Résumé
The three-dimensional (3D) morphology of the facial skeleton is complex because it comprises several curved and small localized surfaces which form may help to differentiate masticatory patterns, species and phylogenetic relationships among fossil hominins. We quantified and visualized the facial shape variation in Late Pliocene hominins using the cutting-edge computational, similarity-based methods of 3D surface fine registration and 3D inspection colour mapping. Samples included specimens from Sterkfontein and Kromdraai B, South Africa. For comparative purposes, we added 10 adult chimpanzees and 10 adult bonobos with equal numbers of males and females, as well as some Early Pleistocene hominins from South and East Africa. Computed tomography data were used to generate three-dimensional triangulated mesh models which midfacial components were then converted into smooth NonUniform Rational B-Spline (NURBS) surfaces. In addition to the overall study of the midface, four separate analyses were conducted, each focused on a surface patch representing an area of morphology which have raised interest in the past (/e.g/., infraorbital region, zygomatic process, anterior pillar ...). Preliminary results suggest that the adult midfacial remains represented in our sample from Sterkfontein show a greater range of morphological differences when compared to the shape differences observed within each of our two extant samples (chimpanzees and bonobos). We discuss the implications of our results for the understanding of the facial differentiation and evolution among the Late Pliocene hominins (particularly, the gracile/robust lineage).