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-Pleistocenevertebrate fossil recordof Africa and the most studied largely due to their significance as biochronologicalindicators. However, despite their abundance in the fossil record, the remains are mostly isolated teeth and fragmentary craniaand 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 Nyanzachoerusjaegeri based on two craniarecovered from middle Pliocene deposits of the Woranso-Mille paleontologicalstudy area, Afar region, Ethiopia. Understanding the cranial morphology of this species is particularly significant given the recent reclassification of Nyanzachoerusjaegeri to the genus Notochoerusbased 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 Notochoerusare variable among tetraconodont species and that Nyanzachoerusjaegeri best fits within the genus Nyanzachoerus.