Category:Synapsids

Synapsids or theropsids, are a group of animals more closely related to mammals than to other living amniotes. The non-mammalian members are described as mammal-like reptiles in classical systematics, and they can also be called "stem mammals" or "proto-mammals". Synapsids were the largest terrestrial vertebrates in the Permian period, 299 to 251 million years ago.