Archaeopteryx was dubbed a "convergently bird-like non-avialan theropod," which means a non-avian feathered dinosaur that acquired bird-like characteristics through the processes of convergent evolution.
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This provides more evidence as to why venom has become a homoplastic trait and why very different animals have convergently evolved.
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In these features, it is the pliosaur that approaches closest to the distantly-related piscivorous polycotylids, having convergently evolved these traits more than 10 million years apart.
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Some catalytic mechanisms have been convergently evolved multiple times independently, and so form separate superfamilies, and in some superfamilies display a range of different (though often chemically similar) mechanisms.
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Because of the size of Haplocheirus and its basal phylogenetic position, a pattern of miniaturization for the Alvarezsauroidea is suggested. Miniaturizations are very rare in dinosaurs, but convergently evolved in Paraves.
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In particular the genus Barbonymus, containing the tinfoil barb and its relatives - for some time included in Puntius - appears to be a kind of carp that has evolved convergently with barbs.
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Nocturnal Birds of Australia. Illustrated by Jeremy Boot. Melbourne: Lansdowne Edns 136 pp. 22 pls [35–36] rather, the cryptic colour seems to be adaptation to terrestrial habits that evolved twice convergently.
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441 one study also records them in Oryzomys.Sánchez et al., 2001, p. 209 In oryzomyines, the fringes are an adaptation for a semiaquatic lifestyle that appeared convergently in the Holochilus-Lundomys and Nectomys-Amphinectomys lineages.
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Ratites, for example, rapidly diversified in the early Paleogene and are believed to have convergently developed flightlessness at least three to six times, often fulfilling the niche space for large herbivores once occupied by non-avian dinosaurs.
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However, other skeletal material from Elanodactylus is otherwise distinct from the skeletons of azhdarchids. Andres and Ji performed a phylogenetic analysis and found that Elanodactylus was a ctenochasmatid. They postulated that ctenochasmatids and azhdarchids convergently evolved similar neck vertebrae.
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Biological Parameters and Damage by Macrosoma tipulata Hübner (Lepidoptera: Hedylidae), in Cupuaçu tree [Theobroma grandiflorum (Wild ex Spreng Schum)] in Amazonas, Brazil. Neotropical Entomology, 36(1):102-106. like certain Nymphalidae. The larvae resemble (probably convergently) those of Apaturinae.
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While arthropod affinities were rejected under the assumption that other Mazon Creek arthropods are preserved in three-dimensions with carbonization of the exoskeleton, this is not actually the case. Although arthropods do not have the melanosomes of vertebrates, some do have convergently evolved spheroid eye cells that may be preserved similarly; however, these pigments (ommochromes and pterines) have unique chemical signatures which were not found in the eyes of Tullimonstrum. Sallen, et al. also suggested that molluscs convergently evolved complex camera-like eyes containing melanosomes, but failed to note that no known molluscs have dual melanosome morphologies.
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Since then most studies have removed Tritylodontidae from Gomphodontia and reclassified it within Probainognathia as a group more closely related to mammals than are the convergently similar gomphodonts. Tritylodontoidea has fallen into disuse while Gomphodontia continues to be used in many studies.
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Threonine proteases are a family of proteolytic enzymes harbouring a threonine (Thr) residue within the active site. The prototype members of this class of enzymes are the catalytic subunits of the proteasome, however the acyltransferases convergently evolved the same active site geometry and mechanism.
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This expansion occurred in both therocephalians and the related cynodonts, indicating that the two groups were convergently acquiring mammalian characteristics in the Permian and Triassic. Although therocephalians died out by the Middle Triassic, cynodonts continued to diversify, giving rise to fully endothermic mammals in the Late Triassic.
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Cruralispennia seemingly belongs to a previously undiscovered ancient lineage of enantiornitheans which had convergently evolved many ornithuromorph-like features. In addition, the presence of such a derived genus so early in the Cretaceous is evidence that the family tree of ornithothoraces is older than currently known fossils suggest.
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Luscinia is a genus of smallish passerine birds, containing the nightingales and relatives. Formerly classed as members of the thrush family Turdidae, they are now considered to be Old World flycatchers (Muscicapidae) of the chat subfamily (Saxicolinae). The chats are a lineage of Old World flycatchers that has evolved convergently to thrushes.
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This study also suggested that many individual genera are polyphyletic, with similar body shapes convergently evolving multiple times. Historically xenophyophores have been divided into the agglutinated psamminida and the flexible, proteinaceous stannomida. However, cladistic analyses based on molecular data have suggested a high amount of homoplasy, and that the division between psamminids and stannomids is not well supported.
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Menadon was unique among non-mammalian synapsids for the presence of hypsodont (high-crowned) postcanine teeth. Hypsodont teeth grow continuously to counteract high wear caused by a diet of abrasive plant material. Menadon's teeth convergently resemble those of hypsodont xenarthrans such as sloths and armadillos, due to their column-like form and dentine which grows from the crown towards the root.
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Galerix kostakii may be part of a lineage that led from the slightly more primitive G. symeonidisi through G. kostakii to Parasorex pristinus, the oldest species of its genus, and then to the other Parasorex species. This lineage may have evolved these traits, which may be adaptations to a herbivorous diet, convergently with Schizogalerix, which appears earlier in the fossil record.
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The pre-collected is concentrated around the enzyme RuBisCO, increasing photosynthetic efficiency. More is then harvested from the atmosphere when stomata open, during the cool, moist nights, reducing water loss. CAM has evolved convergently many times. It occurs in 16,000 species (about 7% of plants), belonging to over 300 genera and around 40 families, but this is thought to be a considerable underestimate.
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An example of a scaled mammal is the pangolin. Its scales are made of keratin and are used for protection, similar to an armadillo's armor. They have been convergently evolved, being unrelated to mammals' distant reptile-like ancestors, except that they use a similar gene. On the other hand, the musky rat-kangaroo has scales on its feet and tail.
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Some mysterious environmental pressures must have driven the bonnet macaque to form an unusually egalitarian social structure. Why this trend crops up convergently in separate macaque species rather than being an ancestral macaque trait is an enigma. A possible driving force may be these pacifist species inhabit more fertile habitats with more abundant food. Bonnet macaques are also fantastic swimmers and enjoy spending time in water.
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A geniculate habit, with reference to the red algae, is one in which the alga branches, tree-like, forming "fronds" that attach to the substrate with a holdfast. Non-calcified "genicula" serve as "knees" or hinges between the calcified intergenicula. The geniculate or non-geniculate form of algae was used to classify them; however either form has been convergently derived many times. The genuculae sometimes contain lignin.
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In other archosaurs, these surfaces are continuous, rather than separate. Moreover, the fibular condyle is hemicylindrical (half- cylinder shaped) in contrast to the more spherical structure of ornithosuchids, avemetatarsalians, and archosaur relatives such as Euparkeria and proterochampsians. A hemicylindrical fibular condyle is also present in phytosaurs, likely convergently. Lastly, the rear edge of the calcaneum has a backwards-extending tube of bone known as a calcaneal tuber.
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Müllerian mimicry is another form of defensive mimicry, except the system involves two or more species that are all toxic, noxious, or harmful. These species develop similar appearances to collectively protect against predators. This adaptation is said to have evolved due to the additive protection of many species that look the same and reliably have harmful defenses. That is to say, this mimicry system evolves convergently.
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Subtilases are a family of subtilisin-like serine proteases. They appear to have independently and convergently evolved an Asp/Ser/His catalytic triad, like in the trypsin serine proteases. The structure of proteins in this family shows that they have an alpha/beta fold containing a 7-stranded parallel beta sheet. The subtilisin family is the second largest serine protease family characterised to date.
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Basal (or "primitive") members had teeth, which disappeared in derived members of the group (those within the superfamily Caenagnathoidea, which includes Oviraptoridae). They were at least partially herbivorous, and brooded their nests in a bird-like posture. Though they are all thought to have to been feathered, they appear to have been flightless. Cranial crests appear to have evolved convergently in different lineages within the group.
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A zooid where the operculum is modified into a very long, hair- like structure is called a vibraculum. The cylcostome family Eleidae, which convergently evolved an opercular structure during the Early Cretaceous to Paleocene,Taylor, P.D. 1994. Systematics of the melicerititid cyclostome bryozoans; introduction and the genera Elea, Semielea and Repromultelea. Bulletin of the Natural history Museum, Geology Series 50:1-103 also possess avicularia-like zooids.
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Lizards have frequently evolved convergently, with multiple groups independently developing similar morphology and ecological niches. Anolis ecomorphs have become a model system in evolutionary biology for studying convergence. Limbs have been lost or reduced independently over two dozen times across lizard evolution, including in the Anniellidae, Anguidae, Cordylidae, Dibamidae, Gymnophthalmidae, Pygopodidae, and Scincidae; snakes are just the most famous and species-rich group of Squamata to have followed this path.
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This movement can be seen by gently poking the anthers of an open Opuntia flower. The same trait has evolved convergently in other species (e.g. Lophophora). The first introduction of prickly pears into Australia is ascribed to Governor Phillip and the earliest colonists in 1788. Brought from Brazil to Sydney, prickly pear grew in Sydney, New South Wales, where they were rediscovered in a farmer's garden in 1839.
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Notable genera in Apteronotoidea that perform JAR include Eigenmannia and Apteronotus. Though they evolved the JAR separately, the South American and African taxa have convergently evolved nearly identical neural computational mechanisms and behavioral responses to avoid jamming, with only minor differences.Kawasaki, M. (1975) Independently evolved jamming avoidance responses in Gymnotid and Gymnarchid electric fish: a case of convergent evolution of behavior and its sensory basis. J. Comp. Physiol. 103:97-121.
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Skull and neck of Daspletosaurus, from the Field Museum of Natural History in Chicago. Skulls of early tyrannosauroids were long, low and lightly constructed, similar to other coelurosaurs, while later forms had taller and more massive skulls. Despite the differences in form, certain skull features are found in all known tyrannosauroids. The premaxillary bone is very tall, blunting the front of the snout, a feature which evolved convergently in abelisaurids.
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They basally used gastroliths to aid in digestion of tough plant matter until they convergently evolved tooth batteries in Neoceratopsia (or "new Ceratopsia") and Pachycephalosauria. Marginocephalia first evolved in the Jurassic Period and became more common in the Cretaceous. They are basally small facultative quadrupeds while derived members of the group are large obligate quadrupeds. Primitive marginocephalians are found in Asia, but the group migrated upwards into North America.
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Nodosaurids did convergently develop a rounded skull. As the massive quadrates were lacking, the skull fragment gave a false impression of being lightly built. Ankylosaur material at the time was typically referred to the Scelidosauridae but because this was the first ankylosaur braincase to be described, the connection was not obvious. The first to understand it represented an armoured dinosaur was Nopcsa who in 1902 placed it in the Acanthopholididae.
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Many of the uses of acetylcholine rely on its action on ion channels via GPCRs like membrane proteins. The two major types of acetylcholine receptors, muscarinic and nicotinic receptors, have convergently evolved to be responsive to acetylcholine. This means that rather than having evolved from a common homolog, these receptors evolved from separate receptor families. It is estimated that the nicotinic receptor family dates back longer than 2.5 billion years.
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Given that small changes in toolbox genes can cause significant changes in body structures, they have often enabled the same function convergently or in parallel. distal-less generates wing patterns in the butterflies Heliconius erato and Heliconius melpomene, which are Müllerian mimics. In so-called facilitated variation, their wing patterns arose in different evolutionary events, but are controlled by the same genes. Developmental changes can contribute directly to speciation.
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APOC3 inhibits lipoprotein lipase and hepatic lipase; it is thought to inhibit hepatic uptake of triglyceride- rich particles. The APOA1, APOC3 and APOA4 genes are closely linked in both rat and human genomes. The A-I and A-IV genes are transcribed from the same strand, while the A-1 and C-III genes are convergently transcribed. An increase in apoC-III levels induces the development of hypertriglyceridemia.
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If early organisms had been driven by the same environmental conditions to evolve similar biochemistry convergently, they might independently have acquired similar genetic sequences. Theobald's "formal test" was accordingly criticised by Takahiro Yonezawa and colleagues for not including consideration of convergence. They argued that Theobald's test was insufficient to distinguish between the competing hypotheses. Theobald has defended his method against this claim, arguing that his tests distinguish between phylogenetic structure and mere sequence similarity.
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Numerous Nigersaurus specimens collected by French and American expeditions remain to be described. Teeth similar to those of Nigersaurus have been found on the Isle of Wight and in Brazil, but it is unknown whether they belonged to relatives of this taxon, or to titanosaurs, whose remains have been found in the vicinity. A lower jaw assigned to the titanosaur Antarctosaurus is likewise similar to that of Nigersaurus, but may have evolved convergently.
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Rugaspidiotina is an obsolete subtribe of armored scale insects. It was established by Balachowsky in 1949 to accept those Diaspidinae which had rugaspidiotine characteristics as exemplified by genus Rugaspidiotus MacGillivray, species Rugaspidiotus arizonicus (Cockerell, 1900), and was moved from the Odonaspidini to the Diaspidini by Borchsenius. It was raised to tribe status as Rugaspidiotini. However, close examination of species assigned to the Rugaspidiotini showed that the rugaspidiotine characteristics convergently evolved in different groups of diaspidids.
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Groups that include all the descendants of a common ancestor are said to be monophyletic. A paraphyletic group is a monophyletic group from which one or more subsidiary clades (monophyletic groups) are excluded to form a separate group. Ereshefsky has argued that paraphyletic taxa are the result of anagenesis in the excluded group or groups. A group whose identifying features evolved convergently in two or more lineages is polyphyletic (Greek πολύς [polys], "many").
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Donatia novae- zelandiae The cushion plant form is not endemic to any single area or plant family. About 338 species worldwide in 78 genera in areas ranging from Tasmania, New Zealand, and Tierra del Fuego to the arctic tundra of Svalbard have convergently evolved the same plant form in response to similar environmental conditions. Thirty-four diverse plant families, such as Apiaceae, Asteraceae, Caryophyllaceae, Donatiaceae, and the Stylidiaceae, include cushion plant species.Heusser, C. J. (1995).
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It underwent a drastic morphological transformation as it aged: while juveniles were toothed, these teeth were completely lost and replaced by a beak with age. Several of these features were convergently similar to the later ornithomimid theropods as well as the earlier non-dinosaurian shuvosaurids. Limusaurus was the first known member of the group Ceratosauria from Asia. It belonged to the Noasauridae, a family of small and lightly built ceratosaurs, along with its closest relative Elaphrosaurus.
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Simple genetic distance calculations will thus undercount the number of mutation events that have occurred in evolutionary history. The extent of this undercount increases with increasing time since divergence, which can lead to the phenomenon of long branch attraction, or the misassignment of two distantly related but convergently evolving sequences as closely related. The maximum parsimony method is particularly susceptible to this problem due to its explicit search for a tree representing a minimum number of distinct evolutionary events.
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The authors of these studies hypothesise that monothecate anthers have most likely evolved convergently in Durioneae and in the Malvatheca clade (comprising Malvaceae s.l. subfamilies Malvoideae and Bombacoideae). A draft genome analysis of durian indicates it has about 46,000 coding and non-coding genes, among which a class called methionine gamma lyases - which regulate the odour of organosulfur compounds - may be primarily responsible for the distinct durian odour. Genome analysis also indicated that the closest plant relative of durian is cotton.
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The methyl group of threonine greatly restricts the possible orientations of triad and substrate, as the methyl clashes with either the enzyme backbone or the histidine base. Consequently, most threonine proteases use an N-terminal threonine in order to avoid such steric clashes. Several evolutionarily independent enzyme superfamilies with different protein folds use the N-terminal residue as a nucleophile. This commonality of active site but difference of protein fold indicates that the active site evolved convergently in those families.
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The name Caenagnathus (and hence Caenagnathidae) means "recent jaws"—when first discovered, it was thought that caenagnathids were close relatives of paleognath birds (such as the ostrich) based on features of the lower jaw. Since it would be unusual to find a recent group of birds in the Cretaceous, the name "recent jaws" was applied. Most paleontologists, however, now think that the birdlike features of the jaw were acquired convergently with modern birds.Barsbold, R., Maryańska, T., and Osmólska, H. (1990).
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The root consists of deep root lobes and a strongly arched base. The A. palatasi dental structure is heterodontic, meaning that the shape of teeth differs between each tooth in a jaw. A. palatasi teeth are most similar in size and form to the teeth of its sister species A. grandis, the only main difference being the presence of serrations in the former. The size, broadness, and serrations of A. palatasi teeth are also convergently similar to the modern great white shark.
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Nearly all adult caddisflies are terrestrial, but their larvae and pupae are aquatic. They share this characteristic with several distantly-related groups, namely the dragonflies, mayflies, stoneflies, alderflies and lacewings. The ancestors of all these groups were terrestrial, with open tracheal systems, convergently evolving different types of gills for their aquatic larvae as they took to the water to avoid predation. About 14,500 species of caddisfly in 45 families have been recognised worldwide, but many more species remain to be described.
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The tibia and fibula of the lower leg were fused to the astragalus and calcaneum of the ankle, forming a 'tibiofibiotarsus' convergently with modern birds. Also similarly to birds, the lower tarsal (ankle) bones and metatarsals were fused to form a 'tarsometatarsus.' There are four digits in the pes (hindfoot), with only the second, third, and fourth contacting the ground. The tail, unlike many other ornithischians, did not have ossified tendons to maintain a rigid posture and was probably flexible.
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Eventually, it develops an aperture, or dries, becomes brittle, and splits, and the spores escape. The spores of puffballs are statismospores rather than ballistospores, meaning they are not forcibly extruded from the basidium. Puffballs and similar forms are thought to have evolved convergently (that is, in numerous independent events) from Hymenomycetes by gasteromycetation, through secotioid stages. Thus, 'Gasteromycetes' and 'Gasteromycetidae' are now considered to be descriptive, morphological terms (more properly gasteroid or gasteromycetes, to avoid taxonomic implications) but not valid cladistic terms.
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Telson of Pterygotus. The large and flattened pterygotid telson is a distinctive feature of the group that is only shared by the closely related Slimonia and by the derived hibbertopterid Hibbertopterus and mycteroptid Hastimima, where a flattened telson had convergently evolved. The telson is in general flat but with a raised thin median keel. The posterior margin (tip) of the telson form a short spine in some genera, such as Pterygotus and Acutiramus, and is indented (giving a bilobed appearance) in Erettopterus.
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It was then reinstated in its own genus and moved to the shelduck subfamily Tadorninae, which also contains the torrent duck and blue duck which convergently have evolved adaptations to mountain stream habitat. All or some of these species may actually be surviving lineages of an ancient Gondwanan radiation of waterfowl (Sraml et al. 1996). The duck's common and genus names both commemorate 18th-century Italian ornithologist Tommaso Salvadori. The species name waigiuensis refers to Waigeo (also known as Waigiu), an island near New Guinea.
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Land vertebrates evolved middle ears independently in each major lineage, and are thus the result of parallel evolution. The configurations of the middle ears of monotreme and therian mammals can thus be interpreted as convergent evolution or homoplasy. Thus evidence from fossils demonstrate homoplasies for the detachment of the ear from the jaw. Furthermore, it is apparent that the land- based eardrum, or tympanic membrane, and connecting structures such as the Eustachian tube evolved convergently in multiple different settings as opposed to being a defining morphology.
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Webbed foot of a 239x239px The webbed foot is a specialized limb present in a variety of vertebrates that aids in locomotion. This adaptation is primarily found in semiaquatic species, and has convergently evolved many times across vertebrate taxa. It likely arose from mutations in developmental genes that normally cause tissue between the digits to apoptose. These mutations were beneficial to many semiaquatic animals because the increased surface area from the webbing allowed for more swimming propulsion and swimming efficiency, especially in surface swimmers.
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Confuciusornis is a genus of primitive crow-sized avialan from the Early Cretaceous Period of the Yixian and Jiufotang Formations of China, dating from 125 to 120 million years ago. Like modern birds, Confuciusornis had a toothless beak, but close relatives of modern birds such as Hesperornis and Ichthyornis were toothed, indicating that the loss of teeth occurred convergently in Confuciusornis and living birds. It is the oldest known bird to have a beak.Ivanov, M., Hrdlickova, S. & Gregorova, R. (2001) The Complete Encyclopedia of Fossils.
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Electric organs have evolved at least six times in various teleost and elasmobranch fish. Notably, they have convergently evolved in the African Mormyridae and South American Gymnotidae groups of electric fish. The two groups are distantly related, as they shared a common ancestor before the supercontinent Gondwana split into the American and African continents, leading to the divergence of the two groups. A whole-genome duplication event in the teleost lineage allowed for the neofunctionalization of the voltage- gated sodium channel gene Scn4aa which produces electric discharges.
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The vascular bundles trifurcate at the nodes, with the central branch becoming the vein of a microphyll, and the other two moving left and right to merge with the new branches of their neighbours. The vascular system itself resembles that of the vascular plants' eustele, which evolved independently and convergently. Very rapid internode elongation results in the formation of a pith cavity and a ring of carinal canals formed by disruption of the primary xylem. Similar spaces, the vallecular canals are formed in the cortex.
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Fossil specimen of H. baitaigouensis Both Hyphalosaurus species were aquatic, a lifestyle reflected by their long necks and tails and relatively small limbs. Superficially, they resembled miniature plesiosaurs, though this resemblance arose convergently and does not reflect a close relationship. Hyphalosaurus was among the most aquatically adapted choristoderans, with smoother, flatter scales than its relatives, a tall and flattened tail for swimming, a long neck and webbed feet. Because the torso was fairly inflexible and the limbs were not particularly adapted for aquatic life, Hyphalosaurus probably swam using mainly its tall, flattened tail.
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Competition from ostriches has been suggested to have caused the extinction of the eogruids, though this has never been tested and both groups do co-exist in some sites. As with most other ratites, ostriches are believed to have developed flightlessness in the wake of the Cretaceous-Paleogene extinction event of about 66 Ma. The sudden absence of non-avian dinosaurs opened ecological niche space for large herbivorous animals and limited predatory threats, prompting volant ancestral paleognaths dispersed across the southern hemisphere to convergently lose the capability for flight.
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Tyrannosaurids are now universally considered to be large coelurosaurs. In 1994, Holtz grouped tyrannosauroids with elmisaurids, ornithomimosaurs and troodonts into a coelurosaurian clade called Arctometatarsalia based on a common ankle structure where the second and fourth metatarsals meet near the tarsal bones, covering the third metatarsal when viewed from the front. Basal tyrannosauroids like Dilong, however, were found with non-arctometatarsalian ankles, indicating that this feature evolved convergently. Arctometatarsalia has been dismantled and is no longer used by most paleontologists, with tyrannosauroids usually considered to be basal coelurosaurs outside Maniraptoriformes.
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Webbed feet take on a variety of different shapes; in birds, the webbing can even be discontinuous, as seen in lobate-footed birds like grebes. However, one of the most common is the delta (Δ) or triangular shape seen in most waterfowl and frogs. This delta wing shape is a solution that has convergently evolved in many taxa, and is also used in aircraft to allow for high lift forces at high attack angles. This shape allows for the production of large forces during swimming through both drag-based and lift-based propulsion.
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The centra (main body) of each caudal (tail) vertebra is flattened from the side in sapheosaurs. Sapheosaur vertebrae also had swollen neural arches (the area above the spinal cord) and zygapophyses (connecting joint plates), features also present in Ankylosphenodon. Some have proposed that sapheosaurs were at least partially aquatic due to some similarities and/or possible close relations to Ankylosphenodon (now believed to be convergently evolved) or Vadasaurus and pleurosaurs. However, they do not share many of the adaptations that these other taxa possess, and some researchers are not convinced by this hypothesis.
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A European mole Moles are small mammals adapted to a subterranean lifestyle (i.e., fossorial). They have cylindrical bodies, velvety fur, very small, inconspicuous ears and eyes, reduced hindlimbs, and short, powerful forelimbs with large paws adapted for digging. The term mole is especially and most properly used for "true moles" of the family Talpidae in the order Eulipotyphla, which are found in most parts of North America, Europe and Asia, although it may also refer to unrelated mammals of Australia and southern Africa that have convergently evolved the "mole" body plan.
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At around 400 million years old, the Rhynie chert contains an assemblage of fossil plants preserved in sufficient detail that mycorrhizas have been observed in the stems of Aglaophyton major. Mycorrhizas are present in 92% of plant families studied (80% of species), with arbuscular mycorrhizas being the ancestral and predominant form, and the most prevalent symbiotic association found in the plant kingdom. The structure of arbuscular mycorrhizas has been highly conserved since their first appearance in the fossil record, with both the development of ectomycorrhizas, and the loss of mycorrhizas, evolving convergently on multiple occasions.
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An entire clade of Hawaiian honeycreepers, the tribe Psittirostrini, is composed of thick-billed, mostly seed-eating birds, like the Laysan finch (Telespiza cantans). In at least some cases, similar morphologies and behaviors appear to have evolved convergently among the Hawaiian honeycreepers; for example, the short, pointed beaks of Loxops and Oreomystis evolved separately despite once forming the justification for lumping the two genera together. The Hawaiian honeycreepers are believed to have descended from a single common ancestor some 15 to 20 million years ago, though estimates range as low as 3.5 million years.
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Several other groups of archosauromorphs also adapted to herbivory in the Triassic, sometimes with dinosaur-like teeth that also caused confusion in their classification. Azendohsaurus is notable, however, for also convergently evolving a similar body shape to sauropodomorphs in addition to its jaws and teeth. Azendohsaurus and sauropodomorphs likely independently evolved to fill a similar ecological niche as long-necked, relatively high browsing herbivores in their environments. However, Azendohsaurus predates the large Late Triassic sauropodomorphs it resembles by several million years, and did not evolve similar body plans under the same environmental conditions.
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The key defining attribute of SLiMs, having a limited number of residues that directly contact the binding partner, has two major consequences. First, only few or even a single mutation can result in the generation of a functional motif, with further mutations of flanking residues allowing tuning affinity and specificity. This results in SLiMs having an increased propensity to evolve convergently, which facilitates their proliferation, as is evidenced by their conservation and increased incidence in higher Eukaryotes. It has been hypothesized that this might increase and restructure the connectivity of the interactome.
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Field research suggests that webs with more decorative bands captured more prey per hour. However, a laboratory study showed that spiders reduce the building of these decorations if they sense the presence of predators. There are several unusual variants of orb web, many of them convergently evolved, including: attachment of lines to the surface of water, possibly to trap insects in or on the surface; webs with twigs through their centers, possibly to hide the spiders from predators; "ladderlike" webs that appear most effective in catching moths. However, the significance of many variations is unclear.
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Docodontans are an early branch of the mammaliaform tree, but unlike other early mammals they developed a more complex tooth shape, allowing them to pierce and crush food. This tooth shape includes a series of tall cusps in two rows, and a basin between them called a pseudotalonid.Luo Z-X, and Martin T. 2007 Analysis of molar structure and phylogeny of docodont genera. Bulletin of the Carnegie Museum of Natural History 39: 27-47 The 'pseudo-' refers to this structure's resemblance to the later true talonid basins on the tribosphenic teeth of crown Mammalia, which evolved convergently with those of the early docodontans.
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In some cases, it is difficult to tell whether a trait has been lost and then re-evolved convergently, or whether a gene has simply been switched off and then re-enabled later. Such a re-emerged trait is called an atavism. From a mathematical standpoint, an unused gene (selectively neutral) has a steadily decreasing probability of retaining potential functionality over time. The time scale of this process varies greatly in different phylogenies; in mammals and birds, there is a reasonable probability of remaining in the genome in a potentially functional state for around 6 million years.
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It also has an oxyanion hole consisting of several backbone amides which stabilises charge build-up on intermediates. The histidine base aids the first leaving group by donating a proton, and also activates the hydrolytic water substrate by abstracting a proton as the remaining OH− attacks the acyl-enzyme intermediate. The same triad has also convergently evolved in α/β hydrolases such as some lipases and esterases, however orientation of the triad members is reversed. Additionally, brain acetyl hydrolase (which has the same fold as a small G-protein) has also been found to have this triad.
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The maxillae are also protected by the large prefrontals (bones in front of the eyes), similar to the condition in turtles. The prefrontals are also contacted by the wide palatine bones of the roof of the mouth, similar to lepidosaurs (squamates and rhynchocephalians), as well as turtles. All of these features exist to strengthen the front part of the skull, which explains how they convergently evolved in multiple different types of reptiles. The original fossil prior to further preparation and 3D rendering Colobops also possesses large orbits (eye holes), although this may be a juvenile feature.
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They have an acute sense of smell, which has developed convergently with that of insects, and which they use to find potential food sources. Adult coconut crabs feed primarily on fruits, nuts, seeds, and the pith of fallen trees, but they will eat carrion and other organic matter opportunistically. Anything left unattended on the ground is a potential source of food, which they will investigate and may carry away--thereby getting the alternative name of "robber crab." The species is popularly associated with the coconut palm, yet coconuts are not a significant part of its diet.
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Modifications to signals in these tissues likely contributed to the origin of an early form of hyperphalangy in fully aquatic cetaceans about 35 million years ago. The process continued over time, and a very derived form of hyperphalangy, with six or more phalanges per digit, evolved convergently in rorqual whales and oceanic dolphins, and was likely associated with another wave of signaling within the interdigital tissues. Although toothed cetaceans have five digits, most baleen whales have four digits and even lack a metacarpal. In the latter (mysticetes), the first digit ray may have been lost as late as 14 million years ago.
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Certain characters are more likely to evolve convergently than others; logically, such characters should be given less weight in the reconstruction of a tree. Weights in the form of a model of evolution can be inferred from sets of molecular data, so that maximum likelihood or Bayesian methods can be used to analyze them. For molecular sequences, this problem is exacerbated when the taxa under study have diverged substantially. As time since the divergence of two taxa increase, so does the probability of multiple substitutions on the same site, or back mutations, all of which result in homoplasies.
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Not only have the three species convergently evolved their lighter variants due to the selection pressures from the environment, they've also evolved ecomorphological differences: morphology, behavior (in is case, escape behavior), and performance (in this case, sprint speed) collectively. Roches' work found surprising results in the escape behavior of H. maculata and S. undulatus. When dark morphs were placed on white sands, their startle response was significantly diminished. This result could be due to varying factors relating to sand temperature or visual acuity; however, regardless of the cause, "…failure of mismatched lizards to sprint could be maladaptive when faced with a predator".
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A similar scheme may have been in use by P. boisei. Such a strategy is similar to that used by modern gorillas, which can sustain themselves entirely on lower quality fallback foods year-round, as opposed to lighter built chimps (and presumably gracile australopithecines) which require steady access to high quality foods. Reconstruction of MGL 95211 skull and jaw In 1980, anthropologists Tom Hatley and John Kappelman suggested that early hominins (convergently with bears and pigs) adapted to eating abrasive and calorie-rich underground storage organs (USOs), such as roots and tubers. Since then, hominin exploitation of USOs has gained more support.
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Eusuchia was originally defined by Thomas Henry Huxley in 1875 as an apomorphy-based group, meaning that it was defined by shared characteristics rather than relations. These characteristics include pterygoid-bounded choanae and vertebrae which are procoelous (concave from the front and convex from the back). The possibility that these traits may have been convergently evolved in different groups of neosuchians rather than one lineage spurred some modern paleontologists to revise the group's definition to make it defined solely by relations. In 1999, Christopher Brochu redefined Eusuchia as "the last common ancestor of Hylaeochampsa and Crocodylia and all of its descendants".
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They also had a downward-projecting flange on the front of the mandible as long as the canine teeth, a feature which also convergently evolved in the sabre-toothed sparassodont Thylacosmilus. The ancestors of nimravids and cats diverged from a common ancestor soon after the Caniformia–Feliformia split, in the middle Eocene about 50 million years ago (Mya), with a minimum constraint of 43 Mya. Recognizable nimravid fossils date from the late Eocene (37 Mya), from the Chadronian White River Formation at Flagstaff Rim, Wyoming, to the late Miocene (5 Mya). Nimravid diversity appears to have peaked about 28 Mya.
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The regions where the coracoids contact is vaulted and thickened to form a weak, ridge-like projection, comparable to but probably convergently acquired from elasmosaurids. The pubes form a somewhat rectangular dish, with a convex front edge and concave outer edge, while the ischia are flat, triangular, and plate-like. The edges of the pubes where they meet the ischia curve inwards from the midline to each side. The corresponding edges of the ischia are similarly-shaped, with the curved edges of the bones collectively forming two rounded fenestrae that are connected in the center by a small rhombus-shaped opening, as also seen in Futabasaurus.
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The second hypothesis suggests that black-and-white plumage evolved convergently on the two separate islands. The third suggests that black-and-white plumage evolved once from the blue-and- white ancestral condition, and later the mainland species re-evolved blue plumage. The distribution of the three bi-coloured fairywren species indicates their ancestors lived across New Guinea and northern Australia in a period when sea levels were lower and the two regions were joined by a land bridge. Populations became separated as sea levels rose, and New Guinea birds evolved into the white-shouldered fairywren, and Australian forms into the red-backed fairywren and the arid-adapted white-winged fairywren.
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In spite of this at least the sternum seems to have developed convergently rather than being a true homology. The earliest known members of the group are the enantiornitheans Protopteryx fengningensis, Eopengornis martini, and Cruralispennia multidonta, as well as the euornithine Archaeornithura meemannae, all from the Sichakou Member of the Huajiying Formation in China, which has been dated to 130.7 million years old. At least one other enantiornithean, Noguerornis gonzalezi, may be even older, at up to 145.5 million years ago, though its exact age is uncertain.Holtz, Thomas R. Jr. (2012) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, Winter 2011 Appendix.
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This change was supported by similarities between Dracovenator, Dilophosaurus wetherilli and Zupaysaurus rougieri, suggesting these taxa might form their own clade sister to Dilophosauridae, although there is no definitive evidence.Yates, A. M. (2005) A new theropod dinosaur from the Early Jurassic of South Africa and its implications for the early evolution of theropods. Sinosaurus and Crylophosaurus are also now classified as basal tetanurans. While all of the dinosaur genera once within Dilophosauridae are characterized by a distinctive cranial crest, it is thought that this distinctive trait was convergently evolved in dilophosaurids and basal tetanurans, and thus not all are necessarily derived from the same common ancestor.
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Maganuco and colleagues suggested that unfused interdental plates are either a synapomorphy of Archosauriformes, or a plesiomorphic (ancestrally present) characteristic of crocodyliforms, theropods, and poposaurids. Considering these characteristics, Maganuco and colleagues placed Razanandrongobe in the Archosauria, but not as part of any basal (early- diverging) lineages due to its heterodont teeth and tall maxilla. While it resembles the Prestosuchidae in the depth and shape of its maxilla, heterodont teeth, paradental shelves, and large size, Maganuco and colleagues considered these traits to have been convergently acquired. Within the Archosauria, they identified two possible positions for Razanandrongobe: Crocodylomorpha and Theropoda, the only lineages of large predatory archosaurs to have survived past the Triassic.
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Moreover, the cheetah is slightly taller than the leopard. The serval resembles the cheetah in physical build, but is significantly smaller, has a shorter tail and its spots fuse to form stripes on the back. The cheetah appears to have evolved convergently with canids in morphology as well as behaviour; it has canine-like features such as a relatively long snout, long legs, a deep chest, tough paw pads and blunt, semi-retractable claws. The cheetah has often been likened to the greyhound, as both have similar morphology and the ability to reach tremendous speeds in a shorter time than other mammals, but the cheetah can attain higher maximum speeds.
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The structure of the foot, particularly the bones of the ankle (such as the calcaneus), demonstrate that avemetatarsalians evolved from ancestors with 'crocodile-normal' ankles, unlike the simple hinge-like ankles characteristic of derived ornithodirans. The 'crocodile-normal' ankle was once thought to be unique to pseudosuchians, but its presence in aphanosaurs like Yarasuchus imply that the evolution of the avemetatarsalian ankle was a more complicated process than initially believed. The anatomy of Yarasuchus also demonstrates that other typical avemetatarsalian features, such as slender limb girdles, had evolved prior to the eponymous 'advanced mesotarsal' ankles. Unusually, Yarasuchus and other aphanosaurs share a number of features convergently evolved with poposauroids.
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Ootheke is Greek for ovary. Oothecae are made up of structural proteins and tanning agents that cause the protein to harden around the eggs, providing protection and stability. The production of ootheca convergently evolved across numerous insect species due to a selection for protection from parasites and other forms of predation, as the complex structure of the shell casing provides an evolutionary reproductive advantage (although the fitness and lifespan also depend on other factors such as the temperature of the incubating ootheca). Oothecae are most notably found in the orders Blattodea (Cockroaches) and Mantodea (Praying mantids), as well as in the subfamilies Cassidinae (Coleoptera) and Korinninae (Phasmatodea).
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Babakotia radofilai skull Weighing between , Babakotia radofilai was a medium-sized lemur and noticeably smaller than the large sloth lemurs (Archaeoindris and Palaeopropithecus), but larger than the small sloth lemurs (Mesopropithecus). In many ways, it had an intermediate level of adaptations for suspensory behavior between the large sloth lemurs and the small sloth lemurs. This includes its highly mobile hip and ankle joints, as well as other specializations in the vertebral column, pelvis, and limbs. Its forelimbs were 20% longer than its hind limbs, giving it a higher intermembral index (~119) than Mesopropithecus (~97 to 113), suggesting that it was convergently similar to arboreal sloths.
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The gait of the epaulette shark is convergently similar to those of tetrapods such as salamanders, suggesting that the movements needed for walking on land may predate, and facilitated the evolution of, the first terrestrial vertebrates. Epaulette sharks are largely nocturnal and are most active in low water. They often hide inside or below coral heads, though it is enough for the head to be covered even if the rest of the body is exposed. Sometimes they perch in the open on sandy flats or atop reefs facing into the current, a form of orientation known as rheotaxis that may improve respiration or predator awareness.
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Tooth paratype of Cadurcotherium nouleti – MHNT Zaisanamynodon protheroi Amynodontidae ("threatening tooth")American Museum of Natural History, "Perissodactyls Glossary" is a family of extinct perissodactyls related to true rhinoceroses. They are commonly portrayed as semiaquatic hippo-like rhinos but this description only fits members of the Metamynodontini; other groups of amynodonts like the cadurcodontines had more typical ungulate proportions and convergently evolved a tapir-like proboscis. Their fossils have been found in North America, and Eurasia ranging in age from the Middle Eocene to the Early Oligocene, with a single genus (Cadurcotherium) surviving into the Late Oligocene in South Asia (Pakistan). The genus Metamynodon may have survived into the early Miocene.
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The other explanation is that Metaspriggina was the ancestor of all gnathostomatans, again closely related to the Agnatha to form the Chordata. However, instead of being a very primitive relative, Pikaia was the ancestor of all cephalochordates, and the gill bars evolved convergently in them somewhere between Pikaia and Branchiostoma. This might explain why Branchiostoma has such a different number of gill bars to chordates (or at least their embryos). Considering that conodonts, the teeth elements of a type of extinct fish belonging to the Agnatha, are already found in Cambrian stage 2 (521-529 MA BP), some 20 million years before the Burgess shale, this latter explanation does not stand.
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Presented above are the most well-documented examples of modern adaptive radiation, but other examples are known. On Madagascar, birds of the family Vangidae are marked by very distinct beak shapes to suit their ecological roles. Madagascan mantellid frogs have radiated into forms that mirror other tropical frog faunas, with the brightly colored mantellas (Mantella) having evolved convergently with the Neotropical poison dart frogs of Dendrobatidae, while the arboreal Boophis species are the Madagascan equivalent of tree frogs and glass frogs. The pseudoxyrhophiine snakes of Madagascar have evolved into fossorial, arboreal, terrestrial, and semi-aquatic forms that converge with the colubroid faunas in the rest of the world.
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The complete skeletal material from Madagascar, however, revealed more basal characteristics ancestral to Archosauromorpha and that Azendohsaurus was not a dinosaur at all. Instead, Azendohsaurus was actually a more primitive archosauromorph that had convergently evolved many features of the jaws and skeleton shared with the later giant sauropod dinosaurs. It was found to be a member of a newly recognised group of specialised, mostly herbivorous archosauromorphs that was named the Allokotosauria. It is also the namesake and typifier of its own family of allokotosaurs, the Azendohsauridae; initially the only member, the family now includes other similar allokotosaurs, such as the larger, horned azendohsaurid Shringasaurus from India.
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In this case the gene Distal-less is very under-expressed, or not expressed at all, in the regions where limbs would form in other tetrapods. In 1994, Sean B. Carroll's team made the "groundbreaking" discovery that this same gene determines the eyespot pattern in butterfly wings, showing that toolbox genes can change their function. Toolkit genes, as well as being highly conserved, also tend to evolve the same function convergently or in parallel. Classic examples of this are the already mentioned Distal-less gene, which is responsible for appendage formation in both tetrapods and insects, or, at a finer scale, the generation of wing patterns in the butterflies Heliconius erato and Heliconius melpomene.
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Placements that required three additional evolutionary steps placed Xingxiulong between Jingshanosaurus and Anchisaurus, or between Yunnanosaurus and Jingshanosaurus. Curiously, Xingxiulong has many characteristics that are normally otherwise seen among the Sauropoda. These include the four-vertebra sacrum (which Mussaurus also convergently acquired); the long pubic plate, or top portion of the pubis, which occupies 40% of the length of the bone (this figure is 25% in most other basal sauropodomorphs, 33% in most sauropods, and 45-50% in the Camarasauromorpha); and the relative robustness of the femoral shaft, first metatarsal, top end of the fifth metatarsal, and scapula. These unique characteristics are probably the product of convergent evolution rather than common ancestry.
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Some plant and animal species use cardenolides as defense mechanisms, notably the milkweed butterflies. Species such as the monarch, queen, and plain tiger ingest the cardenolides contained in the milkweeds (Asclepias) that they mostly feed on and sequester as larvae for defense as adults. The cardenolide content in butterflies deters most vertebrate predators, except a few which have evolved to become cardenolide-tolerant, such as the black-backed orioles (Icterus abeillei Lesson) and black-headed grosbeaks (Pheucticus melanocephalus Swainson) that account for 60% of monarch butterfly mortalities in the overwintering sites in central Mexico. In addition to milkweeds and other members of the Apocynaceae, plants in at least 12 botanical families have convergently evolved cardenolides.
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Soon after the publication of the article, a number of paleontologists have voiced skepticism on whether Oculudentavis is even a dinosaur, due to a much higher number of similarities with squamates than with theropods. The general skull shape is considered the largest argument in favor of bird affinities, but some living lizards (Meroles, Anolis) and extinct reptiles (Avicranium, Teraterpeton) are known to have convergently evolved a bird-like skull shape. The usage of a bird-focused phylogenetic analysis (without considering lizards) also has been criticized. The editors of the Institute of Vertebrate Paleontology and Paleoanthropology's Fanpu publication have published an editorial arguing for an interpretation of Oculudentavis as a lizard rather than an avialan.
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They found that the microwear patterns in P. robustus suggest hard food was infrequently consumed, and therefore the heavy build of the skull was only relevant when eating less desirable fallback foods. Such a strategy is similar to that used by modern gorillas, which can sustain themselves entirely on lower quality fallback foods year-round, as opposed to lighter built chimps (and presumably gracile australopithecines) which require steady access to high quality foods. In 1980, anthropologists Tom Hatley and John Kappelman suggested that early hominins (convergently with bears and pigs) adapted to eating abrasive and calorie-rich underground storage organs (USOs), such as roots and tubers. Since then, hominin exploitation of USOs has gained more support.
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The hadrosaurs and ceratopsians of the Cretaceous Period, as well as many herbivorous mammals, would convergently evolve somewhat analogous dental batteries. As opposed to hadrosaurs, which had hundreds of teeth constantly being replaced, tooth replacement in heterodontosaurids occurred far more slowly and several specimens have been found without a single replacement tooth in waiting. Characteristically, heterodontosaurids lacked the small openings (foramina) on the inside of the jaw bones which are thought to have aided in tooth development in most other ornithischians. Heterodontosaurids also boasted a unique spheroidal joint between the dentaries and the predentary, allowing the lower jaws to rotate outwards as the mouth was closed, grinding the cheek teeth against each other.
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If Eolambia were to be recognized as a lambeosaurine, then the Lambeosaurinae would have to be redefined to exclude those two traits. Alternatively, if Eolambia was instead the sister group of the Lambeosaurinae, then it would represent a morphology in hadrosaurids that is close to the divergence between hadrosaurines and lambeosaurines. This possibility is supported by the presence of a groove on the bottom of the sacrum of Eolambia, which was recognized by Kirkland as a defining trait of hadrosaurines – albeit one convergently present in the Ankylosauria and Ceratopsia. To support the lambeosaurine affinities of Eolambia, Kirkland conducted a phylogenetic analysis; the tree recovered by his analysis, which accordingly places Eolambia as the most basal lambeosaurine, is reproduced below.
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Dinocephalosaurus (meaning "terrible-headed reptile") is a genus of long necked, aquatic protorosaur that inhabited the Triassic seas of China. The genus contains the type and only known species, D. orientalis, which was named by Li in 2003. Unlike other long-necked protorosaurs (which form a group known as the tanystropheids), Dinocephalosaurus convergently evolved a long neck not through elongation of individual cervical vertebrae, but through the addition of cervical vertebrae that each have a moderate length. Like other tanystropheids, however, Dinocephalosaurus probably used its long neck to hunt for prey, utilizing a combination of suction, created by the expansion of the throat, and the fang-like teeth of the jaws to ensnare prey.
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Traits which are prone to being convergently evolved are emphasized less during "steps" in the family trees, while traits that are unique to only a few groups are emphasized more: One particular study which heavily discussed the relations of Acherontiscus and other adelospondyls was a 2016 study on how time sampling can alter phylogenetic trees. This study, Bernardi et al. (2016), noted that specializations in advanced amphibians may pollute the relations of more basal taxa when all of them are placed in a single phylogenetic analysis. In order to test this possibility, the study separated prehistoric stegocephalians into five groups depending on their age: Devonian (D), Mississippian (M), Pennsylvanian (P), Permian (R), and Mesozoic (Z).
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The hedgehog (Erinaceidae), the mongoose (Herpestidae), the honey badger (Mellivora capensis), the opossum, and a few other birds that feed on snakes, are known to be immune to a dose of snake venom. Recently, the honey badger and domestic pig were found to have convergently evolved amino-acid replacements in their nicotinic acetylcholine receptor, which are known to confer resistance to alpha-neurotoxins in hedgehogs. Whether the pig may be considered immune is still uncertain, though early studies show endogenous resistance in pigs tested against neurotoxins. Though the pig's subcutaneous layer of fat may protect it against snake venom, most venoms pass easily through vascular fat layers, making this unlikely to contribute to its ability to resist venoms.
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A pair of Drosophila endobranchiae on the carapace of Gecarcinus ruricola G. ruricola is the host organism for two species of commensal flies in the genus Drosophila. They were first observed on Montserrat by Henry Guernsey Hubbard in 1894, and presented at a scientific meeting later that year (where the crab was misidentified as Cardisoma guanhumi), but no further research was conducted until 1955, when specimens were again collected, this time from Mona Island, and named as Drosophila carcinophila by M. R. Wheeler. In 1967, a second species of fly, Drosophila endobranchia was discovered on Gecarcinus ruricola, although it also inhabits the closely related species Gecarcinus lateralis. Drosohila endrobranchia is not closely related to D. carcinophila, and this trait appears therefore to have evolved convergently.
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In life, species of Kolponomos had downturned snouts and broad, heavy molars that would have been suited to a diet of hard-shelled marine invertebrates, and their narrow snouts and anteriorly directed eyes indicate that they would have had stereoscopic vision. Large neck muscle attachments and robust foot bones combine with these features to suggest that Kolponomos filled a unique niche among marine carnivores, approached today only by the very distantly related sea otter. Due to the lack of a complete skeleton, however, it is difficult to make inferences about this genus' other adaptations. Based on the skull and jaws known, Kolponomos convergently evolved mandibular and bite features that had similarities to extant bears, sea otters, and even the sabretooth Smilodon.
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Cladistics is a technique for working out the "family tree" of a set of organisms. It works by the logic that, if groups B and C have more similarities to each other than either has to group A, then B and C are more closely related to each other than either is to A. Characteristics that are compared may be anatomical, such as the presence of a notochord, or molecular, by comparing sequences of DNA or protein. The result of a successful analysis is a hierarchy of clades – groups whose members are believed to share a common ancestor. The cladistic technique is sometimes problematic, as some features, such as wings or camera eyes, evolved more than once, convergently – this must be taken into account in analyses.
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Superficially, Kraterokheirodon most closely resembles the lower postcanine teeth of traversodont cynodonts, including a ridge with vertical cusps and a posterior shelf at their base. However, in addition to being much larger than any known traversodont cynodont, Kraterokheirodon also possesses more cusps than any traversodont tooth (6 compared to 2 or 3), and they are arranged parallel to each other in traversodonts unlike the curving row of cusps in Kraterokheirodon. Furthermore, traversodonts possess enamel on the posterior shelf, which Kraterokheirodon lacks. Due to these differences, as well as the possibility that the features similar to traversodonts could be convergently evolved, rather than shared homologous structures, Irmis and Parker referred Kraterokheirodon to Amniota incertae sedis and suggested it belonged to an as yet unrecognised clade of tetrapods.
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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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In the 1990s, molecular phylogenetic analyses of DNA sequences produced a coherent scheme showing arthropods as members of a superphylum labelled Ecdysozoa ("animals that moult"), which contained nematodes, priapulids and tardigrades but excluded annelids. This was backed up by studies of the anatomy and development of these animals, which showed that many of the features that supported the Articulata hypothesis showed significant differences between annelids and the earliest Panarthropods in their details, and some were hardly present at all in arthropods. This hypothesis groups annelids with molluscs and brachiopods in another superphylum, Lophotrochozoa. If the Ecdysozoa hypothesis is correct, then segmentation of arthropods and annelids either has evolved convergently or has been inherited from a much older ancestor and subsequently lost in several other lineages, such as the non-arthropod members of the Ecdysozoa.
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They instead found that Dilophosaurus was a coelophysoid, with Cryolophosaurus and Sinosaurus being more derived, as basal members of the group Tetanurae. Belgian paleontologist Christophe Hendrickx and colleagues defined the Dilophosauridae to include Dilophosaurus and Dracovenator in 2015, and noted that while general uncertainty exists about the placement of this group, it appears to be slightly more derived than the Coelophysoidea, and the sister group to the Averostra. The Dilophosauridae share features with the Coelophysoidea such as the subnarial gap and the front teeth of the maxilla pointing forwards, while features shared with Averostra include a fenestra at the front of the maxilla and a reduced number of teeth in the maxilla. They suggested that the cranial crests of Cryolophosaurus and Sinosaurus had either evolved convergently, or were a feature inherited from a common ancestor.
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S. populator skeleton, Museo de La Plata, Buenos Aires Long the most completely known saber-toothed cat, Smilodon is still one of the best-known members of the group, to the point where the two concepts have been confused. The term "saber-tooth" refers to an ecomorph consisting of various groups of extinct predatory synapsids (mammals and close relatives), which convergently evolved extremely long maxillary canines, as well as adaptations to the skull and skeleton related to their use. This includes members of Gorgonopsia, Thylacosmilidae, Machaeroidinae, Nimravidae, Barbourofelidae, and Machairodontinae. Within the family Felidae (true cats), members of the subfamily Machairodontinae are referred to as saber-toothed cats, and this group is itself divided into three tribes: Metailurini (false saber-tooths); Homotherini (scimitar-toothed cats); and Smilodontini (dirk-toothed cats), to which Smilodon belongs.
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Head of adult female rice moth (Corcyra cephalonica) showing its "snout" scale bar: 0.5 mm The caterpillar larvae of Galleriinae usually have a sclerotised (hardened) ring around the base of seta SD1 on the first abdominal segment. Their pupae are comparatively easy to distinguish from other snout moths' by a readily apparent midline ridge running along the thorax and abdomen. In the imagines, the gnathos of the male genitalia is reduced to the point of disappearing altogether or (more rarely) with only the barest vestige remaining; this is quite characteristic except for a few Chrysauginae which have convergently lost the gnathos. Males produce very high chirping sounds with their tegulae, in some cases even regular "mating songs", though without specialized bioacoustics equipment this cannot be used for identification.
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But their relationships are not yet robustly enough determined: The Agoriini (genera Agorius, Synagelides and maybe Pseudosynagelides) are most unusual ant mimics whose relationships are entirely obscure; they are so highly autapomorphic it is hard to tell if they are truly ancient among the salticoids, or are a very strongly divergent offshoot of one of the more conventional tribes - ant mimicry has evolved convergently 5 to 10 times in the salticoids. The Baviini (Bavia, Stagetillus and possibly Piranthus) have a far less unusual appearance and at a casual glance resemble Marpissoida, which are mostly found in and around North America; the yellow-green Itata from South America are singular marpissoids of tribe Dendryphantini which except in the tell-tale synapomorphic details look almost like baviines. Whether this is similarity is superficial, atavistic or genuinely plesiomorphic is also still unresolved.
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Aphanosaurs and poposauroids share only one unique trait (the presence of an accessory articulation facet just above the parapophysis of the cervicals for the three- headed cervical rib), however they have also convergently acquired a similar set of traits that are found throughout archosaurs. The previous phylogenetic position of Yarasuchus as a poposauroid by Brusatte and colleagues was likely due to this convergence. The convergence between Yarasuchus and poposauroids could be attributed to the broader trend of poposauroids converging on coelurosaurian theropods, a derived clade of avemetatarsalians. The similarity between poposauroids and aphanosaurs like Yarasuchus means it is difficult to determine the identity of isolated archosaur material that has features present in both groups, particularly as aphanosaurs are the earliest diverging avemetatarsalians while poposauroids are the oldest known pseudosuchians and so their stratigraphic ranges broadly overlap with each other.
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It works by the logic that, if groups B and C have more similarities to each other than either has to group A, then B and C are more closely related to each other than either is to A. Characters that are compared may be anatomical, such as the presence of a notochord, or molecular, by comparing sequences of DNA or proteins. The result of a successful analysis is a hierarchy of clades – groups that share a common ancestor. Ideally the "family tree" has only two branches leading from each node ("junction"), but sometimes there is too little information to achieve this and paleontologists have to make do with junctions that have several branches. The cladistic technique is sometimes fallible, as some features, such as wings or camera eyes, evolved more than once, convergently – this must be taken into account in analyses.
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For a number of reasons, two organisms can possess a trait not present in their last common ancestor: If we naively took the presence of this trait as evidence of a relationship, we would reconstruct an incorrect tree. Real phylogenetic data include substantial homoplasy, with different parts of the data suggesting sometimes very different relationships. Methods used to estimate phylogenetic trees are explicitly intended to resolve the conflict within the data by picking the phylogenetic tree that is the best fit to all the data overall, accepting that some data simply will not fit. It is often mistakenly believed that parsimony assumes that convergence is rare; in fact, even convergently derived characters have some value in maximum- parsimony-based phylogenetic analyses, and the prevalence of convergence does not systematically affect the outcome of parsimony-based methods.
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The large Neanderthal nose and paranasal sinuses have generally been explained as having warmed air as it entered the lungs and retained moisture ("nasal radiator" hypothesis); but sinuses are generally reduced in cold-adapted creatures, and it may have been that the large nose was caused instead by genetic drift. Also, the sinuses are not grossly large, and are comparable in size to those of modern humans. However, sinus size is not an important factor for breathing cold air, and their actual function is unclear, so they may not be a good indicator of evolutionary pressures to evolve such a nose. Further, a computer reconstruction of the Neanderthal nose and predicted soft tissue patterns shows some similarities to those of modern Arctic peoples, potentially meaning the noses of both populations convergently evolved for breathing cold, dry air.
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The holotype specimen, CHO-BT 4, is a right upper second molar, and the paratypes are a left lower canine, 3 right upper third molars, a left lower third molar, a left lower first molar, and a left and a right lower molar fragment, making for a total of 9 isolated teeth. The discoverers noted the teeth have some of the same adaptations for shearing food as those of gorillas, and classified it as the first fossil member and the only other genus of the tribe Gorillini. Because the Chororapithecus teeth have several specializations not shared with those of gorillas (they exhibit a derived condition compared to the presumed last common ancestor, LCA), they did not consider it as ancestral to the gorilla. However, the discovers also conceded it is possible that Chororapithecus and gorillas instead convergently evolved the same teeth due to a similar diet.
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Dinocephalosaurus is considered to be a member of the Protorosauria, a group of ubiquitous and diverse Permo-Triassic reptiles. This assignment is based upon characteristics including the low and narrow skull with a short and narrow postorbital region; the long nasal relative to the frontal; the reduced backward projection of the jugal; the presence of more than seven cervical vertebrae, with centra longer than those of the dorsal vertebrae; the low neural spines of the cervical vertebrae; the long cervical ribs; the lack of intercentra articulating with the dorsal centra; and the absence of an entepicondylar foramen on the humerus. These characteristics are shared with Tanystropheus, Macrocnemus, and other protorosaurs. Dinocephalosaurus and its close relative Tanystropheus, shown here, evolved their long necks convergently Protorosaurs were formerly considered to be the ancestors of lizards, but phylogenetic analysis has subsequently verified that they are in fact non-archosaur archosauromorphs.
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The fossil record shows that all molluscan classes evolved some 500 million years ago Hugh and Marguerite Stix, Robert Tucker Abbott (1991), The Shell: Five Hundred Million Years of Inspired Design; Bdd Promotional Book CoISBN 978-0792447160 from a shelled ancestor looking something like a modern monoplacophoran, and that modifications of the shell form ultimately led to the formation of new classes and lifestyles.e.g. However, a growing body of molecular and biological data indicate that at least certain shell features have evolved many times, independently. The nacreous layer of shells is a complex structure, but rather than being difficult to evolve, it has in fact arisen many times convergently. The genes used to control its formation vary greatly between taxa: under 10% of the (non-housekeeping) genes expressed in the shells that produce gastropod nacre are also found in the equivalent shells of bivalves: and most of these shared genes are also found in mineralizing organs in the deuterostome lineage.
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The convergently evolved scapulocoracoid in jinguornithids and confuciusornithiforms suggests these basal clades likely reacquired a similar level of osteogenesis present in their non-avian theropod ancestors that is responsible for the co-ossification of the pectoral girdle. Then separation of the coracoid and scapula becomes evolutionarily “fixed” (with a few exceptions in the crown groups) across Ornithothoraces, and underwent further modifications including an ossified sternal keel and formation of the triosseal canal. These developmental changes to the skeleton likely correspond to intense selective pressure to improve flight capability that eventually lead to the musculoskeletal system present among volant crown birds, suggesting developmental plasticity Jinguofortis is morphologically similar to the another stemward avialan Chongmingia (also preserved a fused scapulocoracoid). Differences from Chongmingia include: furcula less robust with a smaller interclavicular angle of 70°; pedal digit I approximately 70% of the length of digit II; and pedal digit II shorter than IV; and these two taxa are separated by approximately seven million years.
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Dorsal vertebra According to D'Emic et al. (2013) Huabeisaurus can be distinguished based on this set of autapomorphies: the division of some presacral vertebral laminae; posterior cervical vertebrae with a divided prezygodiapophyseal lamina; anterior dorsal vertebrae with a divided anterior spinodiapophyseal lamina; the presence of postzygapophyseal spinodiapophyseal fossa that are larger than postzygapophyseal centrodiapophyseal fossa on anterior-middle caudal vertebrae; caudal vertebrae with small caudal ribs that disappear around caudal vertebra eight; ventrally one-third of anterior-middle caudal vertebral centra expanded posteriorly; two longitudinal ridges on the lateral faces of mid-caudal vertebral centra; a coracoid with tubercle near anterodorsal edge of lateral face; the distal end of radius about twice as broad transversely as midshaft (convergently acquired in derived titanosaurs); a tubercle on ischial plate that projects from posterior margin; the development of fossae relative to one another in caudal vertebral neural arches; and a high tibia-to-femur ratio.
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Limusaurus was classified as a basal member of Ceratosauria by Xu and colleagues in 2009 (who also considered the closely related Elaphrosaurus as such). It had several skull features in common with basal theropods such as other ceratosaurs and coelophysoids, but it also shared a number of traits, including the beak and the fused sternum, convergently with the later coelurosaurs. A 2012 study by paleontologists Diego Pol and Oliver Rauhut also found Limusaurus and Elaphrosaurus to be basal ceratosaurians in their phylogenetic analysis, while a 2010 study by paleontologist Martin Ezcurra and colleagues placed them in the more derived group Abelisauroidea within Ceratosauria. A 2016 study by paleontologists Oliver Rauhut and Matthew Carrano found Limusaurus to be more derived, grouping together with Elaphrosaurus within the abelisauroid family Noasauridae. Together with an as-of-yet unnamed taxon represented by specimen CCG 20011, and not included in other analyses), the two taxa formed the clade Elaphrosaurinae; Elaphrosaurus and CCG 20011 were closer to each other than to Limusaurus within this group.
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The large and flattened telson of Slimonia (it is also flattened in Salteropterus, but not to the full extent of that of Slimonia) is distinctive and shared only with the pterygotid eurypterids and with the derived hibbertopterid Hibbertopterus and mycteroptid Hastimima, where a flattened telson had convergently evolved. The function of these specialized telsons has historically been controversial and disputed, and whilst study has mainly been focused on telsons within the Pterygotidae, the similarity between the telson of Slimonia and its close relatives should mean that the function would likely have been similar. The pterygotids were hypothesized to have moved by undulating the entire opisthosoma (the large posterior section of the body) by moving the abdominal plates, as such undulations of the opisthosoma and telson would have acted as the propulsive method of the animal, rendering the swimming legs used by other eurypterid groups useless. Fossil evidence contradicts such an hypothesis however, as eurypterid bodies were stiff dorsally (up and down) and preserve no evidence for any sort of tapering or other mechanism that would have increased flexibility.
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