Late Pleistocene hominin teeth from Laoya Cave, southern China

摘要

Recent fossil finds have complicated the picture of East Asian Late Pleistocene hominin taxonomy and morphology, necessitating analysis of more fossils with secure dates and stratigraphic contexts to better contextualize human evolution during this epoch. Field excavations at the Laoya Cave in Guizhou Province, China in 2013 recovered two isolated human teeth (M-3 and dm(2)). The teeth date from similar to 21-24 kya, according to AMS radiocarbon dating. The present study provides detailed metric and non-metric descriptions of the Laoya teeth, and compares them with the dentition of other Late Pleistocene hominins (Neanderthals and fossil Homo sapiens from around the world) as well as chronologically earlier fossil hominins from the same geographical area (East Asian Early/Middle Pleistocene hominins). To achieve this, descriptive morphological observations, geometric morphometric analysis, and micro-computed tomography were employed. The lower third molar (LYC1) is characterized by several derived features, including the absence of a hypoconulid, the lack of C6 and C7, and an 'X'-type cuspal arrangement. The combination of traits expressed by LYC1 is unique, but very similar to other recent H. sapiens. However, the LYC1 also displays a suite of dental features that are not common in other East Asian Late Pleistocene fossil H. sapiens: the absence of a hypoconulid, the presence of a middle trigonid crest, and a narrowed talonid relative to trigonid. This study of the Laoya teeth expands the known morphological diversity of East Asian Late Pleistocene hominin dentitions, and will contribute to a better understanding of the history of modern humans in this area.