The Middle Triassic procolophonid Kapes bentoni: computed tomography of the skull and skeleton

Procolophonids were diverse small reptiles through the late Permian and Triassic. Relatively complete specimens of various taxa are known from the Early and Late Triassic, but the 10 or so Middle Triassic taxa, from South Africa, Russia, China and the UK, are mostly incomplete, being known only from skulls or partial and poorly preserved isolated elements. Because of their small size, it has often been difficult to establish details of anatomy using physical preparation methods, so application of scanning technology can massively improve knowledge. Here, we describe the first substantial portion of a skull and anterior postcranial skeleton of the genus Kapes, known from Russia and the UK. CT scanning and 3D digital restoration of the new specimen from the Anisian Otter Sandstone of Devon, UK, reveal anatomical details previously unknown for this taxon, most notably the enlarged quadratojugal processes. This is also one of the few mature procolophonid specimens with a preserved postcranium, and it gives valuable insight into ossification patterns. Fused sutures of the skull, fused scapulocoracoid, and heavily worn teeth show evidence of the common reptilian ossification pattern with a possible limitation in tooth replacement. There is sufficient anatomical information to include Kapes bentoni for the first time in a cladistic analysis, which shows that it is sister to the Russian Kapes majmesculae and part of a clade of Anisian taxa phylogenetically more basal than Procolophon. Inferences on the function of the quadratojugal spines and fossorial mode of life are also considered.