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Re: Archaeopteryx running



Not very fast.  I did the numbers on that the week before the Ostrom Symposium.
I don't have them at hand, but was impressed that they were fairly slow.

Jim

Williams, Tim wrote:

> John Hutchinson wrote:
>
> >I am not totally convinced by the
> >thrust-generator arguments, nor am I certain that Archaeopteryx could
> >have run exactly fast enough, or how fast that really would be.
>
> This is going off on a tangent, I know...  But one of the reasons why I'm a
> little uncomfortable with a cursorial origin of avian flight is that the
> hindlimbs of _Archaeopteryx_ are among the *least* cursorial of any
> theropod.

Archeopteryx appears to be pretty far derived from the beginnings of flight.  I
wouldn't expect Archie's hindlimb structure to say much about flight origins.

> If Burgers and Chiappe are correct in emphasising the role of running
> velocity (combined with the motion of the forelimbs), in assisting the first
> birds (and their ancestors) in becoming airborne, then one would expect
> hindlimbs highly evolved for sprinting.

I have serious doubts about using wing thrust to increase running speed.  As
I've said before, consider running along behind a car as fast as you can go, but
with a barely slack rope attaching you to the car.  Now have the car speed up a
bit so the rope becomes taut and starts pulling you forward (simulating wing
thrust).  Now, count the seconds (or fractions thereof) before the car pulls you
off your feet and you go fanny over teakettle.  I see wings as being an asset to
running primarily in allowing a greater achievable zenith angle when turning
more than I see running as an asset to the wings when getting off the ground.  I
would expect that scenario to develop till the wings develop enough to be very
effective (think mute or whooper swan takeoff).

Jim