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.