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Re: Deciduous horn?



Pat wrote:
 << I realize it would be very weird indeed to have deciduous and 
 non-deciduous on the same head, but haven't encountered any satisfactory 
 explanation of why the nasal horn varies so drastically, from the 
 rounded- basal- knob style, through the cute- little- rosebud- stuck- on- 
 the- knob, to the huge mean vicious full-blown pointy horn as in the 
 famous YPM 1922 T. prorsus. >>

I believe that most of those _Triceratops_ specimens that fall within the _T.
horridus_ cloud have the shorter, knobier nasal horn that is farther caudal
on the rostrum, as well as having more erect orbital horns, and a longer
frill.  Those that fall within the _T. prorsus_ cloud tend to have more
forward pointing orbital horns, a shorter frill and a longer nasal horn that
is more farther rostral compaired to _T. horridus_.  Then of course, there is
just individual variation within the genus, hey look at the variable nose
shapes in humans (incidentally a boy asked me a question quite similar to
this while on a field trip to the MOR).

Whether or not _Triceratops prorsus_ is a distinct species from _Triceratops
horridus_ is another question.  I tend to lead towards the seperate species
interpretation, but it could be sexual differences too.

Peter Buchholz
Tetanurae@aol.com

Mike hardly hesitated, "Kissing . . . is a goodness," he explained, "it beats
the hell out of card games."