Re: Pachyrhinosaurus' nose

[Stan Friesen <swf@ElSegundoCA.ATTGIS.COM>]

>From: Stang1996@aol.com
 > 
 > I've been wondering this for a while.
 > 
 > Does anyone know if the thickening/horn on P.'s nose went just as far as the
 > rhinal ornimentation of the bone went, or was the rhinal ornimentation just
 > the base for a really larger conical horn made of carroten or calogen or
 > something?

It was almost certainly "flat" - though it probably *was* covered in
horn (a material, not a shape).
 > 
 > I have seen it the two different ways; NGS's January ?93 map supliment and
 > most other works with the low, ugly version, the PBS documentary "The
 > Dinosaurs" with the big cone.
 > 
 > I would think that PBS's interperatation is a possibility at least because no
 > other Ceratopsians had skull ornimentation that was "flat" and "rumply".

The discovery of the two intermediate forms linking Pachyrhinosaurus
with Centrosaurus by Jack Horner a few years ago pretty much proves
that the boss really *was* "flat", not pointed.  It turns out that
phylogenetically the boss originated by the horn bending over and
fusing with itself, so the outer surface the boss was ancestrally
the rear (?or forward) margin of the older horn.  The original
point is buried inside the boss.

swf@elsegundoca.attgis.com              sarima@netcom.com

The peace of God be with you.