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Re: Science feather strength debate
On 11/4/2010 10:09 AM, Don Ohmes wrote:
Also -- if some flightless birds retain asymmetrical vanes, while others
don't, and those birds that do not have them are "further" from their
earlier volant state -- then that would tend to support the notion that
asymmetrical vanes evolve under flight conditions, would it not?
On 11/4/2010 2:26 PM, Augusto Haro wrote:
Non necessarily, because you may have assymetrical vanes appearing
before or together with flight. Someone knowing more about pennaceous
feathers in non-avialians may tell us if the assymetrical vanes are
actually derived with respect to symmetrical ones or not.
Sorry, I was less than clear -- I meant in living birds. While you are
right in theory, I am skeptical that the geo-record can ever inform us
in this regard, due to it's incompleteness -- should asymmetrical vanes
be found on an early and clearly non-volant animal, even one pre-dating
all other known feathers, I could still say that this animal might be
secondarily flightless, or even be creating aerodynamic effects to some
other purpose such as making noise or cooling...
And I probably would, barring an absolute mountain of evidence to the
contrary -- I accept that feathers in the general sense likely appeared
pre-flight, but doubt as extremely non-parsimonious that flight feathers
evolved to serve some other purpose and then "just happened" to be
More simply -- if asymmetrical vanes appear to be derived relative to
symmetrical vanes in extant birds, that is good enough for me...
Although anything is possible.