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Re: Patagium attachment Was: Re: Pterosaur.net
On Jan 18, 2010, at 11:07 PM, David Peters wrote:
The bracket only predicts split uropatagia in basal pterosaurs if
1) your outgroup is correct (and that is still quite contentious)
2) there are no fossil taxa within the bracket that have a broad
uropatagium. As it turns out, even if you decide to argue #1, the
bracket fails on #2: several basal taxa appear to preserve a broad
uropatagium. Brackets only give the null model, they do not
override existing anatomical evidence.
Send one example, please.
Sordes is the obvious one; Jeholopterus seems to preserve a rather
broad uropatagium as well. Other examples have also be cited in the
literature - see any of the recent reviews regarding pterosaur soft
In all likelihood, a very broad iliacus ran from the anterior edge
of the expanded ilium to the proximal femur, but the other anterior
thigh muscles seem not to have run that far anteriorly, so the
overall thigh was not terribly deep. This is not actually a
surprise, if one looks closely at the particular part of the ilium
which is expanded in pterosaurs.
If what you say holds true for Sharovipteryx (whatever it's
relationship) it would have had sticks for legs. That would be
Not necessarily, as the ilia of Sharovipteryx may not be expanded in
the same manner as pterosaur ilia - the anterior thigh muscles may be
more anteriorly displaced in that animal. In any case, what I am
referring to is the typical hip construction for diapsids (actually,
most tetrapods), so it's a good place to start. Remember, many
muscles in the anterior thigh do not even cross the hip at all.
With regard to "Anurognathus" What you're seeing in the UV images
are the ventral muscles attaching to the pubis and ischium. The
muscles attaching to the ilium would have been over the ribs, which
are exposed, hence, no muscles preserved.
Both the anterior and posterior (i.e. dorsal and ventral) compartments
are visible. The ventral musculature associated with hip extension
and knee flexion is not running to the anterior pubis - that would be
the anterior compartment. The dorsal musculature for the hip and
thigh does not run over the ribs. I agree that it would seem that it
must given the position of the specimen - this seemingly awkward
situation does not occur because that is not how the hindlimb
musculature runs in terrestrial vertebrates (also, some of the ribs in
Anurognathus are displaced). There are intrinsic back muscles that
run from ilium to ribs, however.
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