Human deciduous teeth from the Middle Stone Age layers of Sibudu Cave (South Africa)

In the African Pleistocene, the fossil evidence for early Homo sapiens populations is still relatively limited. Here we present two additional specimens (two deciduous teeth) recovered from the Middle Stone Age (MSA) deposits of Sibudu Cave (KwaZulu-Natal, South Africa). We describe their morphology and metrics, using three-dimensional models of the teeth obtained from high-resolution micro-CT images. The first specimen is a Ldm₁ (HUM. TO 1) recovered in the BS5 layer dated 77.3±2.7 ka, and associated with stone tools assigned to the "pre-Still Bay" assemblage. The other specimen is a Rdi₁ (HUM. TO 2) coming from the Pinkish Grey Sand (PGS) layer, dated 64.7±2.3 ka, and associated with a Howieson's Poort industry. Both teeth are well preserved, with minor post mortem cracks not affecting the overall morphology, and they comprise the intact, worn crown and the remnants of the roots, naturally resorbed. A large carious lesion occupies most of the distal face and part of the occlusal surface in the Ldm₁; also a chip of enamel is missing from the disto-buccal corner. For both teeth, we compared mesio-distal (MD) and bucco-lingual (BL) diameters with those of other Late Pleistocene deciduous teeth and extant Homo sapiens. The analysis has shown that the teeth are comparable in size with the other MSA specimens described in the literature.