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Re: Quetz wing questions



Comments inserted.
JimC

----- Original Message ----- From: "<Bruce Woollatt>" <brucewoollatt@hotmail.com>
To: "dinosaur" <dinosaur@usc.edu>
Sent: Tuesday, January 15, 2008 12:19 PM
Subject: Quetz wing questions



Hello all, particularly Mr Habib and Mr Cunningham;

With regards to Quetz's aspect ratio; maybe I missed this information
upthread (or even in a previous thread), but I was wondering if each of you
could indicate what your assumed flight membrane hindlimb attachment point
is (if any), and the extent of any uropagium.

I usually use about 7.25 sq.M for the wing area and about 2.4 sq.M for the uropatagium area of Qn. Qn has a slighly higher aspect ratio than Qsp, and the allometric ratios are different. With the exception of the wing, the reconstructions of Qn are actually based on allometric blowups of Qsp. The wing attachment of Quetz is not preserved in the fossil record. I tend to attach the trailing edge at the hip with the ilium defining the aft camberline of the wingroot and the dp crest defining the leading edge of the wingroot. I use the uropatagium primarily to support the weight of the hindlimbs and to provide some supplemental yawing moment when required. I set the length of the Qn torso at 2.06 times that of Qsp, and the hindlimbs at 2.27 times that of Qsp. My reasons at the time were supportable, but not definitive. The one thing they were, was rushed..... :-) More on that below.


Also, what is the ratio of
wing outboard of the metacarpal to that inboard, and how does this compare
with Langston's 1981(?) reconstruction of Qn ?

It varies substantially with flight speed, wing retraction, and location in the flapping cycle. Some years ago, I did a wing skeletal reconstruction independently of Wann's. Mine was so close to his, that I use his. I've known him for a decade, and I'm still totally in awe of his skills and talent. His current reconstructions are considerably different than the 1980's reconstruction (if you are referring to the MacCready half scale flying model). Re skull restorations, I deliberately stay at least one generation behind Wann in anything I do, so that I won't inadvertantly release photos of his most recent restoration.


Note that the big skeletal 'restoration' of Qn that is seen in various museums was done in a huge hurry to make the re-opening of the TMM after museum renovations. It is intended for display and entertainment value, not scientific research. If you wish, I can spend hours offlist telling you about the assumptions Matt Smith, Wann, and I made while it was being prepared. For example, the skull is an isometric blowup of an early restoration of the Qsp skull -- it should be allometric instead of isometric and we knew that at the time. The scapulo-coracoid is totally bogus, a rush job -- the result of a miscommunication between Matt and me. Matt's a really good sculptor, and given more time to communicate about it, it'd look more like we expect the real thing would look if it were preserved. The left wing is totally Wann's and extraordinarily good. I wouldn't put too much faith in the positioning of the metacarpals and digits in the sculpture. We were concerned at the time that folks would attempt to do research based on the skeletal sculpture (which was not our intent or desire), and sure enough -- they have. The TMM sculpture is in a viable flight position, but not a minumum power position -- the support hooks were mounted in the ceiling before Matt finished the sculpture, and Wann had to do the best he could with what he had to work with. And, I think he did a great job of it. There is currently an embargo on the release of new information and photographs of the two morphs of Quetz, so both Mike and I are limited in what we can say about the animals in public. Mike and I are aware of the reasons for the embargo and strongly approve. Don't want to put words in your mouth, Mike, -- but know you agree about that.
JimC