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Re: pteroid trouble
Several pterosaurs have an articular process on the inboard side of the
preaxial carpal located about midway down the inboard face approximately in
line anteriorly with the center of the anterior cotyle. In some specimens,
it is quite distinct. That process seems to me to be the articular facet
for the pteroid, and it solves a number of mechanical problems if it is
indeed that. I'm thoroughly convinced that Bennett is right. The large
sesimoid that articulates with the anterior cotyle seems to support a
muscle/tendon that runs from the distal half of the humerus across the
sesimoid to a point just outboard of the proximal end of metacarpal IV. The
outboard portion of that tendon between the sesimoid and MCIV seems to be
responsible (among other things) for storing and releasing energy during the
flapping cycle in order to appropriately modulate the angle of attack of the
outer wing during the flapping cycle. The entire complex also sweeps the
outer wing forward as the elbow is extended.
JimC
----- Original Message -----
From: "David Marjanovic" <david.marjanovic@gmx.at>
To: "DML" <dinosaur@usc.edu>
Sent: Monday, November 17, 2008 5:58 PM
Subject: Re: pteroid trouble
I just read the abstract and Unwin explicitly said the pteroid
articulates with the anterior cotyle of the medial carpal (=preaxial
carpal of Bennet, 2001). Is the "anterior cotyle" what Bennett (2007)
calls the fovea that articulates with the large sesamoid?
Probably -- but keep in mind that Unwin probably changed his opinion after
he submitted the abstract (the deadline for that was in May if I remember
that right!). In his talk he said (in Bennett's presence) he now agrees
with Bennett that the fovea articulated with that sesamoid and not with
the pteroid, and that it took him about a month to change his opinion
while he was looking at good specimens. However, he proposed a _third_
hypothesis on where the pteroid did articulate.