Thursday, May 28, 2009

Unknown Trilobite Cephalons and Pygidiums

I have a cousin who works with a jackhammer in his job sometimes. As a result he comes across a number of interesting items in the rock layers of Louisville. Luckily, his brother took some pictures of his finds and gave me the images. These trilobite cephalons and pygidiums were found in either the Louisville limestone or Jeffersonville limestone layer in Louisville, Kentucky.

Usually, I associate the brown/tan/reddish chert like rock with the Devonian period and the grey-white like rock with the Silurian period.

This first image the pygidium shows signs of being a forked posterior. A Devonian trilobite that had a forked posterior was the Coronura. The cephalon looks pointed so maybe this is a Silurian Trimerus.

Here is a closer view of the cephalon shown in the last picture. Again it might be a Trimerus.

This rock looks to be Devonian and this pygidium looks worn. The apparent point at the end of the pygidium could be a Trimerus or Dalmanites?

Pointed cephalon makes me think Trimerus.

These next three pictures are of the same fossil. It appears the cephalon is 5-7 cm wide. I wonder if this could be Trypaulites in the Jeffersonville limestone?