继2000年在南京汤山直立人地点葫芦洞附近的驼子洞堆积(32°03'17.1"N,119°01'57.6"E)中发现了大量的哺乳动物化石后,2007年在驼子洞又进行了新的发掘工作,出土了不少新材料。根据对新材料的研究将若干种类的分类位置做了修订,其中将原来鉴定为短角丽牛相似种(Leptobos cf. L. brevicornis)的标本厘定为粗壮丽牛(Leptobos(Smertiobos)crassus。通过对驼子洞动物群性质的综合比较,发现驼子洞动物群的组成成分与安徽繁昌人字洞动物群和重庆巫山龙骨坡动物群最接近。驼子洞动物群的组成具有南、北方类型混合的特点,应该属于过渡型动物群,但以具北方特色的成员偏多,说明在早更新世期间有北方的部分种类向南扩散的事件,范围到达南京一带。这一扩散事件可能与气候变化有关。驼子洞动物群指示在早更新世时期江宁一带的地貌特征与现在的差别不大,气候潮湿,但气温可能比现在的低。
英文摘要:
A large quantity of Early Pleistocene mammalian fossils were discovered in 2000 at the Tuozidong (or Tuozi Cave, "Humpback cave in Chinese. GPS: 32°03'17.1"N, 119°01'57.6〃E; 114m a.s.l.) about 872m southwest (heading 244°36'N) of Nanjing Man Site, Tangshan, Nanjing Municipality, Jiangsu Province. Tuozidong is a collapsed karstic cave developed in Honghuayuan Formation of Ordovician limestone, and the Early Pleistocene fossiliferous deposits composed mainly of yellow clay and sandy clay cover directly on the Ordovician limestone bedrock with a thickness of about 6m. New materials were unearthed by a follow-up excavation carried out in 2007 at Tuozidong that enriched the hypodigms of certain taxa. The systematic study on the new materials resulted some taxonomic modifications of some fossils, including the reassignment of the former Leptobos cf. L. brevicornis to Leptobos (Smertiobos) crassus. The comparison of the Tuozidong fauna with 9 selected Early Pleistocene faunas from different parts of China (i.e. Renzidon, Longgupo, Longgudong, Danawu, Liucheng, Sanhe, Xiaochangliang, Gongwangling and Longdan) shows that the composition of Tuozidong fauna is the most similar to that of Renzidong at Fanchang of East China and that of Longgupo at Wushan of Central China. The composition of Tuozidong fauna is characterized by the combination of northern and southern forms, the fauna is therefore typical of transitional zone. But the proportion of northern forms is evidently higher than that of southern ones, indicating that there was a southward dispersal event of northern forms and the scale of dispersal reached in Nanjing in the Early Pleistocene. The event is very likely related to climatic change, colder weather in the north that pushed the less hardy forms southward for example. The presence of Macaca peii, Martes sp., Eirictis sp., Meles sp., Megaviverra pleistocaenica, Lynx shansius, ?Puma pardoides in the Tuozidong fauna indicates that there were some rocky hills with trees around Tuozidong. The presence of Pachycrocuta perrieri, Acinonyx arvernensis, Hipparion (Proboscidipparion) sinense, Equus huanghoensis,Megalovis cf. M. guangxiensis, Gazella sinensis and Leptobos (Smertiobos) crassus in the fauna indicates the open grasslands around the cave. And the presence of Nyctereutes sinensis, Stegodon cf. S. preorientalis,Stephanorhinus kirchbergensis, Sus lydekkeri, Metacervulus capreolinus, Cervavitus ultimus, Axis shansius jiangningensis, Cervus (Sika) cf. C. grayi, Cervus cf. C. (Sika) magnus in the fauna indicates the combined zones of forests and grasslands. The Tuozidong fauna indicates therefore that the physical geographic features in Jiangning area in the Early Pleistocene were similar to those of today; the environment was humid, but the temperature was lower. The Yangtze River is a giant geographical barrier for migration of terrestrial mammals. Tuozidong is situated south of the river with such barrier to resist the northern forms to arrive at Tuozidong if the size and the location of the Yangtze were the same as of today in the Early Pleistocene. The presence of many northern taxa at Tuozidong implies that such barrier was not present in the Early Pleistocene. It can be inferred that in the Early Pleistocene the size of the Yangtze was not very large to form a geographic barrier for the migration of terrestrial mammals, or the size was similar to the present but the location was south of the Ningzhen Mountain ranges rather than as of today.