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Paleontological and evolutionary developmental biological studies on body elongation, limb reduction and adaptive radiation in the evolution of lizards

蜥蜴进化过程中身体伸长、肢体减少和适应性辐射的古生物学和进化发育生物学研究

基本信息

批准号：
15340179
负责人：
MANABE Makoto
金额：
$ 10.18万
依托单位：
National Museum of Nature and Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2006
项目状态：
已结题

项目摘要

1) A new genus and new species Kaganaias hakusanensis was described based upon a small reptile with the elongated body found in Kuwajima Formation, the Tetori Group. K.hakusanensis is most likely to be one of the most basal members of dolicosauridae. K.hakusanensis is the first fossil of the group found outside of Europe and also the first occurrence of a non-marine stratum. Dolichosaurs are sister groups of mosasaurs, and they are found only in the marine sediments deposited in Europe during mid to Late Cretaceous. It has been therefore believed that various lizards adapted to the life in the sea in Europe in mid Cretaceous. Some phylogenetic hypothese placed dolicosaurs as sister groups not only of mosasaurs but also of snakes, and thus argued that the snake like limbless body forms were evolved as the result of aquatic adaptation. The discovery of Kaganaias haskusanensis does not agree to these previous hypotheses. 2) Limb development of six different species of lizards was studied in order to make comparisons to that of chicken where developmental stages are well established. As far as limb development is concerned, a hatching lizard was found to be surprisingly in the advanced developmental stage equal to the 12^<th> stage in chicken. The lizard accelerated its limb development even further after hatching. 3) A pachycormid fish found in the Kuwajima Formation is morphologically most similar to a Late Jurassic species from Europe whereas an osteoglossid fish found together is the oldest fossil record of the group. The fish fauna exhibits the mixture of the Jurassic and Cretaceous forms found together in the Kuwajima Formation. It shows the similarity to the pattern seen in synapsids and dinosaurs. It may lend support for the uniqueness of this temporal mixture of East Asia.

1)本文描述了一个新属、新种-白山Kaganaias hakusanensis。白山克龙可能是长龙科最底层的成员之一。K.hakusanensis是在欧洲以外发现的第一个化石，也是第一个非海洋地层。长角龙是沧龙的姊妹群，它们只在白垩纪中期至晚期的欧洲海洋沉积物中发现。因此，人们认为各种蜥蜴适应了白垩纪中期欧洲海洋中的生活。一些系统发育假说认为长角龙不仅是沧龙的姐妹群，也是蛇的姐妹群，因此认为蛇一样的无肢体型是水生适应的结果。哈斯库山卡根的发现不同意这些先前的假设。2)研究了六种不同蜥蜴的四肢发育，以与发育阶段已确定的鸡进行比较。就肢体发育而言，令人惊讶的是，孵化蜥蜴处于相当于鸡的12^阶段的高级发育阶段<th>。这种蜥蜴在孵化后进一步加速了四肢的发育。3)在岛组中发现的一种厚角鱼在形态上与欧洲晚侏罗世的一种最相似，而一起发现的一种骨舌鱼是该组中最古老的化石记录。鱼类动物群表现出侏罗纪和白垩纪的混合形式，在岛组中一起发现。它显示出与突触动物和恐龙中所见的模式相似。它可能支持东亚这种时间混合的独特性。