Sarcosuchus is an extinct genus of crocodyliform and distant relative of living crocodilians that lived during the Early Cretaceous, from the late Hauterivian to the early Albian, 133 to 112 million years ago of what is now Africa and South America. The genus name comes from the Greek σάρξ (sarx) meaning flesh and σοῦχος (souchus) meaning crocodile. It was one of the largest pseudosuchians, with the largest specimen of S. imperator reaching approximately 9–9.5 metres (29.5–31.2 ft) long and weighing up to 3.45–4.3 metric tons. It is known from two species; S. imperator from the early Albian Elrhaz Formation of Niger, and S. hartti from the Late Hauterivian of northeastern Brazil. Other material is known from Morocco and Tunisia and possibly Libya and Mali.
Champsosaurus is an extinct genus of crocodile-like choristodere reptile, known from the Late Cretaceous and early Paleogene periods of North America and Europe (Campanian–Paleocene). The name Champsosaurus is thought to come from champsai, (χαμψαι) said in an Ancient Greek source to be an Egyptian word for "crocodiles", and sauros, (σαύρος) Greek for "lizard". The morphology of Champsosaurus resembles that of gharials, with a long, elongated snout. It was native to freshwater environments where it likely preyed on fish, similar to living gharials.
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.
Hyphalosaurus is a genus of freshwater aquatic reptiles, belonging to the extinct order Choristodera. They lived during the early Cretaceous period, about 123-120 million years ago. The genus contains two species, H. lingyuanensis from the Yixian Formation and H. baitaigouensis from both the Yixian and Jiufotang Formation of Liaoning Province, China. They are among the best-known animals from the Jehol Biota, with thousands of fossil specimens representing all growth stages in scientific and private collections.
Siamosaurus is a genus of spinosaurid dinosaur that lived in what is now known as China and Thailand during the Early Cretaceous period and is the first reported spinosaurid from Asia. It is confidently known only from tooth fossils; the first were found in the Sao Khua Formation, with more teeth later recovered from the younger Khok Kruat Formation. The only species Siamosaurus suteethorni, whose name honours Thai palaeontologist Varavudh Suteethorn, was formally described in 1986. In 2009, four teeth from China previously attributed to a pliosaur—under the species "Sinopliosaurus" fusuiensis—were identified as those of a spinosaurid, possibly Siamosaurus. It is yet to be determined if two partial spinosaurid skeletons from Thailand and an isolated tooth from Japan also belong to Siamosaurus.
Wannaganosuchus is an extinct genus of small alligatorid crocodilian. It was found in Late Paleocene-age rocks of Billings County, North Dakota, United States.
Pachystropheus is a genus of prehistoric reptile, from the Rhaetian of southwestern England. It was named by Erika von Huene in 1935; Huene described Pachystropheus as a choristodere, but this was overlooked for decades until its redescription by Storrs and Gower in 1993. This reevaluation would extend the fossil record of choristoderes back 45 million years. However, other authors consider attribution of Pachystropheus to Choristodera problematic, stating that it depends on vertebral and girdle characters that are also found in the skeletons of aquatic reptiles other than choristoderes; most of the diagnostic features of choristoderes are skull features, but the presence of these cannot be confirmed in Pachystropheus, as there is no confirmed skull material for this taxon. Silvio Renesto (2005) found similarities in the postcranial skeleton of Pachystropheus and the thalattosaur genus Endennasaurus; according to Renesto, these similarities may indicate that Pachystropheus and Endennasaurus are close relatives, but they might as well simply be a case of a convergent evolution triggered by the aquatic lifestyle of both taxa. The placement as a thalattosaur has been supported by other researchers.
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.
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.
The Akaiwa Formation is an Early Cretaceous (Hauterivian-Barremian) geologic formation in central Honshu, Japan. Indeterminate ornithischian fossils are known from the formation. Fossil ornithopod tracks have been reported from the formation. As well as the turtle Kappachelys
Monjurosuchus is a genus of choristoderan reptile that lived in what is now China and Japan during the Early Cretaceous. It has large eyes, a rounded skull, robust legs with short claws, and a long, thin tail. Fossils have been found that preserve soft tissue, showing that it had soft skin and webbed feet.
Irenosaurus is a genus of choristodere, a type of amphibious reptile. It is known from a single fragmentary postcranial skeleton (PIN 3386/2), discovered in the Aptian-age Lower Cretaceous Hühteeg Formation at Hüren Dukh, central Mongolia. The type species is I. egloni, which was originally described as a new species of the related choristodere Tchoiria in 1983 by Efimov. Efimov transferred the species to the new genus Irenosaurus in 1988. Evans and Hecht (1993) questioned the separation of the taxon from Tchoiria namsarai from the same locality on the grounds that the differences between the two may not have been greater than those of various species of the choristodere Champsosaurus. A later review by Efimov and Storrs (2000) retained the two as separate, noting that some characteristics of Irenosaurus are more like Khurendukhosaurus, also known from the same site, at the same time recognizing the difficulties of distinguishing three genera from the same locality. Irenosaurus was a small choristodere, approximately 1 to 1.5 metres long. It is known from what are interpreted as lake deposits.
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.
Ikechosaurus is an extinct genus of choristodere reptile which existed in China and Mongolia during the Early Cretaceous. It contains the species Ikechosaurus sunailinae and Ikechosaurus gaoi. It belongs to the crocodilian-like clade Neochoristodera and was initially assigned to the Champsosauridae by Sigogneau-Russell (1981). Compared to other neochoristoderes, Ikechosaurus has a rather simple dentition, lacking the speciations seen in latter species. It also has parasphenoid palatal teeth, a feature not seen in any other choristodere.
Coeruleodraco is an extinct genus of choristoderan known from the Late Jurassic (Oxfordian) Tiaojishan Formation in China. Coeruleodraco is significant as the most complete Jurassic choristodere taxon, as the only other named Jurassic choristodere Cteniogenys is based on fragmentary remains. Although similar to Philydrosaurus in its proportions and postcranial characters, it is distinct in retaining several apparently plesiomorphic characters, including a short snout, paired external nares and an open lower temporal fenestra.
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.
Mengshanosaurus is an extinct genus of choristodere from the Early Cretaceous Meng-Yin Formation of China. The type and only known species is M. minimus, known from a juvenile skull, around 3.5 cm long. It was found to be the basalmost neochoristodere.
Kosmodraco is a genus of large bodied choristodere from the Paleocene of North America. Originally described as a species of Simoedosaurus, it was found to represent a distinct genus in 2022. Multiple fossil skulls show a relatively short and robust snout and a skull that is considerably wider behind the eyes. Two species are currently recognized, K. dakotensis and K. magnicornis.
