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



--- On Wed, 9/24/08, Mike Habib <habib@jhmi.edu> wrote:

> So, essentially, we might predict that a greater percentage
> of powered  
> flyers would come from arboreal lineages than terrestrial
> ones.  In  
> practice, this doesn't seem to have worked out - birds
> seem to have a  
> mostly terrestrial ancestry (with some semi-arboreal
> members possibly  
> present), and bats seem to have an arboreal ancestry, while
> pterosaurs  
> and insects are somewhat equivocal at present. 

No telling how many times insects evolved flight, nor in how many ways not 
available to verts, so I will unilaterally exclude them :D. 

Given the presence of easy-to-climb trees (e.g., cycads), and good reasons to 
climb them daily, but perhaps not spend all day there, I do not see where the 
terrestrial ancestry of birds necessarily speaks to a ground-up scenario.

Given an Earth-type planet populated w/ a generic terrestrial vertebrate 
species, and a large block of time, my wager will be that the majority of the 
eventual fliers (and the first) will have taken a gravity-driven route, because 
it is "easier".

This is a much different proposition than betting the farm that the crow 
outside my window "probably" arrived here by jumping out of a tree. I have not 
done that, as I believe you know...

Don