内蒙古上白垩统二连组发现一新镰刀龙类(英文)

A NEW THERIZINOSAUROID (DINOSAURIA,THEROPODA) FROM THE UPPER CRETACEOUS IREN DABASU FORMATION OF NEI MONGOL

镰刀龙类化石主要分布于亚洲白垩纪地层 (RussellandDong ,1 993;Xuetal.,1 999a ;KirklandandWolfe ,2 0 0 1 )。最近发现于内蒙古上白垩统二连组的杨氏内蒙古龙(Neimongosaurusyangi)代表这一类群中较为原始的属种 (张晓虹等 ,2 0 0 1 )。通过研究产自同一化石地点的镰刀龙类新材料 ,我们鉴定出一个不同于杨氏内蒙古龙的新属种 ,美掌二连龙(Erliansaurusbellamanusgen .etsp .nov.)。依据以下特征将Erliansaurusbellamanus归入镰刀龙超科 :肩胛骨干远端狭窄、肱骨近端角状、肱骨有后转子、肱骨的尺骨髁和桡骨髁位于肱骨干前部、肠骨髋臼后支远端加厚、距骨髁小和腓骨近端后缘窄。Erliansaurusbellamanus的以下自近裔特征区别于其他镰刀龙类 :前部尾椎具加大的滋养孔、肱骨后转子嵴状、肱骨后转子内侧有一卵形凹陷、肠骨外侧面坐骨柄上方有一多皱的肿状突起、腓骨近端后缘明显高于前缘以及腓骨前转子大、位置靠远端。本文对镰刀龙类的系统关系进行了初步的分析 ,结论如下 :北票龙 (Beipiaosaurus)代表除Eshanosaurus外最原始的属种 ,它没有以下一些其他镰刀龙类的进步性状 :掌爪近端深、胫骨短于股骨、非常短的骨以及第一骨关连跗骨。Erliansaurus、Alxasaurus。

A partial skeleton is described from the Upper Cretaceous Iren Dabasu Formation of Nei Mon gol that represents a new therizinosauroid theropod, Erliansaurus bellamanus gen. et sp. nov. Distinctive characteristics of the new species include enlarged nutritional foramen on anterior caudals, prominent crest-like posterior trochanter on the humerus bordered medially by an oval depression, rugose swelling lo-cated dorsal to the ischiadic peduncle on the lateral surface of the ilium, posterior margin significantly higher than anterior margin on the fibular proximal end, and distally located hypertrophied anterior tro chanter on the fibula. Preliminaty analysis suggests that E. bellamanus represents an intermediate taxon between the primitive therizinosauroids and the advanced Therizinosauroidae. The discovery of E. bella manus provides important information regarding the diversity within Therizinosauroidea.