Carboniferous reptiles

Petrolacosaurus ("rock lake lizard") is an extinct genus of diapsid reptile from the late Carboniferous period. It was a small, long reptile, and one of the earliest known reptiles with two temporal fenestrae. This means that it was near the base of Diapsida (it may have been the basal taxon), the largest and most successful radiation of reptiles that would eventually include all modern reptile groups, as well as dinosaurs (which survived to the modern day as birds) and other famous extinct reptiles such as plesiosaurs, ichthyosaurs, and pterosaurs. However, Petrolacosaurus itself was part of

Paleothyris is an extinct genus of small reptiliomorph which lived in the Moscovian (Carboniferous) age of the Late Carboniferous in Nova Scotia.

Spinoaequalis is an extinct genus of lizard-like araeoscelidian. It is known from a single species, S. schultzei based on fossils found in Kansas, United States. About 30 cm (1 ft), long it is one of the earliest known amniotes to have returned to the water. Spinoaequalis was not fully aquatic, frequently returning to dry land. It probably swam using its laterally flattened, fanned tail. Its name means "symmetrical spine" referring to its deep, laterally compressed tail. Spinoaequalis was described and named by Michael deBraga and Robert Reisz in 1995.

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