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Mesozoic birds & Pterosaurs

Mesozoic birds & Pterosaurs - Mesozoic birds Pterosaurs...

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Mesozoic birds & Pterosaurs- two different modes of flight http://internt.nhm.ac.uk/resources/nature-online/life/dinosaurs/dino- directory/drawing/Confuciusornis.jpg Confuciusornis sanctus- Cretaceous, China http://upload.wikimedia.org/wikipedia/commons/thumb/d/da/Eudimorphodon_ BW.jpg/656px-Eudimorphodon_BW.jpg Eudimorphodon- Triassic, Italy
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Bird evolution in a nutshell Focused on adaptations for flight; many, but not all, of the adaptations strengthened the skeleton to withstand the stresses associated with flying The apparent sequence of bird evolution is: Development of perching and limited flight Fusion of tail, fully folding wing, etc. Fusion of hand and tarsal region of foot Loss of teeth
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Cladogram of bird evolution Fig. 14.2 F
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Continuing with the clade aviale, the next more modern bird above Archaeopteryx is Rahonavis , from the Late Cretaceous of Madagascar Advanced characters of Rahonavis include: pneumatic foramina A synsacrum However, it still retained some primitive characters, including a long tail
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Even before the evolution of Rahonavis, more advanced birds had begun to evolve in other parts of the world A major evolutionary step occurred with the development of a shortened tail composed of few vertebrae (the pygostyle) The group of birds with a pygostyle is called the pygostylia, and is composed of the Conficiusornithidae and the Ornithothraces
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Major modifications of the ornithothraces include reducing the number of trunk vertebrae alteration of shoulder joint fusing digits into carpometacarpus development of alula- the “bastard wing”, a series of feathers attached to the 1st digit http://www.biology-resources.com/drawing-bird-wing.html
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The alula functions much like the slat on an airplane wing. Both are extended during slow flight to increase lift and prevent stalling http://images.google.com/imgres?
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