A New Model for the Evolution of the Pterosaur Wing--with a twist |
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Authors: | David Peters |
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Institution: | 1247 Highland Terrace, St. Louis, MO, 63117-1712, USA |
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Abstract: | A new hypothesis for the evolution of the pterosaur wing is presented. It is based on the observation that many aspects of pterosaur non-wing anatomy were present in their non-volant, prolacertiform sister taxa. In pterosaurs alone, metacarpal IV was twisted 90° medially, so the wing digit flexed in the plane of the metacarpus, rather than towards the palm as in other tetrapods. While grappling a tree using manual digits I-III, a pre-pterosaur with this character would have been free to flex and extend digit IV in the plane tangential to the circumference of the tree. The addition of a small dermal extension that opened like a Japanese fan would essentially have completed the development of the proto-wing. Its subsequent increase in size was brought on by selective competition. Successful powered flight would have been possible only after a critical wing size had been achieved. |
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Keywords: | Pterosauria Prolacertiformes Flight Wing Behavior Evolution |
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