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Re: Mesozoic mountains & Spinosaur sails with neighboring critters (2 threads)



On Thu, 03 Mar 2005 19:29:44 -0800 (PST), Jura <pristichampsus@yahoo.com> wrote:
> 
> --- Rodlox R <rodlox@hotmail.com> wrote:
> 
> > and for those who earlier said that there are no
> > examples of unrelated
> > creatures sharing an enviroment & evolving something
> > like a sail....in
> > modern times, both *Riftia* worms at undersea
> > volcanic vents and at least
> > one type of clam that shares the enviroment down
> > there, both lack internal
> > organs, and both rely on sulfur-processing bacteria
> > inside them.
> >
> > just a thought.
> 
> +++++++++++++++++++++++++++++++++
> 
> I suppose one could also consider the huge amount of
> times (~100) that viviparity has evolved in squamates
> from all sorts of disparate groups. The only real big
> commonality is that the ovoviviparous/viviparous
> lizards & snakes, all seem to live in cool climates
> that are not conducive to "typical" squamate egg
> laying patterns.

Mickey had a coupla good points about the three EK sail-backed
northern African dinos.

--They all have sail-less relatives in the same locality. (I'm
thinking _Lurdusaurus_ for _Ouranosaurus_,  _Suchomimus_ for
_Spinosaurus_, and _Nigersaurus_ for _Rebbachisaurus_.)

--They didn't all live at the same time.
 
So the picture's a bit more complicated than convergence across three
lineages due to an environmental factor.

--Mike Keesey