(一)引言 每一个地质年代,以其自有的特殊情况,在生物历史的长河中占有重要的位置。因而,很难找出哪个年代来作为动物、植物演化过程中具有特别意义的时代。可是,当我们注意到各种门类有别的生物群时,诸如门、纲、目、或更小的类目,就我们所探讨的动物群进化发展所涉及的范围而言,某些地质年代就显得比其他年代更为重要。以两 (A) Introduction Each geological era, with its own unique circumstances, occupies an important position in the long history of biological history. Thus, it is difficult to find out which age is an age of special significance for the evolution of animals and plants. However, when we noticed that there are other biomes in different categories, such as the phylum, class, class, or smaller category, in terms of the range involved in the evolutionary development of the fauna, some geologic age It seems more important than any other era. Take two