Dicynodontia is an extinct clade of anomodonts, an extinct type of non-mammalian therapsid. Dicynodonts were herbivores that typically bore a pair of tusks, hence their name, which means 'two dog tooth'. Members of the group possessed a horny, typically toothless beak, unique amongst all synapsids. Dicynodonts first appeared in Southern Pangaea during the mid-Permian, ca. 270–260 million years ago, and became globally distributed and the dominant herbivorous animals in the Late Permian, ca. 260–252 Mya. They were devastated by the end-Permian Extinction that wiped out most other therapsids ca. 252 Mya. They rebounded during the Triassic but died out towards the end of that period. They were the most successful and diverse of the non-mammalian therapsids, with over 70 genera known, varying from rat-sized burrowers to elephant-sized browsers.
The Daptocephalus Assemblage Zone is a tetrapod assemblage zone or biozone found in the Adelaide Subgroup of the Beaufort Group, a majorly fossiliferous and geologically important geological Group of the Karoo Supergroup in South Africa. This biozone has outcrops located in the upper Teekloof Formation west of 24°E, the majority of the Balfour Formation east of 24°E, and the Normandien Formation in the north. It has numerous localities which are spread out from Colesberg in the Northern Cape, Graaff-Reniet to Mthatha in the Eastern Cape, and from Bloemfontein to Harrismith in the Free State. The Daptocephalus Assemblage Zone is one of eight biozones found in the Beaufort Group and is considered Late Permian (Lopingian) in age. Its contact with the overlying Lystrosaurus Assemblage Zone marks the Permian-Triassic boundary.
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.
Geikia is an extinct genus of dicynodont therapsids from the late Permian. The abundance and diversity of dicynodonts during this period, combined with incomplete or inadequately prepared specimens, have led to challenges in determining relationships within this taxon. Only two species, Geikia locusticeps and Geikia elginensis have been assigned to this genus. While this is the currently accepted classification, fossil record limitations have led to repeated debate on the genus assignments of these species.
Kwazulusaurus is an extinct genus of dicynodont therapsid from the Late Permian of South Africa. The type species K. shakai was described from the Dicynodon Assemblage Zone of the Beaufort Group in 2002. It has many similarities with the well-known dicynodont Lystrosaurus, and has been placed in the same family, Lystrosauridae. Kwazulusaurus appears to be transitional between early dicynodonts and the more derived Lystrosaurus; it has the wide skull roof of earlier dicynodonts, and a shortened snout like that of Lystrosaurus.
Odontocyclops is an extinct genus of Dicynodonts that lived in the Late Permian. Dicynodonts are believed to be the first major assemblage of terrestrial herbivores. Fossils of Odontocyclops have been found in the Karoo Basin of South Africa and the Luangwa Valley of Zambia. The phylogenetic classification of Odontocyclops has been long under debate, but most current research places them as their own genus of Dicynodonts and being very closely related to Rhachiocephalus and Oudenodon.
Pelanomodon is an extinct genus of dicynodont therapsids that lived in the Late Permian period. Fossil evidence of this genus is principally found in the Karoo Basin of South Africa, in the Dicynodon Assemblage Zone. Lack of fossil record after the Late Permian epoch suggests that Pelanomodon fell victim to the Permian-Triassic extinction event.
Tetragonias is an extinct genus of dicynodont from the Anisian Manda Beds of Tanzania. With tetra meaning “four,” and goni meaning “angle,” the name references the square shape of the Tetragonias skull when viewed dorsally. Not to be confused with the plant Tetragonia,Tetragonias were dicynodont anomodonts discovered in the late 1960s by paleontologist A. R. I. Cruickshank in the Manda Formation. Only the type species, T. njalilus, has been recognized.
Lystrosauridae is a family of dicynodont therapsids from the Permian and Triassic time periods. It includes two genera, Lystrosaurus and Kwazulusaurus. Kwazulusaurus includes a single species, K. shakai, from the Late Permian of South Africa and Lystrosaurus includes many species from the Late Permian and Early Triassic of South Africa, India, and Antarctica.
Elph is an extinct genus of dicynodont therapsids from Russia. Four specimens have been found from the Sokolki Assemblage in European Russia, representing a fauna that dates back to the Late Permian. The holotype, PIN 2353/37, was originally considered a juvenile specimen due to its small size, before being recognized as a mature individual.
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.
Syops is an extinct genus of dicynodont therapsid. The type species S. vanhoepeni was first named in 1938 as Dicynodon vanhoepeni. Fossils of the genus have been found in the Cistecephalus Assemblage Zone in the Usili Formation of the Ruhuhu Basin, Tanzania and the Upper Madumabisa Mudstone Formation of the Luangwa Basin, Zambia. Its phylogenetic placement is somewhat uncertain, with multiple different studies finding it as either a basal geikiid, rhachiocephalid a dicynodontoid more derived than the most basal genera but less derived than Lystrosauridae, or a lystrosaurid.
Gordonia is an extinct genus of dicynodont therapsid from the Late Permian of Scotland. Fossils have been found from the Elgin sandstone of Cutties Hillock Sandstone in Elgin, Moray. These are among the many amniote fossils referred to as the Elgin Reptiles. Gordonia was named in 1893 with four species: G. traquairi, G. duffiana, G. huxleyana, and G. juddiana. Currently, the only recognized species is the type G. traquairi. All other species are considered synonyms of the type.
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.
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.
Kunpania is an extinct genus of dicynodont therapsid from the Quanzijie Formation of Xinjiang, China. The type and only species is K. scopulusa, and it is known only by a single incomplete specimen including parts of the skull and forelimb. Since its initial description in 1978 by palaeontologist Ailing Sun, it has sometimes been considered to be another species of Dicynodon by other researchers, or potentially undiagnostic. However, a redescription in 2021 reaffirmed its distinctiveness, including a uniquely well developed muscle attachment on the humerus. Kunpania is perhaps the oldest known member of the derived dicynodont group Dicynodontoidea, potentially dating to the Middle Permian period during the Capitanian, and so may fill a knowledge gap in the history of dicynodont evolution.
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 Aulacephalodon, although a more basal position is not implausible.
Counillonia is an extinct genus of dicynodont therapsid from the area of Luang Prabang in Laos, Southeast Asia that lived at around the time of the Permian-Triassic boundary and possibly dates to the earliest Early Triassic. Its type and only known species is C. superoculis. Counillonia was related to the Triassic dicynodonts such as Lystrosaurus and the Kannemeyeriiformes that survived the Permian mass extinction, but it was more closely related to the Permian genus Dicynodon than to either of these lineages. Counillonia may then possibly represent another line of dicynodonts that survived the Permian mass extinction into the Triassic period, depending on its age. The discovery of Counillonia in Laos and its unexpected evolutionary relationships hint at the less well understood geographies of dicynodont diversity across the Permo-Triassic boundary outside of well explored regions like the Karoo Basin in South Africa.
Repelinosaurus is an extinct genus of dicynodont from the Purple Claystone Formation of Luang Prabang in Laos, Southeast Asia that lived at around the time of the Permian-Triassic boundary and possibly dates to the earliest Early Triassic. Its type and only known species is R. robustus. Repelinosaurus was originally described as the earliest known kannemeyeriiform dicynodont, supporting the idea of a more rapid radiation of the Triassic kannemeyeriiform dicynodonts during the Early Triassic following the Permian mass extinction. However, it may alternatively be more closely related to the Permian Dicynodon. The discovery of a potential early kannemeyeriiform in an understudied locality like Laos highlights the importance of such places in dicynodont research, which has been largely focused on historically important localities such as the Karoo Basin of South Africa.
Taoheodon is an extinct genus of dicynodont therapsid from the Sunjiagou Formation in the Shanxi province of China, dated to the Wuchiapingian age of the Late Permian. Its type and only known species is T. baizhijuni. Taoheodon was a close relative of the well known Dicynodon, and may represent a biogeographical link between the South African Dicynodon and similar dicynodonts found in Laos.
