Cycloconcha Clam Fossil

This little clam (2.2 cm long by 1.2 cm wide) is found in the Marble Hill Bed, Rowland Member, Drakes Formation of Bedford, Trimble County, Kentucky, USA.  The outer shell does not have much detail but the inner part has nice hinge teeth.  Thanks to Bill Heimbrock of Dry Dredgers for the identification of Cycloconcha milleri?.  Read the paper Review of Ordovician Pelecypods by John J. Pojeta, Jr.  Document is in the DJVU format so you will need a reader program like the Windows version of WinDjView on CNET download.com: CLICK HERE.

This pelecypod fossil is from the Ordovician Period Katian (Richmondian) Stage. This dates to about 450-445 million years ago.

UPDATE (2020): The Review of Ordovician Pelecypods is now available on PDF format at the site linked above. I added a possible species name for the specimen as well.

The author of the paper has since passed away Dr. John Pojeta Jr. (1935 - 2017). He retired from the U.S. Geological Survey in 1994. See link for memorial:
https://www.aaps.net/John-Pojeta-Jr-Memorial.htm

Ordovician Snail: Paupospira bowdeni

Reading from the book A Sea without Fish, I discovered this snail is now known by a new name and also its location is pretty famous and unique. This gastropod (snail) was called Loxoplocus bowdeni but is now known as Paupospira bowdeni (page 125). It was found in Trimble County, Kentucky, USA in the Marble Hill Bed (Rowland Member of the Drakes Formation which is equivalent to the top of the Waynesville Formation). This information was documented by W.C. Swadley in 1979 in a paper entitled "The Marble Hill Bed: An Offshore Bar-Tidal Channel Complex in the Upper Ordovician Drakes Formation of Kentucky" in United States Geological Survey Professional Paper 1126-D. I cannot find the paper on JSTOR, it is listed as a reference to several papers I found.

The location described in the A Sea without Fish book, says the rock lenses with snails species: Paupospira bowdeni, Paupospira tropidophora (Meek), and Paupospira moorei (Ulrich) (page 127). I know what the first one looks like but the other two are somewhat of a mystery. They have a picture of Paupospira moorei on page 122 but it is covered by the tabulate coral Protaraea richmondensis.

The Marble Hill Bed seems to have been named by D.D. Owen in 1859 in a report entitled, "Report of a geological reconnaissance of the state of Indiana made in the year 1837 part 1" page 63. A document (Lithofacies of the Cincinnati Series) found here describes this location as a Gastropod Coquina. It also says that bryozoan and Hebertella brachiopod fragments could be found. I did find a nice brachiopod on the trip but I found a number of cephalopod fragments with the snails. This specimen was about 4 cm long but the papers say they get to be 5 cm in length at this location.