干旱区生态环境知识资源中心

In contrast to the global trend of mid-latitude drying in Late Neogene, North China appears to have experienced an increase in humidity during the latest Miocene, the Baodean land mammal age sensu stricto. This "favourable oasis" in time and space had a strong influence on the evolution of the herbivorous land mammals of the region. The locally improved conditions first caused an influx of immigrants from several directions and later the development of endemic taxa from both native and immigrant stock. Lack of published data hinders a study of the effect on the mammal fauna when the climate became dry, a process well underway by the Middle Pliocene, but ultimately the effects of the Baodean exception were erased and North China Joined the Palaearctic faunal province. We hypothesise that the apparently high diversity and low endemism seen in the North Chinese land mammal faunas of the latest Miocene can be explained by a Koenigswaldian model, in which two separate faunal assemblages cyclically alternate and mingle in a transitional zone.