Character set and phylogenetic analyses of the living and fossil egerniine scincids of Australia

The diverse living Australian lizard fauna contrasts greatly with their limited Oligo-Miocene fossil record. New Oligo-Miocene fossil vertebrates from the Namba Formation (south of Lake Frome, South Australia) were uncovered from multiple expeditions from 2007–2018. Abundant disarticulated material of small vertebrates was concentrated in shallow lenses along the palaeo-lake edges, now exposed on the western shore. The fossiliferous lens occurring within the Namba Formation, also known from Billeroo Creek 2 km northeast of Lake Pinpa, includes abundant aquatic (such as fish, platypus Obdurodon, and waterfowl) and diverse terrestrial (such as possums, dasyuromorphs, and scincids) vertebrates and is hereafter recognised as the Fish Lens. The stratigraphic provenance of these deposits in relation to prior finds in the area is also established. A new egerniine scincid taxon Proegernia mikebulli sp. nov. described herein, is based on a near-complete reconstructed mandible, maxilla, premaxilla, and pterygoid. Postcranial scincid elements were also recovered with this material, but could not yet be confidently associated with P. mikebulli. This new taxon is recovered as the sister species to P. palankarinnensis, in a tip-dated total-evidence phylogenetic analysis, where both are recovered as stem Australian egerniines. These taxa also help pinpoint the timing of the arrival of scincids to Australia, with egerniines the first radiation to reach the continent.