Re: GLOBIDENTINES

[Gothgrrl@aol.com]

In a message dated 12/3/1999 9:51:07 PM Central Standard Time, 
stephen_priestley@sunshine.net writes:

> Mosasaurs leaving puncture marks in ammonoid shells are discussed by Peter
>   Ward in "Time Machines" (1998).  Simulated mosasaur bites on shells
>   (nautiloids, if memory serves) always resulted in shattering not tooth
>   holes - not that the mosasaur cares how it gets at the tasty bits.  The
>   conclusion was that the holes were made by marine borers after the death
>  of
>   the ammonoid.

I can't find the primary literature on the mosasaur bite marks/ammonite 
experiment at the moment, but I know that the results of those experiments 
are controversial and inconclusive. Regardless, the best reasons to suspect 
that globidentines weren't munching pelecypods comes not from Kaufman's 
bitten ammonoids, but rather from the general morphology of globidentine 
skulls, the availability of pelagic non-pelecypod, food sources (such as 
ammonites and turtles) that could have lead to such a specialized dentition, 
and comparisons between globidentines and other animals (such as walruses and 
placodonts) that are or were eaters of clams, mussels, oysters, etc. 

I think the bitten ammonites still stand as evidence that some mosasaurs were 
eating ammonites (though those ammonites were not bitten by a _Globidens_, 
but something with a more orthodox mosasauroid dentition), but should future 
studies conclude that the bite marks are, in fact, post-mortem borings, 
little if any damage is done to the model that posits a diet of shelled 
cephalopods and turtles for globidentines. What is really needed to know 
exactly what _Globidens_ ate are stomach contents (as we have for such 
mosasaurs as _Tylosaurus_ and _Platecarpus_), which, to my knowledge, are 
still unknown.

Caitlin R. Kiernan

P.S. -- An interesting point: isolated alligatorid teeth from the Campanian 
are often mistaken for _Globidens_, teeth that can, upon closer inspection, 
be referred to _Deinosuchus_ or _Bottosaurus_, animals that probably ate a 
lot of turtles and few, if any, bivalves.