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Re: Patagium attachment Was: Re: Pterosaur.net
On Jan 19, 2010, at 1:21 PM, David Peters wrote:
No semantics game involved. Seriously. And if "evidence supplied in
the literature" is going to be used as a "reason" some of that has
been falsified in the literature, yet it still resurfaces. Please
don't send me back to the literature. I've been there. Send me
evidence. Obviously you've thought long and hard about this.
If we're not going to cite evidence in the literature, then what is it
there for? The findings of other authors *is* evidence. If you want
to go beyond citations and images from the literature, then we can
certainly sit down with specimens in any number of museum collections
and compare notes. I don't like working from tracings, however.
Just trace one deep wing membrane or one uropatagium and show me why
you are correct. If you can't, just admit that you can't.
I don't recall arguing that the wing membrane is deep - I argue that
known specimens with preserved wings show narrow membranes - but the
attachment appears to be relatively broad, and probably has a hind
limb attachment in many, if not most taxa. Already indicated
specimens with a broad uropatagium. You mentioned the 2002 study
arguing otherwise - no worries there, but I'm not entirely convinced
of all the arguments therein. Subsequent papers have argued in favor
of the unsplit uropatagium.
On Jan 19, 2010, at 1:12 PM, David Peters wrote:
What is typical about diapsid hip construction? Birds and dinos have
an anterior ilium with associated thigh musculature. Crocs and
lizards don't. In pteros not only do the anteriorly directed ilia
provide for more thigh musculature, they also provide a deeper
horizontal stabilizer for flight.
It makes a difference what part of the ilium is anteriorly expanded,
because not all portions of the anterior thigh compartment cross the
hip to the ilium. The anteriorly expanded ilium in pterosaurs
probably expands the iliacus complex, but not anterior compartment
proper, so there is unlikely to have been the broad band of muscle
going from the tip of the ilium to the knee. If it turns out that
there was (which seems to be countered by the soft tissue in the
little Anurognathus, but like you said, some bits could be missing),
then it would still only be part of the overall compartment, as
several of the muscles don't cross the hip at all. Therefore, be
careful presuming that an anteriorly expanded ilium means huge thighs
- it works that way in birds, but may not be analogous in pterosaurs.
I doubt that the ilia have a stabilization effect on flight, and in
fact, pterosaurs were almost certainly unstable flyers like all living
powered flying taxa, anyway. If the thighs were broad, and the wing
attached near the hip, then there could be a slat effect, but I doubt
that was the configuration, based on the current evidence (though John
Conway did a nice illustration of how this would work, if it had been
the case). You will need to describe how an extended ilium provides
Are you telling me you see muscles lateral to the anterior ilia? Or
And did I forget that among the ventral muscles some would be
directed toward the prepubes? Maybe that's what you're seeing.
There may be very limited traces of an iliacus complex lateral to the
ilia visible in the Anurognathus UV images. Hard to say. Either way,
we should expect such a muscle to be there, and in that sense, there
would be some muscles lateral to the anterior ilia - but they are
running to the proximal femur, not the knee.
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