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Re: Giant birds (again)



In a message dated 11/19/99 5:06:24 PM EST, rowe@psych.ucsb.edu writes 
(quoting Norm King):

<< I thought ankylosaur scutes are composed of dermal bone rather than 
keratin.>>

The dermal bone is covered over with keratin in life (there are a few 
specimens that show this, such as the Sauropelta specimen on display at the 
AMNH). Could well be the same kind of keratin that feathers are made of. 
Also, not at all clear whether the bone or the keratin evolved first to make 
up the scutes. I think this kind of keratin shows up in crocs, too, so it 
might have a long evolutionary history in Archosauria, with feathers simply 
being its "latest incarnation."

<<  I also thought that most people think feathers are related in some way to 
scales, although the details may be unclear.>>

Probably not; different compositions.

<<  I had not heard the same thing about ankylosaur scutes (but maybe I've 
missed something).  Surely the osteoderms of all thyreophorans have a common 
origin.  >>

And a common origin with feathers is not excluded. Not kidding about 
feather-scute connection.