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Re: pterosaur femora sprawl

----- Original Message ----- From: "David Marjanovic" <david.marjanovic@gmx.at>
To: "DML" <dinosaur@usc.edu>
Sent: Wednesday, June 04, 2008 2:40 PM
Subject: Re: pterosaur femora sprawl

If I've understood the quadrupedal-launching scenario, the forward thrust is provided by the hindlimbs, and the forelimbs just push the animal up. Right?

No. The initial forward thrust is provided by the hindlimbs, moving the shoulders forward and slightly down toward the forward planted front feet in order to deflect and preload the forelegs. Then, as the shoulders continue to move forward relative to the position of the front feet, the forelegs release the preload and and take over providing both forward and upward thrust. The hindlimbs are off the ground for the latter part of the launch., and the forelegs provide the preponderence of takeoff power. Takeoff angle varies with mass, but for mid-sized to large pterosaurs can be taken to be about 25 to 35 degrees from the horizontal.