A new feathered maniraptoran dinosaur fossil that fills a morphological gap in avian origin

• Published in: Chinese science bulletin Vol. 54; no. 3; pp. 430 - 435
• Main Authors: Xu, Xing, Zhao, Qi, Norell, Mark, Sullivan, Corwin, Hone, David, Erickson, Gregory, Wang, XiaoLin, Han, FengLu, Guo, Yu
• Format: Journal Article
• Language: English
• Published: Heidelberg SP Science in China Press 01.02.2009
• Subjects: Articles/Geology; Chemistry/Food Science; Earth Sciences; Engineering; Humanities and Social Sciences; Life Sciences; multidisciplinary; Physics; Science; Science (multidisciplinary); 关节进化; 古生物; 白垩纪; coelurosaurian phylogeny; avian origin; Early Cretaceous; wrist evolution; maniraptoran theropod
• ISSN: 1001-6538; 2095-9273; 1861-9541; 2095-9281
• DOI: 10.1007/s11434-009-0009-6

Recent fossil discoveries have substantially reduced the morphological gap between non-avian and avian dinosaurs, yet avians including Archaeopteryx differ from non-avian theropods in their limb proportions. In particular, avians have proportionally longer and more robust forelimbs that are capable of supporting a large aerodynamic surface. Here we report on a new maniraptoran dinosaur, Anchiornis huxleyi gen. et sp. nov., based on a specimen collected from lacustrine deposits of uncertain age in western Liaoning, China. With an estimated mass of 110 grams, Anchiornis is the smallest known non-avian theropod dinosaur. It exhibits some wrist features indicative of high mobility, presaging the wing-folding mechanisms seen in more derived birds and suggesting rapid evolution of the carpus. Otherwise, Anchiornis is intermediate in general morphology between non-avian and avian dinosaurs, particularly with regard to relative forelimb length and thickness, and represents a transitional step toward the avian condition. In contrast with some recent comprehensive phylogenetic analyses, our phylogenetic analysis incorporates subtle morphological variations and recovers a conventional result supporting the monophyly of Avialae.