Re: Regarding Spinosaurus

[Graydon <graydon@dsl.ca>]

On Mon, Jan 07, 2002 at 04:34:26PM -0600, Williams, Tim scripsit:
> Graydon wrote:
> >Not particularly like vultures; I'm thinking that they were active
> >predators, but that they might have had an odd mode of feeding.  The
> >contents of the body cavity tend to the highest food value of any part
> >of the prey animal, and there's problems with using _all_ of a carcass;
> >it might make sense to specialize in getting the most nutritional value
> >from the kill before abandoning it, in preference to defending it.
> [snip]
> >It does all seem to fit; anyone got a suggestion as to how one could
> >test it?
> 
> The only way theory this could be corroborated if we are fortunate enough
> (VERY fortunate) to find a spinosaur specimen with integumentary structures.
> If spinosaurs were not content just to eat the outer muscle layers, and
> delved into the innards of carcasses as well, then you'd expect the
> spinosaur head to be naked - like modern vultures (vulturids/cathartids and
> accipitrids) and the marabou stork.

Isn't the default state for everything in that derived-allosaurid
clade naked skined integument?

> (I ain't holding my breath for that discovery though.)

It would be a very fortunate find, yeah.

> >I can see them eating fish just fine, too; I doubt any theropod has ever
> >been what one would call a picky eater.  I do have some trouble
> >imagining a multi-ton terrestrial facultive fisheater, though.
> 
> "Facultative" might be okay; but I have trouble imagining a multi-ton
> *obligate* terrestrial fisheater.

Has anyone argued for obligate?  Facultative seems pretty reasonable
compared to peak fish sizes available in wading reach; it's the question
of _average_ fish size that troubles me.

River fish, and mangrove fish, get pretty darn big; why those fish would
be anywhere a wading predator could reach them all year round is the
hard part.  The spinosaurids might have had grizzly-style fat storage
adaptations, so that it wasn't a problem that there weren't good food
supplies half the year or whichever, but it still seems like an oddly
unstable niche.

-- 
graydon@dsl.ca   |  Hige sceal þe heardra, heorte þe cenre,
                 |  mod sceal þe mare þe ure maegen lytlað.
                 |   -- Beorhtwold, "The Battle of Maldon"