noun 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; <
Neo-Latin Cotylosauria, equivalent to
cotyl(
lus) 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- +
-sauria; see
-saur,
-ia Related forms cot·y·lo·sau·ri·an, adjective