T.Alexander DECECCHI 1Hans C.E.LARSSON 1David W.E.HONE2
作者信息
- 1. 加拿大麦吉尔大学雷德帕思博物馆 蒙特利尔H3A2K6
- 2. 爱尔兰都柏林大学生物与环境科学学院 都柏林4
- 折叠
摘要
Abstract
We re-examine the partial skeleton of the enigmatic small feathered theropod Yixianosaurus longimanus from the Lower Yixian Formation,China.A phylogenetic analysis recovers Yixianosaurus as a basal maniraptoran,in a polytomy with Alvarezsaurus,Therizinosauria,Alvarezsauroidea excluding Alvarezsaurus,and a well-resolved clade of derived maniraptorans including Oviraptorosauria and Paraves.The blend in Yixianosaurus of primitive traits,such as a low brachial index and robust digit Ⅲ,and derived traits such as a subrectangular coracoid,suggests a more complicated mosaic of forelimb evolution within Maniraptora than previously proposed.The robust forelimb bones and massive,recurved,and pointed manual unguals suggest Yixianosaurus was predatory,although this assessment remains tentative until more complete fossils of this taxon are found.The basal maniraptoran phylogenetic position implies a larger range of forelimb morphologies at this point in coelurosaurian evolution.In many ways,the robust forelimb and hypertrophied recurved unguals are similar to those of Tanycolagreus and Coelurus,and may be morphologically transitional between these taxa and basal therizinosaurs and oviraptorosaurs.The presence of large,veined,pennaceous contour feathers on Yixianosaurus indicates the origin of these integumentary structures may be deeper in coelurosaur phylogeny than previously reported.Finally,the robust,elongate forelimbs suggest a different ecological role than inferred for other sympatric small theropods,and lend support to the idea of niche partitioning among the small non-avian theropods of the Jehol fauna.关键词
热河生物群/恐龙/手盗龙类/指骨指数/古生态学/异速生长Key words
Jehol Biota/ Dinosauria/ Maniraptora/ phalangeal index/ paleoecology/ allometry分类
生物科学
