Tiarajudens : A significant mammal-like reptile

Abstract

Popularly known as the 'mammal-like reptiles', the therapsids are well documented in the fossil record. Their abundance in the Karoo basin has made South Africa world renowned for the diversity of Permian and Triassic therapsids. The earliest known therapsid is Raranimus from China's Middle Permian Dashankou Formation, and besides several poorly known taxa (mainly from Russia) six therapsid lineages are well recognised, although there is still controversy concerning their interrelationships: the heavily built, large-bodied Dinocephalia; the Biarmosuchia, which retain many similarities to the sphenacodontian pelycosaurs (better known as the sail-backed reptiles); the carnivorous Therocephalia and Gorgonopsia; the herbivorous Anomodontia; and the Cynodontia (to which mammals and their ancestors belong). Tiarajudens sheds light on the evolution of the Anomodontia.