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Re: New bird /pterosaur flight paper in PLoS ONE



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.