Dinocephalians are a clade of large-bodied early therapsids that flourished in the Early and Middle Permian between 279.5 and 260 million years ago (Ma), but became extinct during the Capitanian mass extinction event. Dinocephalians included herbivorous, carnivorous, and omnivorous forms. Many species had thickened skulls with many knobs and bony projections. Dinocephalians were the first non-mammalian therapsids to be scientifically described and their fossils are known from Russia, China, Brazil, South Africa, Zimbabwe, and Tanzania.
Gorgonopsia is an extinct clade of sabre-toothed therapsids from the Middle to Upper Permian roughly 265 to 252 million years ago. They are characterised by a long and narrow skull, as well as elongated upper and sometimes lower canine teeth and incisors which were likely used as slashing and stabbing weapons. Postcanine teeth are generally reduced or absent. For hunting large prey, they possibly used a bite-and-retreat tactic, ambushing and taking a debilitating bite out of the target, and following it at a safe distance before its injuries exhausted it, whereupon the gorgonopsian would grapple the animal and deliver a killing bite. They would have had an exorbitant gape, possibly in excess of 90°, without having to unhinge the jaw.
Ericiolacerta is an extinct genus of small therocephalian therapsids from the early Triassic of South Africa and Antarctica. Ericiolacerta, meaning "hedgehog lizard", was named by D.M.S. Watson in 1931. The species E. parva is known from the holotype specimen which consists of a nearly complete skeleton found in the Lystrosaurus Assemblage Zone within the Katberg Formation of the Beaufort Group in South Africa, and from a partial jaw found in the Lower Triassic Fremouw Formation in Antarctica. Ericiolacerta was around 20 centimetres (7.9 in) in length, with long limbs and relatively small teeth. It probably ate insects and other small invertebrates. The therocephalians – therapsids with mammal-like heads – were abundant in Permian times, but only a few made it into the Triassic. Ericiolacerta was one of those. It is possible that they gave rise to the cynodonts, the only therapsid group to survive into post-Triassic times. Cynodonts gave rise to mammals.
Therocephalia is an extinct clade of eutheriodont therapsids from the Permian and Triassic. The therocephalians ("beast-heads") are named after their large skulls, which, along with the structure of their teeth, suggest that they were carnivores. Like other non-mammalian synapsids, therocephalians were once described as "mammal-like reptiles". Therocephalia is the group most closely related to the cynodonts, which gave rise to the mammals. This relationship takes evidence in a variety of skeletal features.
The theriodonts are a major group of therapsids which appeared during the Middle Permian and which includes the gorgonopsians and the eutheriodonts, itself including the therocephalians and the cynodonts.
Euchambersia is an extinct genus of therocephalian therapsids that lived during the Late Permian in what is now South Africa and China. The genus contains two species. The type species E. mirabilis was named by paleontologist Robert Broom in 1931 from a skull missing the lower jaw. A second skull, belonging to a probably immature individual, was later described. In 2022, a second species, E. liuyudongi, was named by Jun Liu and Fernando Abdala from a well-preserved skull. It is a member of the family Akidnognathidae, which historically has also been referred by as the synonymous Euchambersiidae.
Moschorhinus is an extinct genus of therocephalian synapsid in the family Akidnognathidae with only one species: M. kitchingi, which has been found in the Late Permian to Early Triassic of the South African Karoo Supergroup. It was a large carnivorous therapsid, reaching 1.5 m (4.9 ft) in total body length with the largest skull comparable to that of a lion in size, and had a broad, blunt snout which bore long, straight canines.
Viatkogorgon is a genus of gorgonopsian that lived during the Permian period in what is now Russia. The first fossil was found at the Kotelnich locality near the Vyatka River and was made the holotype of the new genus and species V. ivachnenkoi in 1999. The generic name refers to the river and the related genus Gorgonops—the gorgons of Greek mythology are often referenced in the names of the group. The specific name honors the paleontologist Mikhail F. Ivakhnenko. The holotype skeleton is one of the most complete gorgonopsian specimens known and includes rarely preserved elements such as gastralia and a sclerotic ring. A larger, but poorly preserved specimen has also been assigned to the species.
Biseridens is an extinct genus of anomodont therapsid, and one of the most basal anomodont genera known. Originally known from a partial skull misidentified as an eotitanosuchian in 1997, another well-preserved skull was found in the Qingtoushan Formation in the Qilian Mountains of Gansu, China, in 2009 that clarified its relationships to anomodonts, such as the dicynodonts.
Glanosuchus is a genus of scylacosaurid therocephalian from the Late Permian of South Africa. The type species G. macrops was named by Robert Broom in 1904. Glanosuchus had a middle ear structure that was intermediate between that of early therapsids and mammals. Ridges in the nasal cavity of Glanosuchus suggest it had an at least partially endothermic metabolism similar to modern mammals.
Microgomphodon is an extinct genus of therocephalian therapsid from the Middle Triassic of South Africa and Namibia. Currently only one species of Microgomphodon, M. oligocynus, is recognized. With fossils present in the Cynognathus Assemblage Zone (CAZ) of the Burgersdorp Formation in South Africa and Omingonde Formation of Namibia and ranging in age from late Olenekian to Anisian, it is one of the most geographically and temporally widespread therocephalian species. Moreover, its occurrence in the upper Omigonde Formation of Namibia makes Microgomphodon the latest-surviving therocephalian. Microgomphodon is a member of the family Bauriidae and a close relative of Bauria, another South African bauriid from the CAZ. Like other bauriids, it possesses several mammal-like features such as a secondary palate and broad, molar-like postcanine teeth, all of which evolved independently from mammals.
Bauriidae is an extinct family of therocephalian therapsids. Bauriids were the latest-surviving group of therocephalians after the Permian–Triassic extinction event, going extinct in the Middle Triassic. They are among the most advanced eutherocephalians and possess several mammal-like features such as a secondary palate and wide postcanine teeth at the back of the jaws. Unlike other therocephalians, bauriids were herbivorous. They were also smaller than earlier members of the group. Two subfamilies are classified within Bauriidae: Nothogomphodontinae and Bauriinae.
Purlovia is an extinct genus of herbivorous therocephalian therapsids from the Late Permian of Russia. Together with the closely related South African genus Nanictidops, it is a member of the family Nanictidopidae. Fossils have been found from the Tonshayevsky District of Nizhny Novgorod Oblast. The type species of Purlovia, P. maxima, was named in 2011.
Silphedosuchus is an extinct genus of therocephalian therapsids from the Early Triassic of Russia. It is a member of the family Ericiolacertidae, along with the genus Ericiolacerta from South Africa and Antarctica. The type species Silphedosuchus orenburgensis was described in 1977 on the basis of a single holotype skull from Orenburg Oblast.
Blattoidealestes is an extinct genus of therocephalian therapsid from the Middle Permian of South Africa. The type species Blattoidealestes gracilis was named by South African paleontologist Lieuwe Dirk Boonstra from the Tapinocephalus Assemblage Zone in 1954. Dating back to the Middle Permian, Blattoidealestes is one of the oldest therocephalians. It is similar in appearance to the small therocephalian Perplexisaurus from Russia, and may be closely related.
Homodontosaurus is an extinct genus of therocephalian therapsids from the Late Permian of South Africa. The type species Homodontosaurus kitchingi was named by South African paleontologist Robert Broom in 1949. Broom based his description on a small skull found in the Cistecephalus Assemblage Zone near Graaff-Reinet. The skull is very small, at about 55 millimetres (2.2 in) long and 20 millimetres (0.79 in) wide. Homodontosaurus has large eye sockets and an elongated snout. The lower jaw is long, thin, and curved. Numerous small teeth line the upper jaw and are long, pointed, and round in cross-section.
Silpholestes is an extinct genus of therocephalian therapsids from the Late Permian of South Africa. The type species Silpholestes jackae was named by South African paleontologist Robert Broom in 1948 from the Cistecephalus Assemblage Zone.
Ictidodraco is an extinct genus of therocephalian therapsids from the Late Permian of South Africa. The type species Ictidodraco longiceps was named by South African paleontologists Robert Broom and John T. Robinson in 1948 from the Cistecephalus Assemblage Zone. Ictidodraco was once classified as a scaloposaurian in the family Silpholestidae. Scaloposauria and Silpholestidae are no longer regarded as valid groups, and Ictidodraco is now classified as a basal member of the clade Baurioidea.
Karenites is an extinct genus of therocephalian therapsids from the Late Permian of Russia. The only species is Karenites ornamentatus, named in 1995. Several fossil specimens are known from the town of Kotelnich in Kirov Oblast.
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.
