Occurrences of warm-adapted mammals in north China over the Quaternary Period and their paleo-environmental significance

Abstract

The north and south China faunas are subdivided along the line of Huaihe River-Qinling Mountains-Hengduan Mountains-Himalayas, to the north is the Palearctic Region, and to the south is the Oriental Region, which is the result of long-time evolution. Hundreds of Quaternary fossil localities have been known up to now, more than 60 of which contain warm-adapted elements which can be referred to 20 species. Among the warm-adapted elements appearing in north China, Hystrix, Macaca, Palaeoloxodon, Dicerorhinus and Bubalus are the most frequently recorded genera. There are three kinds of causal explanation about the frequent appearance of warm-adapted elements in north China: The first hypothesis attributed them to the dispersal events of warm-adapted mammals from the south during warm stages or warm seasons; the second scenario thinks that these warm-adapted mammals in north China were once derived there in situ and subseqeuntly emigrated to the south with the cooling down of the global climate; the last hypothesis believes that these warm-adapted elements were not real warm-climate animals at that time. This study shows that almost none of the warm-adapted mammals in north China was recovered in the loess, and also almost all of the fossil localities which bear warm-adapted mammals fall within the warm temperate zone of nowadays. In fossil assemblage, those warm-adapted elements rarely co-exist with the cold-adapted mammals. All these evidences mentioned above indicate that the warm-adapted mammals in north China represent warm climate, but not hot one. Because all these warm-adapted mammals are widely distributed oriental elements, some of them even still exist north of the Huaihe River today. Up to now, no typical oriental elements have ever been recovered in north China, such as pangolin, primitive primates (e.g. loris and tarsier), big apes (e.g. Gigantopithecus, Pongo and Hylobates), etc. The Late Pleistocene lasted a relatively shorter time, but the appearance of warm-adapted mammals during that span were the most frequent and most widespread. It means that the climate of the Late Pleistocene experienced the most frequent fluctation over the whole period of Quaternary.