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Re: pterosaur launching tactics


----- Original Message ----- From: "Mark Witton" <Mark.Witton@port.ac.uk>
To: <mhabib5@jhmi.edu>; <dinosaur@usc.edu>
Sent: Monday, June 09, 2008 3:11 AM
Subject: Re: pterosaur launching tactics


So, if I read that correct, you're saying that there's room for _more_
mass using quad lauching? How heavy could they get? I've been asked a
couple of times about the mass of Hatzegopteryx recently, y'see, and all
my answers have accounted to is 'heavier than Quetzalcoatlus'.

Although this question wasn't directed to me, based on morphology my 'hunch' for the launch limit on azdarchid type pterosaurs is about 13 meters in span. Note that the Hatz humerus is slightly larger than the Qn humerus in some dimensions, but substantially smaller in others, and the two are well within individual ranges (after all, long bone lengths can vary by 5% between the left and right sides of individual animals, and we're talking about less relative difference than that). My perception based on the humerus is that Qn was heavier than Hatz, but the Hatz material is beat up enough that I don't think anyone can be sure.

I haven't
played around with Hatzegopteryx mass beyond a very simple extrapolation
of my Quetzalocatlus mass (450 kg or thereabouts, I think): would this
hit your maximum?

My estimate of max mass for a 13 meter span would be about 350 to 400 Kg, with average or flight optimal weight for that span being about 250 Kg.

And does this take into account safety factors? It's
been a while since I looked at this stuff (and I'm sure you're more
informed on it, anyway), but I think animal bones are worked to take
something like 5 times their 'normal' loading - just to be safe if they,
you know, stumble a bit or run into a tree or whatever. Were pterosaur
limbs similarly engineered?

Yes. BTW, hindlimbs aren't exactly payload in flight, together with the uropatagium they are self-supported structures just like the forelimbs. This is the case whichever wing attachment scenario is used.

All the best,
JimC