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Wing membranes



David Unwin wrote:
>>
However, readers of the list should note that the Zittel specimen is an
isolated wing, and that the rear edge of the wing membrane impression
has
clearly been 'prepared'. Consequently, while I would agree that this
specimen can provide very important information on the STRUCTURE of the
brachiopatagium it is quite unreliable with regard to the SHAPE of the
brachiopatagium. Only reasonably complete specimens with fore and hind
limbs and well preserved impressions that clearly show the edge of the
brachiopatagium can provide real data regarding the SHAPE of the
brachiopatagium.
<<

When Dr. Unwin makes a statement, such as the above, readers of the Dino
List should ask themselves several questions:

1. What does 'prepared' mean?  If it means 'chopped off' then why would
any preparer chop away even a flake of that precious and unique (at the
time) wing membrane when it is the wing membrane that makes it _so_
valuable to Science? ~ especially when those flakes support the
traditional view?

2. If it had been 'prepared' then why does it match _every other_ wing
membrane or impression currently available in the literature? ~ and many
of those are complete with fore and hind limbs.

David, I'll send you jpgs that point out what I think you're missing the
day you request them. I'm requesting that you send me what you have if
you want to win this argument. I'll be the first to grant you your
laurels if you can show me what you're telling me.

>>
One such highly instructive specimen (fantastically well
preserved) will be described in the forthcoming pterosaur volume edited
by Eric Buffetaut. Needless to say it shows the brachiopatagium
attaching
all down the leg as far as the ankle.
<<

Tsk. That's the same thing that was said about all the other so-called
'deep wing' specimens. So at the present, I find your statement hard to
swallow, although I'll always look forward to exceptional new data. I'll
email Buffetaut immediately.

>>
The important point I want to make
here, though, is that if we wish to have meaningful discussion of
brachiopatagium SHAPE it should be based on the best preserved examples,

not problematic, isolated specimens such as the Zittel wing.
<<

No argument should be based on a single isolated specimen. And mine
isn't.

>>
One other critical point, as Pennycuick previously noted, the
impressions
of pterosaur wings that we have are essentially 'dead' wings. It would
be
quite wrong therefore, just to assume that their current shape reflects
that of the living animal - ok, it might have done, but this needs to be

clearly demonstrated, not just assumed. We would not, for example,
presume that the wing membranes of Messel bats had the same shape in
life, as is now seen in the fossils, so why make this assumption for
pterosaurs?
<<

What's wrong with 'dead' wings? We're never going to get 'live' ones.
And what's wrong with the Messel bat wings, except to say that the
membranes are often missing? IMHO, forensic scientists (aka
paleontologists) should never dismiss evidence. No matter how seemingly
'dead' or trivial. Or job is to rebuild the living animal from the dead
clues. Following that point, David, I have to ask you, why have you
never created a reconstruction to test the fit of your anatomical work?
And following that point, why have you stopped making original detailed
drawings of specimens?

Your Zhejiangopterus appears to be a tracing or a reprint of the
original figure with no new data included to suggest you worked from the
fossil or even a picture of the fossil. Just from examing published
photographs I found a sclerotic ring inside the nasoantorbital fenestra
and that the premaxillary part of the jaw line is a tiny transverse
strip at the tip of the rostrum, not the rostrum filling excess you and
your predecessor indicated that matches no other pterodactyloid.

And your Dendrorhynchoides is apparently another tracing of an old
figure which includes no new data. That means old mistakes were echoed.
For instance, in your drawing your right "maxilla" turns out to be a
series of phalanges ending in a large ungual!

Let the reader beware.

In the beginning I believed everything I read in the scientific
literature. Now I know better, as many list readers do too. Some dogma
is bad dogma. Some paradigms need to be brought down. The broad
pterosaur wing membrane is one such old clunker that needs new work.

And now for a moment of self-depreciation:

Some of my own work needs a more careful examination. I'm surprised that
of the many errors I've recently discovered that no one else has brought
them to my attention. You need not fret. I'm putting it down on paper in
my current manuscript.

David Peters
St. Louis