-- John Jacobs <[log in to unmask]> wrote:
Evidence shows that molluscs may have existed for at least 500 million
years.  Unfortunately, the further back in time, the less likely fossils
will be found.  Precambrian fossils are extremely rare.  As to their
precursors, no definitive answer yet.

John
John & Cheryl Jacobs
Seffner, Florida
[log in to unmask]
----- Original Message -----
From: <[log in to unmask]>

> Here in Southern Ohio, our basic layers are Ordivician. They are full of
Brachiopods, Horn Corals, etc. But no mollusks. At least, I don't think so.
>   The question is: when did mollusks arise---and (2) from what?
>      Q-Man
>
Art-
Yes there are molluscs (gastropods, 'monoplacophorans',  bivalves and smaller groups) in the Cincinatian limestones, but because they had aragonitic shells, the preservation is very poor compared to the calcitic brachiopods, corals, echinoderms and bryozoa.  Often all that will be seen is a worn internal mold.  If you slice and polish enough limestone, you will start to see the snail shells.  Very hard to identify from sectioned material, however.
Allen Aigen
[log in to unmask]