A Possible Long-tailed Bird with a P

A Possible Long-tailed Bird with a Pygostyle from the Late Mesozoic Yixian Formation,Western Liaoning,China

An incomplete caudal vertebral series (IVPP V11309) from the Yixian Formation of late Mesozoic,Jianshangou area of B eipiao, western Liaoning Province, may represent a new bird. The tail is composed of at least 12 free caudal vertebrae and the most distal 5 caudal vertebrae co-ossified into a pygostyle. The pygostyle is plate-like and slightly curved dorsally. The anterior free caudals are amphiplatyan. The anterior caudal surfaces of the last three free caudals are concave, but their posterior articular surfaces are convex. The pygostyle is regarded as the first appeared flight apparatus during the evolutionary process from Archaeopteryx to neornithes. The pygostyle appeared in most early fossil birds and almost all the modern birds. Although their morphologies are different, they are basically formed by at least four last caudal vertebrae. The specimen V11309 is regarded as a bird rather than a non-avian theropod dinosaur based on the following characters: short caudal vertebrae, numerous pits present on the surfaces of the centra and, a foramen present between the basal part of the fused neural spines, which is similar to that of Struthio camelus. The discoveries of pygostyles from the therizinosauroids and oviraptorosaurs may provide strong evidence for supporting the origin of birds from small theropod dinosaurs. The structure of the pygostyle in specimen V11309 is different from those of Beipiaosaurus (Therizinosauroid) and Nomingia (oviraptorosaur). The most parsimonious interpretation is that these pygostyle-like structures are independently acquired by Beipiaosaurus and Nomingia during their evolutionary process.

作 者： U Junchang HOU Lianhai   作者单位： U Junchang(Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037)

HOU Lianhai(Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences,Beijing 100044; Department of Biology, Capital Normal University, Beijing 100037) 

刊 名： 地质学报(英文版)  SCI 英文刊名： ACTA GEOLOGICA SINICA  年，卷(期)： 2005 79(1)  分类号：   关键词： western Liaoning   Yixian Formation   late Mesozoic   pygostyle  

【A Possible Long-tailed Bird with a P】相关文章：

禽流感 bird flu05-04

The bird and cat英语作文（精选20篇）12-21

论可以P与可以不P的关系04-27

THE CHARACTERISTICS OF THUNDERSTORM FREQUENCY VARIATION AND THEIR POSSIBLE RELATION WITH THE ADJUSTMENT OF CROP DISTRIBU04-27

其他类英语作文：If I were a bird04-25

学科术语 P05-04

p2p业务员工作计划01-07

p2p理财培训心得体会05-17

If I were a bird_1000字英语作文04-25

LALA的美容心得贴P573-P577(8.2+)04-25