A new pipoid anuran from the Late Cretaceous of South Africa

ABSTRACT

Numerous fossil pipoid frogs recovered from Late Cretaceous deposits of a closed crater-lake of Late Cretaceous age in the Marydale District of South Africa are described and referred to a new genus and species of pipoid anuran. The fossils include larvae and adult frogs that are thought to have been killed en masse following breakdown of the thermal stratification or possibly by CO₂ degassing from the underlying magma. A cladistic analysis of fossil and extant pipoid frogs based on 49 osteological characters reveals the new taxon to be a member of the pipinomorph clade, which includes the Late Cretaceous Eoxenopoides reuningi also from South Africa, fossil and Recent hymenochirines from Africa, and living Pipa from South America. The new taxon is distinctly larger than Eoxenopoides and further differs from this contemporaneous taxon in having an antorbital process on the maxilla and seven presacral vertebrae, with the first presacral being formed by fusion of Presacrals I and II. The curved shape of the ventral part of the braincase distinguishes this frog from hymenochirines, Palaeobatrachus, and Eoxenopoides. The new anuran is distinguished from the Israeli fossil Thoraciliacus of about the same age by the possession of a conch-shaped tympanosquamosal bone, a short jaw, and fusion of the sacrum and urostyle.