84-530: Agkistrodon contortrix (the copperhead, a snake ), Dinemellia dinemelli (the white-faced buffalo-weaver, a bird ), various extinct ornithischian dinosaurs , Chelonia mydas (the green sea turtle ), Anurognathus (an extinct pterosaur ), and Alligator mississippiensis (the american alligator, a crocodilian ) Sauria is the clade of diapsids containing the most recent common ancestor of Archosauria (which includes crocodilians and birds ) and Lepidosauria (which includes squamates and
168-463: A camouflage pile. Eastern copperheads breed in late summer, but not every year; sometimes, females produce young for several years running, then do not breed at all for a time. Mating is sometimes preceded by male combat. Females give birth to live young, each of which is about 20 cm (8 in) in total length. The typical litter size is four to seven, but as few as one, or as many as 20 may be seen. Females are capable of storing sperm for up to
252-635: A brightly colored tail to attract frogs and perhaps lizards, a behavior termed caudal luring (see video: [1] ). Sight, odor, and heat detection are used in locating prey, although after the prey has been envenomated, odor and taste become the primary means of tracking. Smaller prey items and birds are often seized and held in the mouth until dead, while larger prey items are typically bitten, released, and then tracked until dead. Copperheads occasionally feed on carrion. Gravid females typically fast, although some individuals occasionally take small volumes of food. An individual may eat up to twice its body mass in
336-400: A close relationship with Pareiasaurus . Alfred Romer in publications in 1956 and 1968 placed Choristodera within the paraphyletic or polyphyletic grouping of " Eosuchia ", describing them, as “an offshoot of the basic eosuchian stock”, a classification which was widely accepted. However, the use of computer based cladistics in the 1980s demonstrated the non-monophyly of "Eosuchia", making
420-467: A darker brown or black within one year. Adults grow to a typical length (including tail) of 50–95 cm (20–37 in). In most of North America, the eastern copperhead favors deciduous forest and mixed woodlands. It may occupy rock outcroppings and ledges, but is also found in low-lying, swampy regions. During the winter, it hibernates in dens or limestone crevices, often together with timber rattlesnakes and black rat snakes . The eastern copperhead
504-428: A fin to propel Hyphalosaurus through the water. Skin impressions of Champsosaurus have also been reported, they consist of small (0.6-0.1 mm) pustulate and rhomboid scales, with the largest scales being located on the lateral sides of the body, decreasing in size dorsally, no osteoderms were present. The Menat specimen of Lazarussuchus preserves some remnants of soft tissue, but no scales, which shows that
588-741: A length of only around 30 cm (12 in), and the largest known choristoderan, Kosmodraco dakotensis is estimated to have had a total length of around 5 m (16 ft). Neochoristoderes such as Champsosaurus are the best-known group of the Choristodera. They resembled modern crocodilians , especially gharials . The skull of these animals have a long, thin snout filled with small, sharp conical teeth. Other choristoderes are referred to collectively as "non-neochoristoderes", which are mostly small lizard-like forms, though Shokawa , Khurendukhosaurus and Hyphalosaurus possess long plesiosaur like necks. The grouping of "non-neochoristoderes"
672-747: A major evolutionary radiation in Asia during the Early Cretaceous , which represents the high point of choristoderan diversity, including the first records of the gharial-like Neochoristodera, which appear to have evolved in the regional absence of aquatic neosuchian crocodyliformes. A partial femur of an indeterminate choristodere is known from the Yellow Cat Member of the Cedar Mountain Formation in North America. They appear to be absent from
756-446: A mean of roughly 197.4 g ( 6 + 15 ⁄ 16 oz). Females do not typically exceed 60 to 66 cm ( 23 + 1 ⁄ 2 to 26 in), and have a mean body mass of 119.8 g ( 4 + 7 ⁄ 32 oz). The maximum length reported for this species is 134.6 cm (53 in) for A. c. mokasen (Ditmars, 1931). Brimley (1944) mentions a specimen of A. c. mokasen from Chapel Hill, North Carolina , that
840-698: A sexual mode of reproduction to an asexual mode. The type of parthenogenesis that likely occurs is automixis with terminal fusion , a process in which two terminal products from the same meiosis fuse to form a diploid zygote. This process leads to genome-wide homozygosity , expression of deleterious recessive alleles, and often to developmental failure ( inbreeding depression ). Both captive-born and wild-born A. contortrix snakes appear to be capable of this form of parthenogenesis. Although venomous, eastern copperheads are generally not aggressive and bites are rarely fatal. Copperhead venom has an estimated lethal dose around 100 mg, and tests on mice show its potency
924-571: A year. Their size apart, the young are similar to the adults, but lighter in color, and with a yellowish-green-marked tip to the tail, which is used to lure lizards and frogs. A. contortrix males have longer tongue tie lengths than females during the breeding season, which may aid in chemoreception of males searching for females. Parthenogenesis is a natural form of reproduction in which growth and development of embryos occur without fertilization. A. contortrix can reproduce by facultative parthenogenesis, that is, they are capable of switching from
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#17328549944251008-410: A year. One study found an individual that ate eight times during an annual activity period, totaling 1.25 times its body mass. Predators of the eastern copperhead are not well known, but may include owls, hawks, opossums, bullfrogs, and other snakes. They will use anti-predatory behaviors to discourage predators. These include: move away or flee, musking, tail vibrating, mouth gaping, or curling up into
1092-420: Is paraphyletic (not containing all descendants of a common ancestor), as the lizard-like bodyform represents the ancestral morphology of the group. According to Matsumoto and colleagues (2019), choristoderes are united by the presence of nine synapomorphies (shared traits characteristic of the group), including a median contact of the elongated prefrontal bones of the skull separating the nasal bones from
1176-496: Is "Carolina". Schmidt (1953) proposed the type locality be restricted to "Charleston, South Carolina". Unlike some other species of North American pit vipers, such as the timber rattlesnake and massasauga , the copperhead has mostly not re-established itself north of the terminal moraine after the last glacial period (the Wisconsin glaciation ), though it is found in southeastern New York and southern New England , north of
1260-893: Is a regional variant of A. c. laticinctus . Five subspecies have been recognized in the past, but recent genetic analysis shows that A c. contorix and two of the subspecies are monotypic, while Agkistrodon laticinctus (formerly Agkistrodon contortrix laticinctus ) and the fifth subspecies are a single distinct species. Agkistrodon contortrix contortrix ( Linnaeus , 1766) Agkistrodon contortrix ( Linnaeus , 1766) Agkistrodon contortrix laticinctus Gloyd & Conant , 1934 Agkistrodon laticinctus Gloyd & Conant , 1934 Agkistrodon contortrix mokasen Palisot de Beauvois , 1799 Agkistrodon contortrix Agkistrodon contortrix phaeogaster Gloyd, 1969 Agkistrodon contortrix Agkistrodon contortrix pictigaster Gloyd & Conant, 1943 Agkistrodon laticinctus Choristodera Choristodera (from
1344-412: Is also present on the flanks, next to the belly, and are largest and darkest in the spaces between the crossbands. The belly is the same color as the ground color, but may be a little whitish in part. At the base of the tail are one to three (usually two) brown crossbands followed by a gray area. In juveniles, the pattern on the tail is more distinct: 7–9 crossbands are visible, while the tip is yellow. On
1428-458: Is among the lowest of all pit vipers, and slightly weaker than that of its close relative, the cottonmouth . Copperheads often employ a "warning bite" when stepped on or agitated and inject a relatively small amount of venom, if any at all. "Dry bites" involving no venom are particularly common with the copperhead, though all pit vipers are capable of a dry bite. The fangs of dead pit vipers are capable of delivering venom in amounts that necessitate
1512-537: Is classified as least concern on the IUCN Red List of Threatened Species (v3.1, 2001). This means that relative to many other species, it is not at risk of extinction in the near future. The population trend was stable when assessed in 2007. Their venom has potential medicinal value to humans. In the Southern United States , copperheads are nocturnal during the hot summer, but are commonly active during
1596-574: Is known to feed on a wide variety of prey, including invertebrates (primarily arthropods ) and vertebrates . Like most pit vipers, the eastern copperhead is generally an ambush predator; it takes up a promising position and waits for suitable prey to arrive. As a common species within its range, it may be encountered by humans. Unlike other viperids, it often "freezes" instead of slithering away and fleeing, due to its habit of relying on excellent camouflage. Bites occur due to people unknowingly stepping on or near them. Copperhead bites account for half of
1680-464: Is made. Like most other New World vipers, copperheads exhibit defensive tail vibration behavior when closely approached. This species is capable of vibrating its tail in excess of 40 times per second— faster than almost any other nonrattlesnake snake species. The eastern copperhead is a diet generalist and is known to feed on a wide variety of prey, including invertebrates (primarily arthropods ) and vertebrates . A generalized ontogenetic shift in
1764-588: Is supported by the ossification sequence of their embryos. Choristoderes must have diverged from all other known reptile groups prior to the end of the Permian period, over 250 million years ago, based on their primitive phylogenetic position. In 2015, Rainer R. Schoch reported a new small (~ 20 cm long) diapsid from the Middle Triassic ( Ladinian ) Lower Keuper of Southern Germany , known from both cranial and postcranial material, which he claimed represented
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#17328549944251848-562: Is usually interpreted to reference the distorted pattern of darker bands across the snake's back, which are broad at the lateral base, but "pinched" into narrow hourglass shapes in the middle at the vertebral area. Adults grow to a typical length (including tail) of 50–95 cm (20–37 in). Some may exceed 1 m (3 ft 3 in), although that is exceptional for this species. Males do not typically exceed 74 to 76 cm (29 to 30 in) and weigh from 101.5 to 343 g ( 3 + 9 ⁄ 16 to 12 + 1 ⁄ 8 oz), with
1932-669: The Greek χωριστός chōristos + δέρη dérē , 'separated neck' ) is an extinct order of semiaquatic diapsid reptiles that ranged from the Middle Jurassic , or possibly Triassic , to the Miocene (168 to 20 or possibly 11.6 million years ago). Choristoderes are morphologically diverse, with the best known members being the crocodile-like neochoristoderes such as Champsosaurus . Other choristoderans had lizard-like or long necked morphologies. Choristoderes appear to have been confined to
2016-537: The Middle Jurassic of Britain. The genus had first been described by Charles W. Gilmore in 1928 from the Late Jurassic of the western United States, and had previously been enigmatic. The studies revealed it to be a small, lizard-like choristodere, different from the crocodile-like forms previously known. Choristoderes vary substantially in size, the smallest genera like Cteniogenys and Lazarussuchus had
2100-434: The copperhead , is a species of venomous snake , a pit viper , endemic to eastern North America; it is a member of the subfamily Crotalinae in the family Viperidae . The eastern copperhead has distinctive, dark brown, hourglass-shaped markings, overlaid on a light reddish brown or brown/gray background. The body type is heavy, rather than slender. Neonates are born with green or yellow tail tips, which progress to
2184-410: The frontal bones , the dorsal flange of the maxilla is inflected medially (toward the midline of the body), the parietal foramen are absent, the squamosal bones are expanded behind ( posterior to) the occipital condyle , the teeth are conical and sub- thecodont (located in shallow sockets), the dentaries are slender with elongated grooves running along the labial (outward facing) surface of
2268-436: The tuatara ), and all its descendants. Since most molecular phylogenies recover turtles as more closely related to archosaurs than to lepidosaurs as part of Archelosauria , Sauria can be considered the crown group of diapsids, or reptiles in general. Depending on the systematics, Sauria includes all modern reptiles or most of them (including birds , a type of archosaur) as well as various extinct groups. Sauria lies within
2352-541: The 2010s, the "non-neochoristoderes" from the Early Cretaceous of Asia (with the exception of Heishanosaurus ) alongside Lazarussuchus from the Cenozoic of Europe were recovered (with weak support) as belonging to a monophyletic clade, which were informally named the "Allochoristoderes" by Dong and colleagues in 2020, characterised by the shared trait of completely closed lower temporal fenestrae, with Cteniogenys from
2436-708: The Campanian aged Grünbach Formation of Austria indicate the presence of choristoderes in Europe during this time period. The only record of choristoderes from Asia in the Late Cretaceous is a single vertebra from the Turonian of Japan. Fragmentary remains found in the Campanian aged Oldman and Dinosaur Park formations in Alberta , Canada, also possibly suggest the presence of small bodied "non-neochoristoderes" in North America during
2520-547: The Late Cretaceous Laramie Formation of the United States, though only two prints are present and it is not possible to distinguish between a manus (forefoot) or pes (hindfoot). Historically, the internal phylogenetics of Choristodera were unclear, with the neochoristoderes being recovered as a well-supported clade, but the relationships of the "non-neochoristoderes" being poorly resolved. However, during
2604-523: The Late Cretaceous. Champsosaurus survived the K-Pg extinction , and together with fellow neochoristoderes Kosmodraco and Simoedosaurus are present in Europe, Asia and North America during the Paleocene, however they became extinct during the early Eocene . Their extinction coincides with major faunal turnover associated with elevated temperatures . Small bodied "non-neochoristoderes", which are absent from
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2688-561: The Middle-Late Jurassic of Europe and North America being consistently recovered as the basalmost choristodere. The long necked "non-neochoristoderes" Shokawa and Hyphalosaurus have often been recovered as a clade, dubbed the Hyphalosauridae by Gao and Fox in 2005. The finding of more complete material of the previously fragmentary Khurendukhosaurus shows that it also has a long neck, and it has also been recovered as part of
2772-617: The Northern Hemisphere, having been found in North America , Asia , and Europe , and possibly also North Africa . Choristoderes are generally thought to be derived neodiapsids that are close relatives or members of Sauria . Choristodera was erected in 1876, originally as a suborder of Rhynchocephalia by Edward Drinker Cope to contain Champsosaurus , which was described from Late Cretaceous strata of Montana by Cope in
2856-766: The Upper Jurassic Alcobaça Formation of Portugal and the Morrison Formation of the United States, with broadly similar remains also known from the late Middle Jurassic ( Callovian ) Balabansai Formation of Kyrgyzstan in Central Asia , the Bathonian Itat Formation of western Siberia, as well as possibly the Bathonian aged Anoual Formation in Morocco, North Africa. Choristoderes underwent
2940-497: The Wisconsin glaciation terminal moraine on Long Island . Eastern copperheads are habitat generalists which are species able to survive in different habitats (fragmented and unfragmented). Within its range, it occupies a variety of different habitats. In most of North America, it favors deciduous forest and mixed woodlands. It is often associated with rock outcroppings and ledges, but is also found in low-lying, swampy regions. During
3024-613: The abdomen) like tuatara and crocodilians . The internal skull anatomy of choristoderes is only known for Champsosaurus. The braincase of Champsosaurus is poorly ossified at the front of the skull (anterior), but is well ossified in the rear (posterior) similar to other diapsids. The cranial endocast (space occupied by the brain in the cranial vault ) is proportionally narrow in both lateral and dorsoventral axes, with an enlarged pineal body and olfactory bulbs . The optic lobes and flocculi are small in size, indicating only average vision ability at best. The olfactory chambers of
3108-474: The abdominal cavity. This has been proposed to represent evidence of cannibalism . However, this proposal has been criticised by other authors, who suggest it is more likely that they represent late-stage embryos. A specimen of Hyphalosaurus has been found with small rib bones in its abdominal cavity, suggesting that it took vertebrate prey at least on occasion. A specimen of Hyphalosaurus baitaigouensis has been found with 18 fully developed embryos within
3192-762: The analysis of Li et al . (2018). It places turtles within Diapsida but outside of Sauria (the Lepidosauromorpha + Archosauromorpha clade). † Parareptilia [REDACTED] † Captorhinidae [REDACTED] † Paleothyris [REDACTED] † Araeoscelidia [REDACTED] † Hovasaurus [REDACTED] † Youngina † Acerosodontosaurus † Claudiosaurus † Eunotosaurus † Pappochelys [REDACTED] † Eorhynchochelys [REDACTED] † Odontochelys Agkistrodon contortrix The eastern copperhead ( Agkistrodon contortrix ), also known simply as
3276-570: The availability of antivenom stated it used 1 Acp to 5 Acp depending on the symptoms and circumstances. Antivenom use however may not be necessary in the majority of cases, A study that analyzed 88 copperhead bite victims reported that all the victims survived and none required antivenom. This species was long considered to contain five subspecies listed below, but gene analysis suggests that A. c. laticinctus represents its own distinct species, while A. c. mokasen and A. c. phaeogaster are regional variants of A. c. contortrix , and A. c. pictigaster
3360-403: The bone, additional sacral vertebrae are present, expanded "spine tables" are present on the vertebrae, and the surfaces of both ends of vertebral centra are flat (amphiplatyan). All known choristoderans possess or are inferred to possess a novel skull bone not found in other reptiles, referred to as the "neomorphic bone" or neomorph, which is a component of the dermatocranium . Ancestrally,
3444-408: The center, but darker towards the edges. They are about two scales wide or less at the midline of the back, but expand to a width of 6–10 scales on the sides of the body. They do not extend down to the ventral scales. Often, the crossbands are divided at the midline and alternate on either side of the body, with some individuals even having more half bands than complete ones. A series of dark brown spots
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3528-504: The clade Sauria also help them be distinguished from stem-saurians in Diapsida or stem-reptiles in clade Sauropsida in the following categories based on the following regions of the body. However, some of these characters might be lost or modified in several lineages, particularly among birds and turtles; it is best to see these characters as the ancestral features that were present in the ancestral saurian. The cladogram shown below follows
3612-511: The clade is uncertain, due to their mix of primitive and derived features, and a long ghost lineage (absence of a fossil record) after their split from other reptiles. After initially being placed in Rhynchocephalia, Cope later suggested a placement in Lacertilla due to the shape of the cervical vertebrae. Louis Dollo in 1891 returned Choristodera to Rhynchocephalia, but in 1893 suggested
3696-654: The clade. Phylogeny from the analysis of Dong and colleagues (2020): Cteniogenys sp. Heishanosaurus pygmaeus Coeruleodraco jurassicus Ikechosaurus pijiagouensis Ikechosaurus sunailinae Tchoiria namsari Tchoiria klauseni C. gigas C. albertensis S. lemoinei S. dakotensis Monjurosuchus splendens Philydrosaurus proseilus L. inexpectatus Lazarussuchus sp. L. dvoraki Khurendukhosaurus orlovi Hyphalosaurus sp. Hyphalosaurus lingyuanensis Shokawa ikoi Choristoderes are universally agreed to be members of Neodiapsida , but their exact placement in
3780-505: The classification of choristoderes again uncertain. Subsequent studies either suggested placement as archosauromorphs , lepidosauromorphs or members of Diapsida incertae sedis . In a 2016 analysis of neodiapsid relationships by Martín Ezcurra they were recovered as members of the advanced neodiapsid group Sauria , in a polytomy with Lepidosauromorpha and Archosauromorpha, with being the earliest diverging members of either group also being plausible. A position as basal archosauromorphs
3864-416: The crossbands were fused together longitudinally to form a continuous, undulating band, surmounted above by a dark stripe that was 2.0–2.5 scales wide. In another specimen, from Lowndes County, Alabama , the first three crossbands were complete, followed by a dark stripe that ran down either side of the body, with points of pigment reaching up to the midline in six places, but never getting there, after which
3948-478: The day during the spring and fall. Unlike other viperids, they often "freeze" instead of slithering away, and as a result, many bites occur due to people unknowingly stepping on or near them. This tendency to freeze most likely evolved because of the extreme effectiveness of their camouflage. When lying on dead leaves or red clay, they can be almost impossible to notice. They frequently stay still even when approached closely, and generally strike only if physical contact
4032-428: The diet include various invertebrates, e.g. millipedes ( Diplopoda ), spiders ( Arachnida ), beetles ( Coleoptera ), dragonflies ( Odonata ), grasshoppers ( Orthoptera ), and mantids ( Mantidae ), as well as numerous species of vertebrates, including salamanders, frogs, lizards, snakes, small turtles, small birds, young opossums, squirrels, chipmunks, rabbits, bats, shrews, moles, rats, and mice. Like most pit vipers,
4116-928: The diet occurs, with juveniles feeding on higher percentages of invertebrates and ectotherms , and adults feeding on a higher percentage vertebrate endotherms . Both juveniles and adults, though, feed on invertebrates and vertebrates opportunistically. The diet is also known to vary among geographic populations. Studies conducted at various locations within the range of the eastern copperhead ( A. contortrix ), including Tennessee, Kentucky , Kansas , and Texas , identified some consistently significant prey items included cicadas ( Tibicen ), caterpillars ( Lepidoptera ), lizards ( Sceloporus and Scincella ), voles ( Microtus ), and mice ( Peromyscus ). Accounts of finding large numbers of copperheads in bushes, vines, and trees seeking newly emerged cicadas, some as high as 40 feet above ground, have been reported from Texas by various herpetologists. Other items documented in
4200-418: The dorsum (upper midline) of the body. The fossil also preserves webbed feet . Hyphalosaurus was covered in scales of varying shape, depending on their position on the body, with at least one and possibly multiple rows of large ovoid scales running down sides of the trunk and tail. The feet display evidence of webbing, and the tail probably had additional tissue at the top and bottom, allowing it to be used as
4284-462: The eastern copperhead is generally an ambush predator; it takes up a promising position and waits for suitable prey to arrive. One exception to ambush foraging occurs when copperheads feed on insects such as caterpillars and freshly molted cicadas. When hunting insects, copperheads actively pursue their prey. They possess facial pit organs which is a complex infrared-imaging system that allows accurate and precise strikes on potential prey. Juveniles use
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#17328549944254368-521: The fossil record after the Early Cretaceous (except for possible North American remains), reappear in the form of the lizard-like Lazarussuchus from the late Paleocene of France. The European endemic Lazarussuchus is the last known choristodere, surviving the extinction of neochoristoderes at the beginning of the Eocene, with the youngest known remains being those of L. dvoraki from the Early Miocene of
4452-453: The head are usually 9 large symmetrical plates, 6–10 (usually 8) supralabial scales , and 8–13 (usually 10) sublabial scales . The color pattern consists of a pale tan to pinkish-tan ground color that becomes darker towards the foreline, overlaid with a series of 10–18 (13.4) crossbands. Characteristically, both the ground color and crossband pattern are pale in A. c. contortrix . These crossbands are light tan to pinkish-tan to pale brown in
4536-500: The head, the crown is usually unmarked, except for a pair of small dark spots, one near the midline of each parietal scale . A faint postocular stripe is also present; diffuse above and bordered below by a narrow brown edge. Several aberrant color patterns for A. c. contortrix , or populations that intergrade with it, have also been reported. In a specimen described by Livezey (1949) from Walker County, Texas , 11 of 17 crossbands were not joined middorsally, while on one side, three of
4620-480: The hindfoot (pes) was not webbed, and a dark stained region with a crenellated edge is present above the caudal vertebrae of the tail, suggestive of a crest similar to those found in some living reptiles, like the tuatara, lizards and crocodiles. Choristoderes are exclusively found in freshwater deposits, often associated with turtles , fish, frogs , salamanders and crocodyliformes . They appear to have been almost exclusively found in warm temperate climates , with
4704-416: The larger total group Sauropsida , which also contains various stem -reptiles which are more closely related to reptiles than to mammals. Prior to its modern usage, "Sauria" was used as a name for the suborder occupied by lizards , which before 1800 were considered crocodilians. Sauria was historically used as a partial equivalent for Squamata (which contains lizards and snakes). The redefinition to cover
4788-510: The last common ancestor of archosaurs and lepidosaurs was the result of papers by Jacques A. Gauthier and colleagues in the 1980s. Genomic studies and comprehensive studies in the fossil record suggest that turtles are closely related to archosaurs as part of Sauria, and not to the non-saurian parareptiles as previously thought. In a 2018 cladistic analysis, Pantestudines (turtles and close relatives) were placed within Diapsida but outside of Sauria. The synapomorphies or characters that unite
4872-881: The last four crossbands on the tail were also complete. A specimen found in Terrebonne Parish, Louisiana had a similar striped pattern, with only the first and last two crossbands being normal. The eastern copperhead is found in North America; its range within the United States is in Alabama , Arkansas , Connecticut , Delaware , Florida , Georgia , Illinois , Indiana , Iowa , Kansas , Kentucky , Louisiana , Maryland , Massachusetts , Mississippi , Missouri , Nebraska , New Jersey , New York , North Carolina , Ohio , Oklahoma , Pennsylvania , South Carolina , Tennessee , Texas , Virginia , and West Virginia . In Mexico , it occurs in Chihuahua and Coahuila . The type locality
4956-399: The more crocodile-like neochoristoderes, there appears to have been niche differentiation , with gharial-like neochoristoderans occurring in association with blunt snouted crocodyliformes, but not in association with narrow snouted forms. Neochoristoderans are presumed to have been piscivorous . Champsosaurus in particular is thought to have fed like modern gharials, sweeping its head to
5040-854: The most likely result found by an analysis of turtle relationships using both fossil and genetic evidence by M.S. Lee, in 2013. This study found Eunotosaurus , usually regarded as a turtle relative, to be only very distantly related to turtles in the clade Parareptilia . † Araeoscelidia [REDACTED] † Claudiosaurus [REDACTED] † Younginiformes [REDACTED] Lepidosauromorpha [REDACTED] † Eosauropterygia [REDACTED] † Placodontia [REDACTED] † Sinosaurosphargis † Odontochelys † Proganochelys Testudines [REDACTED] † Choristodera [REDACTED] † Prolacertiformes [REDACTED] † Rhynchosauria [REDACTED] † Trilophosaurus [REDACTED] Archosauriformes [REDACTED] The cladogram below follows
5124-756: The most likely result found by another analysis of turtle relationships, this one using only fossil evidence, published by Rainer Schoch and Hans-Dieter Sues in 2015. This study found Eunotosaurus to be an actual early stem-turtle, though other versions of the analysis found weak support for it as a parareptile. † Kuehneosauridae [REDACTED] Rhynchocephalia [REDACTED] Squamata [REDACTED] † Eosauropterygia [REDACTED] † Placodontia [REDACTED] † Sinosaurosphargis † Eunotosaurus † Pappochelys [REDACTED] † Odontochelys † Proganochelys Testudines [REDACTED] Archosauromorpha [REDACTED] [REDACTED] The cladogram below follows
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#17328549944255208-399: The mother's body, suggesting that they were viviparous , but another specimen shows that Hyphalosaurus baitaigouensis also possessed soft-shelled eggs, similar to those of lepidosaurs . A possible explanation for this is that Hyphalosaurus was ovoviviparous , with the thin-shelled eggs hatching immediately after they were laid, presumably on land, though it has also been suggested that
5292-418: The mouth, probably in combination with the tongue. In most choristoderes, longitudinal rows of palatal teeth are present on the pterygoid , palatine and vomer , as well as a row on the pterygoid flange. In some neochoristoderes the palatal tooth rows are modified into tooth batteries on raised platforms. The morphology of the palatal teeth is identical to that of the marginal teeth of non-neochoristoderes, and
5376-424: The mouth. The escalation includes 21–25 (usually 23) rows of dorsal scales at midbody, 138–157 ventral scales in both sexes, and 38–62 and 37–57 subcaudal scales in males and females, respectively. The subcaudals are usually single, but the percentage thereof decreases clinally from the northeast, where about 80% are undivided, to the southwest of the geographic range where as little as 50% may be undivided. On
5460-561: The nasal passages and olfactory stalks of the braincase are reasonably large, indicating that Champsosaurus probably had good olfactory capabilities (sense of smell). The nasal passages lack bony turbinates . The semicircular canals of the inner ear are most similar to those of other aquatic reptiles. The expansion of the sacculus indicates that Champsosaurus likely had an increased sensitivity to low frequency sounds and vibrations. Most choristoderes have rather simple undifferentiated ( homodont ) teeth, with striated enamel covering
5544-569: The oldest known choristodere. Pachystropheus from the Late Triassic ( Rhaetian ) of Britain was historically suggested to be a choristodere, but was later demonstrated to be a member of the marine reptile group Thalattosauria . The oldest unequivocal choristoderan is the small lizard-like Cteniogenys, the oldest known remains of which are known from the late Middle Jurassic ( Bathonian ~168-166 million years ago) Forest Marble and Kilmaluag formations of Britain, with remains also known from
5628-453: The presumably sexually dimorphic fusion of the sacral vertebrae and possession of more robust limb bones in presumed females. A skeleton of Philydrosaurus has been found with associated post-hatchling stage juveniles, suggesting that they engaged in post-hatching parental care . Tracks from the Early Cretaceous ( Albian ) of South Korea, given the ichnotaxon name Novapes ulsanensis have been attributed to choristoderans, based on
5712-516: The range of neochoristoderes extending to the high Canadian Arctic during the Coniacian - Santonian stages of the Late Cretaceous (~89-83 Million years ago), a time of extreme warmth. Due to the morphological similarities between choristoderes and crocodyliformes, it has often been assumed that they existed in competition. However "non-neochoristoderes" were smaller than adult aquatic crocodyliformes and were more likely in competition with other taxa. For
5796-409: The replacement of palatal teeth is nearly identical to the replacement of marginal teeth. An exceptionally preserved specimen of Monjurosuchus preserves pleated skin, which indicates that in life it was probably thin and soft. The preserved scales are small and overlapping, and are smaller on the ventral underside of the body than the dorsal surface. A double row of larger ovoid scales runs along
5880-560: The same paper. A year later, in 1877, Simoedosaurus was described by Paul Gervais from Upper Paleocene deposits at Cernay , near Rheims , France. These remained the only recognised choristoderes for over a century, until new taxa were described in the late 20th century. Beginning in the late 1970s, additional taxa were described by Soviet-Mongolian teams from Lower Cretaceous sediments in Mongolia. In studies from 1989 to 1991, Susan E. Evans described new material of Cteniogenys from
5964-459: The side to catch individual fish from shoals, while Simoedosaurus is thought to have been more generalist, being able to take both aquatic and terrestrial prey. Cteniogenys and Lazarussuchus have been suggested to have fed on invertebrates. Preserved gut contents of a Monjurosuchus specimen appear to show arthropod cuticle fragments. Another specimen of Monjurosuchus has been found with preserved skulls of seven juvenile individuals within
6048-409: The similarity of the pentadactyl (five fingered) preserved tracks to the foot morphology of Monjurosuchus . The tracks preserve traces of webbing between the digits. The authors of the study proposed based on the spacing of the prints, that choristoderans could " high walk " like modern crocodilians. Tracks attributed to neochoristoderans dubbed Champsosaurichnus parfeti have also been reported from
6132-495: The skull of choristoderes possess elongated upper and lower temporal fenestrae (openings of the skull behind the eye socket), these are greatly expanded in neochoristoderes, most extremely in Champsosaurus , giving the skull a cordiform (heart shaped) appearance when viewed from above. In many "non-neochoristoderes" the lower temporal fenestrae are secondarily closed. Choristoderes possessed gastralia (rib-like bones situated in
6216-414: The southern copperhead has been found to hold the protein contortrostatin that halts the growth of cancer cells in mice and also stops the migration of the tumors to other sites. However, this is an animal model , and further testing is required to verify safety and efficacy in humans. The antivenom CroFab is used to treat copperhead envenomations that demonstrate localized or systemic reactions to
6300-489: The species employed both viviparous and oviparous reproductive modes. An embryo of Ikechosaurus has been found preserved within a weakly mineralised parchment-shelled egg, suggesting that Ikechosaurus was oviparous, and laid their eggs on land. Monjuruosuchus has been suggested to have been viviparous. In Champsosaurus , it has been suggested that adult females could crawl ashore to lay eggs on land, with males and juveniles appearing to be incapable of doing so, based on
6384-403: The tooth crown but not the base. Neochoristoderes have teeth completely enveloped in striated enamel with an enamel infolding at the base, labiolingually compressed and hooked, the exception being Ikechosaurus which has still rather simple teeth aside from the start of an enamel infolding. Teeth implantation is subthecodont, with teeth being replaced by erosion of a pit in the lingual (side of
6468-457: The tooth facing the tongue) surface of the tooth base. There is some tooth differentiation among neochoristoderes, with the anterior teeth being sharper and more slender than posterior teeth. Choristoderes retain palatal teeth (teeth present on the bones of the roof of the mouth). Unlike most diapsid groups, where palatal teeth are reduced or lost completely, the palatal teeth in choristoderes are extensively developed indicating food manipulation in
6552-454: The treated snake bites in the United States. Five subspecies have been recognized in the past, but recent genetic analysis had yielded new species information. Its generic name is derived from the Greek words ankistron "hook, fishhook" and odon , variant of odous "tooth". The trivial name , or specific epithet , comes from the Latin contortus (twisted, intricate, complex), which
6636-499: The use of antivenom. Bite symptoms include extreme pain, tingling, throbbing, swelling, and severe nausea. Damage can occur to muscle and bone tissue, especially when the bite occurs in the outer extremities such as the hands and feet, areas in which a large muscle mass is not available to absorb the venom. A bite from any venomous snake should be taken very seriously and immediate medical attention sought, as an allergic reaction and secondary infection are always possible. The venom of
6720-483: The venom. As many copperhead bites can be dry (no envenomation), CroFab is not given in the absence of a reaction (such as swelling) due to the risk of complications of an allergic reaction to the treatment. The antivenom can cause an immune reaction called serum sickness . Pain management , tetanus immunization, laboratory evaluation, and medical supervision in the case of complications are additional courses of action. In 2002, an Illinois poison control center report on
6804-730: The well sampled European localities of the Berriasian aged Purbeck Group , Great Britain and the Barremian aged La Huérguina Formation , Spain, though there is a record of a small Cteniogenys -like taxon from the Berriasian aged Angeac-Charente bonebed in France. In the latter half of the Late Cretaceous ( Campanian - Maastrichtian ), the neochoristodere Champsosaurus is found in Utah, Wyoming, Montana, North Dakota, Alberta and Saskatchewan, which were along
6888-663: The western coast of the Western Interior Seaway on the island of Laramidia . Indeterminate remains of neochoristoderes are also known from the Canadian High Arctic, dating to the early Late Cretaceous ( Coniacian – Turonian ) and from the Navesink Formation of New Jersey from the latest Cretaceous (Maastrichtian), which formed the separate island of Appalachia . Vertebrae from the Cenomanian of Germany and
6972-530: The winter, it hibernates in dens or limestone crevices, often together with timber rattlesnakes and black rat snakes . In the states around the Gulf of Mexico , however, this species is also found in coniferous forest . In the Chihuahuan Desert of West Texas and northern Mexico, it occurs in riparian habitats , usually near permanent or semipermanent water and sometimes in dry arroyos (brooks). This species
7056-434: Was "four feet, six inches" (137.2 cm), but this may have been an approximation. The maximum length for A. c. contortrix is 132.1 cm (52 in) (Conant, 1958). The body is relatively stout and the head is broad and distinct from the neck. Because the snout slopes down and back, it appears less blunt than that of the cottonmouth, A. piscivorus . Consequently, the top of the head extends further forward than
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