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Re: Long Horizontal Necks Re: Vertebrae of Early Sauropods



> Date: Wed, 31 Mar 2004 04:22:43 -0500
> From: Graydon <oak@uniserve.com>
> 
> > If [diplodocids can't raise their necks much above horizontal]
> > then it doesn't seem to leave many other uses for the long necks
> > than side-to-side sweeping, or possibly feeding below foot-level
> > at the margins of lakes and rivers.
> 
> Or high browsing in a bipedal/tail down tripod stance.  [...] the
> range of neck motion doesn't at all preclude high feeding, it just
> precludes _quadrupedal_ high feeding.

Thanks, Graydon, you're right of course.  I should have mentioned this
possibility.

That said, the idea of tripodal rearing also remains untested.  See
Matt Bonnan's classic July 2000 message to this list, archived at
        http://www.cmnh.org/dinoarch/2000Jul/msg00256.html
which rants thusly:

        Why not rear up on your hindlegs?  Many, many
        scientists, and many, many threads on this list have
        repeatedly asked, asserted, assumed, or rejected
        sauropod rearing for many various reasons.  The
        astonishing (to some, perhaps, and certainly to me!)
        truth is that no one has yet made an in-depth,
        rigorous study of how a sauropod could rear.  Many
        folks throw around figures about probable mass, the
        massiveness of the hindlimbs, the shortness of the
        forelimbs in diplodocids, the height of the neural
        spines, etc., as "evidence" of rearing up in
        sauropods, but these are just suggestive and
        tantalizing guesses of what is really going on.
        Questions that need to be addressed include: how much
        rotation is possible of the femur in the hip socket of
        a sauropod? what muscles are involved and what
        landmarks can be used to verify that these muscle
        groups are indeed doing what we suggest? what effect
        does the large tail muscle (caudofemoralis longus)
        that pulls the femur back have on a rearing sauropod?
        did sauropods bend their knees when rearing, and if
        so, what sort of strain and stress did this send
        through their pelvis, hindlimb, and foot? sauropods
        have an open hip socket and a cylindrical femoral
        head: how was force transmitted through this during
        normal weight bearing, and could the pelvis and
        hindlimb handle rearing up?

 _/|_    _______________________________________________________________
/o ) \/  Mike Taylor  <mike@indexdata.com>  http://www.miketaylor.org.uk
)_v__/\  "The One-Page Principle: a specification that will not fit
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         Mark Ardis.

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