a large fossil reptile of the late Carboniferous and Permian periods, typically having a line of long bony spines along the back supporting a sail-like crest.
Order Pelycosauria, subclass Synapsida: several families and genera, including Dimetrodon and Edaphosaurus
Origin:
early 20th century: from Greek pelux, peluk- 'bowl' + sauros 'lizard'
pelycosaur in other Oxford dictionaries
Definition of pelycosaur in the US English dictionary
