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RE: Pachyrhinosaur nasal horn? (was RE: OMEISAUR CLUBS, PACHYRHINOSAUR)




-----Original Message-----
From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu]On Behalf Of
Williams, Tim
Sent: Friday, May 24, 2002 7:52 AM
To: 'dinosaur@usc.edu'
Subject: RE: Pachyrhinosaur nasal horn? (was RE: OMEISAUR CLUBS,
PACHYRHINOSAUR)


Mike Taylor wrote:

> > No horn, no horn, NO HORN. It was a BOSS! Why can't people except
> > this? They had a boss, that's it! Leave the horn off!
>
> Well, that about wraps it up, then.  Got _me_ convinced, anyhow.

Yeah, me too.  I guess the debate is over then.<<

Really? If it is, then why are you still debating about it? :)


Tracy Ford wrote:

> I've had this discussion with people for over 10 YEARS now. The
> comments are always the same, they don't change.

And your answer evey time is...?<<

Same as I've already written :)

> A rhinoceros's horn is keratin, but it's hair, dinosaurs don't have
> hair.

I know.  So what?  I was using the rhino as an analog - I by no means
implied that a nasal horn of a pachyrhinosaur was made of hair.  Keratin is
the major component of nails and feathers, as well as hair. <<

Even though they are both keratin, they are formed differently.

> Dinosaurs have a keratinous horn that covers and followings the
> existing skeletal structure.

Since keratin does not usually preserve in fossils, I'm not sure why you can
be so confident of this.  If dinosaurs did build novel epidermal structures
out of keratin, we would not normally expect to find them.

There's no need for keratinized structures in dinosaurs to 'cover or follow'
existing structures.  What about feathers?  What about the 'quills' of that
porcupine-tailed psittacosaur?  There's no fundamental reason why a
ceratopsian couldn't build a horn out of keratin.  Similarly, the swellings
and domes seen on the skull roofs of certain abelisaurs (and _Labocania_?)
may have served as the bases for cornified horns.<<

The keratin on the beak of birds and their feathers are formed differently.
Don't fall into the trap of them being both keratin they are exactly the
same.



Tim



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Tracy L. Ford
P. O. Box 1171
Poway Ca  92074