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Re: Stego/Ankylo limbs (long)



On Fri, 2 Feb 1996, Rob Meyerson wrote:

> hind legs.  The front limbs wouldn't have to do much more than steer.  
> So they wouldn't have to be efficent in locomotion.

Wrong.  unless the front legs have some sort of wheels or runners on 
them, they need to be just as efficient in locomotion as the hind legs, 
or at least able to keep up.

> >        Finally, the reinforcements you mention in the shoulder are
> >consistent with a large charging animal that would have to change course
> >quickly or lunge sideways.
> 
> However, the reinforcements I mentioned only match up (and therefore, only
> apply) if the humerus is held horizontal to the shoulder articulation.

I fail to see how that is true.

> Exactly the reason why ceratopians evolved a similar form.  The dunes of the
> Gobi are about as irregular as one can get.

Yes, but the best way for an animal, which has legs, not wheels, to deal 
with surface irregularity is to develop long legs which can step *over* 
any irregularity.

> 
> >        By sprawling, not only are you moving the Triceratops closer to the
> >ground, but you are placing more weight on the forelimbs making them sink
> >even deeper into the sand.  You are not suggesting "dune surfing" are you?
> 
> Actually, by holding the feet out to the side, it spreads the total weight of
> the animal over a wide area.  This would reduce the total load on the 
> forefeet.

No, it does not.  The weight of the animal is distributed over the area 
of the parts of its feet in contact with the ground.  No more; no less.  If 
the animal slopes down sharply towards the forelimbs, these must bear a large 
portion of the animal's total weight, and, as mentioned above, the animal 
sinks into the sand.

> 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