n. Any of various amniote vertebrates that emerged in the Permian Period and diversified in the Triassic, including the mammals, their ancestors, and their relatives. [From New Latin Thērapsida, order name : Greek thēr, wild animal; see THEROPOD + Greek hapsis, hapsid-, arch, vault (from the enlarged lower temporal opening characteristic of the group); see APSIS.] the·rapsid adj. |
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