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RE: Cretaceous feathers



> However, I would hesitate in referring to
> _Caudipteryx_ or _Protarchaeopteryx_ as
> "fan-tailed", given that the term "rectricial fan"
> is usually reserved for when the rectrices attached
> to the pygostyle are capable of spreading out
> ("fanned") in a radial manner (as in modern fling
> birds - see Gatesy & Dial Evolution 50: 2037-2048). 
> _Caudipteryx_ and _Protarchaeopteryx_ have no
> pygostyle, and the rectrices are essentially
> arranged as a "frond", as in _Archaeopteryx_, except
> they are attached only to the distal caudals.

Well thanks for the "frond" - I have been looking for
a word to distinguist the moveable tail fans of modern
birds from what often gets called "fans" but is
something different, found in non-avians. You are
right of course about the pygostyle - I was thinking
of _Nomingia_ which has one - and quite possibly a
"frond" too, as it was a) close enough to
_Caudipteryx_ and b) it is hard to imagine for what
else such a bone should evolve (that would mean that
the non-avian pygostyle evolved because it improved a
pre-existing or incipient "frond" by making it
structurally more robust)


Regards,

Eike



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