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RE: Sneak Peak at Yale Torosaurus Sculpture

> -----Original Message-----
> From: owner-dinosaur@usc.edu [mailto:owner-dinosaur@usc.edu] On Behalf Of
> Dino Guy Ralph
> Sent: Tuesday, September 27, 2005 12:30 PM
> To: andyfarke@hotmail.com; dinosaur@usc.edu
> Subject: Re: Sneak Peak at Yale Torosaurus Sculpture
> You want cheeks?  Check out the cheeky hornbill hatchlings at
> http://avesinternational.com/softbillnurs.html      .
> Lots more cheeky than Parsons' _Leptoceratops_ illustration at
> http://www.ohiou.edu/news/pix/LEPTOCERATOPS_2.JPG      .

Not sure I see the cheeks on the hornbill hatchlings. . .a little fleshy bit
at the back, I guess. . .

And some aspects of the Leptoceratops illustration are a little odd to me.
But that's for another time. . .

> Furthermore, ceratopsians had immense, powerful jaw muscles and teeth
> adapted for chopping up tough plant material in the manner of oversize
> shears.  I would think that these shearing tooth batteries (even more than
> grinding tooth batteries) would require accessory cheeks, as otherwise
> much
> of the processed food material would be shorn off by the jaws along the
> occlusal cutting edges of the teeth, and without retaining cheeks, the cut
> off material would drop to the ground.  Would you use a Vegimatic without
> a
> cover?  ;^)

Many of those animals without cheeks have incredibly powerful jaw muscles.
For instance, a turtle skull is essentially a (tiny) brain with a beak and a
big bony scaffolding for jaw muscles. Likewise, extremely big jaw muscles
show up in the ceratopsian lineage well before the development of the tooth

> Moreover (as Dr. Tom has noted) the teeth are laterally recessed within
> the
> skull, as in cheeked herbivorous mammals, and most unlike extant
> herbivorous
> reptiles, which aren't adapted for oral processing to the extent we see in
> ceratopsians.

This recess isn't that prominent at the front of the jaw. Undoubtedly, not
all of the teeth were exposed; e.g., the posterior-most maxillary teeth
would have been covered in life by the coronoid process of the jaw. Would
this indicate something about the feeding mode?

> Cheekless ceratopsians?  I wouldn't be so sure about that.

I'm not certain either way--I'm fairly agnostic on the issue at present,
perhaps leaning a little in the "cheekless" direction. Mainly, it's just fun
to play devil's advocate. ;-) Paleontology never gets anywhere unless we
question these old "truths"! (in a scientifically testable way of course. .