Abstract:

The micromammal fossils collected from the upper part of the Jiaozigou Formation near Mansancun in 2015 are described. The sample consists of 10 species of six previously known genera (Amphechinus, Sinolagomys, Parasminthus, Litodonomys, Heterosminthus and Yindirtemys) belonging to three orders. Of them, four genera (Sinolagomys, Litodonomys, Heterosminthus and Yindirtemys) made their first appearance in the Late Oligocene and Sinolagomys kansuensis and Heterosminthus lanzhouensis are known only in the Late Oligocene. In comparison with the other Late Oligocene mammalian faunas known in China and Mongolia, the above assemblage appears to be contemporaneous with Xiagou, Taben-buluk, Yikebulage faunas and Tieersihabahe assemblages, but slightly younger than the Shargaltein-Tal Fauna in age. The Mansancun Fauna is also younger than the three Late Oligocene biozones recognized recently in Asia. Compared with the Yagou Fauna collected from the lower part of the Jiaozigou Formation, the Mansancun Local Fauna is clearly younger. Consequently, the Yagou Fauna would be early Late Oligocene, while the Mansancun Local Fauna may be considered late Late Oligocene. Thus, as a whole, the Jiaozigou Formation is Late Oligocene in age.

Key words: Mansancun, Linxia, Gansu, Late Oligocene, Jiaozigou Formation, micromammal fossils

摘要：

记述了中国科学院古脊椎动物与古人类研究所一野外队于2015年在甘肃临夏盆地东乡县满散村附近的椒子沟组上部首次发现的6属10种小哺乳动物化石。其中4个属(Sinolagomys, Litodonomys, Heterosminthus和Yindirtemys)已知最早出现于晚渐新世；两个种(Sinolagomys kansuensis和Heterosminthus lanzhouensis)仅在晚渐新世出现过。该动物群(及其产出地层)的时代很可能为晚渐新世，可称为晚渐新世满散村动物群。该动物群中有一些在牙沟动物群(产于椒子沟组下部)中尚未出现的更晚的属种，并且缺少那些在牙沟动物群中存在的较古老的属种。结合两个动物群的产出层位，满散村动物群的时代要比牙沟动物群晚。如果牙沟动物群的时代为晚渐新世早期，满散村动物群的时代很可能为晚渐新世晚期。这样，椒子沟组可能代表了整个晚渐新世时期的沉积。满散村动物群与亚洲已知的生物带和中国已知的晚渐新世哺乳动物群比较，比我国内蒙古乌兰塔塔尔生物带III和蒙古湖谷地区的生物带C和C1的时代要晚，而与我国西北地区峡沟、塔奔布鲁克、伊克布拉格和铁尔斯哈巴合动物群(或组合)时代相近，比石羌子沟动物群的时代稍晚。

关键词: 甘肃临夏满散村, 晚渐新世, 椒子沟组, 小哺乳动物化石