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RE: Flying giraffes


  I don't think this says anything that Mike Habib or Mark Witton don't already 
know. Especially regarding the mechanical scaling (iso- versus allometric) when 
it comes to adjusting a "Q." sp. ("Kyoo Spuh," as Darren Naish calls it) animal 
to the size of the wing in *Quetzalcoatlus northropi*, potential taxonomic 
variation is consdiered but, given lack of thorough description of "Kyoo Spuh" 
at the moment, difficult to ascertain. Scaling factors aside, morphology of the 
head, neck and limbs in azhdarchids tend to follow one another across a few 
size ranges, and my understanding is that Witton's illustration, and the 
giraffe-sized possibilities, is derived mostly from composing an animal like 
*northriopi* to *Arambourgiana*, *Zhejiangopterus* and *Hatzegopterus* -- some 
of which can push against that size. These suggest mostly that pushing them up 
to the scale of the *northropi* wing isometrically at least will result in an 
animal that could look a fair-sized giraffe in the eye.

  I would defer to them on the mass issue. volumetric mass estimates not using 
the displacement method seem far more reliable (Henderson, 2010), and it would 
be problematic to use the argument from disbelief to dismiss it; though other 
authors have found values around half the 500 kg mass, including yourself, 
using better adjusted properties, and Henderson has a revision of the mass 
estimate in the works. It should be noted that Chatterjee and Templin's meager 
70kg mass estimate was used to presume that the higher mass of *northropi* 
would make it effectively flightless without strong headwinds (!), cliffs, or 
whatever, such a classical idea as t be absurd in its own right. Your 
statement, though seems to confuse this idea with Habib's, who was summarizing 
the topic.

Below are relevant papers that touch on or are explicit on the masses of flying 
animals and, especially, azhdarchids.

Chatterjee, S. & Templin, R. J. 2004. Posture, locomotion, and paleoecology of 
pterosaurs. Geological Society of America, Special Paper 376.
al mathematical slicing. Journal of Vertebrate Paleontology 30(3): 768–785.
Paul, G. S. 2002. Dinosaurs of the Air: The Evolution and Loss of Flight in 
Dinosaurs and Birds. Johns Hopkins University Press, Baltimore.
Sato K., Sakamoto K. Q., Watanuki Y., Takahashi A., Katsumata N., Bost, C.-A. & 
Weimerskirch, H. 2009. Scaling of soaring seabirds and implications for flight 
abilities of giant pterosaurs. PLoS ONE 4 (4): e5400. (available for free at: 
Witton, M. P. 2008. A new approach to determining pterosaur body mass and its 
implications for pterosaur flight. Zitteliana B28: 143–159.


  Jaime A. Headden
  The Bite Stuff (site v2)

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)

"Ever since man first left his cave and met a stranger with a
different language and a new way of looking at things, the human race
has had a dream: to kill him, so we don't have to learn his language or
his new way of looking at things." --- Zapp Brannigan (Beast With a Billion 

> Date: Thu, 20 Jun 2013 19:38:17 -0400
> From: GSP1954@aol.com
> To: dinosaur@usc.edu
> Subject: Flying giraffes
> About Habib's new paper in Biol Theory. I continue to object to
> illustrations showing pterosaurs as enormous as giraffes, based only on some 
> arm
> elements. Also we are probably getting the skull wrong.
> There has probably been a big mistake made -- moi included. We have been
> assuming what has without justification been called Q. sp. is a half sized
> version of Q. northropi (seriously inadequate holotype by the way). Simply
> scale the former up and you have Q. n. But there is big pterosaur skull 
> material
> from the Javelina that is larger than that of Q. sp., and quite probably
> belongs to Q. n. That of course is the front portion of the skull photographed
> in the 1991 Wellnhofer book. The chances that three giant pterosaur taxa
> were flittering about t
> is no reason to presume that the smaller Javelina azhdarchid is even close to
> being the same genus as Q. n. The robust snout is similar to that of
> earlier members of the group (the possiblity it represents a nonazdarchid when
> there are no other such remains from the Maastrichtian is very dubious).
> It is probable that the robust snout is Q. n. (need to know what level of
> the Javelina these things come from, though, and the time span of the
> formation). For awhile I used that rostrum on my Q. n. illustrations until 
> the half
> sized taxa skull lured me like the sirens onto the Rocks of the Chimerias
> (don't know if that version was published anywhere). But I did the posterior
> skull wrong because we did not have azdarchid posterior skulls to go on. I
> cannot do a rerevised version because I do not have the info needed to scale
> it to the Q. n. arm, partly because the cervicals that are said to go with
> the robust rostrum have never been published (that might not solve the cross
> scaling problem though).
> There is no way a 70-100 kg mass pterosaur will work for the colossal
> humerus and arm of Q. n. The size disparity is absurd. But we cannot even come
> close to presuming that we can just scale up the Q. sp. skull, neck, body and 
> l
> egs to Q. n. and assume we have a giraffe size beast with a super
> heron-stork head as long as a giraffe neck. Doing so probably misrepresents 
> the beast
> in height and form. The body mass probably was in the 150-250 kg range.
> I was the first to point out that super pterosaurs were probably far
> heavier than thought. But these extreme restorations based on dubious
> extrapolations are probably misleading the public.
> Tend to agree with Habib that the biggest pterosaurs known or that evolved
> may not be the biggest possible living fliers by a considerable amount. But
> there probably is some limit. Hard to conceive of airliner sized biofliers.
> GSPaul
> </HTML>