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Display sctructure (was Re: Sci. Am. - present. [long]



Ronald Orenstein wrote:
> 
> 
> I have bored this list before with my conviction that bird ancestors could
> have been both arboreal and non-gliding - a point that even Pat Shipman's
> excellent book does not seem to appreciate this point.  I think this is
> because everyone assumes that the purpose of flight is to get from point A
> to point B - but many living birds do not use flight in this way.  Instead,
> they make short fluttering dashes to reach prey that would otherwise be out
> of reach - either a flying insect, or something sitting on a leaf or limb
> too light to support the bird's weight - often returning to the same perch.
>  A whole range of birds do this - even some fruit-eating birds.
> 
> If proto-wings could have allowed an Archie ancestor to jump a few inches
> higher, or stay airborne for a few seconds longer, they might have greatly
> increased its ability to take a whole range of foods.  This could happen
> either in trees or on the ground, but perhaps is more likely  (as in modern
> birds) in trees.
> 
> At least this makes sense to me, but I do not recall if anyone has
> suggested this as a route to the origin of bird flight.
> --
> Ronald I. Orenstein                           Phone: (905) 820-7886
> International Wildlife Coalition              Fax/Modem: (905) 569-0116
> 1825 Shady Creek Court
> Mississauga, Ontario, Canada L5L 3W2          mailto:ornstn@inforamp.net
> 

I like the idea (as one of many mind you) of feathers being originally
display structures. You just have to look at how birds such as the
peafoul or the birds of paradise have modified their feathers in
the name of sexual display to the detriment of their physical
capabilities. Even the ostrich (and rhea) use their otherwise useless
wings as display structures, in fact they seem to be the only ratites
that have retained anything you could really call a wing.

While we're on display structures, I was watching footage of the
Philippine sail-tailed lizard (is that the correct name?) and
noticed how they used their tall narrow tails to swim. The structure
of the tail reminded me instantly of that of Protoceratops. Some
people have suggested that the "bill board" tail of protoceratopsians
was used as a display device. Is there any chance they could use it
to swim as well? When you look at those heads they seem fairly
aquadynamic (well, almost).

-- 
____________________________________________________
        Dann Pigdon
        Melbourne, Australia

        Dinosaur Reconstructions:
        http://www.geocities.com/capecanaveral/4459/
        Australian Dinosaurs:
        http://www.alphalink.com.au/~dannj
____________________________________________________