重庆穿洞遗址大马蹄蝠化石发现及其意义

2008年，重庆穿洞遗址发掘出一具保存较好的晚更新世大马蹄蝠（Hipposideros armiger）化石，这是中国发现的第5个大马蹄蝠化石地点，同时，也是迄今为止所发现保存最为完整的标本。对该地点化石材料观测显示：大马蹄蝠在与其他翼手目标本进行形态对比时，可以根据其个体大小、颅骨形状及齿式特征等进行多项有效鉴别。在大马蹄蝠演化方面，从化石材料上观察，更新世晚期大马蹄蝠桡骨长度与现生标本基本一致，这反映出大马蹄蝠在更新世晚期其飞翔能力与现生标本相似（桡骨长度增大，这是翼手目与一般哺乳动物相比在演化方面的特化现象）。穿洞大马蹄蝠化石的发现，对研究长江三峡地区第四纪古环境具有重要意义。它证明了更新世晚期时三峡地区有温暖湿润的气候和繁茂的森林植被，并且分布有为翼手目提供居址栖息的大型岩溶洞穴；晚更新世时期，出现于中国其他地区的冰期气候等恶劣环境现象，未曾对长江三峡地区动、植物生存环境造成影响。

Discovery and Significance of Hipposideros Armiger Fossils at Chuandong Site,Chongqing

The researchers from the Laboratory of Scientific Archaeology of Chonqing Normal University discovered a fossil sample of Hipposideros armiger at Chuandong Site, Fengjie County, Chongqing in 2008, which skull, left scapula and some limb bones, vertebras and ribs were well preserved. The sample was collected in a layer of red clay 58 centimeters below the cave ground, accompanied with some remains related with ancient Human activities such as mammal fossils and stone tools. The majority of the accompanying mammals were living species, and the minority of which were distinct species in Pleistocene. The living species included Crocidura ilensis, Chodsigoa smithii, Rattus norvegicus, Trogopterus xanthipes, Rhizomys sinensis, Atherurus macrourus、Arctonyx collaris, Panthera tigris, Sus scrofa, Hydropotes inermis, Cervus unicolor. The extinct species included Crocuta crocuta ultima, Megatapirus augustus. According to the primary taphonomy and fauna analysis at this site, a conclusion could be made that Chuandong Site was one in the Late Period of Pleistocene. Hipposideros armiger, a species of Chiroptera, whose living population habituate in tropic and subtropical zones of east hemisphere like Southern China, India, Nepal and some areas of Southeastern Asia. No fossil record of Hipposideros armiger was discovered outside China until now. Four sites where Hipposideros armiger fossil materials were gathered were reported before the discovery of Chuandong Site, which should be the fifth one, where the most complete Hipposideros armiger fossil material was collected in China. It is demonstrated with Chuandong fossil material study that Hipposideros armiger could be identified efficiently from other species of Chiroptera with the characters such as body size, skull shape and dental formula. The material at Chuandong Site contributes to not only Chiroptera identifications but also evolutionary study. The ulna and radius of Chuandong Hipposideros armiger fossil were completely preserved, which have vital significance of Chiroptera origin and evolution. In other mammal skeleton constitution, the ulna and radius are formed separately and the length of ulna is longer than that of radius. However, both bones of Chiroptera are specialized, which joined together at the distal ends. By contrast, the length of radius is much longer than that of ulna. According to observation of Chuandong material, the radius was developed much bigger than the ulna, which was very weak and small. Further survey of these two bones suggested very close anatomical characters between fossil species and living species. Such close anatomical characters may indicate nearly the same flying ability between fossil and living species. Hipposideros armiger fossil material is also significant to the study of Quaternary paleo-environment and Human evolution in the Three Gorges of the Yangtze River. Some researchers suggested possible existence of glacier in this area in the late Period of Pleistocene, which however conflicted with the fact of abundant Human remains discovered in this area. Hipposideros armiger fossil at Chuandong Site indicated that the Three Gorges was important Hipposideros armiger habitual zone, where balmy and moisture climate, lush forest should develop, as well as enormous Karst caves, which provided ideal habitual place for these mammals. Perhaps, glacier climate in the late Period of Pleistocene did not intrude into this area without impact on the plant and fauna environments. Stable and prospect ecosystem survived successfully in this area, providing excellent environmental conditions for the evolution and surviving of ancient Human beings in the Three Gorges.