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Re: Pterosaur wing membranes


On May 21, 2006, at 8:36 AM, Jaime A. Headden wrote:

David Peters (davidrpeters@earthlink.net) wrote:

<If the membrane in question has ordered (parallel) actinofibrils, then it may
be ripped off of the wing finger. If not ordered, as in the example of Sordes,
then the membrane may be considered uropatagial. Somebody get a microscope on
it!>

Parallel aktinofibrils do not neccessarily apply to "torn" material, only to
relaxed, nonstretched skin between then, as when the wing are folded, which is
the case in *Sordes* as well, so arguing for torn wing material as Dave did in
1996 in reply to Unwin and Bakhurina, does not neccessarily follow.


Torn or untorn has nothing to do with parallel aktinofibrils. Parallel fibers exist only on the wing and the outer wing at that -- except, of course, in the pre-pterosaur hindwing-glider Sharovipteryx. But no one is arguing that here. The uropatagium in pteros has unorganized fibers, as demonstrated by Unwin and Bakhurina. No Pterodactylus has organized fibers in the uropatagium.

The presence or absend of parallel fibers will tell you whether this is outer wing material or not.


An extended
uropatagium, if it existed, would also show a radial arrangement of any
embedded fibres, if present, and parallel when relaxed.

Show me one example among pteros. Otherwise you are clearly mistaken.

In addition, it is also likely that leg-based "fillets" are responsible for
the leg-based membranes in *Sordes*, just as much as a ankle-to-arm broad
chord.

Show me one example of leg-based membranes on Sordes or anywhere, other than the misguided cartoon of Unwin and Bakhurina and earlier Sharov. Both were shown to be examples of geologic breaks in the matrix with continuation beyond the wing finger and legs. Can't blame the scientists involved. They were trying to make something out of nothing in order to match an existing, but nevertheless mythological, paradigm.

David Peters
St. Louis


  Cheers,

Jaime A. Headden
http://bitestuff.blogspot.com/

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

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