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RE: Theropod shoulder movement

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.

Student of Geology
Northern Arizona University
P.O. Box 20840
Flagstaff, Az. 86011
AIM: TarryAGoat
"A _Coelophysis_ with feathers?">cheers

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