Re: Sail vs Hump?

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

>One problem with restoring the sail of _Spinosaurus_ as a hump is
>that it is so darned tall.

However, the neural spines of bison, and some fossil pigs, are not exactly
 short (although they are not up to _Spinosaurus_ dimensions.  Part of the
 hypothesis held that the spines helped to support the tendons used in
 lifting the head (although the head of the critter doesn't seem to be so
 large as to need the extra pulling power).  The premise sounds similar to
 Bakker's hadrosaur reconstruction, where the head couldn't be lifted above
 the hight of the backbone.

>Another is that the dorsal vertebrae are quite opisthocoelous (i.e.,
>the vertebral centra articulate with their neighbors in
>ball-and-socket joints in which the socket is at the back of the
>centrum and holds the ball at the front of the succeeding
>centrum). This indicates mobility of the vertebral column and
>strongly suggests it was not buried/immobilized in a great mass of
>flesh.

Its possible that the hump material was made up of fatty tissue, so the
 flexibility of the vertebra wouldn't be all that restricted.  Since both
 _Spinosaurus_ and _Ouranosaurus_ are desert dwellers, the presenter
 suggested that these two were like dinosaurian camels, where the hump is
 used for fat/water storage.

>Also, there is a natural "water line" (for want of a better term)
>fairly low up the _Spinosaurus_ neural spines, above which the
>lateral profiles and surface texture of the spines change. This
>"water line" is likely where the back ended and the sail began.

Another interpretation could be that the "waterline" marks the spot where
 the back muscles leave off, and the fatty-hump material takes over.

> Anyone else out there recall this baryonychid-like claw?

Actually, the presenter mentioned this claw (and even showed a slide
 containing it, as well as the rest of the known _Spinosaurus_ material); in
 fact, he even discribed it as being like _Baryonyx_.  In his quadrepedal-re
construction of the animal, he does have the claw held aloft.  However, I
 agree that we need an articulated arm before we can say for certain about
 any reconstruction.  I am skeptical of the ideas, but I am trying to keep
 an open mind.

Rob

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