Prolacerta broomi (Parrington 1935) Early Triassic, ~250 mya, was originally considered ancestral to lizards, especially the long-necked Macrocemus and Tanystropheus, but it is not related according to the present reptile tree. Rather, this genus is at the base of the protorosaurs and at the base of lineage that led ultimately to dinosaurs, birds and all the Archosauriformes. Prolacerta was derived from a sister to Oroventaor and the BPI 3859 specimen of Youngina. Prolacerta phylogenetically preceded Protorosaurus, Boreopricea, Pamelaria, the AMNH 5561 specimen of Youngina.
Distinct from Youngina BPI 3859, the skull of Prolacerta had a longer, straighter rostrum and the quadratojugal was reduced to a sliver on the quadrate. The postorbital was more robust. The nares opened dorsolaterally. The quadrate leaned anteriorly. The orbit and lateral temporal fenestra were relatively smaller. The teeth were longer.
The cervicals were all elongated. The tail tapered to a slender whip. The chevrons were deeper anteriorly, but shallower posteriorly.
The pectoral girdle was taller, extending to the top of the vertebrae, and more robust. Manual digits 1 and 5 became reduced and the entire manus was relatively smaller.
The ilium was elongated dorsally. The pedal digits were relatively shorter as the metatarsals were longer. Metatarsal 5 was shorter with an "L"- or hook-shape.