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FW: Diplodocid whip-tails



Whoops, meant to copy the whole list.

Nathan

> -----Original Message-----
> From: Nathan Myhrvold 
> Sent: Thursday, November 13, 1997 9:54 PM
> To:   'Daniel Varner'
> Subject:      RE: Diplodocid whip-tails
> 
> -----Original Message-----
> From: Daniel Varner [SMTP:danvarner@worldnet.att.net]
>  ...  Perhaps you are familiar with S.Czerkas's paper on spines occuring
> on the
> tails of sauropod dinosaurs. His observations are based on specimens
> obtained from diplodocids excavated by European commercial collectors who
> are working the old Howe Quarries of Barnum Brown fame in Wyoming. Czerkas
> illustrates these spines as occuring in the "whiplash" section of the
> caudal
> vertebrae. Even more intriguing is the placement of these spines. They
> eminate from above the articulation or joint of the caudal vertebrae. This
> would seem to inicate a restriction of movement in this area. Any
> comments?
> [Nathan Myhrvold]  
> 
> I am familiar with these specimens, and in fact there are measurements
> from Howe quarry specimens in the paper.
> 
> The spines in question do not appear to constrict motion.  In fact, the
> Howe quarry has ample signs of extreme flexibility in the "whiplash"
> section:
> 
> -  There is a 10 mm gap between vertebrae, allowing for a lens shaped
> cartiledge spacer.  
> 
> -  There is an articulated section that have a loop in it, in which the
> intervertebral joint angles average 30 degrees per joint, which is more
> than enough to cause the effect.
> 
> So, I believe that the spines most likely did not restrict flexibility.
> 
>  I would like to add that others have excavated sauropods from very
> fine-grained sediments in the Morisson Formation and have never
> encountered
> these artifacts.
> [Nathan Myhrvold]  
> 
> Howe quarry appears to have had some sort of dessication to "mummify" the
> tails prior to fossilization.
> 
>  Also, I would note that the Chinese sauropod, Shunosaurus, has a
> well-developed tail club in its distal tail region. Perhaps this may have
> been a trend in these animals. Whatever, I am most interested in your
> comments. Thanks,
> [Nathan Myhrvold]  
> 
> In the paper I compare the tail clubs of Shunosaurus, in part to argue
> that the diplodocid tails were not weapons.
> 
> Nathan
> 
> 
> 
> Dan Varner
>