Doug Shelton writes, "I am especially focused on mollusks of Alabama
(marine=550+species, freshwater=ca. 500 species, terrestrial=150 species,
fossil=?species - Andy help here, how many fossil species are known from
our state)."
 
Doug, I've never counted the species of fossil mollusks from Alabama, but I
have a standing request from Deborah Wills for species lists to compile,
and I've been photocopying and setting aside species lists for her. So
eventually we will find out.
 
The middle Eocene Gosport Sand alone has about 400 named species, more or
less; some are known from unique specimens. The other shell beds are not as
diverse, but there are at least 8 additional Paleocene to Oligocene beds
that each have 50 or more species. Plus I've counted more than 200
molluscan species in the Cretaceous. Without even counting the Paleozoic,
that's a thousand fossil species, and I strongly suspect that this is a
gross undercount. It seems likely (just at a wild guess) that 300-500
species were living at any one time in the area now called Alabama, but
they have not all been preserved or discovered.
 
Diversity of mollusks increases steeply toward the tropics, and, despite
protestations by Yankees to the contrary, Alabama is not tropical. The
Pliocene-Pleistocene beds of Florida have well above 1000 species! And the
diversity of Miocene mollusks in the Caribbean is phenomenal. So the
question goes now to Gary or Kurt: What area has, or ever had, the greatest
diversity of mollusks?
 
Andrew K. Rindsberg
Geological Survey of Alabama
Tuscaloosa, Alabama, USA