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Re: Holes in Frills



Caitlin Kiernan wrote:
 
> Certainly,  a plausible alternate explanation for the tendancy toward large
> parietal fenestrae in ceratopsian frills (in both centrosaurines and
> chasmosaurines) is that they would have served to reduce the considerable
> weight of the frill. Such fenestrae may have allowed ceratopsians to continue
> to evolve large, elaborate frills and enjoy whatever benefits (display, etc.)
> they bestowed. It may be interesting to note that in -Triceratops-, where
> these fenestrae are absent (a condition derived secondarily from the
> chasmosaurine condition), the rim of the frill is slightly recurved
> anteriorly, which, along with the enormous brow and nasal horns, would have
> functioned to counterbalance the weight of the frill.
 
Possibly, but if that's the case, it makes one wonder why Triceratops
closed up it's fenestrae when it's frill was proportionally as big (if
not bigger) than most Centrosaurines.  I happen to think GSP's
assertations in Dinosaurs Past and Present II (and possibly elsewhere)
that the jaw muscles of ceratopians probably extended to nearly the
end of the frill and that the peculiar "tounges" of bone in
Centrosaurus' (or Monoclonius' or Eucentrosaurus' or whatever the hell
they call it now) frill, and the lumpy protrusions on Anchiceratops'
frill were actually muscle processes to help anchor huge jaw muscles.
Perhaps the re-solidification of Triceratops' frill was for this too;
letting the muscle attatch to a greater area of bone (ie the bone that
filled up the fenestrae).

Although I don't doubt that they were used for other purposes like  display 
and possibly defense, I think that their primary function was for making them 
bite hard.

As for the horns counter-balancing the frill...  Wouldn't something along the 
lines of Pachyrhinosaurus' nose be more economical if that's what the horns 
were for rather than an aray of wildly different horns?  Again, I believe 
that the primary function of the horns was for either display or defense 
(intra-or inter-specific), and the possible counter-balancing effects were a 
nice extra.

Peter Buchholz
gpb6845@msu.oscs.montana.edu

Twenty metres tall!