RE: Theropod shoulder movement

["Rob Gay" <rob_redwing@hotmail.com>]

HP Yates wrote:
> Presumably this would be acheived by moving the position of the radius
relative to that of the ulna. Playing around with prosauropod forearms
suggests to me that these guys could do that (as does the orientation of 
manus prints in trackways) but could theropods? Modern birds don't seem to 
able (observation based on a chicken wing that I had for lunch!). So when 
did this motion become impossible? Can we tell from bones alone?
Sorry if this has already been discussed.<
While I don't have a ref (see previous posts of mine), I have seen some sort 
of anti-pronation device (if you will), locking the radius and ulna together 
in a ceratosaur. So, this adaptation probably occured before the 
ceratosaur-tetanurane split.
Peace,
Rob

Student of Geology
Northern Arizona University
P.O. Box 20840
Flagstaff, Az. 86011
AIM: TarryAGoat
http://www.geocities.com/elvisimposter/dinopics.html
http://www.cafepress.com/RobsDinos
"A _Coelophysis_ with feathers?">cheers


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