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



Sorry to be so simplistic, but:
Common tasks = common tools. This is reversible.
Common tools = common tasks. And just because we're
related doesn't mean we do the same thing for a
living...or live in exactly the same neighborhood. and
I can still go to Sears and buy a pair of pliers just
like my great-grandaddy had.
--- Mickey Mortimer <Mickey_Mortimer111@msn.com>
wrote:
> Rodlox R 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.
> 
> There are many examples of two distantly related
> taxa in an ecosystem
> sharing a character not found in other taxa in that
> ecosystem which are more
> closely related to one of the taxa with the trait. 
> For example,
> Struthiomimus and Gorgosaurus both have
> arctometatarsi, but
> Saurornitholestes (more closely related to
> Struthiomimus) does not
> (hypothetically).  But in these cases, the character
> isn't particular that
> ecosystem- it didn't evolve due to Judith River
> conditions.  The
> ornithomimosaur arctometatarsus goes back to
> Turonian Asia at least, and is
> found in many taxa which lived in varying habitats,
> for example.
> 
> It's also important that other more closely related
> taxa in a given
> ecosystem lack the trait (thus showing it's not
> necessary for that
> environment).  So your black smoker example would
> need another polycheate
> which lives there yet has internal organs and a
> plesiomorphic way of
> acquiring nutrition.  Thinking about it further... I
> suppose lots of
> unrelated deepsea fish have photophores, while
> others that are more closely
> related to one of the photophored taxa probably live
> in the same ecosystem
> and lack them.  That could be a counterexample, if
> the specifics were worked
> out.  But the abyssal environment is much larger and
> more stable than any
> terrestrial one.
> 
> Mickey Mortimer
> Undergraduate, Earth and Space Sciences
> University of Washington
> The Theropod Database -
> http://students.washington.edu/eoraptor/Home.html
>