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origin of bipedality (was Re: book reviews, parsimony and some loose ends)

George misunderstands me by writing:

> If bipedality were so easily evolved, and for such seemingly trivial
> reasons,

I never made any claim about the ease with which any particular
selective factor might cause an animal to evolve from a quadrupedal to
a bipedal posture.  George, this is just another example of the
inconsistency in the way that you evaluate the statements of others
with respect to the statements of your own.  You wrote:

> In bipedal animals, the forelimbs lose their portal locomotor
> function because they become adapted to doing something else, such
> as (and probably not limited to) climbing, catching onto trees
> during branch-to-branch leaping, gliding, and/or flying.

You subsequently attempted to discount the possibility that the
animals would be grasping prey rather than branches.  For unknown
reasons (unknown to me anyways) you've decided evolution had to have
taken one particular course.  I don't think nature is constrained by
your imagination, so I'm taking you to task for it.  Feel free to
believe what you want about how bipedality could or couldn't have been
selected for, but stop confusing your beliefs with conclusions reached
by careful (read scientific) examination of evidince sufficient to
convince anyone else.  The bottom line here is that we don't have
enough evidence to firmly support any particular version of how
bipedality arose in dinosaurs.  IMHO, to act otherwise is nothing less
than irresponsible.

Or to use your own techniques (heck I'll use mostly your own words):

If bipedality were so easily evolved, and for such seemingly trivial
reasons, then why aren't more "acronomic" animals bipedal?

Mickey Rowe     (mrowe@indiana.edu)