Ordovican Fossil Rock

Click on this picture to make it larger. This rock is from Carroll County, Kentucky and is full of Ordovician fossils. It has a lot of Cryptolithus trilobite cephalon plates. Some thin crinoid stems and a clam. The back of the rock not shown has more Cryptolithus pieces, gastropod shells and clams along with crinoid pieces.

This two red arrows point to fossils I am not sure about. The one on the left is some type of trilobite remain. I think it if you were looking down on an Isotelus it would be the right side of the cephalon plate.

The other arrow leads to fossil of the same color but it is in the shape of long narrow isosceles triangle. Could be a cephalopod but no texture on the shell.


UPDATE: I visited the Cincinnati GeoFair 2009 and the Dry Dredgers had two members doing fossil identification. One was Bill Heimbrock who also maintains their website. They looked at this fossil rock with a loupe and decided it is a crushed cephalopod shell. The lateral growth lines have worn off. I was shown on another section of the rock the hinge teeth of a cycloconcha (clam). On further study, the opening to the cephalopod shell has some bryozoan coating. I found on other cephalopod shells at this location, that ones with shell detail and aragonite (or calcite) preservation were coated in a bryozoan layer. It seemed to act as sealer keeping air and water away from the shell surface. Another detail I missed earlier (make image larger by clicking on it), there appears to be a crinoid holdfast that looks like a spider web shape. It might be possible to bring out the detail with sandblasting.

This rock is full of diversity and lots of interesting fossils. I will post it again with the whole rock shown and then detailed zoom shots showing individual fossils.