Newly Discovered Crania of Nyanzachoerus jaegeri (Tetraconodontinae, Suidae, Mammalia) from the Woranso-Mille (Ethiopia) and Reappraisal of Its Generic Status

Suids are among the most common mammalian groups in the Plio-Pleistocene vertebrate fossil record of Africa and the most studied largely due to their significance as biochronological indicators. However, despite their abundance in the fossil record, the remains are mostly isolated teeth and fragmentary crania and mandibles. As a result, disagreements have persisted in terms of their taxonomy and phylogenetic relationships. Here, we present for the first time a detailed description of the cranial anatomy of Nyanzachoerus jaegeri based on two crania recovered from middle Pliocene deposits of the Woranso-Mille paleontological study area, Afar region, Ethiopia. Understanding the cranial morphology of this species is particularly significant given the recent reclassification of Nyanzachoerus jaegeri to the genus Notochoerus based largely on the incisor and symphyseal morphology of specimens from Kanapoi, Kenya. Here, we show that the two genera are clearly distinguished from each other by distinct morphological features of the cranium such as the shape of the braincase, orientation of the zygomatic arches, and premolar/molar ratio, among others. Furthermore, we show that the mandibular and dental morphological features identified by some workers as characteristic of Notochoerus are variable among tetraconodont species and that Nyanzachoerus jaegeri best fits within the genus Nyanzachoerus.