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Bride of Holes in Frills



After my last post, I began thinking that perhaps I should clarify a couple
of point, lest anyone get the idea that I'm saying that I think there's
absolutely no connection whatsoever between ceratopsian frills and muscle
attachment. So, to that end, the following:

1. The argument I presented was an alternative and/or accessory explanation
for the existence of parietal fenestrae in most chasmosaurines and
centrosaurines, and not necessarily a refutation of the position that the
large frills afforded no advantages in anchoring musculature. It was intended
to counter claims, such as Paul (1987), that an explanation focusing of
muscle attachment was the *only* "good explanation." Determining which
function was the most selectively advantageous and/or primary, in this case
either display or counterbalance or increased surface area for muscle
attachment, would be difficult, to say the least.

2. There are at least two related, but distinct, arguments here: 1) the
evolution of the ceratopsian frill and 2) the evolution of the parietal
fenestrae located on the ceratopsian frill. I suspect each question might
involve a different answer (i.e., initial evolution of the frill as a display
mechanism, followed by the development of the parietal fenestrae as a means
of lightening the skull, for example).

3. While I personally doubt the connection between the parietal fenestrae and
increased chewing strength, I don't doubt the role that the supratemporal
fenestrae played as a somewhat expanded point for attachment of the jaw
adductor muscle (see Dodson and Currie 1990, for example). 

4. It should be remembered that an increase in the length of a muscle *does
not* increase its strength (see Hill 1950).

Hopefully, that should clarify where I'm coming from with this problem. Also,
as should be obvious, my ideas regarding the ceratopsians have been
influenced more by the work of others than my own (I work primarily with
mosasaurs), though I did spend some quality time with a cast of a
-Triceratops- during my time at the University of Colorado.

References:

Dodson, P. and Currie, P.J. Neoceratopsia. in Weishampel, D.B., Dodson, P.,
and Osmolska, H. 1990. The Dinosauria.  Univ. of CA Press (pp. 593-618).

Hill, A.V. 1950. The dimensions of animals and their muscular dynamics. Sci.
Progress 38 (pp. 209-230).

Paul, G.S. 1987. The Science and Art of Restoring the Life Appearance of
Dinosaurs and Their Relatives: A Rigorous How-to Guide. in Dinosaurus Past
and Present, Vol. II, Univ. of WA Press (pp. 4-49).