Re: Life of Birds (vertical running)

["Ken Kinman" <kinman@hotmail.com>]

    Yes, George, I agree completely.  But note that I said predator evasion 
was the driving force in *both* cases.  The initial development of feathers 
was (in my opinion) probably driven by an earlier predator evasion strategy 
that long preceded the later "vertical running" strategy (which would have 
been driven by somewhat later, faster and more intelligent predators).
      The initial development of feathers was probably simpler, something 
that diverted the attention of the predator toward the distal portion of the 
tail (which was more expendable) and/or possibly with eye spots to confused 
or startle the predator long enough the make escape more likely.
      Then later, as predators started to become faster and more 
intelligent, the "arms race" would have required a more sophisticated 
evasion strategy like vertical running.  But in the meantime, exaptation for 
brooding would have driven the evolution of feathers from just the tail, 
forward to the back and arms as well.  Evolving up the tail and back would 
also help to explain why feathers occur in "tracts" (more so than if they 
had originated on the arms in the first place).
    But not to worry, the spreading of feathers to arms probably occurred 
by Late Triassic or Early Jurassic, leaving plenty of time for the unfolding 
of a "Bird-Came-First" scenario for the secondary evolution of 
terrestriality in many theropods.  Well, it's way past my bedtime.
           ------Cheers,   Ken
********************************************
> From: Dinogeorge@aol.com
> Like so many other uses of feathers, vertical running cannot take place
> before feathers appear, and therefore cannot have been the "driving force 
> for
> the initial development of feathers." Natural selection cannot operate on a
> feature that is absent in order to bring the feature into existence.
> Otherwise, we'd all have feathers, and hair, and hundreds of legs, etc.


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