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Re: MORE FEATHERS & NEKKID MAMMALS
At 02:07 PM 11/3/96 -0500, Jeffrey Martz wrote:
> I still don't understand how feathers are reconciled with a scaley
>skin. Regardless of whether birds are born feathered or naked, they at
>some point get feathers on the smooth skin and scales everywhere else.
>This implies something about the incompatability of feathers and scales
>on the same section of skin. If you are growing feathers somewhere, you
>don't want scales there.
1) Hoatzins are born with two fully functional digits that are later
absorbed into the typical avian carpusmetacarpus (or whatever the hand is
called). I doubt this sort of thing is unique, where juveniles have
characters different from adults.
2) Experimentation has shown that when certain proteins are denied to
the foot when an embryo, feathers form instead of scutes and scuttelae. The
reptilian scales, the reticulae, were also replaced by feathers in one
experiment, but given the extreme difficulty they had doing it, I suspect it
was due more to the chemical bath they received than anything else.
3) Feathers are shed during a bird's life.
Given these factors I see no problem with a dinosaur starting with
feathers as a juvenile and becoming and adult with scales ... or, more
properly, scutes and scuttelae. They could be born with feathers, then as
the animal grows, certain proteins and whatnots kick in after the feathers
are shed and what grows in their place are scutes and scuttelae. Not that
big a stretch.
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