Sukselainen Leena, Kaakinen Anu, Eronen Jussi T, Passey Benjamin H, Harrison Terry, Zhang Zhaoqun, Fortelius Mikael
Department Geosciences and Geography, University of Helsinki, FI-00014, University of Helsinki, Finland.
Department Geosciences and Geography, University of Helsinki, FI-00014, University of Helsinki, Finland.
J Hum Evol. 2017 Jul;108:31-46. doi: 10.1016/j.jhevol.2017.03.014. Epub 2017 May 3.
Damiao, Inner Mongolia, has three main fossil horizons representing the early, middle, and late Miocene. The middle Miocene locality DM01 is the only primate locality from the region and also represents the latest occurrence of pliopithecoids in northern China. The presence of pliopithecoid primates in central Asia after the middle Miocene climatic optimum seems to contradict the general trend of strengthening climatic zonality and increasing aridity. To investigate this enigma, we employ faunal similarity, ecometrics, and stable isotope analysis. Our results support previous inferences concerning the presence of locally humid environments within the increasingly arid surroundings that characterized central Asia. Hypsodonty, estimated mean annual precipitation (MAP), local sedimentology, and large mammal fossils suggest more humid and possibly more forested and wooded environments for the DM01 locality. We compared our results with the adjacent fossil-rich middle Miocene Tunggur localities. However, the small mammal fauna and isotope data are consistent with a mosaic of forest and grassland environment for all Damiao localities. Based on our results, Tunggur may have been too seasonal or not sufficiently humid for pliopithecids. This is supported by the higher mean hypsodonty and lower estimated MAP estimates, as well as slightly higher δC values. We suggest that DM01, the driest known Asian pliopithecid locality, may have been a more humid refugium within a generally drier regional context.
内蒙古大庙有三个主要的化石层位，分别代表中新世早期、中期和晚期。中新世中期的DM01地点是该地区唯一的灵长类动物地点，也是中国北方上新猿类的最新出现地点。中新世气候适宜期之后，中亚地区存在上新猿类灵长动物，这似乎与气候分带性增强和干旱加剧的总体趋势相矛盾。为了探究这个谜团，我们采用了动物群相似性、生态计量学和稳定同位素分析方法。我们的结果支持了先前有关在以干旱为主的中亚地区存在局部湿润环境的推断。高冠齿率、估计的年平均降水量（MAP）、当地沉积学和大型哺乳动物化石表明，DM01地点的环境更为湿润，可能有更多的森林和树木。我们将我们的结果与相邻的富含化石的中新世通古尔地点进行了比较。然而，小型哺乳动物群和同位素数据表明，大庙所有地点的环境都是森林和草原的镶嵌体。根据我们的结果，通古尔对于上新猿类来说可能季节性太强或不够湿润。较高的平均高冠齿率、较低的估计MAP值以及略高的δC值都支持了这一点。我们认为，已知亚洲最干旱的上新猿类地点DM01，可能是在总体较为干旱的区域背景下一个更为湿润的避难所。
