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Re: Sufferin' Sauropods

In a message dated 11/1/2003 8:56:31 PM Eastern Standard Time, 
zone65@bigpond.com writes:

> The way their 
> legs are depicted in popular art, it seems they would have been 
> unsupportable. I propose they had far more heavily-muscled 
> legs than 
> the gazelle-like limbs they're generally depicted with.

     Ok, I have to chime in here.  Statments like these are not consistent with 
biomechanics.  Bones take up a tremendous amount of the compresive stress for 
terrestrial vertebrates, especially in graviportal animals.  Larger muscles are 
really better correlated with increased locomotor function (e.g. running) 
rather than with holding up tremendous amounts of mass.  Also, areas like 
sauropod manus, ankles, and lower shanks are operated by tendons, so making 
them thicker does not add more muscle, but rather more dead weight, making 
locomotion more difficult.  Without intending any offense to Peter Markman or 
others with a similar opinon, "intuitive" views are basically based on on 
traditional restorations, which are often simply in gross error.  Thus our 
intuition is wrong because of art history; there is not some form of special 
knowledge that can be grasped from our preconceptions.
     That being said, I personally restore more muscles on the calves than is 
often done, because the size of the cnemial crest and other muscle origins 
suggest (to me) less elephantive muscles than others see.  Another problem is 
that many people still use mass estimates that are out of date and generally 
way too high (diplodocus does not reach 30 tonnes, not matter what the BBC 
says!).  Either way, work by Alexander and others shows that the bones of 
sauropods are easily strong enough to hold them up.


Scott Hartman
Zoology & Physiology
University of Wyoming
Laramie, WY 82070

(307) 742-3799