| Caseasaur Temporal range: Early Permian - Late Permian |
|
|---|---|
| Ennatosaurus tecton from the Late Permian of Russia | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Subphylum: | Vertebrata |
| Class: | Synapsida |
| Order: | Pelycosauria |
| Suborder: | Caseasauria Williston, 1912 |
| Genera and Families | |
The Caseasauria are one of the two main clades of early synapsids, the other being the Eupelycosauria. They are currently known only from the Permian, and include two superficially different families, the small insectivorous or carnivorous Eothyrididae, and the large herbivorous Caseidae
These two groups share a number of specialised features associated with the morphology of the snout and external naris and it is likely that the latter evolved from the former.
The ancestors of Caseasaurs can be traced back from an insect eating or an omnivorous reptile-like synapsid from the Pennsylvanian time of the Carboniferous, that resembles Archaeothyris. The Caseasaurs were abundant and successful during the later part of the early Permian epoch. But by the middle Permian, the Caseasaurs became less abundant because of the evolving, more successful therapsids and by late Permian, they were facing extinction. The last Caseasaurs became extinct in the Permian–Triassic extinction event; no species of Caseasaurs made it to the Triassic Period.