内蒙古河套盆地晚更新世晚期化石动物群

FOSSIL FAUNA IN THE LATE STAGE OF LATE PLEISTOCENE IN THE HETAO BASIN,INNER MONGOLIA

河套盆地上更新统地层发育,在盆地北侧的山前构成台地,为一套黄色、灰白色河湖相砂砾石层,夹黄绿色粉砂、细砂层,产多种哺乳动物化石,包括5目19属,其中诺氏古菱齿象化石点9处、披毛犀7处、马鹿7处、大角鹿2处,并发现了属于大角鹿演化晚期阶段的新种化石包头大角鹿。哺乳动物群化石中既有喜冷的披毛犀、普氏野马、马鹿等,也有喜温湿的诺氏古菱齿象。除了象类以树干、干草类为食、虎和鬣狗为肉食类外,其余均为以草原生存的大型食草动物。地层和化石的年龄表明该动物群较萨拉乌苏动物群更为年青,建议定名为包头动物群,地质年代为晚更新世晚期,同位素年龄为距今4.0～2.2万年,是在河套古湖周边生息繁演、适应于较为温凉气候条件和稀树草原环境下生存的一个食草动物群,末次冰期以后大多数哺乳动物已灭绝。包头动物群明显地晚于萨拉乌苏动物群,与峙峪动物群和北京周口店山顶洞动物群具有较多的相似处,应同属晚更新世晚期动物群。

Along the north piedmont of the Hetao Basin exits Late Pleistocene stratum, consisting of yellow, gray fluvio-lacustrine sand-gravel deposits, containing thin layers of yellowish green silt and fine sand. This set of deposits bears a number of mammal fossils, including 5 orders, 19 genus and species. There are 9 sites with Palaeoloxodod naumanni,7 with Coelodonta antiquitatis, 7 with Cervus （Elephus） canadensis, 2 with Megaloceros baotouensis sp. nov. belonging to the late evolutionary stage of Megaloceros. Among these fossils, there are not only Coelodonta antiquitatis, Equus cf. przewalskyi, and Cervus （Elephus）canadensis etc. which are sychrophilic, but also Palaeoloxodod naumanni which is thermophilic. Except for Palaeoloxodod naumanni, Panthera tigris, and Crocuta ultima, most of the mammal are graminivorous. The results of the absolute dating of the stratum and the fossils indicate that this fauna is younger than the Sjara - Ossy - Gol Fauna. We suggest that this fauna be named Baotou Fauna in the geological period of the late stage of Late Pleistocene with the isotopic age of 22 - 40kaB. P. The Baotou Fauna is graminivorous with habitat around the Hetao fossil lake, adaptive to cool climate and savanna environment. It is clearly younger than the Sjara - Osso - Gol Fauna, quite similar to the Shiyu Fauna and the Shandingdong Fauna in Zhoukoudian site, Beijing. They all belong to the late stage of Late Pleistocene.