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Re: Quetzalcoatlus may have lived like a giant stork



Keep in mind that while the distal wing is reduced, the outer part of the proximal wing and the inner part of the distal wing are greatly expanded. MC IV is relatively much longer than in most pterosaurs, as is Ph IV-1, and the aspect ratio is still quite high. And, keep in mind that the distal wing of Qn is expanded relative to the distal wing of Qsp while the somewhat transversely held r/u is relatively reduced in length, so the allometry involved in increasing the size of the animal is also increasing aspect ratio at the same time. Qn has a higher aspect ratio than Qsp.

The following is speculative. I haven't investigated it, but may someday. It would please me if someone else would go on and look into it now (hint, hint, Mike). I suspect that Quetz and a number of other pterosaurs may have been capable of either a pacing gait or a 3-beat canter (or both) that could have been quite speedy on the ground. These animals were not terrestrial klutzes.
JimC


----- Original Message ----- From: "Michael Habib" <mhabib5@jhmi.edu>
To: <dinosaur@usc.edu>
Sent: Friday, September 21, 2007 3:11 PM
Subject: Re: Quetzalcoatlus may have lived like a giant stork



Darren is a quite a knowledgeable individual, but I do note that longer legs and shorter wings do not necessarily imply lessened aerial ability. The reduced span does subtract a bit from gliding efficiency, but reducing the distal wing also reduces wing inertia a great deal (which improves flapping ability). Figuring out which scenario is driving distal wing reduction requires looking at the morphology and mechanics of the rest of the animal, and azhdarchids have a range of characteristics that would increase flapping capacity (at least in bursts). Thus, Quetzalcoatlus and relatives come across to me as species adapted to powerful bursts of propulsion, combined with rapid soaring dynamics (see Jim's post for more details). They may also have been adept on the ground; the lengthened hindlimbs wouldn't hurt in that regard.

Cheers,

--Mike H.