from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Any of an extinct order (Cotylosauria) of massive primitive reptiles of the Carboniferous and Permian periods that included the ancestors of all of the reptiles. Also called root reptile, stem reptile.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A member of the Captorhinidae, the earliest group of true reptiles from the Carboniferous through the Permian.
from The Century Dictionary and Cyclopedia
- n. Any member of the order Cotylosauria.
Greek kotulē, hollow object, socket + Greek sauros, lizard.(American Heritage® Dictionary of the English Language, Fourth Edition)