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Re: Feathers from Scales



At 05:14 PM 10/16/96 -0500, Gautam Majumdar wrote:

>       The authors were able to experimentally manipulate the leg scales
>>on chickens so that they were transformed into feathers, fully consistent
>>with the idea that feathers are modified scales.
>
>There is an alternative, and more probable, explanation than to assume
>that the scales were converted to feathers in this experiment. It is now
>known that in embryonic birds the same cells produce either scale or
>feather, feather being the default one. Scale production requires
>additional signalling which can be blocked by retinoic acid.

  I tracked down this article and read it, and will be publishing an article
on Dinosauria On-Line based on what I think of it.  One of the points I make
is that the research of Brush shows the scutes and scuttelae are chemically
very similar, if not identical, to the chemical makeup of feathers.  The
reticula, or scales on the bottoms of the digits, are similar, if not
identical, both chemically and genetically to reptilian scales.

   The scutes and scuttelae turned into feathers.  The reticula did not.  I
don't see this as a minor point.

>May I add - this explanation neither supports nor refutes the theory that
>feathers are modified scales.

   I think this research, along with the research of Brush, very much does
sink the notion of feathers from scales.  It does, however, raise any even
more interesting question:  did scutes and scuttelae evolve from feathers?

   See my article Monday where I go into more detail.

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