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Re: Lemurs and Feathers

> Y'know what? I'm starting to get really dubious about the use of the terms
symmetrical and asymmetrical. Is the preservation of Caudipterix really so
perfect that symmetry can be measured in its remiges to say, plus-or-minus
1%? I sincerely doubt that ANY feather is 100.0% symmetrical. I've seen too
many, and they're all curved left or right, and their barbs are longer or
shorter on the left or right, simply based on which side of the body they
originate from. Perhaps we should start talking about "subsymmetrical" to
suggest, "effectively symmetrical" or some similar term.<

Two very good papers discussing the aerodynamic function of asymmetry in
flight feathers are: Ennos et al. 1995, Functional morphology of the vanes
of the flight feathers of the picgeon _Columba livia_, Journal of
Experimental Biology, 198, 1219-1228; and Muller and Patone, 1998, Air
transmissivity of feathers, JEB, 201, 2591-2559.  The authors didn't compare
symmetrical v asymmetrical feathers, but it is clear from their work that
the effectiveness of a flight feather at producing lift and thrust is
dependent on a lot more variables than the chord-wise location of the vane.