上扬子区三叠纪幻龙类化石及其埋藏环境研究

项目名称： 上扬子区三叠纪幻龙类化石及其埋藏环境研究

项目编号： No.40872019

项目类型： 面上项目

立项/批准年度： 2009

项目学科： 农业科学

项目作者： 尚庆华

作者单位： 中国科学院古脊椎动物与古人类研究所

项目金额： 44万元

中文摘要： 本项目对华南主要是西南地区的三叠纪海生爬行动物重要组成类群之一-幻龙类化石属种进行了系统的整理和研究，对其古地理分布、地层层位以及埋藏环境进行了较深入的调查和分析，并开展了相关的实验室环境模拟。通过野外发掘和标本征集，发现一批有较高研究价值的新材料，并描述了部分新属种。其中一新属种- - 利齿滇东龙已经正式发表，为一较原始的始鳍龙类基干类群。依据新材料，开展分支系统学分析，提出了新的始鳍龙类亲缘关系系统。肿肋龙分支和幻龙分支互为姊妹群,构成幻龙下目（Nothosauroidea）；汉江蜥和贵州龙应属于幻龙分支,而非肿肋龙分支。经过广泛对比和资料收集，对迄今为止发表和报道的中国始鳍龙类属种进行了重新厘定，对共计12属18种始鳍龙类的属种鉴定特征、地层地理分布等做了重新定义，成果将汇编于新版的《中国古生物志》"海生爬行动物"分册中。此外，实验室在设定的物理化学条件下，模拟脊椎动物死亡、埋藏环境，分析温度、酸碱度、氧化和还原条件等的对化石形成的影响，进而探讨三叠纪特异保存的海生爬行动物化石的环境因素。已获得的实验结果表明缺氧环境并非化石精美保存的决定因素，细菌和温度等的影响可能更为重要。

中文关键词： 三叠纪；幻龙类；系统演化；埋藏环境；华南

英文摘要： The Nothosauroidea, which is the main group of the sauropterygia of the Triassic marine reptile in southwestern China, are systematic investigated and reviewed, and fossils buried environment is reconstructed on the bases of field study and laboratory experiment. Marine reptile materials in large quantity and quality are obtained during field excavation and fossil collection. Some of them are new taxa. One skeleton had been published, which is a new genus and new species of stem group of eosauropterygia, and named Diandonsaurus acutidentatus Shang, Wu et Li, 2011. Added the new information the phylogenetic relationships of eosauropterygia is reconstructed. The cladistic analysis yielded two main results, both of them in disagreement with conclusions reached by previous studies on this topic. (1) The Nothosauria is with Pachypleurosauria affinity rather than the Pistosauria, and the two clades make the Nothosauroidea. (2) The Hanosaurus and Keichousaurus are not a pachypleurosaur but a nothosauroid. The systematic revision of the Eosauropterygian from southwestern China results in the recognition of 12 valid genera and 18 valid species. The redefinition and description of these taxa will published in the marine reptile volume of the new edit "Palaeobios Sinica" series. The perfect preserved marine reptile fossils in Panxian fauna and Guanling fauna had been widely consider that their preservation condition resulted from anoxic environments of deposition. Under the controlled physical and chemical condition we designed several experiments to examine the influence of temperature, PH value and anoxic or oxic conditions during the decay process in animals. Our laboratory finding indicated that the anoxic and oxic conditions make no sense in decay process, but it strongly related to microbes, especially to intestinal ones.

英文关键词： Triassic; Nothosauroidea; phylogeny;taphonomy; South China