论龟科和陆龟科

<正> 龟科(Emydidae)和陆龟科(Tesrudinidae)同是隐颈龟亚目(Cryptodira,也叫曲颈龟亚目)中两类最为常见的主要类群。它们不仅有为数众多的化石种类,其现生种类的总数也占所有现生龟鳖类的三分之二。这两科龟类在其起源、地史分布、甚至某些形态构造方面,都有一定的相近之处,无怪有的学者主张将两科合并为一科,但也有持不同意见的。笔者在从事化石龟鳖类的研究过程中,对于这两类动物,有时也遇到某些疑难问题,特别是

REMARKS ON SOME PROBLEMS OF EMYDIDS AND TESTUDINIDS

The emydids and testudinids are two common and main groups of cryptodire turtles. We meet them usually in Cenozoic deposits and recent. In fossils, as other turtles, they represent generally by their shells only. Though the typical species of testudinids can easily be recognized by their structures of neural, costal and epiplastral plates, etc., it is still somewhat difficult to distinguish some testudinids, which are not so typical, from emydids by shells. A general remark of some structural similarities and differences of the shell of these groups, especially the bony plates of them, is presented. In the second section of the present paper, the origin and the flourish and decline of these two groups are talked. It seems reasonable to believe that the emydids and testudinids originated respectively from early Cryptodira, and developed in Cenozoic as two different branches, one adapted chiefly in fresh-water and another on land. It is, therefore, somewhat better to consider them as two groups (Families or Subfamilies) rather than to gathered them as one. At last, a list of species of emydids and testudinids known in China is arranged through geological time. Since the occurrences of Paleocene emydids known recently in China, as we have seen in the list, the earliest record of this chelonian group is thus more certain.