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Re: Pterorhynchus dewlap




----- Original Message ----- From: "Michael Habib" <mhabib5@jhmi.edu>
To: <dinosaur@usc.edu>
Sent: Thursday, February 02, 2006 8:31 PM
Subject: Re: Pterorhynchus dewlap



I'm also not certain if pterosaurs could manage a power upstroke (I don't just mean an active upstroke, but a fully powered one). In fact, pterosaurs probably used passive upstrokes (as part of a continuous vortex gait) most of the time, given their size and speed.

Some of the later, more heavily loaded pterosaurs slightly lowered the position of the glenoid and modified the delto-pectoral crest in a way that substantially increased the power available during the upstroke. In those at least, the upstroke was not passive. In most others, I don't believe it was passive - but it was not as strong as that of birds either. Birds really seem to me to have been focused mostly on flapping till after the pterosaurs were gone. And pterosaurs seem to have been focused more on soaring, increasing their ability to flap as they became more heavily loaded (or vice versa).
Jim