| Waluchelys Temporal range: | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Pantestudines |
| Clade: | Testudinata |
| Family: | † Australochelyidae |
| Genus: | † Waluchelys Sterli et. al., 2020 |
| Species: | †W. cavitesta |
| Binomial name | |
| †Waluchelys cavitesta Sterli et. al., 2020 | |
Waluchelys is an extinct genus of australochelyid that lived during the Late Triassic epoch. It is known from a single species, Waluchelys cavitesta. [1]
An anapsid is an amniote whose skull lacks one or more skull openings near the temples. Traditionally, the Anapsida are considered the most primitive subclass of amniotes, the ancestral stock from which Synapsida and Diapsida evolved, making anapsids paraphyletic. It is, however, doubtful that all anapsids lack temporal fenestra as a primitive trait, and that all the groups traditionally seen as anapsids truly lacked fenestra.
Diapsids are a clade of sauropsids, distinguished from more primitive eureptiles by the presence of two holes, known as temporal fenestrae, in each side of their skulls. The earliest traditionally identified diapsids, the araeoscelidians, appeared about three hundred million years ago during the late Carboniferous period. All diapsids other than the most primitive ones in the clade Araeoscelidia are often placed into the clade Neodiapsida. The diapsids are extremely diverse, and include birds and all modern reptile groups, including turtles, which were historically thought to lie outside the group. All modern reptiles and birds are placed within the neodiapsid subclade Sauria. Although some diapsids have lost either one hole (lizards), or both holes, or have a heavily restructured skull, they are still classified as diapsids based on their ancestry. At least 17,084 species of diapsid animals are extant: 9,159 birds, and 7,925 snakes, lizards, tuatara, turtles, and crocodiles.
Sauropterygia is an extinct taxon of diverse, aquatic reptiles that developed from terrestrial ancestors soon after the end-Permian extinction and flourished during the Triassic before all except for the Plesiosauria became extinct at the end of that period. The plesiosaurs would continue to diversify until the end of the Mesozoic. Sauropterygians are united by a radical adaptation of their pectoral girdle, adapted to support powerful flipper strokes. Some later sauropterygians, such as the pliosaurs, developed a similar mechanism in their pelvis. It is possible that sauropterygians are a distant relatives of turtles, uniting them under the group Pantestudines, although this is still debatable as sauropterygians might be archosauromorphs or completely unrelated to both.
Archosauromorpha is a clade of diapsid reptiles containing all reptiles more closely related to archosaurs rather than lepidosaurs. Archosauromorphs first appeared during the late Middle Permian or Late Permian, though they became much more common and diverse during the Triassic period.
Proganochelys is a genus of extinct, primitive stem-turtle. Proganochelys was named by Georg Baur in 1887 as the oldest turtle in existence at the time. The name Proganochelys comes from the Greek word ganos meaning 'brightness', combined with prefix pro, 'before', and Greek base chelys meaning 'turtle'. Proganochelys is believed to have been around 1 meter in size and herbivorous in nature. Proganochelys had been known as the most primitive stem-turtle for over a century, until the novel discovery of Odontochelys in 2008. Odontochelys and Proganochelys share unique primitive features that are not found in Casichelydia, such as teeth on the pterygoid and vomer and a plate-like coracoid.
Parareptilia ("near-reptiles") is an extinct subclass or clade of basal sauropsids/reptiles, typically considered the sister taxon to Eureptilia. Parareptiles first arose near the end of the Carboniferous period and achieved their highest diversity during the Permian period. Several ecological innovations were first accomplished by parareptiles among reptiles. These include the first reptiles to return to marine ecosystems (mesosaurs), the first bipedal reptiles, the first reptiles with advanced hearing systems, and the first large herbivorous reptiles. The only parareptiles to survive into the Triassic period were the procolophonoids, a group of small generalists, omnivores, and herbivores. The largest family of procolophonoids, the procolophonids, rediversified in the Triassic, but subsequently declined and became extinct by the end of the period.
Pterospondylus is a dubious genus of theropod dinosaur from the Late Triassic. It was a coelophysid theropod which lived in what is now Germany. The type species, Pterospondylus trielbae,, was described by Jaekel in 1913–14 for a single back vertebra found inside the shell of the Proganochelys turtle. Sometimes, it is aligned with Procompsognathus, or even considered to be synonymous with it, despite being based on a vertebra that is twice the size of the corresponding bone in Procompsognathus. P. trielbae has no diagnostic features and is therefore considered a nomen dubium.
Placochelys is an extinct genus of placodont reptiles erected by Otto Jaekel in 1902.
The turtle shell is a shield for the ventral and dorsal parts of turtles, completely enclosing all the vital organs of the turtle and in some cases even the head. It is constructed of modified bony elements such as the ribs, parts of the pelvis and other bones found in most reptiles. The bone of the shell consists of both skeletal and dermal bone, showing that the complete enclosure of the shell likely evolved by including dermal armor into the rib cage.
Syllomus is an extinct genus of sea turtle from the Miocene-age deposits in the US Eastern Seaboard and Egypt.
Odontochelys semitestacea is a Late Triassic relative of turtles before Pappochelys was discovered and Eunotosaurus was redescribed, Odontochelys was considered the oldest undisputed member of Pantestudines. It is the only known species in the genus Odontochelys and the family Odontochelyidae.
Testudinata is the group of all tetrapods with a true turtle shell. It includes both modern turtles (Testudines) and many of their extinct, shelled relatives (stem-turtles), though excluding Odontochelys and Eorhynchochelys, which are placed in the more inclusive Pantestudines.
Owenetta is an extinct genus of owenettid procolophonian parareptile. Fossils have been found from the Beaufort Group in the Karoo Basin of South Africa. Although most procolophonians lived during the Triassic, Owenetta existed during the Wuchiapingian and Changhsingian stages of the Late Permian as well as the early Induan stage of the Early Triassic. It is the type genus of the family Owenettidae, and can be distinguished from other related taxa in that the posterior portion of the supratemporal bears a lateral notch and that the pineal foramen is surrounded by a depressed parietal surface on the skull table.
Psephochelys is an extinct genus of placodont reptile from the Late Triassic of China. It is represented by a single species, Psephochelys polyosteoderma, named in 2002 on the basis of a single partial skeleton found in an outcrop of the Carnian-age Falong Formation in Guizhou Province. Psephochelys is classified as a member of the family Placochelyidae, which is within the larger placodont superfamily Cyamodontoidea. Like other cyamodontoids, Psephochelys has a wide shell covering its body, similar to that of a turtle. However, unlike those of other cyamodontoids, the shell of Psephochelys only covers its back. The plastron, which covers the underside of other cyamodontoids, is absent, and in its place are rib-like gastralia surrounded by loosely connecting osteoderms or bony plates.
Chinlechelys is an extinct genus of stem-turtle belonging to Testudinata. It lived in the Norian age of the Late Triassic and is the oldest turtle known from North America. Among turtles it is unique, mostly because of its very thin shell. The type and only species, C. tenertesta, was named and described with the genus by Walter G. Joyce et al. in 2009. It was probably terrestrial, and was found by Joyce et al. to be closely related to Proganochelys, another terrestrial testudinatan.
Archelosauria is a clade grouping turtles and archosaurs and their fossil relatives, to the exclusion of lepidosaurs. The majority of phylogenetic analyses based on molecular data have supported a sister-group relationship between turtles and archosaurs. On the other hand, Archelosauria had not been historically supported by most morphological analyses, which have instead found turtles to either be descendants of parareptiles, early-diverging diapsids outside of Sauria, or close relatives of lepidosaurs within the clade Ankylopoda. Some recent morphological analyses have also found support for Archelosauria.
Pantestudines or Pan-Testudines is the proposed group of all reptiles more closely related to turtles than to any other living animal. It includes both modern turtles and all of their extinct relatives. Pantestudines with a complete shell are placed in the clade Testudinata.
Pappochelys is an extinct genus of diapsid reptile possibly related to turtles. The genus contains only one species, Pappochelys rosinae, from the Middle Triassic of Germany, which was named by paleontologists Rainer Schoch and Hans-Dieter Sues in 2015. The discovery of Pappochelys provides strong support for the placement of turtles within Diapsida, a hypothesis that has long been suggested by molecular data, but never previously by the fossil record. It is morphologically intermediate between the definite stem-turtle Odontochelys from the Late Triassic of China and Eunotosaurus, a reptile from the Middle Permian of South Africa.
Eorhynchochelys is an extinct genus of stem-turtle from the Late Triassic Xiaowa Formation of southwestern China.
Proterochersis is an extinct genus of turtle from the Late Triassic period of Europe. It is known from a large number of fossils uncovered in Germany and Poland. The genus was named from fossil remains from Germany in 1913 by Fraas, who recognized two species: P. robusta and P. intermedia. Since then, Szczygielski and Sulej have found that the differences described by Fraas could be the result of intraspecific variation, meaning that P. intermedia are synonymous with P. robusta. They also decided to classify more recent fossil findings from Poland as two new species, P. limendorsa and P. porebensis. A study from 2021 concluded that fossil turtle remains described in 1865 as Chelytherium obscurum are probably synonymous with Proterochersis. Generally, the rules of nomenclature advocate that the oldest taxonomic name should replace more recent ones, but Szczygielski choose to keep the name Proterochersis.
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