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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.