Noun
reptile having a pair of openings in the skull behind each eye
Source: WordNetAll Permian anapsid reptiles died out except the procolophonids ( testudines have anapsid skulls but are most often thought to have evolved later, from diapsid ancestors). Source: Internet
Firstly, all known diapsids are uricotelic, meaning they excrete uric acid as nitrogenous waste, and there is no known case of a diapsid re-evolving ureotelism, or the excretion of urea, even when they return to semi-aquatic lifestyles. Source: Internet