关键词: 哺乳类化石;保存特征;埋藏学;古人类活动

Abstract: About 880 specimens were found in Xishuidong , Lantian, Shaanxi in 1981 in association with stone artifacts, bone tools, charcoal and ash layers. About 42% of them are identifiable, and 58% of them are fragmentary bones. Some of the fragmentary bones can also roughly be classified according to their sizes and their remained character. After studying systematically , it is found that these fossils fall into 13 species, nine of which are large mammals. The preservation of the large mammals shows the following statistical feature:
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From the above table we can see that the number of species and the minimum number of individuals of each species are quite different. The PAS( the Preserved Amount of Specimens∶ the number of specimens of one species of total number of specimens) and the RAS ( the Relative Abundance of Species∶ the minimum number of individuals of one species of the total minimum numbers of the fauna) of the herbivore are much higher than thseo f carnivore. The N SI( the number of specimens per individuals) reflects the relative completeness of an individual animal. From the above table we can also see that the N SI seems to be in proportion to the size of the animal body. The higher the N SI, the larger the animal, and the much more the fragmentation.
According to the standards of Behrensmeyer( 1978) , 80% of the fossils are in weathering stage 0, 18% are in weathering stage 1-2 and only 2% are in weathering stage 3-5. So the exposure time of most bones might not be long . Most fossils show no abrasion. This indicates that the fauna had not been moved by water for along distance.
Almost all skeletal elements of the Naemohedus, Cervus, Dicerorhinus, Bison were preserv ed. However, the preservation of them are not proportioned. The expected number of each element has a great difference with the actual number found. One of the reasons might be that many fragmentary bones can not exactly be determined from which species and which part of the body they are derived.
One obvious character of the broken limb bones can be observed. From humerus and femur to metacarpus and metatarsus, the lower position the bone, the much less the frag- mentation. Most autopodium is complete, while almost all stylopodium and zygopodium are damaged. In addition, the completeness of bones seems to be related to their sizes. This is also reflected by the N SI.
On the character of preservation mentioned above, the authors tried to investigate. What was the cause for the animal bones existing in this cave. Four possible ways are analyzed. In conclusion, it is considered that the large mammals must be carried to Xishuidong by ancient human being , and the main force of the breakage of fossilsis closely related with the chopping of the ancient men. This can best explain the above characters.

Key words: Taphonomy, Bone Fracturing , Human Behavior, Xishuidong Fauna, Lantian, Shaanxi