Leucocephalus is a genus of biarmosuchian belonging to the family Burnetiidae dating to the Wuchiapingian (Late Permian).[1] 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.[1] 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.[1]
Biarmosuchians are a group of some of the earliest therapsids, a group of synapsids including mammals and their ancestors.[2]
The skull of Leucocephalus was found in the Tropidostoma Assemblage Zone (Tropidostoma) of the Main Karoo Basin of South Africa.[1] Only a single skull was found which was located in 2012 at a farm called Amandelboom in Northern Cape Province.[1] It was found on a slope with strata that hosted a tetrapod fossil assemblage to the lower Tropidostoma AZ by a local sheep herder who then hung it on a fence on his farm. Although the skull was outside of its site of burial, strata stuck to it was verified to match that of the adjacent cliff section.[1]
The biostratigraphic occurrence of the skull was in the lowermost Tropidostoma Assemblage Zone. Based on previous dating of the surrounding strata, the Leucocephalus skull is estimated to be around 259 Ma.[1] Other Late Permian therapsids have been collected from the same interval and vicinity including dicynodonts (Pristerodon mackay, Tropidostoma dubium, Diictodon feliceps), a gorgonopsian, and a pareiasaur.[1] Based on discoveries of early therapsids and biarmosuchians, what is now southern Africa may have been the area of origin for burnetiamorphs.[3]
During the period Leucocephalus lived, what is considered the most extensive mass extinction in the history of the earth was occurring,[4] which caused over 80% of the all Earth's species to go extinct.[5] The cause of this end-Permian mass extinction is hypothesized to be climate change induced by volcanic CO2 degassing[6] which lead to a cascade of biotic response.[7]
Compared to their pelycosaur ancestors, Leucocephalus and other early therapsids are distinguished by more vertical (mammal like) leg positioning beneath their bodies, larger temporal fenestra and increased jaw complexity and power.[2]