云南昭通水塘坝中新世末期古猿化石点的云南貘化石(英文)

Tapirus yunnanensis from Shuitangba,a terminal Miocene hominoid site in Zhaotong,Yunnan Province of China

此前，中国晚中新世到早上新世的貘化石发现较为稀少。最近几年，在云南省昭通市水塘坝禄丰古猿化石点发现了数量可观的中新世晚期貘化石，其时代为6～6．5Ma。新发现材料包括左上颌骨带P2．M2、4件下颌骨带基本完整颊齿列、若干零散牙齿。新材料可归入先前报道的小型貘类——云南貘Tapirusyunnanensis。云南貘比甘肃的和政貘Tapirushezhengensis时代较晚，体形也稍大；两者都比上新世一更新世的貘类明显较小。新发现的化石材料对更全面认识云南貘的特征提供了新信息。在中一晚中新世期间，云南是我国貘类动物的演化中心，先后发现的化石点有开远（小龙潭）、禄丰（石灰坝）、元谋（小河、竹棚、雷老）、昭通（水塘坝）及其他地点。在晚新生代期间，我国貘类动物演化的主要变化趋势是体形逐渐增大，这一特点或许具有时代意义。在中国发现的中新世貘类毫无例外都是体形较小的类型，这与欧洲及北美的情况迥异。

The fossil tapirid records of Late Miocene and Early Pliocene were quite poor in China as before known. The recent excavations of the terminal Miocene hominoid site （between 6 and 6.5 Ma） at Shuitangba site, Zhaotong in Yunnan Province resulted in the discovery of rich tapir fossils, which include left maxilla with P2-M2 and mandibles with complete lower dentitions. The new fossil materials can be referred to Tapirus yunnanensis, which represents a quite small species of the genus Tapirus. But T. yunnanensis is slightly larger than another Late Miocene species T. hezhengensis from Gansu, northwest China, both of which are remarkably smaller than the Plio-Pleistocene Tapirus species in China. The new fossils provided more information to define the species T. yunnanensis more precisely. Yunnan can be regarded as one of the centers of tapir evolution during the Mid-Late Miocene period, as quite a number of Mid-Late Miocene tapir fossils have been recovered in several localities of Yunnan, which include Xiaolongtan, Yuanmou, Lufeng, Zhaotong and others. Based on the measurements of tooth size, the late Cenozoic tapirs were generally getting larger gradually through time in China, which means the tooth sizes coincide well with their geological ages, the later the larger, and all the Mid-Late Miocene tapirs are exclusively sman-sized; thus, the tooth size of fossil tapirs in China is likely to have some significance in age estimation. By contrary, both the dwarf and the normal-sized or larger-sized tapirs were discovered from Mid-Late Miocene strata in Europe and North America.