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Re: Campbell's even crazier than a MANIAC? (archeopteryx climbing)



--- On Sat, 9/27/08, jrc <jrccea@bellsouth.net> wrote:

> >>>  Yes, clearly competitive exclusion can be
> powerful, but do we
> >>> really expect that the simple existence of
> powered flyers should
> >>> completely shut down gliders with limited
> powered ability?
> >>
> >> Yes, I do. I take the lack of "gliders with
> limited powered ability"  as 
> >> implied support for this assumption.
> 
> The reverse may have happened at least once.  No birds with
> significant 
> soaring capacity seem to have evolved until after the
> demise of the 
> pterosaurs (flap-gliders), after which they seem to have
> evolved very 
> quickly.  So, while birds (powered flyers) don't seem
> to have shut down 
> gliders with limited powered ability (pterosaurian
> flap-gliders), the 
> reverse may have happened, at least to the extent of
> blocking the powered 
> flyers from expanding into the flap-gliding niche while the
> competition was 
> still there.  Note that I toss this out to demonstrate that
> the option is 
> open -- I don't feel that we know that that is actually
> the cause, and I 
> don't feel particularly strongly about it myself.
> JimC

Well, soaring is the derived condition in large volants, and more advantageous 
than simple flapping (especially when bigness is good). We were talking more 
along the lines of hypothetical "gliders just learning to flap". Still, it 
happened.

To change the subject slightly -- Do you think that soaring could precede 
flapping as in Boehm's post?

Don