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Re: Ceratopsians: sprawling or straight?



Larry Dunn writes;

>I know Greg Paul says they couldn't have sprawled because trackways 
>prove otherwise.

Actually, this is not true.  Recently, Bruce Erickson and another researcher 
did a thorough study of the Triceratops mount in the Science Museum of 
Minnesota.  These two took a tape measure to the skeleton and took a series of 
measurements between all of the feet.  Using this information they were able to 
reconstruct the trackway that their Triceratops would make.  The dimentions of 
this trackway fall well within established parameters (I'm sure copies are 
available if you ask nicely ;^).

> But hasn't it been determined that it 
>would've been physically impossible for ceratopsians (or ceratopians, if 
>you're so inclined) to fit their legs under their torsos in a rhino-like 
>manner?  How much of this is a Bakkeristic "they were like rhinos 
>because they are cooler that way?"

Personally, I have yet to see a skeleton of an upright-forelimbed ceratopian.  
Every one that I see has a dislocated look, IMHO.  The limbs simply don't 
appear like they would have functioned efficently.

For the skeleton of a sprawling-forelimbed ceratopian, the bones fit together 
nice and snug.  Also, take a look at the shoulder joint: there is a 
triangular-shaped process of bone on the scapulacoracoid that matches up 
perfectly with a similar process on the humerus.

For the best analysis of the forelimb that I have seen to date, see:

Johnson, R. E., Ostrom, J. H.  1995.  "The forelimb of Torosaurus and an 
analysis of the posture and gait of ceratopsian dinosaurs."  Functional 
Vertebrate Paleontology.


Shalom,

Rob Meyerson

***
Early bird gets the worm, but the second mouse gets the cheese.