Résumé
Advances in micro-computed tomography (micro-ct) and computer-aided tools for three- dimensional (3D) analyses recently allowed studies of morphological variations of the 3D enamel-dentine junction (3D-EDJ) in primate lower molars. However, the elucidation of the taxonomic value of the 3D-EDJ in early hominids is still bristled with difficulties because inter- specific differences among early hominids are investigated in specimens which do not preserve diagnostic craniofacial features or in isolated teeth which position along the molar row is questionable. In order to contribute to the identification of taxonomically relevant 3D-EDJ data in early hominid, we examine through micro-CT, the postcanine morphological features of the 3D- EDJ throughout all four quadrants of one of the most complete Australopithecus africanus specimen ever found (Sts 52, Sterkfontein, South Africa). We investigate (i) the differences in expression of traits between teeth of the same type (molars or premolars) and within each postcanine row (intra-individual metameric variations); (ii) the differences between antimeres (iii) the intra- individual inter-trait associations. When necessary, differences are quantified by using rigid registration methods. Results show important intra- individual metameric variations within each four quadrants, for both premolars and molars. Stability in trait expression is higher in the upper dental arcade. Moreover, the morphology of an EDJ on one side of a postcanine row is not necessarily matched by its equivalent on the other side. We discuss the genetic or functional basis of these observed variations and the potential implications of our results for the identification of inter-specific differences among early hominids. Research supported by the Centre National de la Recherche Scientifique (PEPS-ODENT Project), the French Ministry of Foreign Affairs and the EU PF6 Marie Curie Actions grant MRTN- CT-2005-019564 ‘EVAN'.