Re: Ceratopsian gait

[tlford@ix.netcom.com]

On 03/22/98 20:31:16 you wrote:
>
>
>I have heard a few people use this argument to totally discredit Johnson and 
>Ostrom.  This may 
be going to far.  The experiment that Johnson and Ostrom came up with was to 
make models of the 
shoulder and forelimb bones, and articulate them from there.  Pl
>ease note that they ran their experiment using ONLY these bones (the rib cage 
>never entered the 
equasion).  How they articulate the shoulder on the rib cage is irrelevant to 
their results.  
However, I do agree that they placed the limbs to high on the rib
> cage.
>

It was a good test, but one that I think was carried out the wrong way. The 
only way, IMHO, to 
find he range of movement of the arm is to have the foot planted on the ground 
at the width of 
the Tetrapodosaurus front foot. Then move the body forward and aft, that way 
the total forward 
walking movement would be known of the leg. The way Johnson and Ostrom did it 
was to just move 
the humerus with the ulna, radius and foot dangleing. I brought this up in my 
Dinosaur World 
article.

Tracy