Pterinea brisa from the Osgood shale

While going through some boxes of findings from the Osgood shale I came across this Pelecypod on a large chunk of matrix. After a bit of trimming I got the piece down to a more manageable size. I think it's a Pterinea brisa based on similar specimens that Mike Popp posted on his blog at Louisville Fossils here and here.

The specimen came from the New Point Stone Co. quarry near Napoleon, IN. The Osgood shale is Silurian aged (Telychian to Sheinwoodian stage).

Phragmoceras cephalopod from the Osgood Shale

Phragmoceras is a rare fossil that I found in the Osgood shale. It's a nautiloid (cephalopod ) that has a slightly curved shell. The fossil I found is only a partial but the shell decoration is still evident.

This specimen was found near Napoleon, IN and is from rocks deposited during the Silurian (Telychian to Sheinwoodian stage).

My friend Nathan found a larger and more complete specimen of Phragmoceras in his local Racine formation of Wisconsin.

Holocystites from the Waldron shale

Among the fauna found within the Waldron Osgood shale is a Cystoid called Holocystites. Specimens of this odd echinoderm were the most common fossil I found when I had the opportunity to collect the Waldron Osgood shale a few months ago. It could have been the layer or the particular area that was exposed but I was finding them very easily.

They are about the size of a Quail egg or small Chicken egg and that is the general shape that one looks for. Cleaned off you can see a pebble textured surface that is broken into small plates.

Here are several next to each other to show you variety of shape and size.

This is a chunk of the Waldron Osgood shale with a partial Holocystites embedded in it. I say partial because the plate is thin and the fossil does not go all the way through.

This occurrence was not uncommon and some of the loose specimens even displayed this same feature. My theory is that during storm events some Holocystites were buried quickly but some did not get completely covered. Those specimens were exposed partially above the surface and subject to scavenging/erosion. So in essence we are looking at the underside of the bedding plane in the above picture. Since the piece was not found in situ I am only speculating.

The Waldron Osgood shale is Silurian (Telychian to Sheinwoodian stage) in age and is roughly equivalent to the Rochester shale in New York.

*updated 4/24/14*

Unicinulus stricklandi from the Osgood Shale

Another new brachiopod for me from the Waldron Osgood Shale is Unicinulus stricklandi. This specimen was found near Napoleon, IN and is from rocks deposited during the Silurian (Telychian to Sheinwoodian stage).

Pedicle valve

Anterior

Brachial valve

Posterior

Profile

This brachiopod is easy to ID based on the triangular outline of the valves and the general rounded nature of the shell. Some other species within the genera almost look like spheres.

Thanks to Mike over at Louisville Fossils for the helpful Waldron Shale brachiopod guide which is also useful for Osgood shale ID's.

Eospirifer eudora from the Osgood Shale

In my last post I displayed a Eospirifer eudora from Lockport, NY. Today I have two specimens that I found in the Waldron Osgood Shale near Napoleon, IN.

Specimen 1
Pedicle valve

Anterior

Brachial Valve

Posterior

Profile

Specimen 2
Pedicle valve

Anterior

Brachial valve

Posterior

Profile

Both specimens are larger than the one from Lockport, NY. The Waldron Osgood Shale is Silurian in age (Telychian to Sheinwoodian stage) and found in an area from Indiana down to Alabama. It is correlated to the Rochester Shale of New York and slightly younger than the Irondequoit limestone where the Lockport, NY specimen came from.

Thanks to Mike over at Louisville Fossils for the helpful Waldron Shale brachiopod guide. This guide is also useful to ID specimens from the Osgood Shale as they share some species.

Coolinia subplana from the Osgood Shale

While examining some pieces of the Waldron Osgood Shale that I brought back from Indiana I found a couple of specimens of Fardenia Coolinia subplana. It is within the class Strophomenata (straight hinge line) and order Orthotetida.

I identified these based on this link to the Indiana State Museum's online collection.
I've since had to change my ID on this specimen as I realised that I collected it from the Osgood Shale and not the Waldron Shale. As such, Coolinia is the more likely genus. I based this on the paper "Caradocian-Gedinnian echinoderm associations of Central and Eastern North America" Frest, Brett and Witzke published in the compendium "Paleocommunities - a case study from the Silurian and Lower Devonian", book 2, page 729. The Osgood shale is Silurian in age (Telychian to Sheinwoodian stage).