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Re: Giant birds (again)



Due to technical difficulties (Norm, your system claimed not to know
you, so listproc unsubscribed you) the enclosed message didn't get
distributed.  Since this gives me an opportunity to say something
first, I recommend that people interested in this subject search the
archives for messages by Alan Brush describing some of his data
indicating that feathers did not derive from scales.

-- MPR

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From: "King, Norm R" <NKing@usi.edu>
To: "'dinosaur@usc.edu'" <dinosaur@usc.edu>
Subject: Re:  Giant birds (again)
Date: Fri, 19 Nov 1999 13:11:20 -0600

I know this thread seems to have died, but I've been busy, and just got
around to reading this.

tkeese wrote (11/9/99, 2:25p):  

>> . . . calling ankylosuar "birds" is pretty bad, too.<

To which dinogeorge responded (11/9/99, 3:06p):

> Not really, especially when it gets you to thinking that ankylosaur
> scutes and spines might be modified forms of feathers (or rather,
> that feathers might be modified forms of scutes).  It just seems
> peculiar at first.


I've been mulling over that thought, and some of its implications, since it
was posted.  I still find it peculiar.

I think it's easier to suppose that these are independent structures derived
from the same pre-existing feature.  And I even wonder about that.  Are
scutes and feathers really homologous?  I thought ankylosaur scutes are
composed of dermal bone rather than keratin.  I also thought that most
people think feathers are related in some way to scales, although the
details may be unclear.  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.  So, then, the back plates of
Stegosaurus, with their high degree of vascularization and (blood?) sinuses,
would also be just modifed feathers.  (NOT!)   Are ankylosaur scutes
vascular?

Were you just kidding? 


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