1) Synapsid 2) Synapsid reptile 
(from the article `reptile`) ...it in primitive forms; the opening extends upward to the parietal in later forms. Pineal present. Teeth differentiated. Two coracoids in pectoral ... Synapsids (mammal-like reptiles) are divided into two orders: pelycosaurs and therapsids. They show a remarkably complete transition in skeletal ... [2 r...
Pelycosaurs meaning basin lizards) were the earliest synapsids; they were not dinosaurs. These quadrupeds appeared during the upper Carboniferous and went extinct during the Permian period (before the Triassic period when the dinosaurs evolved). Pelycosaurs began as small, lizard-like animals and evolved into larger, more differentiated types. Some...
[n] - large primitive reptile having a tall spinal sail
noun large primitive reptile having a tall spinal sail; of the Permian or late Paleozoic in Europe and North America