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.
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.
Biarmosuchia is an extinct clade of non-mammalian synapsids from the Permian. Biarmosuchians are the most basal group of the therapsids. They were moderately-sized, lightly built carnivores, intermediate in form between basal sphenacodont "pelycosaurs" and more advanced therapsids. Biarmosuchians were rare components of Permian ecosystems, and the majority of species belong to the clade Burnetiamorpha, which are characterized by elaborate cranial ornamentation.
Burnetiidae is an extinct family of biarmosuchian therapsids that lived in the Permian period whose fossils are found in South Africa and Russia. It contains Bondoceras, Bullacephalus, Burnetia, Mobaceras, Niuksenitia, Paraburnetia and Proburnetia.
Lemurosaurus is a genus of extinct biarmosuchian therapsids from the Late Permian of South Africa. The generic epithet Lemursaurus is a mix of Latin, lemures “ghosts, spirits”, and Greek, sauros, “lizard”. Lemurosaurus is easily identifiable by its prominent eye crests, and large eyes. The name Lemurosaurus pricei was coined by paleontologist Robert Broom in 1949, based on a single small crushed skull, measured at approximately 86 millimeters in length, found on the Dorsfontein farm in Graaff-Reinet. To date, only two skulls of the Lemurosaurus have been discovered, so body size is unknown. The second larger, more intact, skull was found in 1974 by a team from the National Museum, Bloemfontein.
Burnetia is an extinct genus of biarmosuchian therapsids in the family Burnetiidae, from the Late Permian of South Africa. Burnetia is known so far from a single holotype skull lacking the lower jaws described by South African paleontologist Robert Broom in 1923. Due to erosion and dorsoventral crushing, features of the skull are hard to interpret. Stutural lines are further distorted by the unusual shape of the skull roof, including many bosses and protuberances.
Paraburnetia is an extinct genus of biarmosuchian therapsids from the Late Permian of South Africa. It is known for its species P. sneeubergensis and belongs to the family Burnetiidae. Paraburnetia lived just before the Permian–Triassic mass extinction event.
Lobalopex is an extinct genus of biarmosuchian therapsids. It was alive during the Late Permian and has only been found in the Teekloof Formation in South Africa. The only known species of the genus is Lobalopex mordax. Lobalopex is part of the clade of Burnetiamorpha, which have fossil specimens located in multiple areas of Africa and Russia.
Ictidorhinus is an extinct genus of biarmosuchian therapsids. Fossils have been found from the Dicynodon Assemblage Zone of the Beaufort Group in the Karoo Basin, South Africa and are of Late Permian age. It had a short snout and proportionally large orbits. These characteristics may be representative of a juvenile animal, possibly of Lycaenodon. However, these two genera are not known to have existed at the same time, making it unlikely for Ictidorhinus material to be from a juvenile form of Lycaenodon.
Hipposaurus is an extinct genus of basal therapsids known from the Tapinocephalus Assemblage Zone of the Main Karoo Basin, South Africa. Chronologically this is within the Capitanian stage of the Guadalupian Series. The genus was first described by S.H. Haughton as H. boonstrai on the basis of a skull and associated skeleton and was later considered a gorgonopsian in the family 'Ictidorhinidae' by Robert Broom. It is now considered a basal biarmosuchian, but its affinities remain uncertain. H.boonstrai is currently known from only two specimens in the Iziko South African Museum, Cape Town.
Hipposauroides is an extinct genus of biarmosuchian therapsids from the Late Permian of South Africa.
Lycaenodon is an extinct genus of biarmosuchian therapsids from the Late Permian of South Africa. It is known from a single species, Lycaenodon longiceps, which was named by South African paleontologist Robert Broom in 1925. Both are small-bodied biarmosuchians. Two specimens are known, and both preserve only the front portions of the skull. These specimens come from the Cistecephalus Assemblage Zone of the Karoo Basin. Broom attributed the back portion of a third skull to Lycaenodon, but subsequent examiners considered it to belong to a gorgonopsian or dinocephalian and not a biarmosuchian. Most of the distinguishing features of Lycaenodon come from its palate. As a member of Biarmosuchia, the most basal group of therapsids, Lycaenodon shares many features with earlier and less mammal-like synapsids like Dimetrodon.
Pachydectes is an extinct genus of biarmosuchian therapsids from the Middle Permian of South Africa known from a single skull. The etymology of the name Pachydectes is derived from the Greek word pakhus, meaning "thick" or "thickened", and dektes, meaning "biter". In conjunction this name is representative of the unique pachyostotic bone present above the maxillary canine tooth found in the skull of the specimen. There is only one known species within the genus, Pachydectes elsi which is named in honor of the person who discovered the fossil.
Lophorhinus is an extinct genus of biarmosuchian therapsids from the Late Permian of South Africa. The type species L. willodenensis was named in 2007. It is known from the anterior half of a skull.
Herpetoskylax is an extinct genus of biarmosuchians which existed in South Africa. The type species is Herpetoskylax hopsoni. It lived in the Late Permian Period.
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.
Burnetiamorpha is a clade of biarmosuchian therapsids. Burnetiamorphs are the most derived biarmosuchians. The name Burnetiamorpha has been in use since South African paleontologist Robert Broom erected the group in 1923, but it has recently been put to use in phylogenetic classification as a clade including Burnetiidae and its closest relatives, including Lemurosaurus, Lophorhinus, and Lobalopex.
Ustia is an extinct genus of biarmosuchian therapsids from the Middle Permian of Russia. It is known from a single species, Ustia atra, which was described in 2003 from an isolated lower jaw. Ustia was classified in the family Ictidorhinidae, which also includes the genus Ictidorhinus from South Africa. Both are relatively small biarmosuchians. Several other Russian therapsids known only from lower jaw bones have been placed in Ictidorhinidae, and the family is likely a paraphyletic assemblage representing a small body type than a true clade.
Lende is an extinct genus of biarmosuchian from Malawi. It contains one species, Lende chiweta, first described by Jacobs and colleagues in 2005 and is a burnetiamorph – a group of biarmosuchians characterized by numerous bosses and swellings on the skull. The type specimen was discovered in the early 1990s in the Permian Lower Bone Bed (B1) of the Chiweta Beds of Malawi, which are believed to correlate with the Cistecephalus Assemblage Zone of the South African Karoo Supergroup, the Usili Formation of Tanzania, and the Upper Madumabisa Mudstone of Zambia. The holotype of the genus Lende is MAL 290, which comprises an almost complete skull and lower jaw.
Leucocephalus is a genus of biarmosuchian belonging to the family Burnetiidae dating to the Wuchiapingian. It was found in the Tropidostoma Assemblage Zone of the Main Karoo Basin of South Africa. It is a monotypic taxon which contains one only species, Leucocephalus wewersi. The genus name Leucocephalus is derived from Greek. Leucos, meaning white; kephalos, meaning skull, as the Leucocephalus skull discovered was unusually pale. The species epithet wewersi comes from the farm employee who found the skull, Klaus ‘Klaasie’ Wewers.
