Data from: Ventilatory mechanics from maniraptoran theropods to extant birds
Data files
Jan 06, 2012 version files 21.68 MB
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mechadv AV418.tif
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mechadv AV419.tif
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mechadv AV421.tif
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mechadv2 AV422.tif
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Mm. appendicocostales projection angle.xlsx
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Abstract
Shared behavioural, morphological and physiological characteristics are indicative of the evolution of extant birds from non-avian maniraptoran dinosaurs. One such shared character is the presence of uncinate processes; respiratory structures in extant birds. Recent research has suggested a respiratory role for these processes found in oviraptorid and dromaeosaurid dinosaurs. By measuring the geometry of fossil rib cage morphology we demonstrate that the mechanical advantage, conferred by uncinate processes, for movements of the ribs in the oviraptorid theropod dinosaur, Citipati osmolskae, basal avialan species Zhongjianornis yangi, Confuciusornis sanctus, and the more derived ornithurine Yixianornis grabaui, is of the same magnitude as found in extant birds. These skeletal characteristics provide further evidence of a flow-through respiratory system in non-avian theropod dinosaurs and basal avialans, and indicate that uncinate processes are a key adaptation facilitating the ventilation of a lung air sac system that diverged earlier than extant birds.