The therapsids include all mammals plus the many mammal-like reptiles, such as Dicynodon and the sabre-toothed gorgonopsids. The therapsids rose to prominence in the Permian to become the most successful land animals of their day. The secret of their success was in their teeth, as therapsids evolved new and better methods of chewing plant and animal food. However, the group took a hammering in the mass extinction at the end of the Permian, and was sidelined for millions of years as the dinosaurs diversified. The therapsids' ultimate successors - mammals - now rule the Earth courtesy of those efficient therapsid teeth and jaws.
Scientific name: Therapsida
South Africa's lifeless Karoo Basin was once an oasis for strange, forgotten creatures.
Almost 300 million years ago, South Africa's barren Karoo Basin was an oasis for strange and forgotten creatures. It was a stable world until a cataclysmic event caused almost every living thing to die. This programme was first shown in 2002.
Discover what these behaviours are and how different plants and animals use them.
Additional data source: Animal Diversity Web
Discover the other animals and plants that lived during the following geological time periods.
Learn more about the other animals and plants that also form these fossils.
Therapsida is a group of synapsids, and includes mammals and their ancestors. Many of the traits today seen as unique to mammals had their origin within early therapsids, including an erect posture. The earliest fossil attributed to Therapsida is Tetraceratops insignis from the Lower Permian. Therapsids evolved from pelycosaurs (specifically sphenacodonts) 275 million years ago. They replaced the pelycosaurs as the dominant large land animals in the Middle Permian and were replaced, in turn, by the archosauromorphs in the Triassic, although one group of therapsids, the kannemeyeriiforms, remained diverse in the Late Triassic. The therapsids included the cynodonts, the group that gave rise to mammals in the Late Triassic around 225 million years ago. Of the non-mammalian therapsids, only cynodonts and dicynodonts survived the Triassic–Jurassic extinction event. The last of the non-mammalian therapsids, the tritylodontid cynodonts, became extinct in the Early Cretaceous, approximately 100 million years ago.