crest of the longfin sawtail catshark (G. cadenati); such crests are shared by all Galeus species. The two dorsal fins are nearly equal in size and shape, and are placed well back on the body, behind the origins of the pelvic fins. The pectoral fins are fairly large and broad, with angular to rounded corners.

The skin is thick and roughened by well- calcified dermal denticles; each denticle is triangular and pointed. This species is light grayish brown to purplish above, including the upper surface of the pectoral fins, and paler below. A series of 6-7 faint darker saddles are present along the back and tail, which are more obvious in younger sharks. The fins lack obvious lighter margins.

Its conidiogenous hyphae are hyaline, measuring approximately 1–2.5μm wide, often found in fascicles in aerial mycelium. These are reduced to a single denticle that is 0.5–1.0μm long and 1.0–2.0μm wide. Conidia are two-celled, either solitary or distributed side by side in clusters. Its terminal cell is 4.5–5.5 by 4.0–5.5μm, being globose to subglobose, transitioning to a dark brown colour; its conidial walls are slightly thick.

The shaft is set in a chitinous yellow socket, which is extended on the back of the tooth so as to form a little hooked knob. Opposite this many of the teeth show a small sharp basal denticle. The anterior arm of the U is shorter than the other and obliquely trimmed off toward the apex of the fang. There is a well-marked oval poison gland, about 2.5 mm.

The aperture is bordered externally with a strong varix forming a rim, normally unique - not repeated at the earlier growth stages on the spire. The inner side of the outer lip bears ca. 10 denticles, elongated in the spiral direction. The parietal edge of the aperture forms a very thin, appressed callus, with a distinct adapical denticle, continued into a thicker columellar callus with a slightly raised edge.

The columella has a strong denticle. The colour of the shell is whitish with the inner nacre showing through, with vague brownish flames on specimens from shallower sites. The inside of the round aperture is nacreous. This species is distinguished from Danilia tinei in having the axial lamellae minute and about three times more numerous, the whitish colour and the more inflated and more fragile shell, with more convex whorls.

Its conidiogenous hyphae are hyaline, measuring approximately 1–2μm wide, often found in fascicles in aerial mycelium. These are reduced to a single denticle that is 0.5–1.5μm long and 1.0–3.5μm wide. Conidia are two-celled, either solitary or distributed side by side in clusters. Its terminal cell is 4.5–6.0 by 4.0–5.5μm, being globose to subglobose, transitioning to a dark brown colour; its conidial walls are slightly thick.

The columella is very oblique, slightly tortuous above and enters very deeply, terminating below in a strong plicate tooth, and with a smooth margin, save for a small denticle immediately above the basal tooth. The parietal tract is wrinkled. The umbilicus has a plicate-denticulate border. In the typical form, the 1st, 3d, 5th, 7th and 9th lirae, and one or two upon the base are articulated with black.

Another identifying feature is a "pearl organ" (enlarged dermal denticle) at the center of the back, found in individuals of all ages. All of the original specimens of the roughback whipray were found with extensive wounds to the fins and tail. The International Union for Conservation of Nature (IUCN) has assessed this species as Endangered, citing the extensive habitat degradation and heavy fishing pressure within its limited range.

The skin, excluding on the fins, is densely covered with irregularly arranged, nonoverlapping dermal denticles. Each denticle has a swollen rhombic shape with 10–40 facets on the crown. The viper dogfish is black with distinct darker markings on the underside. These markings contain large numbers of tiny light-producing photophores; more photophores are found sparsely scattered over the rest of the body, as well as in a translucent patch on the upper eyelid.

The outer lip is more curved and more finely crenulate within than that of Monodonta labio. The columella is short, squarely dentate at its base. Its edge is more or less rugose, and separated from the columellar area by a deep narrow straight sulcus, extending from the place of the umbilicus to the notch at base of columella. The basal notch is deep and divided by a small denticle in the middle.

The very oblique columella arises deep within the perforation, and ends in a large projecting triplicate tubercle (the left intrusion). Above the tubercle is a fold, and above that a small denticle. The opposite intrusion is a massive tricuspid rooted within the margin of the lip, and hanging deep into the aperture. On the palate between the perforation and right insertion are three short entering bars, followed by another winding far into the interior.

It has about 20 transverse rows of teeth; the rhachidian tooth is broad, depressed quadrangular with rounded upper angles and pointed basal ones. It has a large reflected cusp with one strong median denticle and two smaller ones on each side. The laterals, one on each side, have a depressed rhombic base, with a reflected margin, ending in a sharp cusp at the proximal side. The other teeth have the characters of being uncini.

The skin is soft and covered by tiny, flattened dermal denticles (scales), lending a velvety texture. Each denticle has three horizontal ridges that lead to teeth on the posterior margin. The dorsal coloration is a medium to dark gray or slate, extending to the bases of the pectoral fins. The underside is white; adults in the Southern Hemisphere often have dark coloring under the head and dusky blotches scattered over the belly.

The base is concentrically, rather deeply furrowed, the 6 furrows narrower than the intervening ridges. In the umbilicus, which perforates almost to the apex, all of the whorls are visible, encircled by an acute carina. The aperture is subquadrate, nacreous, smooth within, and has a groove indicating the place of the external keel. The columella is S-shaped, and ends in a blunt tooth, before which there is a small acute denticle.

11(12): e0167800. Features that are characteristic of the genus Fiona includeWillan R. C. (1979) "New Zealand locality records for the aeolid nudibranch Fiona pinnata (Eschscholtz)". Tane 25: . PDF the similar-looking oral tentacles and rhinophores; the cerata with a membrane and lacking a cnidosac; a dorsal anal opening; a reproductive system with two genital openings; two jaws with a cutting-edge, and a radula with only one central denticle in each row of teeth.

Both dorsal fins have very long free rear tips, and there is a subtle midline ridge between them. A prominent notch is present on the caudal peduncle at the dorsal origin of the caudal fin. The caudal fin has a well-developed lower lobe and a longer upper lobe with a ventral notch near the tip. The skin is covered by overlapping, oval-shaped dermal denticles; each denticle has three horizontal ridges leading to marginal teeth.

The caudal peduncle has a deep crescent-shaped notch at the upper caudal fin origin. The asymmetrical caudal fin has a well-developed lower lobe and a longer upper lobe with a notch in the trailing margin near the tip. The skin is covered by overlapping dermal denticles; each denticle has three horizontal ridges leading to three (rarely five) marginal teeth. This species is gray above and white below, with an obvious pale stripe on the flanks.

Along with marine applications, the aerospace industry can also benefit from these biomimetic designs. Parametric modeling has been done on shark denticles with a wide range of design variations such as low and high-profile vortex generators. These biomimetic models were designed and analyzed to see the effects of applying the denticle-like structures to the wings of various airplanes. During the simulation, it was noted that the sample altered how the low and high angles of attack reacted.

Expression of the flb gene can be seen as early as four hours into the development of Drosophila melanogaster. At four hours the gene is facilitating the retraction of the germ band as well as structuring the beginnings of the CNS. At six hours the gene is used to differentiate epidermal cells to secrete denticle belts which begin segmentation of the larva. At nine hours the gene is used for the differentiation of midline glial cells.

Restoration of two individuals playing in snow Stenonychosaurus are thought to have been predators, a view supported by its sickle claw on the foot and apparently good binocular vision. Stenonychosaurus teeth, however, are different from most other theropods. One comparative study of the feeding apparatus suggests that Stenonychosaurus could have been an omnivore.Holtz, Thomas R., Brinkman, Daniel L., Chandler, Chistine L. (1998) Denticle Morphometrics and a Possibly Omnivorous Feeding Habit for the Theropod Dinosaur Troodon. Gaia number 15.

Each dermal denticle is diamond-shaped and bears horizontal ridges leading to posterior marginal teeth, which increase in number as the shark grows. The back is metallic golden-brown to dark gray and the belly is snowy white, which extends onto the flank as a faint lighter stripe. The fins (except for the first dorsal) darken at the tips; this is more obvious in young sharks. The coloration quickly fades to a dull gray after death.

The smaller species, D. milleri, had no serrations since it ate small prey. As prey grew larger, several Dimetrodon species started developing serrations on their teeth and increasing in size. For instance, D. limbatus had enamel serrations that helped it cut through flesh (which were similar to the serrations that can be found on Secodontosaurus). The second largest species, D. grandis, has denticle serrations similar to those of sharks and theropod dinosaurs, making its teeth even more specialized for slicing through flesh.

Usually a single serrated, stinging spine is placed on the dorsal surface, relatively close to the tail base. Adults have a broad band of small, flattened dermal denticles running centrally from before the eyes, over the back, onto the tail. At the center of the disc, there is an enlarged, round "pearl" denticle trailed by 2-3 smaller thorns along the midline; there are no enlarged denticles on the base of the tail. Newborns have large, well-spaced dark spots covering the disc.

Hadrosteidae is a family of arthrodire placoderms from the Late Devonian. It was originally erected for the late Frasnian Hadrosteus, from the Kellwasserkalk facies. Later, the family was subjectively subsumed into Dinichthyidae due to Hadrosteus' anatomical similarities with Dunkleosteus and Dinichthys. In 1967, Obruchev placed the enigmatic arthrodire incertae sedis Diplognathus, from the Eastern American Famennian, within Hadrosteidae, on the basis of how the two genera have similar denticle ("teeth") patterns of the inferognathals, though, Denison (1978) contests this placement.

The caudal fin is short and broad, with an indistinct lower lobe and a ventral notch near the tip of the upper lobe. The very thick skin is covered by well-calcified dermal denticles. Each denticle has an arrowhead-shaped crown with three posterior points, mounted on a short stalk. The background color of the leopard catshark ranges from off-white to glossy jet black above and white to almost black below, sometimes with an abrupt transition between the two.

Little is known of the natural history of the Australian reticulate swellshark. Like other members of its genus, this species can inflate itself with water or air as a defensive measure. The eggs of this oviparous species are contained in smooth, light yellow flask-shaped capsules, which have a flanged margin and horns at the corners that support long, coiled tendrils. The hatchlings seem to lack the specialized denticle used by other swellsharks to break out of the egg case.

The oblique aperture is somewhat contracted and subcircular. The outer and basal lips are thickened and finely crenulated within. The columella is oblique, with a tooth-like fold above, solute, and deeply inserted upon the side of the umbilicus The middle portion is concave, with a reflexed subdenticulate edge, ending beneath in a minute denticle. The profound umbilicus is smooth and polished within, bordered by a strong rib bearing 6 or 7 projecting white teeth, the upper one the largest.

The curvature and length of the holotype tooth and the length of its hindmost cutting edge (carina) indicates it was in the front of the jaw. Estimated size of Dromaeosauroides, and possible placement of the two known teeth The tooth is recurved with a backward bend, and is oval in cross-section. Its front and back cutting edges are finely serrated, extending two-thirds down each edge. There are six denticles per millimeter (0.04 in), and each denticle is square and chiseled.

Sharklet material was developed by Dr. Anthony Brennan, materials science and engineering professor at University of Florida, while trying to improve antifouling technology for ships and submarines at Pearl Harbor. Brennan realized that sharks do not experience fouling. He observed that shark skin denticles are arranged in a distinct diamond pattern with millions of tiny ribs. The width-to-height ratio of shark denticle riblets corresponded to his mathematical model for the texture of a material that would discourage microorganisms from settling.

The dermal denticles are scattered irregularly over the body and vary greatly in size, measuring up to across. Each denticle is thorn-like in shape, with ridges radiating out from the central point over the base. As many as ten denticles may be fused together to form multi-pointed plates. The underside of the snout and the area around the mouth is densely covered by small denticles in sharks under long; these denticles become larger and sparser in larger sharks.

Varixes are situated along the broadest section of the shell, moderately thick, repeated after a little more than half a whorl so that they are slightly and regularly offset along the spire, overrun by the spirals. The aperture is oval; outer lip faintly fluted inside; parietal and columellar edge forming a continuous callus, the parietal edge with a small but well- marked denticle, the columella is faintly tuberculate. Siphonal canal is open, moderate in length. Shell colour is from very light tan to whitish.

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.

Organs that perform similar functions in non-arthropods are often referred to as "stings". These organs include the modified dermal denticle of the stingray, the venomous spurs on the hind legs of the male platypus, and the cnidocyte tentacles of the jellyfish. The term sting was historically often used for the fang of a snake,Oxford English Dictionary, 2nd ed. "Sting ... Applied also to the fang or venom-tooth (and erroneously to the forked tongue) of a poisonous serpent." although this usage is uncommon today.

The shell is 17 to 27 mm in length, 10 to 16 mm in greatest diameter, with a low conical spire and an indistinct suture. The outer lip is thickened, and strongly reflected outward, with a sharp edge overhanging the exterior of the body whorl. The inside of the lip of the shell has 15-25 small irregular denticles, plus one very strong isolated denticle near its posterior end. The aperture is quite high for the genus, and it narrows both anteriorly and posteriorly.

Another feature distinguishing the group from other eurypterid groups is their flattened and expanded telsons, likely used as rudders when swimming. J. howelli, known from over 30 specimens, has an almost identical pattern of denticulation on the chelicerae as J. rhenaniae and also preserves a flattened posterior margin of the telson, which results in a triangular shape, as in J. rhenaniae. Its serrated telson margin and the massive elongation of the second intermediate denticle clearly distinguishes it from J. rhenaniae. Furthermore, the type A genital appendage is not bifurcated at its end.

Though such growth in the denticles of pterygotids has been described in other genera, the massive elongation of the second intermediate denticle through ontogeny is unique to Jaekelopterus, particularly to J. howelli. The metastoma of Jaekelopterus also altered its dimensions as the animal matured. In J. rhenaniae, the relative width of the metastoma decreased through ontogeny. The metastoma in J. howelli is also broader in juveniles than in adults, although the length–width ratios measured in juveniles and adults were not as disparate as assumed, being 1.43 in juveniles and 1.46 in adults.

The caudal peduncle has a deep notch on its upper surface at the caudal fin origin. The caudal fin is asymmetrical, with a well-developed lower lobe and a longer upper lobe with a notch in the trailing margin near its tip. The skin is covered by rather large dermal denticles, which become more tightly packed and overlapping with age; each denticle bears three to five horizontal ridges and five posterior teeth. This species is grey above and white below, with a faint pale band on the flanks.

Shark skin is almost entirely covered by small placoid scales. The scales are supported by spines, which feel rough when stroked in a backward direction, but when flattened by the forward movement of water, create tiny vortices that reduce hydrodynamic drag and reduce turbulence, making swimming both more efficient and quieter compared to that of bony fishes. It also serves a role in anti-fouling by exhibiting the lotus effect. All denticles are composed of an interior pulp cavity with a nervous and arterial supply rooted in the dermis to supply the denticle with mucus.

The first dorsal fin is low with a minute leading spine; the second dorsal fin is twice as high as the first with a much larger spine. The caudal peduncle is short, leading to a long caudal fin with the upper lobe much larger than the lower. The dermal denticles of this shark are tiny and densely placed with no regular pattern; each denticle has a four-cornered base and rises to a narrow, slightly curved point. The denticles of females are firmly attached, while those of males are easily removed.

The mantle is strongly pigmented and can be totally black; pigmentation is also present in the areas of muscle insertion (foot and tentacles). The anterior right muscle impression is elongated, extending to the middle region of the body. The left impression is elliptical and transversely arranged while the posterior impression is rounded. The rachidian tooth has two long main cusps and might have a denticle between them, with one to two cusps to the side of the left main cusp and one to the side of the right one.

The abdominal cuticular segments of the Drosophila embryo consist of repeating denticle bands separated by naked cuticle. One of the best understood examples of pattern formation is the patterning along the future head to tail (antero-posterior) axis of the fruit fly Drosophila melanogaster. There are three fundamental types of genes that give way to the developmental structure of the fly: maternal effect genes, segmentation genes, and homeotic genes. The development of Drosophila is particularly well studied, and it is representative of a major class of animals, the insects or insecta.

Off South Africa, the newborns measure across and sexual maturation is attained at a disc width of approximately , which corresponds to an age of 4-5. Off Australia, the newborns measure across, with males reported to mature at across. The juveniles of this species, H. leoparda, and H. undulata differ in birth size, disc shape, denticle development, and amount of spotting, and are in fact more distinct from each other than are adults of the three species. Shark Bay may serve as a nursery area for young rays.

The skin is covered by overlapping dermal denticles; the denticle crowns are narrow and placed on narrow stalks, with three teeth on their posterior margins. The coloration is distinctive, consisting of a dense variegated pattern of dark markings ranging from tiny to larger than the eye, on a brownish background. In particular, there are three spots above a fourth curved spot, forming a "clown face", beneath each dorsal fin. The spots extend onto the dorsal and anal fins, and the upper surfaces of the pectoral and pelvic fins.

The daisy stingray, Dasyatis margarita, is a little-known species of stingray in the family Dasyatidae, found in shallow waters along the coast of West Africa. This species typically grows to across and has a rounded pectoral fin disc and (in adults) a wide band of dermal denticles over its back. It is characterized by a greatly enlarged, nacreous denticle in the middle of its back called a "pearl spine"; this feature is shared with the similar but much smaller pearl stingray (D. margaritella), which has often been confused with this species.

The pearl stingray (Dasyatis margaritella) is a little-known species of stingray in the family Dasyatidae, found in shallow coastal waters from Mauritania to Angola. Growing to across, this species has a rounded pectoral fin disc with a pointed snout, and a wide band of dermal denticles over the back in adults. It closely resembles and is often confused for the much larger daisy stingray (D. margarita); both species are characterized by the presence of an enlarged, nacreous denticle in the middle of the back called a "pearl spine".

The outer lip is provided with 6-7 elongate denticles of which the third (from adapical side) is markedly larger. The parietal edge has a broad, thin and shiny callus, continued to form a broad shield also bordering the columella; provided with small blunt tubercles and molded over the varix of the preceding whorl but never bearing a distinct plait or denticle on the adapical side. The columellar edge forms a thick outgrowth which extends over the aperture, provided with denticles which increase in size towards the adapical side. The siphonal canal is short.

The skin is thick and densely covered by small, overlapping, well-calcified dermal denticles; each denticle has a leaf- shaped crown with a horizontal ridge and three teeth on the posterior margin. There is a prominent, saw-like crest of enlarged denticles along the dorsal margin of the caudal fin. G. murinus and G. springeri also have a similar crest along the ventral margin of the caudal fin. Galeus species are typically grayish or brownish above and lighter below, and most have a pattern of darker saddles and/or blotches along the back and tail.

Its conidiogenous hyphae are hyaline, measuring approximately 1.5–2.0μm wide, often found in fascicles in aerial mycelium. These are reduced to a single denticle that is 1.0–3.0μm long and 1.5–3.5μm wide. Conidia are two-celled, either solitary or distributed side by side in clusters. Its terminal cell is 4.0–5.5 by 4.0–5.0μm, being globose to subglobose, transitioning to a pale brown to dark brown colour; its conidial walls are slightly thick, smooth or verrucose, with warts measuring 0.75 to 1.5μm, incrusted with a brown-coloured slime that is 1–2μm thick around the apex.

Denticles contain riblet structures that protrude from the surface of the scale; under a microscope this riblet can look like a hook or ridges coming out of the scale. The overall shape of the protrusion from the denticle is dependent on the type of shark and can be generally described with two appearances. The first is a scale in which ridges are placed laterally down the shark and parallel with the flow of the water. The second form is a smooth scale with what looks like a hooked riblet curling out of the surface aiming towards the posterior side of the shark.

The overall form of the tooth, its width and shape in cross-section and its curvature resemble those in the maxilla (upper jawbone) and mandible of the species Dromaeosaurus albertensis from North America. Blood grooves are indistinct or absent, also similar to Dromaeosaurus, and differing from members of the Velociraptorinae subfamily. Dromaeosauroides differs from Dromaeosaurus in that the cutting edge at the front side is further from the middle of the tooth. Although the tooth is larger and the denticles similar, each denticle was smaller than those of Dromaeosaurus, which had only 13–20 denticles per , instead of Dromaeosauroides' 30.

The pelvic fins are short and can be rotated forwards; the males have short, stout claspers. The slender tail measures over twice the length of the disc and lacks fin folds. A single stinging spine is found on the upper surface of the tail near the base, but is frequently missing in adults. The upper surface of the disc and tail are covered by minute, blunt dermal denticles, with slightly larger plate-like denticles forming a distinct, broad band extending from before the eyes to the base of the tail; this denticle band is present at birth.

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.

The anal fin is nearly as large as the first dorsal fin and placed slightly ahead of the second dorsal fin. The caudal fin is large and broad, with the upper lobe longer than the lower and bearing a prominent ventral notch near the tip. The skin is thick and sparsely covered by large, well-calcified dermal denticles; each denticle has a diamond-shaped crown with three horizontal ridges. This shark is cream- colored with dark brownish to grayish mottling on the back and sides, and seven dark brown dorsal "saddles" on the body and tail.

Denticle comparison with four other sclerorhynchid species (Atlanticopristis in blue) The teeth on the rostrum (snout) of Atlanticopristis have a varied number of barbs at the front and rear margins. They are also laterally compressed, with both sides displaying thin enamel ridges extending outward from the base of the tooth, forming a fan shape. Some of the teeth also have grooves running down their length on both sides. The peduncle (or base) of the tooth is enlarged, and covered in irregular ridges, the bottom is typically concave, having a sub-rectangular or ellipsoid shape. The specimens range in size from 11.5 mm (0.45 inches) to 18.8 mm (0.74 inches).

However, it is uncertain whether they intended to resurrect Figaro or were simply unaware of its synonymy with Galeus, and their use of the ventral denticle crest to define the genus posed taxonomic problems. In 2008, Commonwealth Scientific and Industrial Research Organisation (CSIRO) researchers Daniel Gledhill, Peter Last, and William White resurrected Figaro with additional defining characters, to contain F. boardmani and the new species F. striatus. The genus has since been generally accepted as distinct. One of the key characteristics of Figaro, the ventral crest of denticles on the caudal fin, is also present in several species of the genus Parmaturus, as well as the Springer's sawtail catshark (G.

Despite having large tusks, male strap-toothed beaked whales likely only use a small protruding denticle on each tooth in agnostic interactions. Subsequently this species may travel in groups with multiple males as the risk of serious injury is lessened The species is reported to bask at the water’s surface on calm days, but is noted to be difficult to approach in vessels. Strap-toothed beaked whales typically do not show their flukes upon diving. A number of observations suggest that diving is typified by a slow descent beneath the surface , with dive duration lasting between 10 and 15 minutes. The species can travel at speed, and may show ‘porpoising’ behaviour.

Analyzing the three components of the scale it can be concluded that the base of the denticle does not come into contact with any portion of the fluid flow. The crown and the neck of the denticles however play a key role and are responsible for creating the turbulent vortices and eddies found near the skin's surface. Due to the fact that denticles come in so many different shapes and sizes, it can be expected that not all shapes will produce the same type of turbulent flow. During a recent research experiment biomimetic samples of shark denticles with a crescent like microstructure and tested in a water tank using a traction table as a slide.

The outer margin of the premaxillaries bear six rows of long, conical, recurved teeth; the teeth in the lower jaw are much shorter. The number and length of the teeth increases as the fish grows. The distinctive lure of Thaumatichthys is achieved by an "upside-down" orientation of the illicium (the "fishing rod"): its base is embedded in the skin fold connecting the anterior ends of the premaxillaries, and the short illicium projects down and back so that the esca at the tip hangs down from the roof of the mouth. The escal bulb terminates in a pair of forked tendrils and bears varying numbers of lateral lobes and a single curved denticle.

The short and broad caudal fin has an indistinct lower lobe and a ventral notch near the tip of the upper lobe. The skin is very thick and bears well-calcified dermal denticles; each denticle has an arrowhead-shaped crown with three posterior points, mounted on a short stalk. The dorsal coloration is distinctive, consisting of 5-7 thick, parallel, dark stripes running from the snout to the caudal peduncle on a variably grayish or brownish background; the stripes become broken near the tail and the belly. In some sharks, the main stripe on either side may fork behind the eye, the stripes may be split in two by lighter central lines, or one or more large dark spots may be present.

Shell up to 12.0mm in length, ovate and soild, some specimens broader than others, teleconch of only 3-3 ½ convex whorls, protoconch of 1 ½ embryonic whorls, partly macroscopically axially striate; shell smooth except for very fine axial growth lines and a heavy, flattish spiral cord at base of body whorl. Aperture moderately narrow, outerlip thickened but not strongly variced, interior with 4-5 denticles decreasing in size anteriorly. Columella concave and with a moderately broad and thick callus, a strong fold at the anterior end and occasionally with another weak plication; siphonal notch deep and broad, parietal denticle swollen, anal canal distinct. Color fawn to brown, last whorl decorated with a moderately broad, interrupted brown subsutural band and a broad dark brown band on the posterior half.

Hindeodus is characterized by a P element with a large cusp, denticles that increase in width anteriorly (toward the head) except for the anterior-most denticle and generally decrease in height anteriorly, except for the posterior-most three denticles (the ones furthest back) which are at equal heights. Their cusps are much higher than denticles, and they possess S elements with a short lateral processes that are slightly upturned laterally with denticles of variable size. Hindeodus is differentiated from other conodonts by having P elements with large fixed cusps located at the anterior end of the blade and usually grow primarily by adding new denticles only to the posterior end of the element. Other conodonts vary in growth pattern and location of their cusps.

The teeth are much wider than those of the strap-toothed, and a peculiar denticle on the tip of the teeth present on both species is much more pronounced in the spade-toothed whale. The common name was chosen because, in life, the part of the tooth that protrudes from the gums (unlike the strap-like teeth of strap-toothed whales) has a shape similar to the tip of a flensing spade as used by 19th-century whalers. Despite the rather similar dentition, the spade-toothed whale and strap-toothed whale seem to be only distantly related. The present species' relationships are not known with certainty, though, because this species is very distinct morphologically, and the DNA sequence information is contradictory and is currently not good enough to support a robust phylogenetic hypothesis.

Features shared between the two specimens include: a straight and only slightly compressed shape; a somewhat oval cross section; no serrations on the carinae (possibly due to bad preservation); and flutes on the crown surface, the Japanese specimen having 12 on each side. The teeth also share a crown surface with numerous small granular structures oriented parallel to their lengths. Because of these resemblances, Hasegawa and colleagues regarded GMNH-PV-999 as nearly identical to the S. suteethorni holotype tooth. The blood grooves (tiny furrows in the gaps between each denticle) of GMNH-PV-999 have an oblique orientation of 45 degrees, as in Baryonyx and KDC-PV-0003, the second Sebayashi formation tooth, which consists of a slightly recurved crown fragment with an almost circular cross section.

Likewise in 2010, British palaeontologist David Hone and colleagues placed Siamosaurus and "S." fusuiensis in the Spinosaurinae. British palaeontologist Thomas Arden and colleagues identified Siamosaurus as a basal (early diverging or "primitive") member of this subfamily in 2019; their cladogram can be seen below: Vertebra from specimen SM-KK14, which may belong to Siamosaurus Later in 2019, the Khok Kruat Formation teeth were also referred to the Spinosaurinae by Kamonrak and colleagues, on the basis that both the Khok Kruat and Siamosaurus morphotypes lack characteristics seen in baryonychines, such as long and slender roots, 0–10 flutes on each side, no well defined carinae, a sculptured surface of the crown base, and 45 degree orientation of the blood grooves. But they share with spinosaurines a sub-circular to oval cross section, fluted tooth crowns, well defined front and rear carinae, distinct striations on the crown, varying denticle size, and a wrinkled surface of the crown base. The authors also noted that unlike spinosaurines such as Irritator and Spinosaurus, Asian spinosaurines usually have more laterally compressed tooth crowns, and wrinkles across more of the enamel surface.