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Re: Moasaurus



At 11:03 PM 13/02/01 +0000, Zoe Heraklides wrote:
OK, I've taken a look around me. I see a kiwi bird. It has long, hairlike structures coming out of its skin. Are these feathers? They look very different to the feathers of a duck or chicken.

What makes a feather a "feather" is probably a bit uncertain these days! However, external appearance has little or nothing to do with it. For example, a bird's eyelashes are feathers. So are such special display features as the plumes on the head of a King of Saxony Bird of Paradise, which look as though they are made of plastic. Either of these looks less like a "typical" chicken feather than does the contour feather of a kiwi. However, I know of no structure on any living bird that is ambiguous, in that some authorities think they are feathers but others disagree.


I suspect that any really useful definition of feathers would have to take two things into account: their embryological development (which, at least in living birds, has some quite distinct features) and their microstructure. Unfortunately the former is going to be tricky to discern from fossils (though it would be most interesting to look for things like signs of moult, "pin" feathers still in their sheaths etc). Microstructure is being looked at, though; there was a paper on this at the Ostrom Symposium by Mary Higby Schweitzer. She was very careful not to draw conclusions, but it seems that the feathers of Caudipteryx and modern birds show more regularity of microfibril organization than the structures on the integument of Sinosauropteryx or Shuvuia (which says absolutely nothing about whether these structures are "protofeathers" that have simply not reached the level of organization in modern feathers or something not homologous to feathers at all).



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Ronald I. Orenstein Phone: (905) 820-7886
International Wildlife Coalition Fax/Modem: (905) 569-0116
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