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Re: How did dromaeosaurs use their arms?

I suspect what you are describing about turning ability is the ability
to 'turn on one's heel'?

Can modern birds 'turn on their heels"

How do you interpret the knee and hip joint geometry of Archeopteryx,
who had both a long tail and wings?  Was Archie's stride powered by teh
tail or had this mechanism been diminished by this point?  The tail was
probably a retained trait from earlier ancestors (unless Archie's
ancestors lost the tail at some point and Archie got it back again). 

The possibility does exist that feathers predates arboriality.
Especially as the suggested use of the (ground)brooding ovi using
armfeathers to shield it's eggs from overheating and sandstorms.

-Betty Cunningham

Matthew Bonnan wrote:
> To reiterate: the basic joint geometry of theropods shows that the femur was
> mostly restricted to a parasagittal plane where it could swing fore and aft
> very nicely but could not rotate or swing away from the body as observed in
> mammals.
> 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.

Flying Goat Graphics
(Society of Vertebrate Paleontology member)