RE: The Aerodynamic Origin of Bird Flight

[Tim Williams <twilliams_alpha@hotmail.com>]

Jim Cunningham wrote:

> Interestingly enough, though pterosaurs are almost certainly endothermic, 
> for the most part they use a flight style that would for the most part, work 
> just as well if they were cold-blooded.  With this exception, which I think 
> is important.  Cold-bloodedness would have hurt their ability to reach high 
> altitudes assist in traveling long distances;the atmosphere cools 
> substantially with altitude increase, limiting a cold-blooded animal's 
> ability to function at higher altitudes.

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').

(As a postscript, this thread was started by someone ["ProtoArt"/"Arthur 
Havert"] who turns out to be a thoroughly unpleasant individual, with a very 
strange contempt for biology and paleontology.  He's now relegated to my Spam 
list.)

(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.

Cheers

Tim
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