Any of a group of amniote vertebrates that first emerged in the late Permian Period, characterized by a single opening in the temporal region on each side of the skull and including the mammals along with various extinct groups more closely related to mammals than to other amniotes.
Any of various amniotes with one temporal opening on each side of the skull. Synapsids emerged in the late Permian Period and were characterized by carrying their limbs under their body and developing front teeth that were different from their back teeth. One group of synapsids, the therapsids, gave rise to the mammals.
Origin of synapsid
New Latin Synapsida taxon name syn- Greek hapsis hapsid- arch (from the former belief that the single temporal opening on each side of the synapsid skull evolved by the fusion of the two temporal openings on each side of the diapsid skull) apsis