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Re: Birds again



Jeff Martz wrote:

>     I just finished Ruben's 1991 paper in Evolution on Archaeopteryx, in
>which he makes a very interesting argument that implicates ectothermy in
>Archaeopteryx.

You should read Speakman's (1993) refutation of Ruben's paper. Basically
Archae was probably like grebes in that it could not take off from a
standing start, but probably could with a long run up (and of course from
trees). The muscle arguments put forward by Ruben do not hold up. Besides,
the shoulder jount (Jenkins 1993) and relatively unfused wrist (Vazquez
1992) would preclude Archae from power flight anyway (power flight =
ability to take off from a standing start and controlled flight at low
speeds). Jeremy Rayner (1988) pointed out that flying at faster speeds is
actually easier than at slow speeds.

Chris

Jenkins, F.A (1993) The evolution of the avian shoulder joint. American
Journal of Science, 293A: 253-267.

Rayner, J.M.V. (1988) The evolution of vertebrate flight. Biological
Journal of the Linnean Socirty, 34: 269-287.

Speakman, J.R. (1993) Flight capabilities in _Archaeopteryx_. Evolution,
47: 336-340.

Vazquez, R.J. (1992) Functional osteology of the avian wrist and the
evolution of flapping flight. Journal of Morphology, 211: 259-268.

cnedin@geology.adelaide.edu.au                  nedin@ediacara.org
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Many say it was a mistake to come down from the trees, some say
the move out of the oceans was a bad idea. Me, I say the stiffening
of the notochord in the Cambrian was where it all went wrong,
it was all downhill from there.