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Holes in Frills



Rob Meyerson wrote:

> Hogwash!  If what you say is true, how does one explain the
> chasmosaurines tendancy for large fenestra in their frills?  How
> else does one explain the holes in the skull which lead from the
> lower jaw to the fenestra?  The only plausible explanation is that
> the frills are attachment sites for the jaw muscles.  Since this is
> the case, is it not reasonable to suggest that those with longer
> frills had stronger chewing power than those with shorter frills?
> The frills were most certainly related to muscle attachment.

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.

It's also important to look at the dorsal and ventral surfaces of the frill,
where the bone is sometimes smooth (indicating possible muscle attachment)
and sometimes vascularized (indicating an epidermal covering).

Personally, I'm very uncertain of the precise function and advantages of the
frills, but clearly there's more than a single viable explanation.

Just a thought...

Caitlin R. Kiernan