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Re: Spinosaurs as what?



Mickey wrote (excerpted from below):
> I can't think of an
> ecosystem today where a few unrelated taxa (but not
> other taxa which are
> more closely related to one of the taxa in question)
> all evolve a trait for
> a common purpose.

Do you know of a common trait evolved under those
criteria for different purposes? Or are just no "few
unrelated taxa" with common traits at all?

Don

--- Mickey Mortimer <Mickey_Mortimer111@msn.com>
wrote:

> T. Michael Keesey wrote:
> 
> >_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.
> 
> Actually, very likely in my mind.  For one thing,
> the taxa were NOT
> contemporaneous.  Spinosaurus is from the Cenomanian
> Baharija Formation of
> Egypt, Rebbachisaurus is from the Albian Tegana
> Formation of Morocco, and
> Ouranosaurus is from the Aptian Elrhaz Formation of
> Niger.  Elrhaz
> spinosaurids and rebbachisaurids are Suchomimus and
> Nigersaurus,
> respectively, neither of which have very high neural
> spines.  The Baharija
> has large theropod dorsals (Bahariasaurus?,
> Deltadromeus?) without tall
> neural spines.  And even if they were
> contemporaneous, I can't think of an
> ecosystem today where a few unrelated taxa (but not
> other taxa which are
> more closely related to one of the taxa in question)
> all evolve a trait for
> a common purpose.
> 
> Mickey Mortimer
> Undergraduate, Earth and Space Sciences
> University of Washington
> The Theropod Database -
> http://students.washington.edu/eoraptor/Home.html
>