Re: Sail vs Hump?

[Robert.J.Meyerson@uwrf.edu (Rob Meyerson)]

Adam Yates writes;

> How do we tell how long the presacral column of Spinosaurus was? At
> the moment there are only illustrations of a few dorsal vetrebrae
> and no pelvis.

The presenter that gave the talk put up a slide showing all (I think)
 currently known pieces of _Spinosaurus_, he then put up a probable skeletal
 reconstruction of the animal, with the known material shaded (I think what
 he did was compare vertebral sizes known from _Spinosaurus_ and other
 theropods in order to place where the vertebra should be located). 
 Although it seemed that there was too few skeletal elements to make any
 definate conclusions, it appeared some of the vertebra were placed in the
 spot where the pelvis is located in other theropods.  Apparantly, these
 vertebra show no signs of pelvic bone attachment sites, leading to the
 conclusion that the pelvis was located further back on the animal,
 seemingly behind the center of gravity.  This placement puts the animal off
 balance, threatening to put it on it's face.  This leads to the possible
 conclusion of the animal being quadrepedal.

Granted, we need to locate a far more complete animal before we can make any
 definate conclusions either way; but the implications, if this new
 reconstruction is accurate, may provide some interesting insights into the
 processes of evolution.

Rob

***
"What sad times are these when passing ruffians can say 'Nee' at will
 to old ladies!"
                -MPATHG