Pelycosaur
Informal grouping composed of basal or primitive Late Paleozoic synapsids
Pelycosaur is an older term for basal or primitive Late Paleozoic synapsids, excluding the therapsids and their descendants. Previously, the term mammal-like reptile was used, and Pelycosauria was considered an order, but this is now thought to be incorrect and outdated. The terms stem mammals, protomammals, and basal or primitive synapsids are instead used where needed.