侏罗纪的蛇颈龙类化石主要发现于欧洲 ,在世界的其他地区则比较少见。亚洲的蛇颈龙化石 ,尤其是侏罗纪的属种大多破碎而难以鉴别 (Sato,1 998)。到目前为止 ,Bishanopliosaurusyoungi(Dong,1 980 )和Yuzhoupliosauruschengjiangensis(Zhang,1 985)是亚洲地区最为完整的侏罗纪蛇颈龙类化石 ,并且化石产自对于蛇颈龙而言比较罕见的淡水沉积 ,因此这些材料对于了解该类群的系统发育、历史动物地理和古生态来说非常重要。本文重新详细描述了采自中国重庆自流井组东岳庙段的杨氏璧山上龙2 ) (董枝明 ,1 980 )。愈合情况不好的椎体和椎弓以及耻骨的边缘形态表明 ,杨氏璧山上龙的正型标本是一个幼年个体的头后骨架。我们的研究表明杨氏璧山上龙主要依分叉的荐肋为特征 ,而这一性状在初次发表时作为颈肋特征被描述。璧山上龙的其他特征包括侧扁的神经棘以及狭窄的乌喙骨和肱骨上有一个突。经过重新修理的标本显示 ,坐骨和耻骨相对的面呈沟槽状 ,这一现象表明它们之间的接触关系要较原来描述的情况复杂 ,是一种依靠软骨的连接 ,而非直接接触。本文对杨氏璧山上龙的腰带部分进行了重新复原。O’Keefe (2 0 0 1 )的支序分析支持将Plesiosauria二分为Plesiosauroidea和Pliosauroidea,后者包含两个科 :Pliosauridae和 Jurassic plesiosaur fossils found mainly in Europe, the rest of the world is relatively rare. Psittacos fossils in Asia, especially the Jurassic, are mostly broken and difficult to distinguish (Sato, 1998). So far, Bishanopliosaurus youngi (Dong, 1 980) and Yuzhoupliosauruschengjiangensis (Zhang, 1985) are the most complete Jurassic plesiosaur fossils in Asia and fossils are produced from relatively rare freshwater deposits for plesiosaur, Therefore, these materials are very important for understanding the phylogeny of this group, the history of animal geography and the paleontology. This article details the Yangshang Bishan 2) collected from Dongyuemiao, Ziliujing, Chongqing, China (Dong Zhiming, 1980). The healing of the vertebral body and vertebral arch, as well as the marginal morphology of the pubic bone, indicates that the positive specimen of the Shanglong Mountain in Bishan is a posterior posterior skeleton of an individual. Our study shows that the Yangshan Bishan dragon is mainly characterized by the bifurcated girdle, which was described as a cervical spine feature at the time of initial publication. Other features of the Bishan dragon include the lateral flat spine, the narrow black coracoid bones and the humerus. The newly repaired specimen showed a grooved appearance between the ischial and pubic surfaces, a phenomenon that suggests that the contact between them is more complicated than the one originally described and is a reliance on cartilage instead of direct contact. This article on the Young’s Bishan Shanglong part of the belt was restored. The ordinal analysis by O’Keefe (2001) supports the dichotomy of Plesiosauria into Plesiosauroidea and Pliosauroidea, which consists of two families: Pliosauridae and