A therapsid is a member of the clade Therapsida which is a major group of eupelycosaurian synapsids that includes mammals and their ancestors and relatives. Many of the traits today seen as unique to mammals had their origin within early therapsids, including limbs that were oriented more underneath the body, as opposed to the sprawling posture of many reptiles and salamanders.
Cynodonts are eutheriodont therapsids that first appeared in the Late Permian, and extensively diversified after the Permian–Triassic extinction event. Mammals are cynodonts, as are their extinct ancestors and close relatives (Mammaliaformes), having evolved from advanced probainognathian cynodonts during the Late Triassic.
Ecteninion is an extinct genus of meat-eating cynodonts that lived during the Late Triassic (Carnian) in South America. The type species Ecteninion lunensis was named by R.N. Martinez, C.L. May, and C.A. Forster in 1996. E. lunensis is known from a nearly complete skull of about 11 centimetres (4.3 in) in length. It was found in the Cancha de Bochas Member of the Ischigualasto Formation in the Ischigualasto-Villa Unión Basin in northwestern Argentina. It has been interpreted as a basal eucynodont. The holotype is in the collection of the Universidad Nacional de San Juan.
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.
Epicynodontia is a clade of cynodont therapsids that includes most cynodonts, such as galesaurids, thrinaxodontids, and Eucynodontia. It was erected as a stem-based taxon by Hopson and Kitching (2001) and defined as the most inclusive clade containing Mammalia and excluding Procynosuchus, a Late Permian genus that is one of the most basal cynodonts.
Cromptodon is an extinct genus of cynodonts from the Triassic of Cerro Bayo de Portrerillos, Cerro de las Cabras Formation, Argentina, South America. It is known only from PVL 3858, a mandible.
Progalesaurus is an extinct genus of galesaurid cynodont from the early Triassic. Progalesaurus is known from a single fossil of the species Progalesaurus lootsbergensis, found in the Lystrosaurus Assemblage Zone of the Balfour Formation. Close relatives of Progalesaurus, other galesaurids, include Galesaurus and Cynosaurus. Galesaurids appeared just before the Permian-Triassic extinction event, and disappeared from the fossil record in the Middle-Triassic.
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.
Madysaurus is an extinct genus of cynodonts which existed in Kyrgyzstan. It was first named by Leonid Petrovich Tatarinov in 2005. Madysaurus is known from the Madygen Formation, a Triassic Lagerstätte that also includes well-preserved remains of insects and small reptiles like Sharovipteryx and Longisquama. Madysaurus is one of the most primitive cynodonts and is placed in its own family, Madysauridae.
Therioherpeton is an extinct genus of small, carnivorous cynodonts belonging to the clade Prozostrodontia, which lived in what is now Brazil during the Late Triassic. Its type species is Therioherpeton cargnini. It was named in 1975 by the palaeontologists José Bonaparte and Mário Costa Barberena based on remains collected in the Hyperodapedon Assemblage Zone of the Santa Maria Formation in the Paraná Basin.
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.
Ordosiodon is an extinct genus of therocephalian therapsids from the Early Triassic of China. It includes two species, O. lincheyuensis and O. youngi.
The Ermaying Formation is a geological formation of Anisian age in north-central China. It is found across much of the Ordos Basin, at outcrops within the provinces of Shaanxi, Shanxi, and Inner Mongolia. It is composed of up to 600 m thick sequence of mudstone and sandstone, overlying the Heshanggou Formation and underlying the Tongchuan Formation. In the southern part of the Ordos Basin, the Zhifang Formation is equivalent to the Ermaying Formation.
Kunminia is a genus of cynodont synapsids from the Early Jurassic (Sinemurian) Lufeng Formation of China.
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.
Siriusgnathus is a traversodontid cynodont from the Carnian channel sandstones and mudstones of the Candelária Formation, belonging to the Santa Maria Supersequence of the Paraná Basin in southeastern Brazil. It includes one species, Siriusgnathus niemeyerorum and was described in 2018. The species epithet refers to the Niemeyer locality in Agudo, Rio Grande do Sul. It was found together with various archosauromorphs, dinosauromorphs and other cynodonts, such as Brasilitherium riograndensis, Brasilodon quadrangularis, Irajatherium hernandezi and Prozostrodon brasiliensis.
The Omingonde Formation is an Early to Middle Triassic geologic formation, part of the Karoo Supergroup, in the western Otjozondjupa Region and northeastern Erongo Region of north-central Namibia. The formation has a maximum thickness of about 600 metres (2,000 ft) and comprises sandstones, shales, siltstones and conglomerates, was deposited in a fluvial environment, alternating between a meandering and braided river setting.
The Candelária Formation, in other literature also referred to as Candelária Sequence, is a sedimentary formation of the Santa Maria Group in the Paraná Basin in Rio Grande do Sul, southeastern Brazil. The formation dates to the Carnian of the Late Triassic, locally referred to as Tuvalian, from 231.4 to approximately 222 Ma.
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.
