The Collaborative International Dictionary of English v.0.48:
Pelycosauria \Pelycosauria\ prop. n. 1. An order of extinct reptiles including edaphosaurus and dimetrodon. Syn: order Pelycosauria. [WordNet 1.5]WordNet (r) 3.0 (2006):
Pelycosauria n 1: edaphosaurus; dimetrodon [syn: Pelycosauria, order Pelycosauria]