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.

The gamut of known protorosaurs, including a sister of their common ancestor, Orovenator. Youngina is a sister to the protorosaurs ancestral to the Archosauriformes. Click to enlarge. Taxa once considered prolacertiforms, such as Tanystropheus and Sharovipteryx, now nest within the Tritosauria within the Squamata.

Malerisaurus robinsonae (Chatterjee 1980) was found within the skeleton of the phytosaur, Parasuchus. After partial digestion, it was completely disarticulated. Malerisaurus was originally considered a facultatively bipedal prolacertiform eosuchian, equally at home in the water or in the trees. Malerisaurus has not yet been entered into the reptile matrix, but in comparison to Prolacerta, the skull and neck of Malerisaurus was relatively larger. The pectoral girdle was relatively smaller. I switched metatarsals 3 and 4 because in other prolacertiforms mt4 was larger than mt3 and doing so simplified the PILs.

Chatterjee S 1980. Malerisaurus. A new eosuchian reptile form the Late Triassic of India. Royal Society of London Philosophical Transactions (B) 291:163-200.

Gow CE 1975. The morphology and relationships of Youngina capensis Broom and Prolacerta broomi Parrington. Palaeontologia Africana, 18:89-131.

Modesto SP and Sues H-D 2002. The skull of the Early Triassic archosauromorph reptile Prolacerta broomi and its phylogenetic significance. Zoological Journal of the Linnean Society, 140:335-351.

Parrington FR 1935. On Prolacerta broomi gen. et sp. nov. and the origin of lizards. Annals and Magazine of Natural History 16, 197–205.

wiki/Prolacertiformes