La calotte crânienne de l’Homo erectus de Kocabaş (Bassin de Denizli, Turquie)

Abstract

In 2002, a fragmentary skullcap was discovered in Denizli basin, in the locality of Kocabaş, in the southwest of Turkey (Kappelman et al., 2008). The skullcap was ascribed to Homo erectus on the basis of morphological and metric similarities with the Chinese fossils from Zhoukoudian L-C (Vialet et al., 2012). An in-depth morphological and metric analysis (2D and 3D) was carried out on a new 3D reconstruction of the fossil, made up of the frontal bone and parietal fragments. The results confirm that the morphology of the frontal bone, the conformation and the dimensions of the Kocabaş specimen, clearly differentiate it from Homo habilis-Homo georgicus, on one hand, and Homo heidelbergensis-Neanderthal, on the other. It displays similar metric characteristics to African (KNM-ER3733, OH9, Daka-Bouri) and Asian (skulls from Zhoukoudian L-C, Nankin 1, Sangiran 17) Homo erectus, a marked post-orbital constriction, a supraorbital torus bordered posteriorly by a supratoral sulcus and showing, on its inferior border, a supraorbital notch and tuber, temporal lines in a medium high position delimiting an infratemporal frontal zone with a clear bulge. However, the proportions of the short and large Kocabaş frontal bone (without the supraorbital torus) differentiate it from Asian Homo erectus, which present a longer squama frontalis. This feature is also present on African Homo erectus. Consequently, the Turkish fossil appears to be intermediary between the Homo erectus from Africa and Asia, both from an anatomic and geographic point of view. In the light of the new dates advanced for this fossil, at least 1.1Ma (Lebatard et al., 2014a, b; Khatib et al., 2014; Boulbes et al., 2014), it contributes, along with OH9, to bridging a palaeoanthropological gap between KNM-ER3733 (1.78Ma) and the Chinese fossils from Zhoukoudian L-C, Sangiran 17 (earlier than 0.78Ma) and Nankin 1 (approximately 0.63Ma). This study, which mainly concerns the frontal bone, implies that Homo erectus is a species with a vast geochronological distribution and marked morphometric variability.