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Re: four winged Archaeopteryx
> Feathers started as insulative structures, not aerodynamic structures.
> All known birds can fluff their insulative feathers, and it's very
> hard to see how a non-mobile insulative structure could survive
> selection pressure, so the least hypothesis is that the proto-feather
> could move. Not a lot, but there would have to be some mechanism to
> raise and lower it to control the amount of trapped air.
Feathers are only raised to help a bird to cool down. I doubt that a
long thin appendage like a bony tail - with likely little flesh and a
huge surface area to volume ratio - would specifically need cooling down
(in fact, the opposite is more likely). Therefore tail feathers in early
volant theropods may never have had any insulatory mobility to begin
GIS / Archaeologist http://heretichides.soffiles.com
Melbourne, Australia http://www.geocities.com/dannsdinosaurs