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Any of various large reptilelike extinct tetrapods of the Carboniferous and Permian Periods, traditionally placed in the order Cotylosauria.
[Greek kotulē, hollow object, socket + Greek sauros, lizard.]
(Animals) any of various members of the extinct order of primitive and massive reptiles known as Cotylosauria, which lived between the Carboniferous and Triassic ages
cot•y•lo•saur(ˈkɒt l əˌsɔr)
any reptile of the extinct order Cotylosauria, comprising heavy-bodied splay-limbed forms that arose during the Pennsylvanian Period and that include the ancestors of all other reptiles.
[1900–05; < New Latin Cotylosauria < Greek kotýl(ē) socket, cup + New Latin -o- -o- + -sauria; see -saur, -ia]