WordReference Random House Unabridged Dictionary of American English © 2026
cot•y•lo•saur
(kot′l ə sôr′),USA pronunciation n.
cot′y•lo•sau′ri•an, adj.
- Paleontologyany 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.
- Greek kotýlē socket, cup, anything hollow) + -o- -o- + -sauria; see -saur, -ia
- Neo-Latin Cotylosauria, equivalent. to cotyl(lus) a hollow space in the bones forming the distinctive articulation of skull and vertebrae, which origin, originally defined the order (masculine noun, nominal
- 1900–05