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Re: Bone heads



>However, that bony dome is exactly the kind of shape that is useful for an
>offensive weapon against a larger object. It is the classic mace-shape to
>be swung through the air. It is not a battering-ram which, because of the
>momentum involved and the chance of a glancing blow, could be cause
>catastrophic instability while at close range of a predator (ie, it might
>trip over).

Hi Paul! -

        This has been a nicely thought-out piece of logic!  And, in fact,
if we were limited to the bony domes atop the noggins o' pachys, it would
probably be the most parsimonious explanation.  However, the bony domes
aren't the only evidence to support the "ramming" reason for their
existence.  The entire vertebral column of pachys (such as they are
known...) is set up to brace for impact -- the neck and the back verts are
especially well-suited for this.  They are, quite simply, shock absorbers.
For the shock to travel all the way down like that, impacts would have to
be close to head-on...not by swinging the head from side-to-side (as I
understand it).  I'd be happy to try and dig up some references on this for
you if you like...but my library is still in boxes in a warehouse
somewhere!  Can someone else help for the nonce?  Thanks!  8-)



Jerry D. Harris
Schuler Museum of Paleontology
Southern Methodist University
jdharris@lust.isem.smu.edu
        (Compuserve:  73132,3372)

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