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Forelimb posture in dinosaurs and the evolution of the avian flapping flight-stroke

Forelimb posture in dinosaurs and the evolution of the avian flapping flight-stroke
Forelimb posture in dinosaurs and the evolution of the avian flapping flight-stroke
Ontogenetic and behavioral studies using birds currently do not document the early evolution of flight because birds (including juveniles) used in such studies employ forelimb oscillation frequencies over 10 Hz, forelimb stroke-angles in excess of 130°, and possess uniquely avian flight musculatures. Living birds are an advanced morphological stage in the development of flapping flight. To gain insight into the early stages of flight evolution (i.e., prebird), in the absence of a living analogue, a new approach using Strouhal number inline image was used. Strouhal number is a nondimensional number that describes the relationship between wing-stroke amplitude (A), wing-beat frequency (f), and flight speed (U). Calculations indicated that even moderate wing movements are enough to generate rudimentary thrust and that a propulsive flapping flight-stroke could have evolved via gradual incremental changes in wing movement and wing morphology. More fundamental to the origin of the avian flapping flight-stroke is the question of how a symmetrical forelimb posture—required for gliding and flapping flight—evolved from an alternating forelimb motion, evident in all extant bipeds when running except birds.
bird, locomotion, morphology, strouhal number, wing
0014-3820
994-1002
Nudds, Robert L.
da7053c3-320b-4189-a228-534b95d80815
Dyke, Gareth J.
600ca61e-b40b-4c86-b8ae-13be4e331e94
Nudds, Robert L.
da7053c3-320b-4189-a228-534b95d80815
Dyke, Gareth J.
600ca61e-b40b-4c86-b8ae-13be4e331e94

Nudds, Robert L. and Dyke, Gareth J. (2009) Forelimb posture in dinosaurs and the evolution of the avian flapping flight-stroke. Evolution, 63 (4), 994-1002. (doi:10.1111/j.1558-5646.2009.00613.x).

Record type: Article

Abstract

Ontogenetic and behavioral studies using birds currently do not document the early evolution of flight because birds (including juveniles) used in such studies employ forelimb oscillation frequencies over 10 Hz, forelimb stroke-angles in excess of 130°, and possess uniquely avian flight musculatures. Living birds are an advanced morphological stage in the development of flapping flight. To gain insight into the early stages of flight evolution (i.e., prebird), in the absence of a living analogue, a new approach using Strouhal number inline image was used. Strouhal number is a nondimensional number that describes the relationship between wing-stroke amplitude (A), wing-beat frequency (f), and flight speed (U). Calculations indicated that even moderate wing movements are enough to generate rudimentary thrust and that a propulsive flapping flight-stroke could have evolved via gradual incremental changes in wing movement and wing morphology. More fundamental to the origin of the avian flapping flight-stroke is the question of how a symmetrical forelimb posture—required for gliding and flapping flight—evolved from an alternating forelimb motion, evident in all extant bipeds when running except birds.

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e-pub ahead of print date: 14 January 2009
Published date: April 2009
Keywords: bird, locomotion, morphology, strouhal number, wing
Organisations: Ocean Biochemistry & Ecosystems

Identifiers

Local EPrints ID: 205177
URI: http://eprints.soton.ac.uk/id/eprint/205177
ISSN: 0014-3820
PURE UUID: 70eb221d-2dd2-423c-9657-6bc3e709efa3

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Date deposited: 07 Dec 2011 10:17
Last modified: 14 Mar 2024 04:33

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Contributors

Author: Robert L. Nudds
Author: Gareth J. Dyke

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