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Re: flapping from gliding



At 01:17 PM 9/26/96 -0500, John C. McLoughlin wrote:

>I wonder at the absence of speculation on braking and turning.  Assuming 
[...]
>comparatively low body mass, I have always guessed that a little 
>(Archaeopteryx-sized) theropod that could brake suddenly by pumping 
>feathered forelimbs forward and use these forelimbs' configuration to 
>change direction rapidly, would perhaps more frequently escape their 
>perhaps swifter but less agile (because of greater mass) relatives.  

        Y'know, Larry Martin is paraphrased (in Dinosaur Discoveries #1)
that Archy couldn't turn very fast because of it's tail.  I think he's
wrong.  It had those big feathers, I'm sure it had developed some way of
using them as a giant control surface.
        The problem with using feathered arms for ground steering is that
the animal already has developed its tail for maneuverability.  Also, and
more importantly, the arms are in *front* of the animal's center of gravity.
This would make it unstable when using its arms for cursorial
maneuvering.

[ Instability frequently accompanies high maneuverability.  Look into
  the designs of the F-16, F-117 and most of all the F-22.  Sorry to
  keep throwing comments into other people's messages, but it's faster
  for me this way and you guys are keeping me busy! -- MR ]

And Mickey wrote:

> 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 ]

        I think a lot of us see it, although not all of us think it's
directly related to flight...

        Wagner
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