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Re: Dinosaur article



In a message dated 95-12-08 04:23:19 EST, jpoling@infinet.com (Jeff Poling)
writes:

>>In his book "Evolution: A Theory in Crisis" (Adler & Adler,1986) molecular
>>biologist Michael Denton blows out of the water any notion that scales
>>could evolve into feathers, given a million years, a zillion years, take
>>your pick, since the structures of scales and feathers are ENTIRELY
>>different. Jeff, have you ever seen pictures of scales and feathers taken
>>with an electron microscope?
>
>   I, too, have read studies that involve the relationship between scales
>and feathers and the conclusions were not favorable.  I do not know what the
>majority opinion on this is right now.  However, there seems to be an
>assumption that bird feathers *had* to come from scales if birds truly
>evolved from "reptiles."  The problem is that 1) there is no certainty that
>dinosaurs, especially those considered to be ancestral to Archaeopteryx even
>had scales; and 2) dinosaurs and other archosaurs had an amazing variety of
>"things" growing in their skin.  Feathers could have evolved from just about
>anything.

Alan Brush has been arguing recently on the list that feathers are an avian
neomorph, like mammalian hair--they did not arise from scales but are a
genuinely new structure. He has analyzed feather proteins and found them to
be different from the proteins of scales; they are, however, more or less the
same proteins as in bird beaks, claws sheaths, and leg scutes.

I wish we had some protein samples from the keratinous covering of ankylosaur
and stegosaur scutes, sauropod dorsal ornaments, and hadrosaur beaks. I would
bet money that it's the same stuff as that which makes up feathers.