Kembawacela yajuwayeyi n. sp., a new cistecephalid species (Dicynodontia: Emydopoidea) from the Upper Permian of Malawi

Abstract

Cistecephalidae are a relatively basal clade of dicynodonts, well-nested within emydopoids, and known to have multiple adaptations to a fossorial lifestyle. In recent years cistecephalid taxonomic diversity has been progressively increasing and important insights into the osteology, soft-tissue anatomy, and paleobiology of the clade have improved considerably. Here we describe a new species of the cistecephalid Kembawacela from the Chiweta Beds (northern Malawi, Wuchiapingian), a poorly sampled area of Karoo sediments. Due to the minute dimensions and delicate nature of specimen DMMM-PK-16-1, we utilized propagation phase-contrast synchrotron X-ray micro-computed tomography, revealing conspicuous contrast between rock matrix and bone and allowing reconstruction of its cranial osteology in great detail. DMMM-PK-16-1 is here recognized as a new species based on the morphology of the crista oesophagea of the pterygoid, which has an acute posterior process separate from its contralateral. Despite the affinities with Kembawacela kitchingi there are various distinguishable features absent in the taxon (e.g., posterior border of the pterygoids is smoothly concave, rather than interdigitating with the basipostsphenoid). The erection of a new species in this region seems to support the growing evidence for species-level diversity in East African Karoo basins when contrasted to the Main South African Karoo basin. Furthermore, the anatomical resolution obtained allowed us to reconstruct the osseous labyrinth, the paths for several nerve branches, arteries and veins for the first time in cistecephalids, and we develop new hypotheses for their paths and nomenclature for dicynodonts. We found remarkable resemblance in the brain endocast of DMMM-PK-16-1 and another cistecephalid, Kawingasaurus, which is distinct from other dicynodonts in which it is known.