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RE: Archaeopteryx had black feathers
> Now how does that work when the
> melanin is restricted to the contents of melanosomes? In
> other words, how can it cross-link the keratin that makes up
> the feather structure if the melanin is only inside the
> capsule - like melanosome? perhaps there is also melanin
> outside the melanosomes?
IIRC the melanosomes are formed when the melanin polymerizes (ie the melanin
inside is already polymers, not amorphous). They (as a structural component in
the keratin matrix) are part or most of the stabilizing effect; the polymers
themselves are on the molecular scale and have an effect on the macro scale
only as aggregates.
For a very coarse analogy, think about cement and concrete (cement + pebbles).
For a parallel but unrelated phenomenon that is similar on the molecular scale,
think sickle cell anemia (RBC shape distorted by agggregates of
sickle-hemoglobin polymers, blood inside vessels more "viscous" on macro scale)
PS: what was the specimen analyzed?