Re: Ceratopian jaws

[Jonathon Woolf <jwoolf@erinet.com>]

Robert J Meyerson (Rob Meyerson) wrote:
 
> I don't see the problem in this.  I envision the jaw muscle being similar
> to the strap on my backpack: Long but thin, with the long muscle fibers
> oriented with the long axis of the muscle.  

I am probably suffering from acute lack of information (it happens
with depressing frequency when dinosaurs are the topic <g>), but I
don't understand why anyone would think that the ceratopsid frill
served to anchor jaw muscles at all.  I recently read Peter Dodson's
book THE HORNED DINOSAURS, in which he makes a convincing (to me, at
least) case that the frill's primary function was display, possibly
with a secondary protective function.  Put together, these two reasons
seem to more than adequately explain the frill.  I don't see any need
for the "jaw muscles" idea, and I don't see any good reason to accept
it.  I do see a lot of questions that it raises, though.  For example:

     * No other type of dinosaur had enormous jaw muscles, not even
       the ceratopsids' own ancestors.

     * Different ceratopsid genera had different frill sizes and
       shapes, and also different sizes, shapes, and placements of the
       frill openings.  Why such a variety of forms to answer a single
       common requirement (jaw muscle anchorage)?

Can anyone help straighten me out on this matter?  What evidence is
there that the frill had anything to do with jaw-muscle anchorage?

Jon W.