Permian reptiles

Sauria is the clade of diapsids containing the most recent common ancestor of Archosauria (which includes crocodilians and birds) and Lepidosauria (which includes squamates and the tuatara), and all its descendants. Since most molecular phylogenies recover turtles as more closely related to archosaurs than to lepidosaurs as part of Archelosauria, Sauria can be considered the crown group of diapsids, or reptiles in general. Depending on the systematics, Sauria includes all modern reptiles or most of them (including birds, a type of archosaur) as well as various extinct groups.

Parareptilia ("near-reptiles") is an extinct subclass of basal sauropsids ("reptiles"). Traditionally considered the sister taxon to Eureptilia (the group that likely contains all living reptiles and birds), its validity as a monophyletic clade has been disputed by modern cladistic analyses.

Millerettidae is an extinct family of early reptiles from the Middle Permian to the Late Permian period (Capitanian - Changhsingian stages) of South Africa and possibly Russia. Although they were interpreted as a group of 'parareptiles', recent anatomical studies and phylogenetic analyses have suggested that they are better interpreted as close relatives of the Neodiapsida as part of the larger clade Parapleurota. The millerettids were small insectivores and probably resembled modern lizards in appearance and lifestyle, even possessing a tympanum, or eardrum, on the side of their skull.

Procolophon (from , 'before' and , 'summit') is a genus of lizard-like procolophonid parareptiles that first appeared in the Early Triassic (Induan) of South Africa, Brazil, and Antarctica. It persisted through the Permian–Triassic extinction event, but went extinct in the beginning of the Early Middle Triassic.

Procolophonia is an extinct clade of basal reptiles, traditionally classified as "parareptiles", that lived from the Middle Permian till the end of the Triassic period. The group includes the largest known parareptiles, the up to oxen-sized herbivorous pareiasaurs, as well as the longest lived "parareptiles", the small lizard-like procolophonoids. Although traditionally grouped in Parareptilia, this classification scheme has been questioned.

Bolosauridae is an extinct family of amniotes known from the latest Carboniferous (Gzhelian) or earliest Permian (Asselian) to the early Guadalupian epoch (latest Roadian stage) of North America, China, Germany, Russia and France. The bolosaurids were unusual for their time period by being bipedal, the oldest known tetrapods to have been so. Their teeth suggest that they were herbivores. The bolosaurids were a rare group and died out without any known descendants.

thumb|left|Restoration

Avicephala ("bird heads") is a potentially polyphyletic grouping of extinct diapsid reptiles that lived during the Late Permian and Triassic periods characterised by superficially bird-like skulls and arboreal lifestyles. As a clade, Avicephala is defined as including the gliding weigeltisaurids and the arboreal drepanosaurs to the exclusion of other major diapsid groups. This relationship is not recovered in the majority of phylogenetic analyses of early diapsids and so Avicephala is typically regarded as an artificial or unnatural grouping. However, the clade was recovered again in 2021 foll

thumb|Skull dome of Stegoceras (AMNH 5450) showing cross-section thickness

Ankyramorpha ("anchor forms") is a proposed clade of early stem reptiles which lived between the early Cisuralian epoch (middle Sakmarian stage) and the latest Triassic period (latest Rhaetian stage) of Africa, Antarctica, Asia, Australia, Europe, North America and South America.

Deltavjatia is an extinct species of pareiasauromorph procolophonoid from the Tatarian stage of the Permian time period. It had a large body of about in length. Deltavjatia was an herbivore and lived in what is now Russia. The first specimen of Deltavjatia was a specimen of a skull and lower mandible (PIN 2212/1), found in the Urpalov Formation in Kotelnich, Vyatka River. Since then, numerous mostly complete skeletons have been found, many of them being so well preserved due to the silty, anaerobic environment of the Kotelnich deposits that fossilised white blood cells are able to be distingui

Lanthanosuchidae is a family of procolophonomorph parareptiles that lived 268–255 million years ago. The group was named in 1946 by Ivan Antonovich Efremov.