Re: The Aerodynamic Origin of Bird Flight

[jrc <jrccea@bellsouth.net>]

----- 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