Portal de Periódicos da CAPES

Primitive Wing Feather Arrangement in Archaeopteryx lithographica and Anchiornis huxleyi

2012; Elsevier BV; Volume: 22; Issue: 23 Linguagem: Inglês

10.1016/j.cub.2012.09.052

1879-0445

Nicholas R. Longrich, Jakob Vinther, Qingjin Meng, Quangguo Li, Anthony P. Russell,

Amphibian and Reptile Biology

In modern birds (Neornithes), the wing is composed of a layer of long, asymmetrical flight feathers overlain by short covert feathers [1Lucas A.M. Stettenheim P.R. Avian Anatomy: Integument. US Government Printing Office, Washington, DC1972Google Scholar, 2Gill F.B. Ornithology.Third Edition. W.H. Freeman and Company, New York2006Google Scholar, 3Spearman R.I.C. Hardy J.A. Integument.in: King A.S. McLelland J. Form and Function of Birds. Volume 3. Academic Press, London1985: 1-56Google Scholar]. It has generally been assumed that wing feathers in the Jurassic bird Archaeopteryx [4Rietschel S. Feathers and wings of Archaeopteryx and the question of her flight ability.in: Hecht M.K. Ostrom J.H. Viohl G. Wellnhofer P. The Beginnings of Birds: Proceedings of the International Archaeopteryx Conference, Eichstätt, 1984. Freunde des Jura-Museums, Eichstätt, Germany1985: 251-260Google Scholar, 5Feduccia A. The Origin and Evolution of Birds. Yale University Press, New Haven, CT1996Google Scholar, 6Wellnhofer P. Archaeopteryx: Der Urvogel von Solnhofen. Verlag Dr. Friedrich Pfeil, Munich2008Google Scholar, 7De Beer G.R. Archaeopteryx lithographica: A Study Based on the British Museum Specimen. British Museum Natural History, London1954Google Scholar, 8Heilmann G. The Origin of Birds. Witherby, London1926Google Scholar, 9Elzanowski A. Archaeopterygidae (Upper Jurassic of Germany).in: Chiappe L.M. Witmer L.M. Mesozoic Birds: Above the Heads of Dinosaurs. University of California Press, Berkeley, CA2002: 129-159Google Scholar] and Cretaceous feathered dinosaurs [10Li Q. Gao K.-Q. Meng Q. Clarke J.A. Shawkey M.D. D'Alba L. Pei R. Ellison M. Norell M.A. Vinther J. Reconstruction of Microraptor and the evolution of iridescent plumage.Science. 2012; 335: 1215-1219Crossref PubMed Scopus (144) Google Scholar, 11Xu X. Zhou Z. Wang X. Kuang X. Zhang F. Du X. Four-winged dinosaurs from China.Nature. 2003; 421: 335-340Crossref PubMed Scopus (350) Google Scholar] had the same arrangement. Here, we redescribe the wings of the archaic bird Archaeopteryx lithographica [3Spearman R.I.C. Hardy J.A. Integument.in: King A.S. McLelland J. Form and Function of Birds. Volume 3. Academic Press, London1985: 1-56Google Scholar, 4Rietschel S. Feathers and wings of Archaeopteryx and the question of her flight ability.in: Hecht M.K. Ostrom J.H. Viohl G. Wellnhofer P. The Beginnings of Birds: Proceedings of the International Archaeopteryx Conference, Eichstätt, 1984. Freunde des Jura-Museums, Eichstätt, Germany1985: 251-260Google Scholar, 5Feduccia A. The Origin and Evolution of Birds. Yale University Press, New Haven, CT1996Google Scholar] and the dinosaur Anchiornis huxleyi [12Hu D. Hou L.-H. Zhang L. Xu X. A pre-Archaeopteryx troodontid theropod from China with long feathers on the metatarsus.Nature. 2009; 461: 640-643Crossref PubMed Scopus (273) Google Scholar, 13Xu X. Zhao Q. Norell M. Sullivan C. Hone D. Erickson G.M. Wang X.L. Han F. Guo Y. A new feathered maniraptoran fossil that fills a morphological gap in avian origin.Chin. Sci. Bull. 2008; 54: 430-435Crossref Scopus (130) Google Scholar] and show that their wings differ from those of Neornithes in being composed of multiple layers of feathers. In Archaeopteryx, primaries are overlapped by long dorsal and ventral coverts. Anchiornis has a similar configuration but is more primitive in having short, slender, symmetrical remiges. Archaeopteryx and Anchiornis therefore appear to represent early experiments in the evolution of the wing. This primitive configuration has important functional implications: although the slender feather shafts of Archaeopteryx [14Nudds R.L. Dyke G.J. Narrow primary feather rachises in Confuciusornis and Archaeopteryx suggest poor flight ability.Science. 2010; 328: 887-889Crossref PubMed Scopus (80) Google Scholar] and Anchiornis [12Hu D. Hou L.-H. Zhang L. Xu X. A pre-Archaeopteryx troodontid theropod from China with long feathers on the metatarsus.Nature. 2009; 461: 640-643Crossref PubMed Scopus (273) Google Scholar] make individual feathers weak, layering of the wing feathers may have produced a strong airfoil. Furthermore, the layered arrangement may have prevented the feathers from forming a slotted tip or separating to reduce drag on the upstroke. The wings of early birds therefore may have lacked the range of functions seen in Neornithes, limiting their flight ability.