Any of a group of amniote vertebrates that are characterized by two openings in the temporal region on each side of the skull. The first diapsids emerged in the Pennsylvanian Period, and their descendants include the lizards, snakes, crocodiles, dinosaurs, pterosaurs, birds, and, in some classifications, the turtles.
Any of various amniotes having a skull with two pairs of temporal openings. Diapsids evolved in the Permian Period and grew longer and better-developed hindlimbs than forelimbs (unlike therapsids). Diapsids evolved into the archosaurs (including the dinosaurs and their descendants the birds) and all modern reptiles except, in some classifications, the turtles.
Origin of diapsid
- New Latin Diapsida taxon name di– Greek hapsis hapsid- arch (from the two temporal openings on each side of the skull) apsis
From American Heritage Dictionary of the English Language, 5th Edition