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Re: feather origins (was Help Please)



philidor11 wrote:
> 

> >From a post by Alan Brush dated January 17, 1995:
> 
> Dino-netters,
> It is difficult to accept the traditional hypothesis that reptalian
> scales gave rise, more-or-less, directly to avian feathers. Or, as can be
> shown, to most of the scales on birds. That is, the null hypothesis that
> reptalian scales and feathers shared a close common ancestry is easily
> disproven.

There is another factor that I have not seen discussed before. Scaled
reptiles shed their skin on a regular basis. If scales did give rise to
feathers, then at some point along the way the skin would have stopped
being sheddable. I don't see anything with feathers shedding its skin
without becoming completely bald first.

Do crocodilians shed their skin? I don't think they do, or at least I've
never heard of it happening before. It would seem a waste of perfectly
good scutes and dermal ossicles (depending on the depth of skin shed).
Personally I don't advocate scaled skin-shedding ectotherms developing
into feathered skin-keeping endotherms. Ectotherms are just way too
adaptable. Why mess with perfection? :) I suspect (speculation mode
activated) the origin of feathers, or at least "feathery-like-thingys"
(protofeathers, dinofuzz, whatever you're comfortable with) probably
goes back to the most basal of archosaurs, and that feathers and scutes
are perhaps kissing cousins with scales being more like a long-lost aunt
several times removed (and even then, perhaps related only by
marriage!).


-- 
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Dann Pigdon                   Australian Dinosaurs:
GIS Archaeologist           http://dannsdinosaurs.terrashare.com
Melbourne, Australia        http://www.alphalink.com.au/~dannj/
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