|Named By:||H. H. Lane in 1945|
|Time Period:||Pennsylvanian, 302 Ma|
|Size:||40 centimetres long|
|Fossil(s):||Well enough preserved to reveal the full morphology|
|Classification:||| Chordata | Reptilia | Diapsida | Araeoscelida | Petrolacosauridae ||
Petrolacosaurus was a small, 40-centimetre (16 in) long reptile, and the earliest known diapsid. It is at the base of the largest reptilian radiation that includes eosuchians, thecodonts, rhynchosaurs, pterosaurs, dinosaurs, and eventually birds.