Parareptilia

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.

Millerosauria is a proposed extinct order of early reptiles that contains the families Millerettidae and Eunotosauridae. It was named in 1957 by Watson and represents a group of reptiles that were thought to be ancestral to Eosuchia (a now-defunct clade roughly corresponding to the non-saurian Neodiapsida) and modern reptiles. Many cladistic studies have interpreted members of the Millerosauria as an early-diverging group of 'parareptiles', but some phylogenetic analyses have demonstrated that 'Parareptilia' represents a group of unrelated early reptiles and is therefore polyphyletic. In 2025,

Erpetonyx is an extinct genus of bolosaurian parareptile from the Gzhelian stage of the Carboniferous period, with a single known species: Erpetonyx arsenaultorum. It is known from a single articulated and mostly complete specimen from Prince Edward Island in Canada. Phylogenetics has predicted that parareptiles first evolved in the Carboniferous, parallel to eureptiles ("true reptiles"). However, Hylonomus, the oldest eureptile known from fossil evidence, lived millions of years before parareptiles appeared in the fossil record. The discovery of Erpetonyx helped to shorten this gap between pa