Cranial anatomy of Allosaurus jimmadseni , a new species from the lower part of the Morrison Formation (Upper Jurassic) of Western North America

PeerJ

article

Daniel J. Chure¹  Mark A. Loewen³ 

[1] Dinosaur National Monument;Independent Researcher;Natural History Museum of Utah, University of Utah;Department of Geology and Geophysics, University of Utah

关键词: Allosaurus;    Allosaurus jimmadseni;    Dinosaur;    Theropod;    Morrison Formation;    Jurassic;    Cranial anatomy;   

DOI  :  10.7717/peerj.7803

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

Allosaurus is one of the best known theropod dinosaurs from the Jurassic and a crucial taxon in phylogenetic analyses. On the basis of an in-depth, firsthand study of the bulk of Allosaurus specimens housed in North American institutions, we describe here a new theropod dinosaur from the Upper Jurassic Morrison Formation of Western North America, Allosaurus jimmadseni sp. nov., based upon a remarkably complete articulated skeleton and skull and a second specimen with an articulated skull and associated skeleton. The present study also assigns several other specimens to this new species, Allosaurus jimmadseni, which is characterized by a number of autapomorphies present on the dermal skull roof and additional characters present in the postcrania. In particular, whereas the ventral margin of the jugal of Allosaurus fragilis has pronounced sigmoidal convexity, the ventral margin is virtually straight in Allosaurus jimmadseni. The paired nasals of Allosaurus jimmadseni possess bilateral, blade-like crests along the lateral margin, forming a pronounced nasolacrimal crest that is absent in Allosaurus fragilis.

【 授权许可】

CC BY