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Re: Archie a non-flyer?

Surely. But if it was an *indirect* result of increased drag the
latter could be a target for selection.

I'm sure that LEV production is under selection, but it's not dependent on total drag, per se, so I wouldn't consider that as an example of direct selection for increased drag. LEV's are often most important at high lift coefficients, at which point drag coefficients also tend to be high, but that's not the same as selection for high drag itself.

A symmetric feather can be built to resist the loads just as well, but at the
cost of being more robust, and thus more massive. Therefore, an asymmetric
feather is structurally advantageous in terms of material distribution.

How much weight it could reduce?

Depends on the size of the animal, planform of the wing, and some details of feather shape itself. Suffice it to say the weight reduction could add up quickly. The feathers of a bird can outweigh its skeleton, which is saying something because the skeletons are not as light as often perceived. I can do some rough calculations for weight saving in a fairly generalized bird - I suspect it's in the 10-15% range overall, but take that with a big grain of salt until I actually run some numbers (Jim may have done so already).



Michael Habib, M.S. PhD. Candidate Center for Functional Anatomy and Evolution Johns Hopkins School of Medicine 1830 E. Monument Street Baltimore, MD 21205 (443) 280 0181 habib@jhmi.edu