Eureptilia

Eureptilia ("true reptiles") is one of the two major clades of the Sauropsida, the other being Parareptilia. Eureptilia includes not only all Diapsids, but also a number of primitive Permo-Carboniferous forms previously classified under the Anapsida, in the old (no longer recognised) order "Cotylosauria".
Primitive were all small, superficially lizard-like forms, that probably scurried through the Paleozoic undergrowth in search of insects. The diapsids are the only eureptilian clade to continue beyond the Permian Period. Eureptilia is characterized by the skull having greatly reduced supraoccipital, tabular, and supratemporal bones that are no longer in contact with the postorbital.
Classification.
Eureptilia was defined as a stem-based clade, specifically, the most inclusive clade containing "Captorhinus aguti" and "Petrolacosaurus kansensis" but not "Procolophon trigoniceps", by Tsuji and Müller (2009). The cladogram here was modified after Muller and Reisz (2006):