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At 12:56 AM 11/16/98 -0700, Jim Kirkland wrote:

>Baryonx was associated with Lepidotes (a big fish) scales. My research
>on the freshwater fish in the Cretaceous of western North America
>incates that Lepidotes was very common in Cenomanian river systems well
>inland. The response I got was that Lepidotes was known from marine
>rocks so it is a marine fish. My data suggests that perhaps some large
>species were like Salmon and went up rivers to reproduce. THUS,
>seasonally perhaps Lepidotes was present in very large numbers and was
>thus a food resource not to be ignored.
>       Also of interest is that this group goes extinct at the end of the
>Cenomanian, when Spinosaurids disappear. Even in the Late Cenomanian
>these fish are very abundant, but there is not a sign in the Turonian.
>This is a big extinction level for fresh water fish in North America
>(see Eaton et al. GSA Bull. 109(5):560-567, 1997).

Very interesting...

Incidentally, since I was betting on the discovery of pre-Tithonian
maniraptoriforms of various lineages last week, let me add another to the bet:

I'm willing to bet that _Baryonyx_ or related spinosaurid will show up in
the Lakota Fm. or Yellow Cat Member of the Cedar Mountain Fm. or similar
aged unit from western North America.  Some of the same herbivorous
dinosaurs are there as in the Wessex & Vectis Fms. (upper Wealden), some of
the same fish, so I wouldn't be surprised if some of the same carnivores
were as well.

Thomas R. Holtz, Jr.
Vertebrate Paleontologist     Webpage: http://www.geol.umd.edu
Dept. of Geology              Email:tholtz@geol.umd.edu
University of Maryland        Phone:301-405-4084
College Park, MD  20742       Fax:  301-314-9661