湖北鳄研究现状及其环境演变的初步认识

Research Status of Hupehsuchia and Preliminary Understandingof Their Environmental Evolution

在专题研究工作开展基础上,对湖北最具特色和代表性的史前生物——湖北鳄的前人认识成果进行充分梳理,对其化石发现沿革和属种厘定、系统发育特征、形态生理学等方面的研究现状进行概要说明,并简要介绍近期在远安开展的湖北鳄化石层野外调查和化石发掘取得的新认识进展,对湖北鳄化石产出的地层及其上下层位的岩石学和古环境意义进行分析,对湖北鳄生活环境及演变过程进行初步探讨。综合认为湖北鳄是一类具高分异度演化特征并与鱼龙有亲缘关系的特殊早三叠世海生爬行动物,至少包含两种生态类型,并与更高营养级的捕食动物鱼龙、幻龙等共生,在生态食物链中扮演重要的角色,其生存和发展可能与早三叠世中扬子浅海台地的一处局限盆地或凹陷演化关系密切,其灭绝可能与动物食性、运动能力及区域规模巨大的造山事件综合相关。湖北鳄的研究对中生代海洋生态复苏重建及海生爬行动物的起源和早期演化研究有重要启示意义,但研究程度尚浅,研究工作尚需进一步加快推动。

On the basis of special research work,the most distinctive and representative prehistoric creature in Hubei Province,Hupehsuchia,has been thoroughly sorted out,including its fossil discovery history,genera and species determination,phylogenetic characteristics,morphophysiology,etc.The current research status in Yuan’an is summarized,and the new understanding of the field investigation of the fossil layers and the fossil excavation recently carried out in this area are introduced.According to the analysis of petrology and paleogeography of the related strata,the evolution history of the living environment of Hupehsuchia is well discussed.This marine clade is related to ichthyosaurs and has high disparity of evolutionary characteristics.So far,at least two ecological habits of Hupehsuchia have been illustrated.Its co-occurrence with ichthyosaurs and nothosaurs suggests that Hupesuchia has played an important role in the food web which includes ichthyosaurs and nothosaurs,while the latter two occupy higher trophic levels.Its existence and development may be closely related to the evolution of the restricted basin or depression which locates at the middle Yangtze platform,while its extinction may be related to the feeding habits,locomotivity and local orogenic events.Moreover,study of Hupehsuchia has important implications for the reconstruction of the recovery history of Mesozoic marine ecosystem as well as the origin and early evolution of marine reptiles.However,further researches are demanded if we want to know more details about these processes.