Thrinaxodon is an extinct genus of cynodonts, including the species T. liorhinus which lived in what are now South Africa and Antarctica during the Early Triassic. Thrinaxodon lived just after the Permian–Triassic mass extinction event, its survival during the extinction may have been due to its burrowing habits.
Cynognathia is one of two major clades of cynodonts, the other being Probainognathia. Cynognathians included the large carnivorous genus Cynognathus and the herbivorous or omnivorous gomphodonts such as traversodontids. Cynognathians can be identified by several synapomorphies including a very deep zygomatic arch that extends above the middle of the orbit.
Massetognathus is an extinct genus of plant-eating traversodontid cynodonts. They lived during the Triassic Period about 235 million years ago, and are known from the Chañares Formation in Argentina and the Santa Maria Formation in Brazil.
Tritylodontidae is an extinct family of small to medium-sized, highly specialized mammal-like cynodonts, with several mammalian traits including erect limbs, endothermy and details of the skeleton. They were the last-known family of the non-mammaliaform synapsids, persisting into the Early Cretaceous.
Traversodontidae is an extinct family of herbivorous cynodonts. Traversodonts were primarily Gondwanan, with many species known from Africa and South America. Recently, traversodonts have also been found from Europe and North America. Traversodonts first appeared in the Middle Triassic and diversified in the Late Triassic before going extinct at the end of the epoch. The family Traversodontidae was erected by Friedrich von Huene in 1936 for cynodonts first found in São Pedro do Sul in Paleorrota, Brazil.
Prozostrodon is an extinct genus of probainognathian cynodonts that was closely related to mammals. The remains were found in Brazil and are dated to the Carnian age of the Late Triassic. The holotype has an estimated skull length of 6.7 centimetres (2.6 in), indicating that the whole animal may have been the size of a cat. The teeth were typical of advanced cynodonts, and the animal was probably a carnivore hunting reptiles and other small prey.
Brasilodon is an extinct genus of small, mammal-like cynodonts that lived in what is now Brazil during the Norian age of the Late Triassic epoch, about 225.42 million years ago. While no complete skeletons have been found, the length of Brasilodon has been estimated at 12 centimetres (4.7 in). Its dentition shows that it was most likely an insectivore. The genus is monotypic, containing only the species B. quadrangularis. Brasilodon belongs to the family Brasilodontidae, whose members were some of the closest relatives of mammals, the only cynodonts alive today. Two other brasilodontid genera, Brasilitherium and Minicynodon, are now considered to be junior synonyms of Brasilodon.
Microgomphodon is an extinct genus of therocephalian therapsid from the Middle Triassic of South Africa and Namibia. Currently only one species of Microgomphodon, M. oligocynus, is recognized. With fossils present in the Cynognathus Assemblage Zone (CAZ) of the Burgersdorp Formation in South Africa and Omingonde Formation of Namibia and ranging in age from late Olenekian to Anisian, it is one of the most geographically and temporally widespread therocephalian species. Moreover, its occurrence in the upper Omigonde Formation of Namibia makes Microgomphodon the latest-surviving therocephalian. Microgomphodon is a member of the family Bauriidae and a close relative of Bauria, another South African bauriid from the CAZ. Like other bauriids, it possesses several mammal-like features such as a secondary palate and broad, molar-like postcanine teeth, all of which evolved independently from mammals.
Langbergia is an extinct genus of trirachodontid cynodont from the Early Triassic of South Africa. The type and only species L. modisei was named in 2006 after the farm where the holotype was found, Langberg 566. Langbergia was found in the Burgersdorp Formation in the Beaufort Group, a part of the Cynognathus Assemblage Zone. The closely related trirachodontids Trirachodon and Cricodon were found in the same area.
Neotrirachodon is an extinct genus of therapsids which existed in Russia during the Middle Triassic period. Its type and only species is Neotrirachodon expectatus.
Trirachodontidae is an extinct, possibly paraphyletic family of cynognathian cynodonts from the Triassic of China and southern Africa. Trirachodontids appeared during the Early Triassic soon after the Permian-Triassic extinction event and quickly spread over a wide geographic area in a comparatively brief amount of time from 250 to 237 million years ago.
Andescynodon is a genus of traversodontid cynodonts from the Middle Triassic of Argentina. Fossils are known from the Cerro de las Cabras and Cacheutá Formations. Andescynodon is one of the most basal traversodontids. Another traversodontid called Rusconiodon has also been identified from the Cerro de las Cabras Formation but is now considered a junior synonym of Andescynodon.
Gomphodontia is a clade of cynognathian cynodonts that includes the families Diademodontidae, Trirachodontidae, and Traversodontidae. Gomphodonts are distinguished by wide and closely spaced molar-like postcanine teeth, which are convergent with those of mammals. Other distinguishing characteristics of gomphodonts include deep zygomatic arches, upper postcanines with three or more cusps spanning their widths and lower postcanines with two cusps spanning their widths. They are thought to have been herbivorous or omnivorous. Gomphodonts first appeared in the Early Triassic and became extinct at the end of the Late Triassic. Fossils are known from southern Africa, Argentina and southern Brazil, eastern North America, Europe, China, and Antarctica.
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.
Cricodon is an extinct genus of trirachodontid cynodonts that lived during the Early Triassic and Middle Triassic periods of Africa. A. W. Crompton named Cricodon based on the ring-like arrangement of the cuspules on the crown of a typical postcanine tooth. The epithet of the type species, C. metabolus, indicates the change in structure of certain postcanines resulting from replacement.
Aleodon is an extinct genus of cynodonts that lived from the Middle to the Late Triassic. Relatively few analyses have been conducted to identify the phylogenetic placement of Aleodon, however those that have place Aleodon as a sister taxon to Chiniquodon. Two species of Aleodon are recognized: A. brachyramphus which was discovered in Tanzania, and A. cromptoni which was discovered most recently in Brazil.
Abdalodon is an extinct genus of late Permian cynodonts, known by its only species A. diastematicus.Abdalodon together with the genus Charassognathus, form the clade Charassognathidae. This clade represents the earliest known cynodonts, and is the first known radiation of Permian cynodonts.
Bonacynodon is an extinct genus of cynodonts that lived in what is now southern Brazil during the Triassic period. The genus is monotypic, containing only the type species Bonacynodon schultzi. B. schultzi is known from two specimens, consisting of two partial skulls and some badly preserved parts of the postcranium. Both specimens were recovered from the Pinheiros-Chiniquá Sequence, part of the Santa Maria Supersequence of the Paraná Basin. This sequence preserves a faunal association known as the Dinodontosaurus Assemblage Zone, which contains numerous other species of cynodonts, dicynodonts and reptiles. Bonacynodon was a small, likely insectivorous cynodont, whose length has been estimated at around 30 centimetres (12 in). It can be distinguished from other cynodonts by its large, serrated (saw-like) canine teeth. Together with the genus Probainognathus of Argentina, it made up the family Probainognathidae, one of the earliest-diverging lineages of the clade Probainognathia. It was a fairly close relative of mammals, the only group of cynodonts alive today.
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.
Arctotraversodontinae is a subfamily of Late Triassic cynodonts belonging to the family Traversodontidae. Members of the subfamily include Arctotraversodon, Boreogomphodon and Plinthogomphodon from North America, and Habayia, Maubeugia, Microscalenodon and Rosieria from Europe.
