any of a group of large primitive reptiles belonging to the extinct order Pelycosauria, abundant in North America and Europe during the Permian Period, often having a tall spinal sail.
Origin of pelycosaur
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
any extinct mammal-like reptile of the order Pelycosauria, of Upper Carboniferous to Lower Permian times, from which the therapsids are thought to have evolved
Word Origin for pelycosaur
C19: from New Latin Pelycosauria, from Greek pelyx bowl, pelvis, + -saur
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012