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.
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.
The Cynognathus Assemblage Zone is a tetrapod biozone utilized in the Karoo Basin of South Africa. It is equivalent to the Burgersdorp Formation, the youngest lithostratigraphic formation in the Beaufort Group, which is part of the fossiliferous and geologically important Karoo Supergroup. The Cynognathus Assemblage Zone is the youngest of the eight biozones found in the Beaufort Group, and is considered to be late Early Triassic (Olenekian) to early Middle Triassic (Anisian) in age. The name of the biozone refers to Cynognathus crateronotus, a large and carnivorous cynodont therapsid which occurs throughout the entire biozone.
Trirachodon is an extinct genus of cynodonts. Fossils have been found in the Cynognathus Assemblage Zone of the Beaufort Group in South Africa and the Omingonde Formation of Namibia, dating back to the Early and Middle Triassic.
Lumkuia is an extinct genus of cynodonts, fossils of which have been found in the Cynognathus Assemblage Zone of the Beaufort Group in the South African Karoo Basin that date back to the early Middle Triassic. It contains a single species, Lumkuia fuzzi, which was named in 2001 on the basis of the holotype specimen BP/1/2669, which can now be found at the Bernard Price Institute in Johannesburg, South Africa. The genus has been placed in its own family, Lumkuiidae. Lumkuia is not as common as other cynodonts from the same locality such as Diademodon and Trirachodon.
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.
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.
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
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.
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.
Ufudocyclops is an extinct genus of stahleckeriid dicynodont from the Middle Triassic of South Africa. It was found in the Burgersdorp Formation, part of the uppermost Cynognathus Assemblage Zone of the Beaufort Group in the Karoo Basin. The type and only known species is U. mukanelai. It was a large, beaked herbivore like other Triassic dicynodonts, lacking tusks, and is mostly characterised by unique features of the skull. It is known from three specimens, two of which were previously referred to the Tanzanian dicynodont Angonisaurus. The separation of Ufudocyclops from Angonisaurus indicates that the Middle Triassic fauna of the Beaufort Group in South Africa was not part of a larger shared fauna with those of the Manda Beds in Tanzania, as was previously supposed, and suggests that they were separated as more localised faunas, possibly by geographic barriers or in time. Ufudocyclops then would have been a unique part of the uppermost Cynognathus Assemblage Zone in South Africa. It is also the oldest known member of the family Stahleckeriidae, and implies that the family was already diversifying in the Middle Triassic alongside other kannemeyeriiforms, not just in the Late Triassic after other families died out.
Etjoia is an extinct genus of traversodontid cynodonts that lived during the Middle Triassic or Late Triassic period in southern Africa. This medium-sized omnivorous cynognathian provides important information on the dental evolution of early diverging gomphodonts and traversodontids.
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.
Scalenodontoides is an extinct genus of Traversodontidae, a family of herbivorous cynodonts. It lived during the Late Triassic in what is now South Africa. Its type species is Scalenodontoides macrodontes. It was named in 1957 by A. W. Crompton and F. Ellenberger. Arctotraversodon plemmyrodon was originally classified as a species of Scalenodontoides, but was given its own genus in 1992. It is found in the Scalenodontoides Assemblage Zone of the Elliot Formation, which is named for it. It is one of the geologically youngest traversodontids, alongside the putative traversodontid Boreogomphodon. It is closely related to Exaeretodon and Siriusgnathus, but is distinguished by the presence of a shelf-like expansion of its parietal called the nuchal table. Though the largest known complete skull is only 248 millimetres (9.8 in) long, it may have been the largest non-mammalian cynodont, as an incomplete snout would have belonged to a specimen with an estimated skull length of 617 millimetres (24.3 in).
Impidens is an extinct genus of large omnivorous cynodont from the Triassic of South Africa and Antarctica. Its type and only species is Impidens hancoxi. Impidens inhabited high-latitude environments of southern Gondwana during the Middle Triassic, where it was probably the apex predator.
