The cynodonts are a clade of eutheriodont therapsids that first appeared in the Late Permian, and extensively diversified after the Permian–Triassic extinction event. Cynodonts occupied a variety of ecologies, including as carnivores and herbivores. Mammals are cynodonts, as are their extinct ancestors and close relatives, having evolved from advanced probainognathian cynodonts during the Late Triassic. All other cynodont lines went extinct, with the last known non-mammalian cynodont group, the Tritylodontidae, having its youngest records in the Early Cretaceous.
Sinosaurus is an extinct genus of theropod dinosaur which lived during the Early Jurassic Period. It was a bipedal carnivore approximately 5.5 metres (18 ft) in length and 300 kilograms (660 lb) in body mass. Fossils of the animal were found at the Lufeng Formation, in the Yunnan Province of China.
The theriodonts are a major group of therapsids which appeared during the Middle Permian and which includes the gorgonopsians and the eutheriodonts, itself including the therocephalians and the cynodonts.
Euchambersia is an extinct genus of therocephalian therapsids that lived during the Late Permian in what is now South Africa and China. The genus contains two species. The type species E. mirabilis was named by paleontologist Robert Broom in 1931 from a skull missing the lower jaw. A second skull, belonging to a probably immature individual, was later described. In 2022, a second species, E. liuyudongi, was named by Jun Liu and Fernando Abdala from a well-preserved skull. It is a member of the family Akidnognathidae, which historically has also been referred by as the synonymous Euchambersiidae.
Bauria is an extinct genus of the suborder Therocephalia that existed during the Early and MiddleTriassic period, around 246-251 million years ago. It belonged to the family Bauriidae. Bauria was probably a carnivore or insectivore. It lived in South Africa, specifically in the Burgersdorp Formation in South Africa.
Moschorhinus is an extinct genus of therocephalian in the family Akidnognathidae with only one species: M. kitchingi. It was a carnivorous synapsid which has been found in the Late Permian to Early Triassic of the South African Karoo Supergroup. It was a large carnivore, reaching 1.5 m (4.9 ft) in total body length with the largest skull comparable to that of a lion in size. It had a broad, blunt snout which bore long, straight canines. It appears to have replaced the gorgonopsids ecologically, and hunted much like a big cat. While most abundant in the Late Permian, it survived a little after the Permian Extinction, though these Triassic individuals had stunted growth.
Tillodontia is an extinct suborder of eutherian mammals known from the Early Paleocene to Late Eocene of China, the Late Paleocene to Middle Eocene of North America where they display their maximum species diversity, the Middle Eocene of Pakistan, and the Early Eocene of Europe. Leaving no descendants, they are most closely related to the pantodonts, another extinct group. The tillodonts were medium- to large-sized animals that probably feed on roots and tubers in temperate to subtropical habitats.
Platyognathus is an extinct genus of protosuchian crocodylomorph. Fossils are known from the Early Jurassic Lower Lufeng Formation in Yunnan, China and belong to the type and only species, P. hsui.
Daqingshanodon is an extinct genus of dicynodont therapsid from the Late Permian of Inner Mongolia, China. The type species D. limbus was described in 1989 from a single skull found in the Naobaogou Formation. Daqingshanodon belongs to a group of dicynodonts called cryptodonts. It is the smallest known cryptodont, and the only one known from China. Like other cryptodonts, it has a pair of rounded nasal bosses above its nostrils and a ridge of bone on the upper jaw called the postcaniniform process. Daqingshanodon has a pair of elongated, recurved tusks extending from its beak-like snout. It is distinguished from other dicynodonts by the presence of a distinct ridge running along the side of the skull from below the eye socket to the area around the tusks. The skull of Daqingshanodon is less than 10 centimetres (3.9 in) long, yet this specimen is thought to have been an adult on the basis of its well-developed nasal bosses.
Blattoidealestes is an extinct genus of therocephalian therapsid from the Middle Permian of South Africa. The type species Blattoidealestes gracilis was named by South African paleontologist Lieuwe Dirk Boonstra from the Tapinocephalus Assemblage Zone in 1954. Dating back to the Middle Permian, Blattoidealestes is one of the oldest therocephalians. It is similar in appearance to the small therocephalian Perplexisaurus from Russia, and may be closely related.
Guchengosuchus is an extinct genus of erythrosuchid archosauriform from the Early Triassic of China. It is known from a single holotype skeleton called IVPP V 8808, described in 1991 from the lower Ermaying Formation in Shanxi. The lower Ermaying Formation dates back to the Olenekian stage of the Early Triassic, making Guchengosuchus one of the earliest archosauriforms. IVPP V 8808 is a disarticulated skeleton including a partial skull, lower jaw, some vertebrae, a scapula, and forelimb bones. Like some other erythrosuchids, Guchengosuchus has a tall skull with a notch between the premaxilla and maxilla bones of the upper jaw. The ribs of Guchengosuchus each have three heads, a feature also seen in the Russian erythrosuchid Vjushkovia. When it was first described, Guchengosuchus was placed in the suborder Proterosuchia, a group that included the families Erythrosuchidae, Proterosuchidae, and Proterochampsidae and was thought to be closely related to a primitive group of reptiles called Eosuchia. Proterosuchia is now considered a paraphyletic assemblage of basal archosauriforms representing a series of successive branches of stem group archosaurs.
Glyphoderma is an extinct genus of placodont reptile from the Middle Triassic of China. It differs from its relative Psephochelys in having three, rather than one, fused osteoderms on the posterior skull surface, and has an earlier temporal range, from the Ladinian epoch rather than the Late Triassic. Otherwise, it is similar in most respects to the other plachochelyids found in China. The name comes from the Greek 'γλυφος', 'sculpture' and 'δερμα', 'skin' referring to its unique carapace structure. The specific name honours a Mr. Kang Ximin.
Diademodontidae is an extinct family of Triassic gomphodonts. The best-known genus is Diademodon from South Africa. Titanogomphodon from Namibia may also be a member of Diademodontidae. The Chinese genera Hazhenia and Ordosiodon have also been included in the family, but were more recently identified as baurioid therocephalians. Remains of a diademodontid were reported in the Early-Middle Triassic Fremouw Formation in Antarctica, but that specimen was later referred to the trirachodontid Impidens
Urumchia is an extinct genus of therocephalian therapsids from the Early Triassic of China. The type species Urumchia lii was described by Chinese paleontologist C. C. Young in 1952 from the Jiucaiyuan Formation in Xinjiang. The holotype skull has been lost, but Young was able to describe the species on the basis of a detailed cast of the skull. Urumchia is similar to the South African therocephalian Regisaurus in having an expanded pair of vomer bones on the underside of the skull that form a secondary palate. In Urumchia the front end of the vomers narrow to a point, while in Regisaurus they do not. Urumchia has six incisors on either side of the upper jaw, a primitive condition among baurioid therocephalians that usually have fewer incisors.
Yikezhaogia is an extinct genus of therocephalian therapsids from the Early Triassic of Mongolia. It is known from a single fragmentary skull and associated postcranial bones representing the species Yikezhaogia megafenestrala. It is identifiable as a therocephalian by its thin postorbital bar behind the eye socket, its elongated temporal opening behind the bar, and a thin lower jaw with a low coronoid process. Large tooth sockets in the upper jaw indicate that Yikezhaogia had large caniniform teeth. The teeth of the lower jaw are blunt-tipped and cylindrical. Although its exact position among therocephalians is uncertain, Yikezhaogia is probably a basal member of the group Baurioidea.
Hazhenia is an extinct genus of therocephalian therapsids from the Early Triassic of China, of which Hazhenia concava is the only species. Hazhenia was named in 1981 from the Heshanggou Formation in the Ordos Desert of Inner Mongolia. It lived during the Olenekian Age of the Early Triassic, about 247 million years ago. Hazhenia belongs to a group of therocephalians called Baurioidea and possesses many mammal-like features such as cusped teeth and a secondary palate, both of which evolved independently in baurioids. Within Baurioidea it is most closely related to the genus Ordosiodon, which is also known from Inner Mongolia but comes from the slightly younger Ermaying Formation. Both genera were once placed in the family Ordosiidae, but as the name is preoccupied by a family of Cambrian trilobites, it is no longer valid.
Titanogomphodon is an extinct genus of diademodontid cynodonts from the Middle Triassic Omingonde Formation of Namibia. It is known from a single partial skull that was described in 1973 from the Omingonde Formation. The type and only species is Titanogomphodon crassus. At about 40 centimetres (16 in), the skull of Titanogomphodon was significantly larger than that of its closest relative, Diademodon. Its teeth are similar to those of another group of cynodonts called Traversodontidae, but the similarities are likely the result of convergent evolution. Aside from its larger size, Titanogomphodon differs from Diademodon in having a bony projection on the postorbital bar behind the eye socket.
Sanchiaosaurus is an extinct genus of a basal nothosauroid known from the Middle Triassic of Guizhou Province, southwestern China. It contains a single species, Sanchiaosaurus dengi.
Vetusodon is an extinct genus of cynodonts belonging to the clade Epicynodontia. It contains one species, Vetusodon elikhulu, which is known from four specimens found in the Late Permian Daptocephalus Assemblage Zone of South Africa. With a skull length of about 18 centimetres (7.1 in), Vetusodon is the largest known cynodont from the Permian. Through convergent evolution, it possessed several unusual features reminiscent of the contemporary therocephalian Moschorhinus, including broad, robust jaws, large incisors and canines, and small, single-cusped postcanine teeth.
Sinognathus is an extinct genus of gomphodont cynodonts from the Middle Triassic Ermaying Formation of China. Its type and only species is Sinognathus gracilis, which was named in 1959 by the Chinese palaeontologist C. C. Young.
