Friday, December 11, 2009

Mississippian Period Trilobite Pygidium

Rare is a find than that of a trilobite fragment in the Mississippian Period (Lower Carboniferous - 359 to 318 million years ago) Fort Payne Formation of Lake Cumberland, Kentucky. This picture is of such a find that being a trilobite pygidium found in a gray rock shale with a lot of compressed Fenestella like bryozoan pieces.

This specimen is quite small and hard to get a detailed image of. It is about 1.5 cm wide. Looking at the article in the Journal of Paleontology, November 1966 entitled "Mississippian Trilobites from Northwestern Georgia" by Mark Rich of the University of Georgia in Athens, two trilobite genus are mentioned being in the Fort Payne Chert: Australosutra and Proetus.  I am not familiar with the Australosutra trilobite and do not see one in the Google Image database.  The Proetus trilobite has more of a bubble like hump in the middle lobe of the pygidium so it might not be that genus.  Next time I am on JSTOR I will try and look at that article and see if the images look anything like this one.