贵州毕节发现的巨猿牙齿化石及其意义

NEW DISCOVERY OF Gigantopithecus blacki TOOTH FOSSIL FROM BIJIE,GUIZHOU AND ITS SIGNIFICANCE

文章报道了发现于贵州毕节的一枚巨猿牙齿化石,介绍了巨猿化石发现的历史过程及与之相关的毕节扒耳岩早更新世哺乳动物化石。贵州毕节巨猿化石的发现,填补并扩大了巨猿化石的地史分布范围,对研究巨猿演化及云贵高原地质环境变化等相关问题有着重要意义。

A tooth fossil of Gigantopithecus blacki, according to history record collected from Bijie, Guizhou was identified from the collection of Institute of Vertebrate Paleontology and Paleoanthropology, which was acquired from the Chinese drug store of Bijie, Guizhou Province in 1964. The tooth is a right upper fourth premolar with a well preserved tooth crown and a little part of root. The slightly worn cusps indicate that it belongs to a young individual. The length, width and height of the crown are 12.8mm, 19.6mm, and 10.6mm respectively. The tooth size coincides with the small type of Gigantopithecus blacki from Liucheng of Guangxi and Jianshi of Hubei, and is smaller than that of Wuming＇s of Guangxi. The small size of Bijie Gigantopithecus tooth might be due to either a female individual within the larger sex dimorphism, or an earlier geological age such as Early Pleistocene. The geological age is problematic because the original deposit bearing the tooth is unknown. However, a nearby fossil site, called Ba＇eryan, a probably contemporaneous site, might provides us some age information. It is a fissure deposit site （27°22′12″N, 105° 15′16″E）in limestone, about 7km north-west from Bijie city, 1630m above sea level. Since 1983, a lot of large mammal fossils have been found there, including Ailuropoda microta, Stegodon, Tapirus, Rhinoceros, Hystrix subcristata et al., especially new discovered Gigantopithecus blacki （not described）. Preliminary study on the fauna, particularly the key fossils of Ailuropoda microta, indicates that the geological age of Bijie Ba＇eryan fauna is Early Pleistocene, comparable to Liucheng Gigantopithecus cave fauna and Wushan Longgupo Fauna. Bijie is located at the Yunnan-Guizhou Plateau on the second geomorphic level in China, south-eastern to Tibetan Plateau. The presence of Gigantopithecus blacki in Bijie, likely in Early Pleistocene, represents the most west site with the highest altitude among all sites of Gigantopithecus blacki. Discovery of Gigantopithecus blacki in Bijie of Guizhou broadens its geographic distribution in Early Pleistocene, connecting the north sites （ up to Wushan and Jianshi near the Three Gorges of Changjiang River） and the south sites （down to Guangxi Province） together. The Middle Pleistocene fossils of Gigantopithecus are only limited to Guangxi Province. No Late Pleistocene Gigantopithecus fossil is found by far in China. It is an interesting question whether the dramatic uplift of Tibetan Plateau, or Yunnan-Guizhou Plateau and Three Gorges area during 1.2 - 0.6MaB. P. had made strong effect on the habitat and survival of Gigantopithecus blacki.