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.
Origin: 1900–05; Related forms
< Neo-Latin Cotylosauria,
equivalent to cotyl
) a hollow space in the bones forming the distinctive articulation of skull and vertebrae, which orig. defined the order (masculine noun < Greek kotýlē
socket, cup, anything hollow) + -o- -o-