[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Re: Quetzalcoatlus mass



I have just finally done a full thorough read of the paper: some great work, nicely written, and very transparent. However, the Quetz model is significantly inaccurate, which explains the mass issue: torso is much too large. Not Don's fault, he was using the measurements from the classic 1981 and 1990 papers, but they are out of date in this regard. Most of the other models look really good, though. Wings are probably far too broad across the board, but that's not the thrust of the paper.

Cheers,

--Mike H.


Sent from my iPhone

On May 21, 2010, at 4:34 PM, Mike Habib <habib@jhmi.edu> wrote:

I am in agreement with Greg Paul on this one. It is worth noting that Greg P. , Jim Cunningham, and Mark Witton all derive roughly the same body mass estimates for giant pterosaurs, using three different methodologies (in all three cases, the methodology works on extant species for confirmation).

At a quick glance, it seems that the slicing technique is basically overestimating at large sizes - hence it seems to work for living birds alright, and animals near that size range, but accumulates error at large body sizes. The methods used by the three authors above, by contrast, were verified on larger animals.

Incidentally, Quetz was probably a long-distance flyer, just not by continuous flapping flight.

Cheers,

--Mike H.


Sent from my iPhone

On May 21, 2010, at 4:10 PM, GSP1954@aol.com wrote:

I was the first to explain that Quetzalcoatlus was far more massive than
the conventional wisdom. I was in charge of the restoration for Paul
McCready's robotic QN project and quickly realized that the skeletal framework was way to big to accomodate the human-like 70 kg mass thought necessary to achieve flight, and I published more realistic weights starting in 1987 in Nature. As one who thinks superpterosaurs were real massive the new estimate of about a half tonne is a real stretch. The half size Q. sp are sufficient to get a reasonable volumetric estimate, and scaling up from that results in a quarter tonne for Q. northropi assuming a normal avian specific gravity. The existence of what appear to be fully developed wings on the superpterosaur indicate it was a true flier, albeit perhaps a short range burst flier. A number of researchers including myself have shown that the span/ mass ratio was simialr to some gliders and there was plenty of muscle power to take off.

GSPaul</HTML>