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Re: DinoMorph Strikes Back!... or does it?



> --- Ursprüngliche Nachricht ---
> Von: "Kent A. Stevens" <kent@cs.uoregon.edu>
> Datum: Thu, 12 Jan 2006 21:54:22 -0800

> 3) Regarding the remarkable _Camarasaurus_ specimen with two fused  
> vertebrae (AMNH 5761/X-a-5-605).  Just look at them.  They sure seem  
> to be in collinear alignment when you are right there in the big bone  
> room at the AMNH looking at them.  The pictures kindly taken by Rick  
> Edwards and facilitated by Carl Mehling convey much of the story.   
> Here are shortcuts to the images:
> 
> http://www.cs.uoregon.edu/~kent/DinoMorph/Camarasaurus/images/AMNH/ 
> 5761a-02.jpg
> http://www.cs.uoregon.edu/~kent/DinoMorph/Camarasaurus/images/AMNH/ 
> 5761a-03.jpg

Well, the caudal rim of the 12th vertebra is clearly above the table (best 
visible in 03.jpg), and if the parapophyses weren't there on the 11th, the  
two would rock mightily. Judging from the undistorted-looking laminae, I 
think the whole construct has not experienced dorsoventral distortion -- 
but, again, what do I know.

> 4) In the 1999 Science article Mike Parrish and I published, the  
> manuscript originally included data for 25% and 75% overlap as well  
> as the 50% overlap, but the other estimates were dropped in the  
> editing in order to save column inches.  But curiously the height  
> results for 25% safety factor were rather similar to those for 50%,  
> for reasons that seem to escape GSP:  to raise the head (and NOT  
> merely curl the neck into an arc), almost all the dorsiflexion must  
> arise at the base of the neck.  The mid neck, and especially the  
> cranial few cervical vertebrae must remain STRAIGHT in order to  
> maximize the elevation of the head.

Still a curled neck would raise the head much farther than a horizontal 
one.

(Especially if coupled with a low, more horizontal than vertical position 
of the shoulder girdle -- something GSP has argued against in the past.)

> Such simple numerology does not yield the desired
> giraffe-like neck, the kind with a sharp kink at the bottom and a
> derrick-like ascent.

Indeed not. But it might get the head at least as high as a giraffe's.

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