Southern Wyoming has nice exposures of the Green River Formation
(Eocene), deposited in vast lakes.  The snails are probably Juga,
though in popular literature they are often misidentifed as
"Turritella".  Most of the other specimens are bivalves (not
brachiopods-they have left and right valves, not top and bottom valves,
and the fact that many are molds with the shell lost suggests
aragonitic bivalves rather than calcitic/phosphatic brachiopods).
Possible non-marine bivalves would include unionoids and corbiculids,
but I don't know the full fauna of the region.

There are also lots of vertebrates (if you have a whole fossil fish,
it's probably from the Green River Formation).

----------------------------------------
Dr. David Campbell
425 Scientific Collections
University of Alabama, Box 870345
Tuscaloosa AL 35487
"James gave the huffle of a snail in
danger But no one heard him at all"  A.
A. Milne

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