title: Soft-tissue and dermal arrangement in the wing of an Early Cretaceous bird: Implications for the evolution of avian flight.
abstract: Despite a wealth of fossils of Mesozoic birds revealing evidence of plumage and other soft-tissue structures, the epidermal and dermal anatomy of their wing's patagia remain largely unknown. We describe a distal forelimb of an enantiornithine bird from the Lower Cretaceous limestones of Las Hoyas, Spain, which reveals the overall morphology of the integument of the wing and other connective structures associated with the insertion of flight feathers. The integumentary anatomy, and myological and arthrological organization of the new fossil is remarkably similar to that of modern birds, in which a system of small muscles, tendons and ligaments attaches to the follicles of the remigial feathers and maintains the functional integrity of the wing during flight. The new fossil documents the oldest known occurrence of connective tissues in association with the flight feathers of birds. Furthermore, the presence of an essentially modern connective arrangement in the wing of enantiornithines supports the interpretation of these primitive birds as competent fliers.
authors.affiliation: School of Earth Sciences, University of Bristol, Wills Memorial Building, Queens Road, Bristol, BS8 1RJ, UK.|Unidad de Paleontología, Facultad de Ciencias, Universidad Autónoma de Madrid, Campus de Cantoblanco, Madrid, Spain.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Navalón
authors.affiliation: Unidad de Paleontología, Facultad de Ciencias, Universidad Autónoma de Madrid, Campus de Cantoblanco, Madrid, Spain.|Dinosaur Institute, Natural History Museum of Los Angeles, 900 Exposition Boulevard, Los Angeles, CA 90007, USA.
authors.forename: Jesús
authors.initials: J
authors.lastname: Marugán-Lobón
authors.affiliation: Dinosaur Institute, Natural History Museum of Los Angeles, 900 Exposition Boulevard, Los Angeles, CA 90007, USA.
authors.forename: Luis M
authors.initials: LM
authors.lastname: Chiappe
authors.affiliation: Unidad de Paleontología, Facultad de Ciencias, Universidad Autónoma de Madrid, Campus de Cantoblanco, Madrid, Spain.
authors.forename: José
authors.initials: J
authors.lastname: Luis Sanz
authors.affiliation: Unidad de Paleontología, Facultad de Ciencias, Universidad Autónoma de Madrid, Campus de Cantoblanco, Madrid, Spain.
authors.forename: Ángela D
authors.initials: ÁD
authors.lastname: Buscalioni
mesh_terms: D000818:Animals; D005075:Biological Evolution; D001717:Birds; D005241:Feathers / Q000033:anatomy & histology* / Q000648:ultrastructure; D005426:Flight, Animal / Q000502:physiology*; D005580:Fossils; D046529:Microscopy, Electron, Transmission; D009132:Muscles / Q000033:anatomy & histology* / Q000648:ultrastructure; D010802:Phylogeny; D012867:Skin / Q000033:anatomy & histology* / Q000648:ultrastructure; D014921:Wings, Animal / Q000033:anatomy & histology* / Q000648:ultrastructure