Re: Origin of feathers

[Earl Wood <candles@jps.net>]

Norton, Patrick wrote:

> >But if you state that pre-feathers appeared >for< insulation, you imply
> that homeothermy was already present >before< the pre-feathers appeared.
> (Otherwise, what would they be insulating?) <
>
> An insulator will keep heat out just as effectively as it will keep heat
> in.  What Regal suggested ["The evolutionary origins of feathers." 1975.
> Q. Rev. Biol. 50:35-66] was that the evolution of feathers began in
> facultative homeotherms with the elongation of scales that reduced heat
> flow to the body (a form of insulation) by providing shade. Once
> obligatory homeothermy developed, that feather would would function
> equally well in reducing heat flow from the body.
>
> >I don't think we know enough about homeothermy to say anything coherent
> about how it may have developed in birds and archosaurs.<
>
> I'm not speculating on the evolution of homeothermy. But to speculate
> just a bit on the topic of this thread----I believe that the origin of
> feathers will eventually be found to have a thermoregulatory explanation,
>  .02  cents.....Of interest to me and perhaps others ,on Discovery channel
> it was shown that the reason reindeer can run for long periods and muskox
> can not is that the  reindeer can lift thier hair thereby dumping heat,
> whereas muskox can not and would  fataly overheat if they ran far.    More
> to speculate on........Earl



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