TABEPatterns of craniofacial variation and taxonomic diversity in the South African Cercopithecidae fossil record

The rich paleontological record of South Africa is central in our understanding of Plio-Pleistocene mammalian evolution due in large part to the number of crania recovered. Because of the difficulty of chronometric control in many of the cave systems from which these fossils derive, extinct Old World Monkeys (OWMs) are often employed as biochronological markers, making the taxonomic identification of these primate remains particularly relevant to pursuing broader evolutionary questions relating to human evolution and faunal diversity shifts. The taxonomic relationships for the OWM fossils are reconstructed through phylogenetic systematics that rely heavily on craniodental traits. These analytical methods assume that these characters are developmentally, functionally, and genetically independent. This assumption is increasingly being questioned by analyses of extant phenotypic datasets and genetics. We statistically explored cranial variation in South African fossil papionins (n = 99) to determine whether or not extinct taxa reflect the same phenotypic covariance structure as has been reported for extant OWMs. Our results show that many of the cranial measurements are statistically significantly correlated and fail to distinguish between species or even genera of fossil papionins despite distinguishing extant species. Overall, our results suggest that these extinct OWM taxa cannot be discriminated using craniofacial measurements alone, or that the taxonomic designations, as they currently stand, are confounded.