辽西热河生物群一新的巨龙型类恐龙

A new titanosauriformes dinosaur from Jehol Biota of western Liaoning,China

初步研究了辽西地区热河生物群的一具近完整的蜥脚类恐龙骨架,其代表了一新的巨龙型类恐龙——中国辽宁巨龙(Liaoningotitan sinensis gen.et sp.nov)。其主要特征为:上颌骨腹缘下凸,上颌齿列短且位于前部;颧骨前端近平齐于眶前窗的前缘;翼骨的方骨支基部收缩;上颌齿呈叠瓦状排列;上颌齿冠窄勺形,切面呈D字形,缺失唇侧沟和小锯齿;下颌齿9枚,明显小于上颌齿,排列稀松;下颌齿冠不对称,切面呈椭圆形,舌侧的沟和嵴发育,齿冠基部向舌侧膨大;肱骨近端扩展,约为长度的54.9%;肠骨前髋臼突前端较尖。初步的支序分析显示,辽宁巨龙属于巨龙型类恐龙,是比盘足龙和梁龙更为进步的类群。

A nearly complete sauropod skeleton,collected from the Jehol Biota of western Liaoning,is described briefly as a new titanosauriformes,Liaoningotitan sinesis gen.et sp.nov.Its diagnostic characters include：ventral margin of maxilla is convex,upper tooth row is short and anteriorly positioned;anterior extension of jugal nearly reaches the level of the anterior margin of the antorbital fenestra;quadrate wing of the pterygoid constricted basally;upper teeth are imbricated,narrow spatulate crown is D-shaped in cross section,with labial grooves anddenticles absent;well reduced and un-imbricated nine lower teeth;lower tooth crown is asymmetric,elliptical-like in cross section,lingual grooves and ridge present,basal crown bulbous lingually;proximal expansion of the humerus is about 54.9% the length of the humerus,ilium with a pointed preacetabular process.Preliminary result of the phylogenetic analysis shows that Liaoningotitan falls into the clade of titanosauriformes,and is more derived than Euhelopus and Brachiosaurus.