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Re: birds scales



>To repeat myself, since down is the *first* feather type to appear on a chick,
>down should have been the first feather to appear on the group.
>
>Rob

There is simply no principle in biology that states this.  SOME juvenal
characters are equivalent to ancestral character states, but this does not
mean at all that ANY juvenal character state must be.  Down may appear first
for many functional reasons having to do with development - it may simply be
more  adaptive for the type of thermoregulatory problems chicks face, or it
may develop earlier because of energetic requirements in feather production,
or because it acts as a stimulus of some sort to parents, or for any number
of other reasons.  Juvenal animals are not simply suites of ancestral
characters - they possess many characteristics that are derived adaptations
to being a juvenile.  There are so many such characters (the egg-tooth, just
to give one example) that a statement such as the one you make above simply
cannot be justified.
--
Ronald I. Orenstein                           Phone: (905) 820-7886 (home)
International Wildlife Coalition              Fax/Modem: (905) 569-0116 (home)
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