[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

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: Thursday, May 23, 2002 10:15 AM
To: 'dinosaur@usc.edu'
Subject: Pachyrhinosaur nasal horn? (was RE: OMEISAUR CLUBS, PACHYRHINOSAUR)


Tracy Ford wrote:

> No specimen that has a boss, not just Pachyrhinosaurus, shows ANY
> evidence of a horn. The Pipestone Creek specimens have both Concave and
> Convex bosses. There are juveniles that have a rudimentary horn (or more
> properly, a split ridge) and at least one specimen that has both a
> ridge and the starting of a boss.

I'm not sure I follow this argument.  The rationale behind the possible
presence of a pachyrhinosaur nasal horn is that the boss formed the base for
a large keratinous horn on the snout - analogous to the nasal horn(s) of the
rhinoceros.  It don't see how the shape of the dorsal surface (whether it
was concave or convex) really matters.  Also, as a cornified structure, we
would not expect the horn to be fossilized as readily as the underlying
bone. <<

I've had this discussion with people for over 10 YEARS now. The comments are
always the same, they don't change. A rhinoceros's horn is keratin, but it's
hair, dinosaurs don't have hair. Dinosaurs have a keratinous horn that
covers and followings the existing skeletal structure.

>> I know Dodson (1996) does not favor this interpretation - why go to all
the
trouble of transforming the nasal horn just to support a large cornified
horn when the same result (a very large horn) could be achieved by just
modifying the bony horn already there?  A good question.  However, it
doesn't mean that pachyrhinosaurs didn't do this.  Perhaps a cornified nasal
horn held certain advantages over a horn with a bony core.<<

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! Darren Tanke has studied (as well
as Scott Sampson) pachyrhinosaurs, they had no HORN!!! I suggest you look at
the specimens and write up what you want after studying the specimens (which
I have done).



Reference

Dodson, P. (1996).  The horned dinosaurs.



Tim

------------------------------------------------------------



Timothy J. Williams, Ph.D.


> Perhaps a cornified nasal
> horn held certain advantages over a horn with a bony core.

David Marjanovic [david.marjanovic@gmx.at]

Wrote

Maybe keratin is cheaper to maintain than bone. Of course this would beg the
question why not all centrosaurines had pure keratin horns...<<

Me

Right, there is no reason for any having a pure keratin horn.

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