Choristodera is an extinct order of semiaquatic diapsid reptiles that ranged from the Middle Jurassic, or possibly Triassic, to the Miocene. 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 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.
Simoedosaurus is an extinct reptile known from the Paleocene of North America, Europe and western Asia, and a member of the Choristodera, a group of aquatic reptiles that lived in the Northern Hemisphere from the Jurassic to the early Cenozoic.
Shamosuchus is an extinct genus of neosuchian crocodyliform that lived during the Late Cretaceous (Campanian) period in what is now the Djadokhta Formation of Mongolia, approximately 75 million to 71 million years ago.
Shokawa is an extinct genus of choristoderan diapsid reptile, known from the Lower Cretaceous of Japan. It is only known from one species, Shokawa ikoi. The only known remains are a postcranial specimen lacking the skull, discovered at the KO2 locality in sediments belonging to the Okurodani Formation near the village of Shokawa in Gifu Prefecture. Shokawa possessed a long neck with at least 16 cervical vertebrae, and closely resembles and is closely related to the smaller choristoderan, Hyphalosaurus. The generic name refers to the village near where it was found, while the specific name honors the collector of the first specimen, one Mr. Ikoi Shibata.
Lazarussuchus is an extinct genus of amphibious reptile, known from the Cenozoic of Europe. It is the youngest known member of Choristodera, an extinct order of aquatic reptiles that first appeared in the Middle Jurassic. Fossils have been found in Late Paleocene, Late Oligocene, Early Miocene and possibly Late Miocene deposits in France, Germany, and the Czech Republic. Two species have been named: the type species L. inexpectatus ("unexpected") from the late Oligocene of France. and L. dvoraki from the early Miocene of the Czech Republic. It was not a large animal; with the total preserved body and tail length of L. inexpectatus being just over 30 centimetres. A complete specimen of Lazarussuchus with preserved soft tissue was found from the Late Paleocene of France, but has not been assigned to a species.
Undorosaurus is an extinct genus of ophthalmosaurid ichthyosaur known from western Russia, Svalbard, and Poland. It was a large ichthyosaur, with the type species measuring 4–6 metres (13–20 ft) long.
Zholsuchus is a genus of crocodyliform that may have been a goniopholidid mesoeucrocodylian, but is only known from scanty material. This specimen was found in the Coniacian-age Upper Cretaceous Bissekty Formation of Dzharakhuduk, Uzbekistan. Zholsuchus was described in 1989 by Lev Nesov and colleagues. The type species is Z. procevus.
Kansajsuchus is an extinct genus of paralligatorid mesoeucrocodylian. It is based on PIN 2399/301, a right premaxilla, one of the bones of the tip of the snout. This specimen was found in rocks of the lower Santonian-age Upper Cretaceous Yalovach Svita of Kansai, in the Fergana Basin of Tajikistan. Additional fossils including vertebrae and bony armor have been assigned to this genus. It would have been a large animal, estimated at between 5–7 metres (16–23 ft) long. Kansajsuchus was described in 1975 by Mikhail Efimov. The type species is Kansajsuchus extensus.
Zhyrasuchus is an extinct monospecific genus of crocodylomorph that may have been a crocodylid eusuchian, but is only known from scanty material including a frontal. Its fossils were found in the Coniacian-age Upper Cretaceous Bissekty Formation of Dzharakhuduk, Uzbekistan. Zhyrasuchus was described in 1989 by Lev Nesov and colleagues. The type species is Z. angustifrons. A 2000 review by Glenn Storrs and Mikhail Efimov could not determine how Zhyrasuchus and the contemporaneous Tadzhikosuchus were related, or even if they were synonyms, due to the poor fossils available.
Tadzhikosuchus is an extinct genus of neosuchian crocodyliform from the Late Cretaceous of Tajikistan. Three species have been named: the type species T. macrodentis, described by Efimov in 1982 from the lower Santonian-age Upper Cretaceous Ialovachsk Formation of Kansai, Tajikistan, in the Fergana Basin of Tajikistan; T. neutralis from the same location, by Efimov in 1988; and T. kizylkumensis from Turonian-age rocks of the Upper Cretaceous Bissekty Formation of Dzharakhuduk, Uzbekistan, by Nesov and colleagues in 1989. However, a 2000 review by Glenn Storrs and Mikhail Efimov could not differentiate between the species based on their type material, and recommended grouping the specimens of all three species under T. macrodentis. They also could not determine how Tadzhikosuchus and the contemporaneous Zhyrasuchus were related, or even if they were synonyms, due to the poor fossils available. The name of Tadzhikosuchus is derived from the Russian spelling of Tajikistan.
Nominosuchus is a genus of protosuchian-grade crocodyliform. It is known from several specimens discovered in ancient lake deposits of the Tithonian-age Upper Jurassic Tsagaantsav Formation, southwestern Mongolia. The type specimen is PIN 4174/4, a partial skull. Nominosuchus was not large; its skull length is estimated at 60 millimetres (2.4 in). It was similar to Shartegosuchus, and is assigned to the same family (Shartegosuchidae). Nominosuchus was described in 1996 by Mikhail Efimov, and the type species is N. matutinus.
Shartegosuchus is a genus of protosuchian-grade crocodyliform. It is known primarily from PIN 4174/2, the partial deformed skull and jaws of a juvenile. This specimen was discovered in ancient lake deposits of the Tithonian-age Upper Jurassic Tsagaantsav Formation, southwestern Mongolia. The estimated length of the holotype skull is 40 millimetres (1.6 in). This genus was similar to Nominosuchus, and both are assigned to the same family (Shartegosuchidae). Shartegosuchus was described in 1988 by Mikhail Efimov, and the type species is S. asperopalatum.
Turanosuchus is an extinct genus of paralligatorid crocodyliform. It is based on PIN 2229/507, a partial lower jaw consisting of the area where the two halves of the lower jaw meet. This specimen was found in rocks of the lower Santonian-age Upper Cretaceous Bostobe Svita of Shakh-Shakh, southern Kazakhstan. Turanosuchus was described in 1988 by Mikhail Efimov. The type species is T. aralensis. Halliday et al. (2015) revised the material attributed to T. aralensis and concluded that it represents non-diagnostic neosuchian material, and as such the genus was considered to be a nomen dubium.
Karatausuchus is an extinct genus of atoposaurid crocodylomorph. It is known from a single specimen discovered in the Late Jurassic Karabastau Svita from the vicinity of Mikhailovka in the Karatau Mountains of southern Kazakhstan. The type specimen is PIN 25858/1, a complete but poorly preserved juvenile skeleton with some possible soft tissue preservation. It is notable for having over 90 teeth, but its other anatomical details are difficult to discern. The length of this individual is estimated at 160 millimetres (6.3 in). Karatausuchus was described in 1976 by Mikhail Efimov, and the type species is K. sharovi.
Cteniogenys is a genus of choristodere, a morphologically diverse group of aquatic reptiles. It is part of the monotypic family Cteniogenidae. The type and only named species, C. antiquus, was named in 1928 by Charles W. Gilmore. The holotype, VP.001088, was collected in the Morrison Formation, Wyoming in 1881 by William H. Reed. More specimens have been discovered since then, including specimens from the Late Jurassic of Portugal and Middle Jurassic of Britain, which have not been assigned to species.
Paralligator is an extinct genus of neosuchian crocodylomorph that lived during the Late Cretaceous (Cenomanian-Maastrichtian) period in what is now the Bayan Shireh and Nemegt formations of Mongolia, approximately 96 million to 70 million years ago. P. gradilifrons reached up to 4 m (13 ft) in length.
Khurendukhosaurus is a genus of choristodere, a type of amphibious reptile. It is known from Lower Cretaceous rocks of Mongolia and Russia. Two species have been named. The type species, K. orlovi, was named in 1984 by Sigogneau–Russell and Efimov for the fragmentary postcranial skeleton PIN 3386/3. This specimen was discovered in the Albian-age Lower Cretaceous Khuren Dukh Formation Formation at Hüren Dukh, central Mongolia. The lake deposits at this site also contain fossils of the choristoderes Irenosaurus and Tchoiria. Other postcranial bones of K. orlovi have been found at this site as well.
Tchoiria () is a genus of neochoristoderan reptile from the Early Cretaceous of Mongolia. The name Tchoiria comes from the city of Choir which is nearby to where the holotype was found. Tchoiria is thought to have a similar diet to another neochoristoderan reptile, Champsosaurus, due to morphology of the skull. It would hunt in freshwater environments, like the living gharials, where it would prey on many different types of fish and turtles.
Neochoristodera is a lineage of specialised crocodile-like fully aquatic choristodere reptiles. Noted for their long jaws and large size, these animals were predominant across the Northern Hemisphere, occurring in freshwater and coastal environments across the Cretaceous and early Cenozoic.
Heishanosaurus is an extinct genus of choristodere reptile from the Early Cretaceous of China. The type and currently only known species is Heishanosaurus pygmaeus. It is unusual as it is much more primitive than other known choristoderes from the Early Cretaceous of Asia, and retains many plesiomorphic characters.
