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Re: Biplaneraptor



"James R. Cunningham" wrote:
> 
> Sounds intriguing and worth consideration.  Is stabilizing the rear legs
> during a strike the known function in these extant animals?  How does it
> work for the extant beasties?

Fishing eagles will orient a large caught fish so that it is held in
they claws facing forward, thus reducing drag. Until they do so, they
have a lot of trouble getting back into the air again. I suspect that
streamlining of the hind legs via feathers may also contribute to
reducing drag in a similar way. I'm no expert on aerodynamics, but a
gradually trailing edge would seem to reduce eddies forming behind a
structure, while something more cylindrical in shape probably wouldn't.  

If Microraptor was more terrestrial than an eagle (and just about
everything is - many eagles are reduced to a clumsy hop on the ground),
then it would have had to have made a compromise between flying/gliding
ability and having long (and strong) enough legs to get about on the
ground.

It seems to me that the only way to prevent yourself from being
'butt-heavy' while flying or gliding when you have long legs is to sweep
them backwards like those of a stork (and a long counter-balancing neck
would probably help). If Microraptor's skeletal structure precluded it
from sweeping its legs back, and given its very un-stork-like neck, then
perhaps streamlining the legs was a good compromise. If they had some
moderate amount of lift as well, then maybe they functioned like the
tail of a kite, helping to lift the rear end so as to point the entire
animal in a more horizontal direction. A slight twist of the legs near
the end of a flight/glide may have negated their streamlining/lifting
abilities, thus orienting the animal in a more vertical plane for
landing on a target tree trunk.

Again, I'm no aerodynamic expert, so perhaps my aimless musings are well
off the mark...

-- 
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Dann Pigdon                   Australian Dinosaurs:
GIS / Archaeologist         http://www.geocities.com/dannsdinosaurs
Melbourne, Australia        http://www.alphalink.com.au/~dannj/
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