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Re: feathers



At 04:18 PM 7/16/97 -0400, Nick Longrich wrote:
>I noted a while back the similarity of feathers to the branched structures
>which are used by plants to parachute their seeds (thistle down and
>whatnot). At the time I was of the belief that feathers (albeit
>ratite-like ones) originally evolved for insulation, but in light of some
>skepticism about branching in the insulatory structures of Sinosauropteryx
>(assuming it does have insulation) I'm a little more open to looking at
>this. 
>    Basically, it seems to me that these downy seeds are the only example
>of convergent evolution of a feather-like structure (at least that I know
>of)- i.e. a central rachis with barbs branching off. And I wonder if this
>argues (however circumstantially) that the branching of feathers evolved
>for aerodynamics, not insulation, although perhaps the feathers started
>out as insulatory bristles/hairs without secondary branching. Something to
>think over...
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