Meaning of cotylosaur

cot•y•lo•saur

Pronunciation: (kot'l-u-sôr"), [key]
— n.
  1. any member of the extinct order Cotylosauria, comprising heavy-bodied, splay-limbed, plant-eating reptiles that arose during the Carboniferous Period and that are considered to include the ancestors of all other reptiles.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.