A new feathered maniraptoran dinosaur fossil that fills a morphological gap in avian origin
- 573 Downloads
- 48 Citations
Abstract
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.
Keywords
Early Cretaceous maniraptoran theropod coelurosaurian phylogeny wrist evolution avian originPreview
Unable to display preview. Download preview PDF.
References
- 1.Chinsamy-Turan A. The Microstructure of Dinosaur Bone. Baltimore and London: The Johns Hopkins University Press, 2005. 1–195Google Scholar
- 2.Chinsamy-Turan A. Histological perspectives on growth in the birds Struthio camelus and Sagittarius serpentarius. In: Third Symposium of the Society of Avian Paleontology and Evolution. Senckenberg, Germany: Courier Forschungsinstitut Senckenberg, 1995. 317–323Google Scholar
- 3.Xu X, Zhou Z H, Wang X L. The smallest known non-avian theropod dinosaur. Nature, 2000, 408: 705–708CrossRefGoogle Scholar
- 4.Turner A H, Pol D, Clarke J A, et al. A basal dromaeosaurid and size evolution preceding avian flight. Science, 2007, 317: 1378–1381CrossRefGoogle Scholar
- 5.Sereno P C. The evolution of dinosaurs. Science, 1999, 284: 2137–2147CrossRefGoogle Scholar
- 6.Xu X. Deinonychosaurian fossils from the Jehol Group of western Liaoning and the coelurosaurian evolution. Dissertation for the Doctoral Degree. Beijing: Chinese Academy of Sciences, 2002. 322Google Scholar
- 7.Norell M A, Clark J M, Makovicky P J. Phylogenetic relationships among coelurosaurian dinosaurs. In: Gauthier J, Gall L F, eds. New Perspectives on the Origin and Evolution of Birds. New Haven: Yale University Press, 2001. 49–67Google Scholar
- 8.Makovicky P J, Norell M A. Troodontidae. In: Weishampel D B, Dodson P, Osmolska H, eds. The Dinosauria, 2nd ed. Berkeley: University of California Press, 2004. 184–195Google Scholar
- 9.Elzanowski A. Archaeopterygoidae. In: Chiappe L M, Witmer L M, eds. Mesozoic Birds: Above the Heads of Dinosaurs. Berkeley: University of California Press, 2002. 129–159Google Scholar
- 10.Makovicky P J, Apesteguía S, Agnolín F L. The earliest dro-maeosaurid theropod from South America. Nature, 2005, 437: 1007–1011CrossRefGoogle Scholar
- 11.Chiappe L M, Ji S A, Ji Q, et al. Anatomy and systematics of the Confuciusornithidae (Theropoda: Aves) from the late Mesozoic of Northeastern China. Bull Amer Mus Nat Hist, 1999, 242: 1–89Google Scholar
- 12.Zhou Z H, Zhang F C. Anatomy of the primitive bird Sapeornis chaoyangensis from the Early Cretaceous of Liaoning, China. Can J Earth Sci, 2003, 40: 731–747CrossRefGoogle Scholar
- 13.Christiansen P, Bonde N. Limb proportions and avian terrestrial locomotion. J Ornithol, 2002, 143: 356–371Google Scholar
- 14.Forster C A, Sampson S D, Chiappe L M, et al. The theropod ancestry of birds: new evidence from the Late Cretaceous of Madagascar. Science, 1998, 279: 1915–1919CrossRefGoogle Scholar
- 15.Mayr G, Pohl B, Peters S. A well-preserved Archaeopteryx specimen with theropod features. Science, 2005, 310: 1483–1486CrossRefGoogle Scholar
- 16.Chatterjee S. The rise of birds. Baltimore: John Hopkins University Press, 1997. 1–311Google Scholar
- 17.Middleton K M, Gatesy S M. Theropod forelimb design and evolution. Zool J Linn Soc, 2000, 128: 149–187CrossRefGoogle Scholar
- 18.Vazquez R J. Functional osteology of the avian wrist and the evolution of flapping flight. J Morphol, 1992, 211: 259–268CrossRefGoogle Scholar
- 19.Ostrom J H. Archaeopteryx and the origin of birds. Biol J Linn Soc, 1976, 8: 91–182CrossRefGoogle Scholar
- 20.Padian K, Chiappe L. Bird origins. In: Currie P J, Padian K, eds. Encyclopedia of Dinosaurs. San Diego: Academic Press, 1997. 71–79Google Scholar
- 21.Feduccia A. The Origin and Evolution of Birds, 2nd ed. New Haven: Yale University Press, 1999. 466Google Scholar
- 22.Chure D J. The wrist of Allosaurus (Saurischia: Theropoda), with observations on the carpus in theropods. In: Gauthier J A, Gall L F, eds. New Perspectives on the Origin and Early Evolution of Birds. New Heaven: Yale University Press, 2001. 122–130Google Scholar
- 23.Gishlick A D. The function of the manus and forelimb of Deinonychus antirrhopus and its importance for the origin of avian flight. In: Gauthier J A, Gall L F, eds. New Perspectives on the Origin and Early Evolution of Birds. New Heaven: Peabody Museum of Natural History, Yale University, 2001. 301–318Google Scholar
- 24.Hinchliffe J R. ’One, two, three’ or ‘Two, three, four’: an embryologist’s view of the homoliges of the digits and carpus of modern birds. In: Hecht M K, Ostrom J H, Viohl G, et al, eds. The Beginnings of Birds. Eichstatt: Freunde des Jura-Museums Eichstatt, 1985. 141–148Google Scholar
- 25.Hillis D M. Taxonomic sampling, phylogenetic accuracy, and investigator bias. Syst Biol, 1998, 47: 3–8CrossRefGoogle Scholar
- 26.Goloboff P A, Mattoni C I, Quinteros A S. Continuous characters analyzed as such. Cladistics, 2006, 22: 589–601CrossRefGoogle Scholar