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Re: pterosaurs, bats, flying theropods (fwd)

> > One may argue with and ridicule pet hypotheses based upon extrapolating
> > extant behavior back to the Cretaceous.  However, one should not
> > argue that an extant, fully observable phenomenon, is not generally
> > true by arguing it's only a generality!
> One should appreciate both the way things generally are and every single
> exception. Otherwise wrong explanations for both are easy to find.

Of course.

> What about another idea: birds were already there in the daytime, and, in
> order to _avoid_ competition, most microbats stayed nocturnal. (Assuming
> nocturnal ancestors is of course not so easy to test, but nocturnal
> are not exactly something rare, maybe this condition is the plesiomorphy
> placentals.) The whole niche partitioning and competitive exclusion thing.

Check out: http://www.cmnh.org/dinoarch/1996Aug/msg00050.html

Where raptors are absent, microbats forage diurnally.  If they didn't have
to deal with predation they may well outcompete birds in the day time!  But,
this _is_ a form of competition: birds can cope with the predation regime,
bats can't.  
Who knows what was going on in the Mesozoic.  But this phenomenon in
extant species could be an important clue for birds
vs. pterosaurs.