Re: New bird /pterosaur flight paper in PLoS ONE

["jrc" <jrccea@bellsouth.net>]

Comments inserted.
JimC

----- Original Message ----- 
From: "Michael Habib" <habib@jhmi.edu>
To: <Mark.Witton@port.ac.uk>
Cc: <dinosaur@usc.edu>
Sent: Thursday, April 30, 2009 5:33 AM
Subject: Re: New bird /pterosaur flight paper in PLoS ONE


> The authors state that:
> "Some studies have proposed that large pterosaurs such as Pteranodon and 
> Quetzalcoatlus may have had narrow wings similar to those of albatrosses, 
> and used slope soaring and dynamic soaring [18]. However, our study of 
> living Procellariiformes as model animals suggests that if pterosaurs 
> larger than 41 kg (or 5.1-m wingspan) had the narrow wings, they could not 
> have attained sustainable flight in environments similar to the present."

I missed their proof.  Could someone steer me toward it?

> Semi-terrestrial predators need a strong ability to launch and gain 
> altitude, at least for bursts.

Correct, and the big pterosaurs had that strong ability to launch, and a 
reasonable rate of climb for flapping bursts long enough for them to travel 
for roughly a couple of miles using anaerobic power alone (flapping for 
about a mile and then gliding back down during the subsequent mile).

> The other major issue, in my mind, comes from the assumptions regarding 
> launch.  Still, after all the years and fine work that have gone into 
> launch mechanics (Tobalske, Earls, Rayner, etc), we have biologists that 
> are confused about how launch works in birds at a general level.  The 
> authors suggest that:
>
> "Takeoff is the transition from being supported by something that is 
> essentially part of the earth's surface to being supported entirely by 
> aerodynamic forces in flight, and these depend on air flowing over the 
> wings [7]. Takeoff seems to be the most crucial task for flying birds and 
> requires more active flapping than level flight because the flight speed 
> is zero at the beginning and the birds must raise their body mainly by 
> muscular effort."
>
> Overall takehome message (in my opinion, anyway): Nice data, neat 
> analysis, possible limit for procellariiforms.  Application to pterosaur 
> is, however, quite weak.

Yeah.  More like nonapplicable.