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

Re: FOUR, THREE, TWO, ONE . . . PTEROSAURS HAVE LIFT OFF!

Dann, they could and most likely did stand that erect, though a Quetz would stand only about 8 feet high at the shoulder and about 14 feet at the head (vs. a giraffe's roughly 17 feet). A very heavy Quetz would have weighed about 400 pounds, but average would most likely be closer to 330. Based on the humerus of both animals and the back of the Hatz skull, a Hatz would most likely be similar in height to a Quetz.

Re that launch scenario, it has been presented at conferences on occasion for a decade now. Paul MacCready was the honoree at the SSA 99 conference, and he asked me to give an hour long presentation on Quetz at SSA 99 in Knoxville, TN in late February of 1999. I believe my presentation there was the first time that the terrestrial quad launch scenario was presented at a conference, and John Conway and I also did a time-stepping illustration of a Quetz doing a terrestrial quad launch on a poster that we presented at ICVM-7 in Boca Raton, FL in late July of 2004. I just looked back at a letter I wrote to MacCready the week after the SSA 99 presentation, and note that I commented to Paul therein about having done the quad launch calculations the night before the presentation (which touched on a lot of other things besides launch). I would say that from that time on, terrestrial quad launch was based on calculation and was not a hypothetical 'just-so' scenario. My presentation at the Munich Flugsaurier conference was to have been on the terrestrial quad launch, and when I let Mike know that I wasn't going to be able to attend, he decided to modify his presentation to include his take on it -- he had come up with the concept independently of me, and was courteous enough to touch base with me prior to describing it in his presentation. Mike has a lot of class -- not everyone would have shown that courtesy. I want to reiterate -- Mike came up with the concept independently of me and though we approached it from different directions, our conclusions about it are virtually identical. That pleases me -- there ain't no other feasible way for a big pterosaur to consistently get off the ground at will.

BTW, if I remember correctly, Chris Bennett mentioned the possibility of arboreal quad launch from trees in a paper he did back in the mid 80's. That remains a viable scenario for smaller pterosaurs.
JimC


----- Original Message ----- From: "Dann Pigdon" <dannj@alphalink.com.au>
To: <dinosaur@usc.edu>
Sent: Wednesday, January 07, 2009 6:23 PM
Subject: Re: FOUR, THREE, TWO, ONE . . . PTEROSAURS HAVE LIFT OFF!


Quoting Janet m vandenburgh <van02@cox.net>:

http://www.hopkinsmedicine.org/Press_releases/2009/01_06_09.html

--Hopkins researcher reports that ancient flying reptiles used four legs to
launch

It's great to see research like this actually published, rather than the sort of anecdotal back-and-forth
discussions such as we've seen here on the DML in the past (or elsewhere on the internet). The only
surprising thing about this research is why it's taken so long for someone to actually publish it (using
actual biomechanical calculations that is, rather than hypothetical 'just-so' scenarios).

Does anyone have the full reference for this paper?

A modern-day man and giraffe, drawn to scale, flank the extinct pterosaur
known as Hatzegotpteryx. Unlike birds, pterosaurs used four legs to launch
themselves into flight, according to new research. Illustration by Mark
Witton.

It's certainly an impressive illustration - but what is the likelihood that Hatzegotpteryx could have
raised it's head as high as a giraffe can? Or that it could stand with such straight limbs, for that matter?
I've always envisaged them as having a more bat-like stance on the ground, with the neck at a much
shallowed angle. Although I imagine that wouldn't make quite as impressive an illustration.