Abstract: Large mammals are very sensitive to climatic and environmental changes, and the composition of a fauna depends on the ecology and environment. As a result, knowing how the population is structured is very important when trying to understand envimnmental characteristics by studying mammal fossils. First, we found the percentages of each age group, then estimated the causes of death in each population, and finally classify the habitat of these animals. The Hipparion fauna from the Linxia Basin is very similar in composition to assemblages from Baode, Shanxi and Fugu , Shaanxi, with rhinoceroses as the most abundant mammalian fossil (Deng, 2002) . 'Ibe genus Chilotherium from northern China was first recorded by Ringstlürn (1924) , and it was the richest during the Late Miocene in the Linxia Basin (Deng, 2001a) . It is valuable to recognize the age structure and habitat of the dominant Chilotherium wimani from the Upper Miocene in the Linxia Basin .

摘要： 甘肃临夏盆地的晚中新世红粘土堆积中含有大量的三趾马动物群化石，其中犀科化石，特别是大唇犀最为丰富。通过对临夏盆地晚中新世具有代表性的大唇犀化石的年龄结构的分析，初步了解到化石群各年龄段个体的百分比和种群动态。大唇犀化石中成年个体的数量占优势，明显多于老年个体，与正常生活群中的年龄结构吻合，由此可初步断定是突发性事件引起了犀牛种群的灾害性死亡。再进一步对化石的风化、磨蚀、聚集状态及所受的水动力特征等进行分析，发现骨骼受到了弱水流的短距离搬运，说明化石埋藏地离动物死亡地不远。以上分析结果与沉积学特征相结合，说