South African fossils Prolacerta was first described by
Francis Rex Parrington in 1935 from a single skull discovered near the small town of
Middelburg in the
Eastern Cape of
South Africa. The fossil was recovered from an exposure of rock from the Katberg Formation in the
Lystrosaurus Assemblage Zone. This original skull, the
holotype, is now stored at the
Cambridge University Museum of Zoology as specimen UMZC 2003.40 (or UCMZ 2003.41R). The
generic name Prolacerta is derived from
Latin, meaning "before lizard", and its species name
broomi is in commemoration of the famous
paleontologist Robert Broom, who discovered and studied many of the
fossils found in rocks of the
Karoo Supergroup. Later authors concluded that
Pricea was a
junior synonym of
Prolacerta, only distinguishable by its style of preservation. Modesto and
Sues (2004) redescribed the skull as a whole, focusing on the UCMP specimen alongside 5 specimens stored at BPI. The holotype skull in Cambridge was redescribed by Gabriela Sobral (2023).
Antarctic fossils Prolacerta was first reported from Antarctica by
Edwin H. Colbert in 1987. The original Antarctic fossils were collected from 1969 to 1971 by
James Kitching and his colleagues, working in the
Fremouw Formation near the junction of the
McGregor and
Shackleton glaciers. Colbert described 17 different
Prolacerta specimens from Antarctica, all of which are stored at the
American Museum of Natural History (AMNH). Most of the AMNH specimens are rather fragmentary, but two nearly complete skulls are included among the sample: AMNH 9520 and AMNH 9521. The Antarctic
Prolacerta fossils were amended by Stephan Spiekman (2018), with the description of a new articulated skeleton stored at the
Burke Museum of Natural History and Culture (UWBM). This specimen, UWBM 95529, is both the largest and most complete
Prolacerta skeleton which has been described, though only fragments of the skull are preserved. The 2018 study re-evaluated Colbert's sample, finding that 14 of the AMNH specimens are still validly referable to
Prolacerta. The AMNH fossils are distinctly smaller than the South African remains, and several anatomical differences are apparent. The AMNH fossils tend to have a shorter snout, more conical teeth, dorsal neural spines which are slanted backwards, and a proportionally shorter tibia, among other traits. Colbert preferred the hypothesis that they simply represent juvenile fossils, though he could not disprove the idea that they were from a second species which was smaller than
P. broomi. Some of the differences between the AMNH and South African fossils are ambiguous due to quirks of preservation and limited overlap between specimens. UWBM 95529 is not only comparable in size to the South African fossils, but also anatomically indistinguishable from them. This supports the interpretation that the AMNH fossils are juveniles, while dissuading the idea that the Antarctic remains are from a dwarfed species. ==Description==