Re: Moasaurus

[Ronald Orenstein <ornstn@home.com>]

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).



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