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BI = 0.75. BI = 1.0. BI = 1.25. Effect of brachial index on wing flexure , with uniform humerus angle (left) and with uniform wrist span (right) With the same humeral protraction, higher BI shortens the wingspan more: stiffer wings and lower BI are derived. Flexing with uniform humerus angle.
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BI = 0.75 BI = 1.0 BI = 1.25 Effect of brachial index on wing flexure, with uniform humerus angle (left) and with uniform wrist span (right)With the same humeral protraction, higher BI shortens the wingspan more: stiffer wings and lower BI are derived Flexing with uniform humerus angle
Different skeletal mechanisms of shortening the wing during the upstroke in flying vertebrates
pterodactyloid pterosaur “rhamphorhynchid” pterosaur bat Archaeopteryx bird human Comparison of wing skeletons in flying vertebrates(after Steinbacher 1960)
Distribution of brachial index for Gruiformes (left) and Charadriiformes (right)(from Dyke & Rayner 2001)
(A) (B) (C) Pterosaurs: flight control with the wing, with long-axis humeral rotation. Note the large delto-pectoral crests (A) Rhamphorhynchus (faked!) (B) Pterodactylus kochi (C, D) Quetzalcoatlus humeri (Wellnhofer 1991) (D)
Consensus phylogeny of the origin of birds and the evolution of flight adaptations
Consensus phylogeny of the origin of birds and the evolution of flight adaptations
Avian phylogeny Left: morphological tree for major Mesozoic groups (from Cracraft 1986)Right: molecular tree of extant groups (from van Tuinen et al. (2000)
Theropod caudal vertebrae Gatesy & Dial (1996)