Therapsida is a major group of eupelycosaurian synapsids that includes mammals, 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.
Cistecephalus is an extinct genus of dicynodont therapsid from the Late Permian of southern Africa. It was a small, specialised, burrowing dicynodont, possibly with habits similar to a modern mole. The head was flattened and wedge-shaped, the body long, and the forelimbs very strong, with similarities in structure to the forelimb of modern burrowing mammals.
Galechirus is an extinct genus of anomodont therapsids. It was about 30 cm (1 ft) long.
Ischigualastia is an extinct genus of large dicynodont therapsids that lived during the Late Carnian age and the Early Norian age of the Late Triassic Period. The genus was found in and named after the Ischigualasto Formation of the Ischigualasto-Villa Unión Basin in northwestern Argentina. It has been placed in the family Stahleckeriidae.
Eodicynodon is an extinct genus of dicynodont therapsids, a highly diverse group of herbivorous synapsids that were widespread during the middle-late Permian and early Triassic. As its name suggests, Eodicynodon is the oldest and most primitive dicynodont yet identified, ranging from the middle to late Permian and possessing a mix of ancestral Anomodont/therapsid features and derived dicynodont synapomorphies.
Myosaurus is a genus of Anomodontia in the order Therapsida. They are also classified as Dicynodontia, which is a subclade of Anomodontia. The Mysosaurus was a small, herbivorous reptile that existed around the early Triassic period. All of the fossils found of this species were found in Antarctica and South Africa. Compared to other fossils found from species that existed during this time, the Myosaurus is not common in the fossil record. This is due to a shortage of discovered fossils that possess characteristics unique to the Myosaurus. Notably, under 130 fossil fragments have been found that have been classified as Myosauridae, and almost all have been skulls. These skulls can be classified as Myosaurus because this species, unlike other dicynodonts, do not possess tusks or postfrontal teeth. The only species identified in the family Myosauridae is the Myosaurus Gracilis, or M. Gracilis. It should be recognized that the Myosaurus is almost always referred to as the M. Gracilis in scientific research.
Dimacrodon is an extinct genus of non-mammalian synapsid from the latest Early Permian San Angelo Formation of Texas. It is distinguished by toothless, possibly beaked jaw tips, large lower canines and a thin bony crest on top of its head. Previously thought to be an anomodont therapsid related to dicynodonts, it was later found to lack any diagnostic features of anomodonts or even therapsids and instead appears to be a 'pelycosaur'-grade synapsid of uncertain classification.
Digalodon is an extinct genus of kistecephalian dicynodont. For a time it was considered synonymous with other dicynodonts as a small juvenile of a larger genus, such as Aulacephalodon or Dicynodontoides, however it has since been recognised as a distinct species.
Dicynodontoides is a genus of small to medium-bodied, herbivorous, emydopoid dicynodonts from the Late Permian. The name Dicynodontoides references its “dicynodont-like” appearance due to the caniniform tusks featured by most members of this infraorder. Kingoria, a junior synonym, has been used more widely in the literature than the more obscure Dicynodontoides, which is similar-sounding to another distantly related genus of dicynodont, Dicynodon. Two species are recognized: D. recurvidens from South Africa, and D. nowacki from Tanzania.
Eosimops is an extinct genus of pylaecephalid dicynodonts. They were small synapsids superficially resembling modern mammals. Eosimops is known from several skull specimens, as well as one complete skeleton. Eosimops lived during the Middle Permian of South Africa.
Venyukovioidea is an infraorder of anomodont therapsids related to dicynodonts from the Permian of Russia. They have also been known as 'Venjukovioidea', as well as by the similar names 'Venyukoviamorpha' or 'Venjukoviamorpha' in literature. This in part owes to a misspelling by Russian palaeontologist Ivan Efremov in 1940 when he mistakenly spelt Venyukovia, the namesake of the group, with a 'j' instead of a 'y', which permeated through subsequent therapsid literature before the mistake was caught and corrected. The order Ulemicia has also been coined for a similar taxonomic concept in Russian scientific literature, which notably excludes Suminia and Parasuminia.
Chainosauria is a large and speciose clade of anomodont therapsid that includes the highly diverse dicynodonts and a small number of closely related basal genera —although the total composition and taxonomic scope of Chainosauria is in flux. Chainosauria was named in 1923 to group together the dicynodonts and their close relatives, namely three small anomodont genera from South Africa that made up the now defunct group 'Dromasauria'. The name soon fell into disuse, however, as it was functionally replaced by Anomodontia. Chainosauria was later revived cladistically in 2009, preserving the association of dicynodonts and the 'dromasaurs' and has since served in effect as both a cladistic and a biogeographic counterpart to the Laurasian venyukovioids, with early chainosaurs appearing to have been a Gondwanan radiation.
Pylaecephalidae is a family of dicynodont therapsids that includes Diictodon, Robertia, and Prosictodon from the Permian of South Africa. Pylaecephalids were small burrowing dicynodonts with long tusks. The family was first named in 1934 and was redefined in 2009. Diictodontidae and Robertiidae are considered junior synonyms of Pylaecephalidae; although Pylaecephalus itself is considered a junior synonym of Diictodon, the name Pylaecephalidae predates these names and therefore takes priority.
Dicynodontoidea is an infraorder of dicynodont therapsids that includes the famous dicynodont Dicynodon, Lystrosaurus and the Triassic Kannemeyeriiformes, as well as numerous other closely related species. The name was coined by American paleontologist Everett C. Olson in 1941 as an infraorder, despite using the typical "-oidea" suffix of superfamilies, and was later redefined under a phylogenetic context in 2009 by paleontologist Christian F. Kammerer.
Therochelonia is a group of dicynodont therapsids. The group was named by British paleontologist Harry Seeley in 1894 and fell into disuse in the following century. Therochelonia was redefined as a node-based clade in 2009. It is defined as the last common ancestor of Cistecephalus microrhinus and Dicynodon lacerticeps, and all of its descendants. Below is a simplified cladogram from Kammerer et al. (2011) showing the phylogenetic placement of Therochelonia:
Bidentalia is a group of dicynodont therapsids. Bidentalia was one of the first names used to describe dicynodonts; the group was established in 1876, while the name "bidentals" dates back as far as 1845. With the increasing prominence of phylogenetics, the group was redefined as a clade in 2009. Bidentalia is now considered a stem-based taxon that includes all taxa more closely related to Aulacephalodon bainii and Dicynodon lacerticeps than Emydops arctatus.
Rhachiocephalidae is an extinct family of dicynodont therapsids. It includes two genera from the Late Permian of southern Africa, Rhachiocephalus and Kitchinganomodon. Rhachiocephalids were the largest dicynodonts in the Permian, although the kannemeyeriiform dicynodonts of the Late Triassic grew to larger sizes. Rhachiocephalids are also unusual in that they have long, low skulls.
Niassodon is an extinct genus of endothiodontid dicynodont therapsid known from the Late Permian of Niassa Province, northern Mozambique. It contains a single species, Niassodon mfumukasi.
Rastodon is an extinct genus of dicynodont. Uniquely among dicynodonts, its tusks curve forward. The type and only species is R. procurvidens.
Bulbasaurus is an extinct genus of dicynodont that is known from the Lopingian epoch of the Late Permian period of what is now South Africa, containing the type and only species B. phylloxyron. It was formerly considered as belonging to Tropidostoma; however, due to numerous differences from Tropidostoma in terms of skull morphology and size, it has been reclassified the earliest known member of the family Geikiidae, and the only member of the group known from the Tropidostoma Assemblage Zone. Within the Geikiidae, it has been placed close to Aulacocephalodon, although a more basal position is not implausible.
