黄土高源古今脊椎动物兴衰演替

The Succession of Vertebrate on Loess Plateau in the Past and Present

黄土高原古脊椎动物丰富，其中古爬行类在甘肃、宁夏等地均有发现．大约在白垩纪前后灭绝，生存了大约五千万年至一亿年．古哺乳类更为丰富，特别是陇东黄土高原上发现了大量有蹄类、食肉类、长鼻类化石．这些动物大部分在更新世灭绝，个别种类一直延续至今． 现代生存的鸟类、哺乳类大部分种群密度下降，有些种类甚至绝迹．个别种类密度回升．

The loess plateau was rich in ancient vertebrates. The fossils of such ancient animals have been discovered in Gansu and Ningxia. They died out approximately in the Cretaceous period after living for about 50 to 100 million years. Many kinds of ancient mammalian fossils have been discovered in Gansu, especially in its eastern area, which included ungulates and carnivores, etc. The majority of them became extinct in pleistocene epoch, and a few of them have survived till today. At present, the population density of the majority of the descendants drops year by year, and some of them have even vanished while that of a few of the birds and animals rises again.