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Re: How to Build a Pterosaur



My estimated dimensions are about the same as Jim's; a few differences (I think) in preferred span and head size, but that's just due to subjective calls on things like the amount of joint flexion during cruising flight (which varies across every stroke anyway, so the span is an average to begin with), and some of the unknowns with allometry. In any case, while Mark might have made the neck a bit shorter than it would have been in life, I greatly applaud him for being one of the first individuals ever to make an azhdarchid neck thick enough to be reasonable. I would reconstruct it thicker, myself, but that's back in the realm of small personal choices. An azhdarchid neck that can support itself, enclose the skeleton, and house all the needed soft tissue - wow, who would have thought?

Cheers,

--Mike


Michael Habib
Assistant Professor of Biology
Chatham University
Woodland Road, Pittsburgh PA  15232
Buhl Hall, Room 226A
mhabib@chatham.edu
(443) 280-0181



On Aug 18, 2009, at 9:44 AM, jrc wrote:

The only real evidence for sizing large azhdarchoid necks would be allometric comparisons using the Hatz occiput and humerus, combined with the Qn humerus and Arambourgiana cervical vertebra, and since it isn't really known whether the Aramb vertebra is CV4 or CV5, it leaves some room for doubt about neck length (also, Aramb appears to be maybe about 10% smaller in linear dimensions than Qn or Hatz and has a relatively gracile CV). So that leaves quite a bit of uncertainty in the lengths of the necks of the really big critters. That said, based on the neck of Qsp, the single Aramb CV, and the Hatz and Qn maeterials, I'd guess the probable neck length to be about 3 meters for an azhdarchoid with 10 meter span. Mark's neck looks to be roughly about 50-60% of that length, but I think it is quite possible that some of the big guys could have had very short necks, so I don't believe one could say that Mark is wrong about the neck length for his particular animal (I don't know which species he is emulating). Personally, I restore Qn with an 11 meter span (don't see how to shorten it to 10 meters without throwing away some of the preserved material :-), and with a 3 meter neck and 2.4 meter head, and I also restore torsos with a lot less volume than Mark. -- but, I think there's quite a margin for variation available, and I admire what he is doing.

What I'm curious about, is -- is he going to make one or more of the replicas flightworthy? (Mark, I encourage you to do so, if that's not already in your plans)
JimC

----- Original Message ----- From: "Mike Taylor" <mike@indexdata.com>
To: <tholtz@umd.edu>
Cc: <VRTPALEO@usc.edu>; "Dinosaur Mailing List" <dinosaur@usc.edu>
Sent: Tuesday, August 18, 2009 6:53 AM
Subject: Re: How to Build a Pterosaur


The truly shocking thing about the second photo on that page is: the
neck is not long enough. Not by a long way. (I don't dare tell Mark,
though.)