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 whether all anapsids lack temporal fenestra as a primitive trait, or whether all the groups traditionally seen as anapsids truly lacked fenestra.