What is "anapsid"

n. (context biology English) Any amniote whose skull does not have openings near the temples.

n. primitive reptile having no opening in the temporal region of the skull; all extinct except turtles [syn: anapsid reptile] [ant: diapsid]

An anapsid is an amniote whose skull does not have openings near the temples. Traditionally, the Anapsida are the most primitive subclass of reptiles, the ancestral stock from which Synapsida and Diapsida evolved, making anapsids paraphyletic. It is however doubtful that all anapsids lack temporal fenestra as a primitive trait, and that all the groups traditionally seen as anapsids truly lacked fenestra.