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Re: The Aerodynamic Origin of Bird Flight




----- Original Message ----- From: "Tim Williams" <twilliams_alpha@hotmail.com>
To: <dinosaur@usc.edu>; <jrccea@bellsouth.net>; <twilliams_alpha@hotmail.com>
Sent: Monday, January 14, 2008 5:28 PM
Subject: RE: The Aerodynamic Origin of Bird Flight




Agreed. I would also have said (and I'm arguing this solely from an intuitive perspective here, so take it with a grain of salt) that the aerobic expenditure required for flapping would favor endothermy over ectothermy. Especially during the incipients stages of flight, and especially if flight evolved 'ground-up' (or had a 'ground-up' component').<

I don't believe that pterosaur flapping was primarily aerobic. They function as flap-gliders, a flight style that acentuates use of anaerobic burst power. And many of the later pterosaurs had such long necks combined with limited lung capacity (small torsos) that the dead air column in the neck would appear to have limited production of continuous aerobic power. Speculatively, the pterosaurian route to flight may generally have made use of anaerobic flap-gliding (though Anurognathids seem to have been an exception to this generalization).


(from another thread...)>

Actually, we've been discussing this rather than arguing it. I don't think
either of us consider a single scenario to be proven.

Ah yes; didn't mean to imply otherwise. I guess I was implying that you were both arguing in favor of a certain point vis-a-vis the problem of >reconstructing the early stages of pterosaur flight, rather than arguing *against* each other.

I've noticed that even when we disagree, we tend to do it in a mood of searching for additional pertinent information rather than in an argumentative manner (is argumentative a word ? ). The same is true of our discussions with John Conway.


JimC