Mesozoic birds & Pterosaurs

Mesozoic birds - Mesozoic birds& Pterosaurs two different modes of flight http/internt.nhm.ac.uk/resources/nature-online/life/dinosaurs/dino

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Unformatted text preview: 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 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 Cladogram of bird evolution Fig. 14.2 F • 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 • 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 • 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 • 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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This note was uploaded on 04/22/2008 for the course GEOL 111 taught by Professor Getty during the Fall '07 term at UConn.

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Mesozoic birds - Mesozoic birds& Pterosaurs two different modes of flight http/internt.nhm.ac.uk/resources/nature-online/life/dinosaurs/dino

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