广西化石猩猩牙齿釉质厚度研究

华南和东南亚发现大量更新世的猩猩牙齿化石。本研究应用CT扫描三维重建的技术方法研究了广西更新世化石猩猩牙齿釉质厚度,并与现生类人猿、现代人、化石类人猿以及早期人类进行比较分析。结果显示:广西猩猩同类牙齿的釉质厚度与牙齿大小相关性很小;臼齿和前臼齿釉质厚度在上下颌之间不存在显著性差异;来自广西不同地区的猩猩化石牙釉质厚度无显著差异。与早期人科成员相比,广西猩猩的牙釉质相对较薄,平均与相对釉质厚度值都明显小于南方古猿、傍人。与早期人属相比,小于直立人、尼人以及非洲和欧洲的早期人属化石。与现代人和现生灵长类相比,广西化石猩猩釉质厚度明显大于大部分猴类和非洲大猿;平均釉质厚度稍大于现生猩猩,而与现代人更为接近;相对釉质厚度小于现代人,而与现生猩猩差异不大,都属于偏厚型釉质。本文讨论了釉质厚度与系统分类演化、食性适应的相关问题,作者推测釉质厚度可能是物种的特征属性,与牙齿功能适应有密切关联。

CT Analysis on Enamel Thickness of Pleistocene Fossil Orangutan from Guangxi,South China

Thousands of fossil teeth of Pleistocene orangutan were found in South China. In this study, we analyzed enamel thickness of 23 fossil teeth of Pleistocene orangutan from Guangxi by micro-CT scanning and three-dimensional reconstruction, and made some comparisons with other extant primates and modern humans, fossil apes and hominins, and discussed the issues of functional adaptability and taxonomy of enamel thickness of Guangxi fossil orangutan. The results are as followings. Enamel thickness of Guangxi fossil orangutan is not significantly related to the tooth size within the same tooth type, and there is no significant difference between maxillary and mandibular cheek teeth, and there is no significant difference with other fossil orangutans from different sites of Guangxi. Compared with other fossil apes, enamel thickness of Guangxi fossil orangutan is intermediate/thick. Both average enamel thickness (AET) and relative enamel thickness (RET) of Guangxi fossil orangutan are smaller than ones of Australopithecus and Paranthropus, and also smaller than Homo erectus, Neanderthal and early fossil Homo found in Africa and Europe. Compared with extant primates, enamel thickness of Guangxi fossil orangutan is thicker than most of monkeys and African apes obviously. Average enamel thickness of Guangxi fossil orangutan is a little thicker than extant orangutan but closer to modern human. Relative enamel thickness of Guangxi fossil orangutan is thinner than modern humans, and little difference with extant orangutan and both belong to intermediate/thick enamel. Concerning the taxonomy and phylogeny and diet adaptation of enamel thickness, we suggest that enamel thickness might be an intrinsic property that had evolved independently, and have a relationship with dental function. The intermediate/thick enamel thickness of Guangxi fossil orangutan maybe show that they had a relatively hard food adaptation.