title: A basal alvarezsauroid theropod from the early Late Jurassic of Xinjiang, China.
abstract: The fossil record of Jurassic theropod dinosaurs closely related to birds remains poor. A new theropod from the earliest Late Jurassic of western China represents the earliest diverging member of the enigmatic theropod group Alvarezsauroidea and confirms that this group is a basal member of Maniraptora, the clade containing birds and their closest theropod relatives. It extends the fossil record of Alvarezsauroidea by 63 million years and provides evidence for maniraptorans earlier in the fossil record than Archaeopteryx. The new taxon confirms extreme morphological convergence between birds and derived alvarezsauroids and illuminates incipient stages of the highly modified alvarezsaurid forelimb.
authors.affiliation: Department of Biological Sciences, The George Washington University, Washington, DC 20052, USA. jonah.choiniere@gmail.com
authors.forename: Jonah N
authors.initials: JN
authors.lastname: Choiniere
authors.forename: Xing
authors.initials: X
authors.lastname: Xu
authors.forename: James M
authors.initials: JM
authors.lastname: Clark
authors.forename: Catherine A
authors.initials: CA
authors.lastname: Forster
authors.forename: Yu
authors.initials: Y
authors.lastname: Guo
authors.forename: Fenglu
authors.initials: F
authors.lastname: Han
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001717:Birds / Q000145:classification; D001842:Bone and Bones / Q000033:anatomy & histology; D001133:Bones of Upper Extremity / Q000033:anatomy & histology; D002681:China; D025061:Dinosaurs / Q000033:anatomy & histology / Q000145:classification; D005552:Forelimb / Q000033:anatomy & histology; D005580:Fossils; D010802:Phylogeny; D012863:Skeleton; D012886:Skull / Q000033:anatomy & histology; D013131:Spine / Q000033:anatomy & histology; D014070:Tooth / Q000033:anatomy & histology