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Re: Spinosaurs as what?



On Fri, 25 Feb 2005 14:52:33 -0700 (MST), Richard W. Travsky
<rtravsky@uwyo.edu> wrote:
> On Fri, 25 Feb 2005, Tim Williams wrote:
> > Renato Santos wrote:
> >
> > >the animal could use its shade as a way to diminish the glare the water's
> > >surface produces thus being able to see the fish more clearly.
> >
> > Dorsal sails are also seen in _Ouranosaurus_ and some "pelycosaurs".
> > _Altispinax_ may have had a sail too; although it's also been suggested that
> > its elongated spines supported a hump rather than a sail.
> >
> > The idea that _Spinosaurus_ used its sail as a shade-giver is interesting,
> > but highly speculative.  It's also undermined by the fact that evidence for
> > dedicated piscivory in spinosaurs is ambivalent.  Interestingly, there is an
> 
> Since the sail runs down the back, it would have to stand sideways for
> this to provide shade. If this then was supposed to attract fish, then the
> critter would have to be looking over its shoulder to see if any fish
> showed up (not to mention the difficulty in striking at a fish from this
> position).

_Ouranosaurus_ was already mentioned, and _Rebbachisaurus_ had long
vertebral spines as well: three dinosaurs from distinct lineages
(_Spinosaurus_ a theropod, _Ouranosaurus_ and ornithischian,
_Rebbachisaurus_ a sauropodomorph) with the same trait, all living at
the same time and in the same place. Coincidence? Not likely. And I'm
pretty sure _Ouranosaurus_ and _Rebbachisaurus_ weren't living on
fish....
 
--Mike Keesey