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.
Robertia is an extinct genus of small herbivorous dicynodonts from the Middle to Late Permian of South Africa, between 260 and 265 million years ago. It is a monospecific genus, consisting of the type-species R. broomiana, which was classified by Lieuwe Dirk Boonstra in 1948 and named in honor of Robert Broom for his study of South African mammal-like reptiles.
Diictodon is an extinct genus of pylaecephalid dicynodont. These mammal-like synapsids lived during the Late Permian period, approximately 255 million years ago. Fossils have been found in the Cistecephalus Assemblage Zone of the Madumabisa Mudstone of the Luangwa Basin in Zambia and the Tropidostoma Assemblage Zone of the Teekloof Formation, Tapinocephalus Assemblage Zone of the Abrahamskraal Formation, Dicynodon Assemblage Zone of the Balfour Formation, Cistecephalus Assemblage Zone of the Middleton or Balfour Formation of South Africa and the Guodikeng Formation of China. Roughly half of all Permian vertebrate specimens found in South Africa are those of Diictodon. This small herbivorous animal was one of the most successful synapsids in the Permian period.
"Dromasaurs" are an artificial grouping of small anomodont therapsids from the Middle and Late Permian of South Africa. They represent either a paraphyletic grade or a polyphyletic grouping of small non-dicynodont basal anomodonts rather than a clade, and as such are considered an invalid group today. "Dromasaurs" were historically united by their superficially similar appearances that were unlike other known anomodonts. They are all small in size with slender limbs and long tails, and have short skulls with very large eye sockets. "Dromasauria" traditionally includes three genera, all from the Karoo Supergroup of South Africa: Galepus, Galechirus, and Galeops. These genera have sometimes been divided into two subgroups, the monotypic family Galeopidae and the Galechiridae for Galechiris and Galepus.
Emydops is an extinct genus of dicynodont therapsids from the Middle Permian to Late Permian of what is now South Africa. The genus is generally small and herbivorous, sharing the dicynodont synapomorphy of bearing two tusks. In the following years, the genus grew to include fourteen species. Many of these species were erected on the basis of differences in the teeth and the positioning of the frontal and parietal bones. A 2008 study narrowed Emydops down to two species, E. arctatus and the newly described E. oweni.
The Tapinocephalus Assemblage Zone is a tetrapod assemblage zone or biozone which correlates to the middle Abrahamskraal Formation, Adelaide Subgroup of the Beaufort Group, a fossiliferous and geologically important geological Group of the Karoo Supergroup in South Africa. The thickest outcrops, reaching approximately 2,000 metres (6,600 ft), occur from Merweville and Leeu-Gamka in its southernmost exposures, from Sutherland through to Beaufort West where outcrops start to only be found in the south-east, north of Oudshoorn and Willowmore, reaching up to areas south of Graaff-Reinet. Its northernmost exposures occur around the towns Fraserburg and Victoria West. The Tapinocephalus Assemblage Zone is the second biozone of the Beaufort Group.
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.
The Tropidostoma Assemblage Zone is a tetrapod assemblage zone or biozone which correlates to the lower Teekloof Formation, Adelaide Subgroup of the Beaufort Group, a fossiliferous and geologically important geological Group of the Karoo Supergroup in South Africa. The thickest outcrops, reaching approximately 240 metres (790 ft), occur from east of Sutherland through to Beaufort West and Victoria West, to areas south of Graaff-Reinet. Its northernmost exposures occur west/north-west of Colesberg. The Tropidostoma Assemblage Zone is the fourth biozone of the Beaufort Group.
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.
Angonisaurus is an extinct genus of kannemeyeriiform dicynodont from the Middle Triassic of Africa between 247 and 242 million years ago. Only one species, Angonisaurus cruickshanki has been assigned to this genus. This genus is thought to have been widely spread but rare in southern Gondwana. Though few in number, the fossil record of Angonisaurus cruickshanki contains multiple specimens giving it a measurable stratigraphic range. Sexually dimorphic features are found in Angonisaurus which include presence or absence of tusks and difference is size and robustness of the temporal arch and the rostral.
Brachyprosopus is an extinct genus of dicynodont therapsid from the middle Permian Tapinocephalus Assemblage Zone in the Abrahamskraal Formation belonging to the Beaufort Group of the Karoo Basin, South Africa.
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.
Koupia is a dubious extinct genus of non-mammalian synapsid. The type species, K. koupensis, was coined by Lieuwe Dirk Boonstra in 1948, with a well-preserved skull from the Tapinocephalus Assemblage Zone of South Africa, SAM-PK-11796, designated the holotype. This specimen has since been lost, and K. koupensis is currently considered a nomen dubium or a possible junior synonym of Brachyprosopus broomi.
Tropidostoma is a medium-sized herbivorous oudenodontid dicynodont therapsid that lived during the Late Permian (Lopingian) period in South Africa. The first Tropidostoma fossil was described by Harry Govier Seeley in 1889. Later two subspecies were identified. Tropidostoma fossils are an index fossil in a biozone of the Karoo Basin known as the Tropidostoma Assemblage Zone. This biozone is characterized by the presence of this species in association with another dicynodont species, Endothiodon uniseries.
Christian Alfred Sidor is an American vertebrate paleontologist. He is currently a Professor in the Department of Biology, University of Washington in Seattle, as well as Curator of Vertebrate Paleontology and Associate Director for Research and Collections at the Burke Museum of Natural History and Culture. His research focuses on Permian and Triassic tetrapod evolution, especially on therapsids.
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.
The Abrahamskraal Formation is a geological formation and is found in numerous localities in the Northern Cape, Western Cape, and the Eastern Cape of South Africa. It is the lowermost formation of the Adelaide Subgroup of the Beaufort Group, a major geological group that forms part of the greater Karoo Supergroup. It represents the first fully terrestrial geological deposits of the Karoo Basin. Outcrops of the Abrahamskraal Formation are found from the small town Middelpos in its westernmost localities, then around Sutherland, the Moordenaarskaroo north of Laingsburg, Williston, Fraserburg, Leeu-Gamka, Loxton, and Victoria West in the Western Cape and Northern Cape. In the Eastern Cape outcrops are known from Rietbron, north of Klipplaat and Grahamstown, and also southwest of East London.
Anomocephaloidea is a clade of basal anomodont therapsids related to the dicynodonts known from what is now South Africa and Brazil during the Middle Permian. It includes only two species, Anomocephalus africanus from the Karoo Basin of South Africa and Tiarajudens eccentricus from the Paraná Basin of Brazil. Anomocephaloidea was named in 2011 with the discovery of Tiarajudens, although Anomocephalus itself has been known since 1999.
