作者：邱铸鼎  李强

摘要：描述了2002—2005年间在青海德令哈深沟上油砂山组采集的小哺乳动物化石。化石共有16种，隶属食虫目、啮齿目和兔形目的12科，代表了迄今青藏高原发现种类最多、材料最丰富的小哺乳动物群。深沟动物群的组成与陕西蓝田灞河组下部层位发现的小哺乳动物组合最为接近，两者有相似的群体结构，共有Sciurotamias, Lophocricetus, Protalactaga, Myocricetodon, Nannocricetus, Pararhizomys和Ochotona7属。但由于深沟动物群含有略进步的属、种，其时代似乎稍晚，很可能属晚中新世早期，或者中国陆生哺乳动物时代的保德期早期，与欧洲MN10上部或MN11下部的时代相当。深沟动物群指示了一个温带开阔干旱草原为主体的景观。晚中新世柴达木盆地的气候似乎没有现在这样干燥，在草原中尚有一些灌丛甚至林地。动物群的组成及所指示的生态环境都表明，青藏高原在中新世以后有过较大幅度的上升。
    深沟动物群中含有一鼠科新种——细弱许氏鼠(Huerzelerimys exiguus sp．nov)。Huerzelerimys属过去只发现于欧洲，新种为该属在亚洲的首次发现。其特征为：与现知最小种H．minor相比，其臼齿更小，M1中t1的位置相对靠后，t6和t9间有超过50％的标本具一弱脊连接，m1和m2的唇侧齿带狭窄、附尖弱小。
   Ochotonoma primitiva(Zheng＆Li，1982)是动物群中较为多见的一种鼠兔。该种最先发现于甘肃天祝，并作为Ochotona属描述。正型地点的标本不多，但尺寸和形态完全落入深沟标本的变异范围，因此认为同属一种。该种的特征增订为：中等大小的鼠兔。P2冠面长三角形，舌侧长度明显大。p3的下前边尖宽大，一般具有两个前褶或凹槽，而且至少有一褶具水泥质充填物；连接前边尖和后边尖间的齿桥(dentine isthmus)宽；前褶(paraflexis)比O．anatolica 的短而狭窄，向后延伸没有O．csarnotana那样明显。

关键词：青海柴达木盆地深沟，晚中新世，上油砂山组，小哺乳动物群

卷期：46卷 04期

 Late Miocene micromammals from the Qaidam Basin in the Qinghai-Xizang Plateau

　　Qiu Zhu-Ding,  Li Qiang 　　  

　　
Abstract  This paper deals with an assemblage of small mammals collected from the upper Youshashan Formation at Shengou, Delingha, Qinghai Province during the field seasons of 2002−2005. The Shengou micromammalian fauna is composed of 16 species from 12 families belonging to the orders Insectivora, Rodentia and Lagomorpha. It is the most diverse and abundant micromammalian fauna known from the vast Qinghai-Xizang Plateau. One species of Muridae (Huerzelerimys exiguus) is described as new, and represents a new record of the genus in China. The Shengou Fauna appears to closely resemble the assemblage from the lower part of the Bahe Formation of Shaanxi, but slightly younger than the latter. It is most probably attributable to early Late Miocene, or the early Baodean of the Chinese Land Mammal Ages, correlated, in European terms, with late MN10 or early MN11. The fauna reflects a faunal distribution of the modern temperate region in China, and suggests a dry and open environment. Nevertheless, the climate in Qaidam area was unlike the exact situation of the present day, but was less arid with more vegetation during the early Late Miocene than it is today. Both habitats and composition of the fauna may imply that the Qinghai-Xizang Plateau had undergone a definite uplift in relation to the loess plateau after Miocene.  
Key words  Shengou, Qaidam, Qinghai; Late Miocene; Youshashan Formation; micromammals