Cycloconcha milleri pelecypod from the Marble Hill Bed

I've only found one Pelecypod in the "Marble Hill Bed" and it called Cycloconcha milleri.  I knew in a previous post that the genus was Cycloconcha but could not find anything to nail down the species. I finally came across a research report, by PM Novack-Gottshall and A. Miller, that listed Cycloconcha milleri as being found in the "Marble Hill Bed".

Part of the reason I could not settle on a species name is the lack of good photos of the species.  The Atlas of Ordovician Life only had this nondescript picture, and the UGA Stratigraphy Lab did not have much more. These are two of the online resources I use to help ID fossils from the Cincinnati region but I can't blame them for the lack of information. Pelecypods don't always preserve well and are not easily studied as the more common and well preserved Brachiopods in the Ordovician.  Also the "Marble Hill Bed" is a very limited geologic feature and not as paleontologically or economically important as other formations.

Onto the fossils!

Specimen #1 - right valve exterior

 Right valve interior, note the hinge teeth

Specimen #2  - Left valve exterior

 Left valve interior

 Left valve profile looking at the anterior end towards the posterior

The "Marble Hill Bed" is part of the Rowland Member of the Drakes formation (equivalent the Whitewater formation in Ohio and Indiana). It is upper Ordovician in age, Katian stage (450-445 mya) and located near Carrollton, KY. I collected these fossils in July of 2016.