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Re: Pterosaur arm supination

----- Original Message ----- From: "Tim Williams" <twilliams_alpha@hotmail.com>
To: <dinosaur@usc.edu>; <mhabib5@jhmi.edu>; <twilliams_alpha@hotmail.com>
Sent: Sunday, January 13, 2008 7:15 PM
Subject: RE: Pterosaur arm supination

..... patagial gliders in which all four limbs were incorporated into the flight surface.

For pterosaurs, this is an open question - as Michael and Jim have been arguing.

Actually, we've been discussing this rather than arguing it. I don't think either of us consider a single scenario to be proven. I believe Mike leans toward all limbs being involved in a single flight surface (acknowledging that the properties of that surface vary substantially with location within the surface) while I think that all three of the common scenarios may have been in use in different species over evolutionary time. I tend to lean toward a disassociation of the tail complex from the wing in the later pterosaurs, but there is presently no fossil evidence either way and I don't consider it to be proven -- both scenarios are still worth investigating.

Thus, it may be unhelpful to treat bipedality and quadrupedality as mutually exclusive. (These comments are not directed at Michael, BTW. I haven't disagreed with anything he [or Jim] have written regarding pterosaur evolution or flight thus far,

And though I don't want to speak for Mike, I think this is an area where we would agree with you. I certainly do.