RE: Peculiar Femoral Feathers

[Waylon Rowley <whte_rbt_obj@yahoo.com>]

Tim Williams wrote: 

> The time that elapsed between (a) the animal 
> launching itself into the air and (b)
> the animal positioning its hindlimbs for landing on
> terra firma, may probably have been minimal, and 
> left little time (or need) for tucking the
> legs under the body.  As you said, the lift
> generating abilities of the plumage were 
> undoubtedly extremely weak.

That's a good point. Maybe there was a need for
holding the legs in (however brief). Something to do
with the center of gravity after launch. Maybe the
very act of pulling the legs up and forward gave a bit
of thrust - like a rubber band snapping back. Or, it
put them in a good position for a slashing stroke on
the prey below. Who knows....   

> Ahh, but are the two functions (launching and
> running) mutually exclusive?

No, not at all. I just see these long spindly legs as
being a bit *too* long for high-speed running. 

> Also remember that, if basal dromaeosaurids are any
> guide (and I suspect that they are), then the 
> ancestors of birds were probably not strong runners
> (i.e. not highly cursorial).

Don't primitive dromies like Sinornithosaurus have
cursorial hindlimb ratios? Is there any way to
distinguish between a dromie adapted for launching
itself from trees or running swiftly? I would think
you'd see the same configuration of muscle insertions.
I'm not really good with dino musculature, but it is
possible that the retroverted pubis had a muscle which
attached to the femur? If so, it would add alot of
power to a leap. I assume that it would have to be
anchored more proximally, though. 
 
> I share Ruben's astonishment.  The sheer audacity of
> Natural Selection in putting pinnate feathers on 
> the thighs of non-avian theropods!  

It must have looked pretty strange when they walked!
Like little "butt fans" expanding and contracting :^)
 
> Actually, most birds have feathers on their thighs.
(snip)
> Some birds even have feathers sprouting from the 
> tibia. Ptarmigans even have feathers on their feet.

They probably aren't very large and are aligned with
the axis of the leg though, right?

Cheers,
Waylon Rowley

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