anapsid

adjective

1. belonging or pertaining to the Anapsida, a subclass of reptiles, extinct except for the turtles, characterized by having no opening in the temporal region of the skull.

noun

2. a reptile of the subclass Anapsida.

1. Any of a group of mostly extinct reptiles having a skull with no temporal openings. Anapsids first appeared in the Permian Period. Modern turtles and tortoises may be surviving members of this group, or they may be descendants of diapsids that lost their skull openings. Compare diapsid synapsid therapsid.