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Re: How did dromaeosaurs use their arms?



Matthew Bonnan wrote:
>
> My original point was that the development of feathers in theropods does not
> necessarily indicate that they have an arboreal ancestor and could have
> developed for other reasons, later being exapted for flight.

Or, perhaps developed for flight, then were exapted by secondarily
flightless descendants for better maneuverability on the ground. It's
the old chicken and egg problem. It can be difficult to see exactly what
came first. It could well have been any of the following:

> Insulation -> flight ->  2F Manoueverability
(endothermy precedes flight, with secondarily flightless descendants)

> Display -> Insulation -> Flight etc
(variation of above)

> Flight -> Insulation and/or 2F Manoueverability
(the "cold blooded archaeopteryx" idea, with flight leading to
endothermy and eventual 2F. Fuzzy Sinosauropteryx-like coverings and
feathered fans are both acounted for)

> Insulation and/or Display -> 2F Manoueverability -> Flight
(ground up, with endothermy leading to both fuzzy 2Fs and eventual
flying varieties)

I suspect there are other combinations of the above possibilities, plus
no doubt other factors that I haven't considered.

-- 
____________________________________________

        Dann Pigdon
        GIS Archaeologist
        Melbourne, Australia

        Australian Dinosaurs:
        http://home.alphalink.com.au/~dannj
        http://www.geocities.com/dannj.geo
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