Re: Stego/Ankylo limbs

["Nicholas J. Pharris" <pharrinj@PLU.edu>]

On Thu, 1 Feb 1996 Dinogeorge@aol.com wrote:

> The huge olecranon process on the ulna, together with the massive crests on
> the humerus, virtually compel the forelimb to have had a permanent bend at
> the elbow. 

Much as theropod hindlimbs were permanently flexed at the knee, and they 
didn't sprawl!

> The forelimb architecture is quite similar to that of the large
> Permian therapsids. The question is whether or not the bend was directed
> backward or outward. The glenoid is not much help, since it had a
> saddle-shaped articulating surface, allowing the arms to move outward as well
> as back-and-forth. 

> Ceratopian trackways show the manual
> prints pointing outward as well as forward, farther from the center line than
> the pedal prints, but not much. 

Yes, strongly implying that the elbows were tucked in close to the 
sides.  If the animal had sprawled, the forelimb tracks would have been 
much farther apart than the hindlimb tracks,  If the animal had been 
bow-legged, the forelimb prints would most likely have been closer 
together than the hindlimb tracks, and also in-toed.

> I
> don't see how ceratopians could have held their forelimbs _completely_ erect,
> but on the other hand I don't see them hunkering down with their
> forequarters, either, the way they've often been restored.
> 

Ceratopians *didn't* hold their forelimbs (or their hindlimbs) completely 
erect.  The elbows pointed backwards, and the knees pointed forwards.  Of 
course, by that criterion, horses don't hold their limbs "_completely_ 
erect," either.

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