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Re: Eating a Nautilus (attn: Gothgrrl)

I visited Tyrrell Museum a week or so ago and while there, I spoke with Dr. Paul Johnston. He is studying ammonite shells with holes in them that were supposedly made by mosasaur teeth. He suggests that some of the holes may not have been made by mosasaur bites. The evidence is very interesting. Some of that evidence comes from an experiment they did using a mechanical device that simulates the bite of a mosasaur. They used it on modern nautilus shells and compared the resulting damage to fossil specimens. The holes made by the device created different patterns of damage than is seen in the fossils. He suspects that other reasons, such as limpets, could have been responsible for making some of the holes.
Shane Leuck
The Gateway Country Fossil Page

Daniel Varner wrote:

At 10:38 PM 11/15/97 +0000, you wrote:
>Just slightly off topic for a change.
>Did Mosasaurs and Pliosaurs eat nautiloids whole?  Did they crack them
>open with their jaws?  Did stomach muscles crush the shells?  Does the
>fossil record help with these questions?

Dear Larry, I can't answer your question as far as Pliosaurs are concerned.
I am not aware of any ammonite shells with bite marks that can be attribited
to those plesiosaurs. Remember that the shells are made of calcium carbonate
and are easily dissolved by the stomach acids.
 The mosasaurs are another matter, however. Their bites are conspicuous on
numerous specimens of ammonites, indicating that the animal was removed from
the shell. Prognathodon is a prime suspect when it comes to this behavior. A
new specimen is nearing completion in the prep stages at the South Dakota
School of Mines and Technology. The skull is massive with very robust teeth.
The European species, Prognathodon solvayi, has very protrusive teeth in the
premax that seem to be perfectly formed as an escargot fork.
 Globidens, of course, is the mosasaurian bivalve-eater (we think). Another
SDSMT specimen may have stomach contents,so stay tuned. Interestingly,
Prognathodon and Globidens are very closely related. See Gorden Bell's
article in Nicholl's and Callaway's _Ancient Marine Reptile_ volume.