title: A short-armed dromaeosaurid from the Jehol Group of China with implications for early dromaeosaurid evolution.
abstract: Recent discoveries of basal dromaeosaurids from the Early Cretaceous Jiufotang and Yixian formations of Liaoning, China, add significant new information about the transition from non-avian dinosaurs to avians. Here we report on a new dromaeosaurid, Tianyuraptor ostromi gen. et sp. nov., from the Early Cretaceous Yixian Formation of western Liaoning, China, based on a nearly complete skeleton. Tianyuraptor possesses several features only seen in other Liaoning dromaeosaurids, although to a less developed degree, and it also exhibits features unknown in Laurasian dromaeosaurids but present in the Gondwanan dromaeosaurids and basal avialans, thus reducing the morphological gap between these groups. Tianyuraptor possesses a comparatively small furcula and proportionally short forelimbs. This lies in stark contrast to the possible capacity for flight in the microraptorines, which have proportionally long and robust forelimbs and large furculae. The presence of such striking differences between the Early Cretaceous Jehol dromaeosaurids reveals a great diversity in morphology, locomotion and ecology early in dromaeosaurid evolution.
authors.affiliation: Tianyu Museum of Nature, Pingyi, Shandong, 273300, China.
authors.forename: Xiaoting
authors.initials: X
authors.lastname: Zheng
authors.forename: Xing
authors.initials: X
authors.lastname: Xu
authors.forename: Hailu
authors.initials: H
authors.lastname: You
authors.forename: Qi
authors.initials: Q
authors.lastname: Zhao
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Dong
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001842:Bone and Bones / Q000033:anatomy & histology; D002681:China; D025061:Dinosaurs / Q000033:anatomy & histology* / Q000145:classification; D005121:Extremities / Q000033:anatomy & histology; D005580:Fossils; D010802:Phylogeny
references.citation: Science. 1999 Jun 25;284(5423):2137-47
references.pmid: 10381873
references.citation: Proc Biol Sci. 2009 Mar 22;276(1659):1101-7
references.pmid: 19129109
references.citation: Proc Natl Acad Sci U S A. 2007 Jan 30;104(5):1576-80
references.pmid: 17242354
references.citation: Science. 2007 Sep 7;317(5843):1378-81
references.pmid: 17823350
references.citation: Nature. 2005 Oct 13;437(7061):1007-11
references.pmid: 16222297
references.citation: Nature. 2003 Jan 23;421(6921):335-40
references.pmid: 12540892
references.citation: Nature. 2000 Dec 7;408(6813):705-8
references.pmid: 11130069
references.citation: Proc Biol Sci. 2002 Mar 22;269(1491):613-21
references.pmid: 11916478
references.citation: Integr Zool. 2006 Mar;1(1):4-11
references.pmid: 21395983
references.citation: Science. 1998 Mar 20;279(5358):1915-9
references.pmid: 9506938
references.citation: Nature. 2004 Oct 14;431(7010):838-41
references.pmid: 15483610
references.citation: Nature. 2005 Feb 24;433(7028):858-61
references.pmid: 15729340
references.citation: Nature. 2001 Apr 26;410(6832):1084-8
references.pmid: 11323669