山东新泰乌珠台人类牙齿的形态学特征

Morphological studies on Wuzhutai tooth,Xintai of Shandong Province

近些年在东亚发现的晚更新世现代人化石及其研究使得关于该地区现代人起源问题更加复杂,更多该时段人类标本的研究有助于对其有更清晰的认识。1966年在山东新泰乌珠台发现一枚古人类下颌臼齿,吴新智和宗冠福(1973)对其进行了报道,而后再无详细研究。本文将使用牙齿非测量性状的半定量化(分级)、齿冠外轮廓形状的几何形态测量、基于显微断层扫描(Micro-computed tomography 或micro-CT)的釉质厚度、釉质厚度分布规律和齿质表面三维结构复原等方法对乌珠台人类牙齿进行综合研究,进而对东亚晚更新世古人类牙齿形态特征变异有一个进一步的了解。结果显示,乌珠台人类牙齿的形态特征基本与现代人接近,但其所表现出的三角座横脊、Y型齿沟排列、原附尖在现代人中出现率较低,而更多发现在直立人或尼安德特人中。相对于东亚其他晚更新世现代人,乌珠台M3所表现出的特征组合具有特殊性,增加了东亚晚更新世现代人的牙齿形态特征多样性。未来研究可尝试测定乌珠台人类牙齿的绝对年代,以更好的将其归入到现代人演化序列中去。

Recent fossil findings have complicated the scenario of East Asian modern human evolution and dispersal in Late Pleistocene, necessitating more fossil from this period to better elucidate it. In 1966, a lower molar of fossil human was recovered at Wuzhutai, Xintai of Shandong province, and Wu and Zong reported it in 1973. However, there is no further detailed study on this tooth afterwards. The present study will reassess its morphologies using grading system of dental non-metrics, geometric morphometric analysis of the crown outline shape, measurement of two- and three- dimensional (2D and 3D) enamel thickness, and visualization of 3D enamel thickness distribution. We aim at a further understanding of morphological variation of East Asian Late Pleistocene hominins. The results show that the dental morphologies of Wuzhutai tooth generally fit into the spectrum of modern human variations. However, its trigonid crest, Y pattern of occlusal groove arrangement, and high-degree protostylid are more likely found in Homo erectus or Neanderthals rather than in modern human. Compared with the other East Asian Late Pleistocene hominins, the combination of traits expressed by Wuzhutai tooth is unique and expanding the known morphological diversity. The future study could try to acquire the absolute living chronology of Wuzhutai hominin, in order to better add it into the evolutionary sequence of modern human evolution.