辽宁西部早白垩世义县组一新的手盗龙类(英文)

我国辽西早白垩世热河群义县组和九佛堂组近年来产出大量恐龙化石 ,已知兽脚类恐龙包括 8属 1 0种 ,其中 6属 8种保存有原始羽毛或者羽毛结构。已经报道的属种均产自朝阳地区。 2 0 0 1年 ,中国科学院古脊椎动物与古人类研究所辽西野外考察队在邻近朝阳的锦州地区义县头台乡王家沟义县组下部采集到一件恐龙标本。这一标本保存了较为完整的肩带和前肢 ,在骨骼化石附近还保存了皮肤结构。通过研究对比 ,我们建立了手盗龙类的一个新属种 :长掌义县龙 (Yixianosauruslongimanusgen .etsp .nov .)。依据以下特征将长掌义县龙归入手盗龙类 :肩胛骨明显短于肱骨、肩臼窝的乌喙骨部分小、乌喙骨近四方形、尺骨向后弯曲以及挠骨细。长掌义县龙手部的相对长度以及手指各指节的相对比例不同于已知手盗龙类。原始兽脚类恐龙的手部一般短于肱骨 ;手盗龙手部加长 ,长于肱骨 ;原始鸟类的手部相对更长 ,但进步鸟类出现反转 ,手部次生变短。长掌义县龙手部的相对长度在非鸟兽脚类恐龙当中仅比原始祖鸟 (Protarchaeopteryx) (Jietal.,1 998)和树息龙 (Epidendrosaurus) (Zhangetal.,2 0 0 2 )短。次末端指节加长是兽脚类恐龙的一个进步特征 ,长掌义县龙具有这一特征。比如 ,长掌义县龙的手指指节Ⅱ 2长于掌骨Ⅱ ,在已知兽?

A NEW MANIRAPTORAN DINOSAUR FROM THE EARLY CRETACEOUS YIXIAN FORMATION OF WESTERN LIAONING

A specimen collected from the Early Cretaceous Yixian Formation, Jehol Group of Liaoning,China, represents a new genus and species of maniraptoran theropod. It comprises almost complete articulated pectoral girdles, forelimbs and some ribs and is here named Yixianosaurus longimanus gen. et sp. nov. Diagnostic features of the new species include manus 140% as long as humerus, manual phalanx Ⅱ-2 longer than metacarpal Ⅱ, manual phalanx Ⅲ-3 244% as long as phalanx Ⅲ-1, and manual phalanx Ⅲ-2 bearing a proximoventral heel. With the integuments preserved on the holotype specimen, Y. longimanus represents the ninth feathered dinosaur species reported from western Liaoning. The elongated penultimate phalanges of Y. longimanus indicate an improved grasping capability and might represent an adaptation to the arboreal habit. The discovery of Y. longimanus increases the diversity of theropod dinosaurs in the Jehol Fauna.