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Re: flapping from gliding



In a message dated 96-09-26 14:27:02 EDT, darwincr@laplaza.org (JCMcL)
writes:

> It does seem to me that in a world of fast light predators, the ability 
> to stop and turn on the Mesozoic version of a dime would confer 
> considerable selective advantage.  
> 
> [We actually had this discussion here on the list last December (LN
>  Jeff started it with a reference to running chickens).  You might
>  want to check the archives.  I know it's not unusual for us to
>  revisit topics here, but this particular topic stands out in my
>  head because I never felt George understood my reasoning as to why
>  feathered arms could have been advantageous to a non-volant
>  cursorial theropod.  I'm glad someone else sees it...  -- MR ]
> 
> Many thanks.  
>
> John C. McLoughlin

I certainly could see uses for feathered arms in locomotion, but I still
can't see why they would evolve >for that purpose<. In those rather rare
living forms that employ feathered arms as air brakes (mainly flightless
cursorial birds that still have some of their wings left), this function
strikes me as an exaptation: They have feathered arms, so they use
them--converting a lemon into lemonade, evolutionarily speaking. But if
feathered arms, or similar structures, evolved as air brakes, perhaps we
should see more of this behavior among living animals than we do.