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Re: Stego/Ankylo limbs



On Fri, 2 Feb 1996, Rob Meyerson wrote:

> > > Impossible.  The humerus range of motion would be hampered by the
> > > rib cage (with the elbows constantly smashing into them).  This
> > > becomes even more true with the new rib articulation.
> > 
> >Even if the main movement was in the lower arm - from the elbow joint.
> >I do not see why the humerus has to move all that much, really.
> 
> The only way this would work is if the arm was held racehorse-style, with the
> humerus going back at an angle.  This would mean that the humerus would be
> either close to, or resting on, the rib cage.  At that close proximity, high
> speed motion by the animal would result in broken ribs, as the humerus smashes
> into the ribs.

Ungulates solve this problem by having their scapulae swing across their 
often rather bulky ribcages.  Like ungulates, ceratopians have no 
clavicles, and this may well have allowed the scapulae to swing, which 
would also increase the reach of the rather short forelimbs.  This was, 
AFAIK, first suggested by Bakker.

> Rob
> 


Nick Pharris
Pacific Lutheran University
Tacoma, WA 98447
(206)535-8204
PharriNJ@PLU.edu

"If you can't convince them, confuse them." -- Harry S. Truman