Monday, May 18, 2009

Silurian Dawsonoceras Cephalopod Imprint

This was found somewhere in Louisville, Kentucky. I found the images on my computer but I did not note where it was found. It is Silurian period and probably Louisville Limestone. It is the imprint of a Dawsonoceras cephalopod shell. These are great finds when they still have parts of the shell texture. The growth lines are sinusoidal in nature and quite a work of art. One section of the fossil has some pyrite crystals.

Ordovician Worm Oenonites Scolecodont

This fossil was found on a road cut on Bardstown Road in eastern Louisville, Kentucky. Originally, I picked it up because it had an intact Hebertella brachiopod embedded in a rock. Later, after washing it off and studying the fossil in the sunlight, I spotted a black shape on the matrix side.

I found my first Scolecodont (Latin for worm jaw)! This fossil is 5 mm long and about 0.2-1.0 mm wide. The Dry Dredgers have a nice web page with diagrams and names for ones found in Cincinnati. Using their web page diagrams, this one matches the genus Oenonites (G.J. Hinde, 1879, publication: On Annelid jaws from the Cambro-Silurian, Silurian and Devonian formations in Canada and from Lower Carboniferous in Scotland).

About a 3 hour drive south of Louisville is the city of Nashville in the state of Tennessee. One can find a nice website by Jim Davison on Ordovician Conodonts with a section on Scolecodonts.
What I find nice is this site has been in existence for more than 12 years on the Internet.

In the Late Ordovician period polychaete worms (annelids of the order Eunicida) existed. A common part of these creatures that are found today is the Scolecodont or hard jaw. The fossil is composed of jet black material typically. Here are some pictures of it taken from different angles.

Find out more at this detailed website on Scolecodonts.