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Re: Deciduous horn?

Pat Grant writes;

>Is it at all plausible that the nasal horn of Triceratops might have been 
>deciduous?  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.  Even if there is some sort of differential 
>preservation involved, one wonders why it is so frequently the nasal horn 
>that disappears.  Or is there a perfectly good explanation that I've 
>somehow overlooked?

There is a very quick way to tell the difference between an animal with antlers 
and horns.  Since antlers are dropped every year, there will be no central, 
bony horncore.  For an example, take a look at the skull of a white-tail deer 
buck; there are cylidrical (sp) projections behind the eye (these don't mimic 
the shape of the antler), the flat tops of these are the base for the antlers.  
For an animal with a true horn, like a cow, the bony part of the horncore will 
mimic the shape of the horn.  For ceratopians, the latter model fits, so they 
didn't have antlers, they had true horns.

I have heard many theories about horn shape.  The different shapes could be due 
to sexual dimorphism, age, natural variation, or all of the above.

Rob Meyerson
Orphan Vertebrate Paleontologist

When the going gets wierd, the wierd turn pro.