The first Plio-Pleistocene Cordylidae (Squamata) from Aves Cave I, Bolt's Farm Palaeokarst System, South Africa: Anatomical keys and palaeoecological significance

Abstract

The herpetofaunal record of the Plio-Pleistocene in the Cradle of Humankind World Heritage Site remains critically underexplored, creating a significant gap in our understanding of past biodiversity and palaeoenvironments. While large reptiles, such as Varanus, have been briefly mentioned, small squamates have been largely ignored. This paper describes the first fossil cordylid lizard from the region, a fragmentary mandible (specimen AC 774) from Aves Cave I in the Bolt's Farm Palaeokarst System. Recovered from breccia via acid preparation, the specimen was identified through comparative osteology with extant taxa. Following the anatomical nomenclature of Čerňanský et al. and the dental character definitions of Kosma, we identify key features, including a deep Meckel's groove, homodont pleurodont teeth, a prominent cuspis labialis formed by a longer crista mesialis and shorter crista distalis, and the presence of dominant striae, that align the fossil with Cordylidae. Due to its fragmentary state, it is conservatively assigned to Cordylidae indet. (subfamily Cordylinae). This find provides the first tangible evidence of cordylids in the Plio-Pleistocene of the COH, of which the extant members of the family are rupicolous and endemic to sub-Saharan Africa. The presence of this ecological specialist in deposits dated to ∼2.5–3.0 Ma supports palaeoenvironmental reconstructions of a heterogeneous, rocky woodland–grassland mosaic. This study underscores the importance of microvertebrate fossils and establishes essential anatomical keys for future palaeoherpetological research in southern Africa.