A comparative study of adult facial morphology and its ontogeny in the fossil macaque Macaca majori from Capo Figari, Sardinia, Italy

Abstract

This study examines the morphology of the face in the fossil macaque Macaca majori from Capo Figari (north-eastern Sardinia, Italy) in a comparative ontogenetic context. Thus, a fairly complete face from an adult representative of this fossil species is compared with 3 extant macaque species: Macaca sylvanus (of which species it is questioned whether it is a subspecies, M. sylvanus majori), Macaca mulatta and Macaca fascicularis. Additional incomplete subadult and adult specimens are also examined in order to compare their facial ontogeny with that of the same living species. The comparisons are based on facial landmark data and are undertaken using geometric morphometric methods. These studies indicate that the adult facial morphology and ontogeny of face size and shape in M. majori share much in common with extant macaque species. However, the adult M. majori face displays some unique morphological features, in particular with regard to lateral flaring and relative size of the zygomatic roots. From the study of a limited sample of fossils there is an indication that this flaring arises during postnatal growth, and in consequence the ontogeny of the face of this fossil species may be different from that of M. sylvanus and the other macaque species included in this analysis. From these studies, we conclude that M. majori shows differences in adult facial morphology and possibly in ontogeny from M. sylvanus compatible with a specific rather than subspecific distinction.