Orthospirifer sp. brachiopod from the Silica Shale

Years ago I purchased some brachiopods that came from the middle Devonian aged Silica Shale in Ohio. These were fossils that had been collected in the 80's and 90's and came from older collections. Among the various species were these two articulated shells. The label that came with them called them Orthospirifer sp. but they look very similar to Mediospirifer audaculus which is a somewhat common brachiopod species from the middle Devonian. I've done a little research and it seems to me that the most visual difference between Orthospirifer and Mediospirifer is that the brachial valve on Orthospirifer is a little more convex and the interarea is slightly recurved. On Mediospirifer the brachial valve is nearly flat and the interarea is straight. This is just based on my collecting experience and visual inspection of fossils in my collection.

Specimen #1 - brachial valve

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Pedicle valve

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Profile

Specimen #2 - brachial valve

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Pedicle valve

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Both specimens side by side.

Ambocoelia umbonata Brachiopod from the Silica Shale

Ambocoelia umbonata is an index fossil for me indicating the rocks layers can be dated to the Middle Devonian. It's distinctive size and shape make it hard to misidentify and it can be quite prolific in certain layers. The specimen below comes from the Silica Shale (Devonian, Givetian stage) and was collected at Sylvania, OH.

Brachial valve - With the foramen (circular opening through which the pedicle muscle extended) visible on the recurved pedicle valve

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Pedicle valve

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Here is a small specimen from the Widder Formation near Arkona.

I found this cool illustration from  "Revised Taxonomy and Autecology for the Brachiopod Genus Ambocoelia in the Middle and Late Devonian Northern Appalachian Basin (USA)" by James J. Zambito IV and Mena Schemm-Gregory, Journal of Paleontology 87(2):277-288. 2013. It shows what the possible life positions were for Ambocoelia umbonata (view 1) and Ambocoelia gregaria (view 2).

Cupularostrum prolificum brachiopod from the Silica Shale

Cupularostrum prolificum is a small ryhnchonellid type brachiopod from the Silica Shale (Devonian, Givetian stage). It is similar looking to brachiopods that are referred to as Camarotoechia and it seems as though there has been some name changes/swaps. I have not yet been able to find any papers which explain the reasoning or if both genus are valid or cospecific. The specimen below was collected in Pauldin, OH.

Brachial valve

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Pedicle valve

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I have found a similar looking specimen called Cupularostrum sappho in the Ludlowville Fm. along Lake Erie, NY.

Hercostrophia robusta brachiopod from the Silica Shale

Hercostrophia robusta is a new Strophomenid brachiopod for me. It was part of a lot of fossils from the Silica Shale of Paulding, Ohio but only had the partail, single valve. It has a superficial resemblance to Strophodonta demissa but the valve of H. robusta appears to be flatter and more like Protoleptostrophia perplana. The Silica Shale is Devonian in age (Givetian stage).

Pedicle valve exterior

Pedicle valve interior

Posterior hinge

Longispina lissohybus Brachiopod from the Silca Shale

I have found one specimen that I can ID as belonging to the Genus Longispina and that specimen was found in the Mahantango formation. Below is a specimen I purchased as part of a lot from E-bay that comes from the Silica Shale in Paulding, OH. The label indicates that it is Longispina lissohybus but the shell is missing the tell tale spines that normally extend from the hinge line on the left and right sides. The radial ribs that decorate the surface are a bit muted as well so I'm not sure if this really is L. lissohybus. Interestingly, there appears to be a predatory gastropod boring on the pedicle valve.

Pedicle valve

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The Silica Shale is Devonian (Givetian stage) in age.

Devonochonetes scitulus brachiopod from the Silica Shale

I'm pleased to have an example of Devonochonetes scitulus from the Silica Shale near Sylvania, OH. This is a somewhat common brachiopod in the Givetian stage of the Devonian and I've found it in several units across the US.

Pedicle valve

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Brachial valve

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Here are some other examples of this species from the Arkona and Widder Formations at Arkona, Canada, the Mahantango Formation of Pennsylvania and a specimen from Germany that looks very similar.

Devonochonetes fragilis brachiopod from the Silica Shale

As comparison to the previous Devonochonetes coronatus, here is Devonochonetes fragilis from the Silica Shale (Devonian, Givetian stage) of Sylvania, OH. The difference between this species and D. coronatus appears to be the number and thickness of the rays that extend from the hinge line. At least this is what I can discern from just a visual perspective since they are both about the same size and shape.

Pedicle valve

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Brachial valve

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Devonochonetes coronatus Brachiopod from the Silica Shale

Devonochonetes coronatus is a species that I know well from Givetian aged deposits in Pennsylvania and New York. Below is a specimen from the Silica Shale (Devonian, Givetian stage) near Sylvania, OH. It follows the form that I have used in the past to ID similar shells: Large size, rectangular shape, 1 valve covex while the other is concave. The specimen below has partially been replaced with Pyrite (darker areas) which is why it has a mottled appearance.

Pedicle valve

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Brachial valve

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Compare this to specimens I've found in the Centerfield mbr. of the Ludlowville Formation of New York and the Mahantango Formation of Pennsylvania.

Mucrospirifer prolificus brachiopod from the Silica Shale

After M. mucronatus, the next most common species of Mucrospifier in the Silica Shale (Devonian, Givetian stage) is M. prolificus. It has a somewhat ornate shell exterior like M. mucronatus but the interarea is wider (because the beak of the pedicle valve doesn't curl quite as much). The specimen below comes from Sylvania, OH.

Compare this specimen to M. thedfordensis and M. arkonensis from Arkona, Canada, and Eleutherokomma diluvianoides from Poland

Euglyphella ostracod from the Silica Shale

There are five different species of Euglyphella ostracod found in the Silica Shale. Below is one I found in my sample from Sylvania, Ohio.

I referred to "Ostracods of the Middle Devonian Silica Formation" to see if I could figure out which one the above specimen was. It's not particularly clean and is still embedded in the matrix so that hides some of the detail. On plate 76 (pg. 355) is a comparison of all five species. After reviewing the plate I think this most closely resembles Euglyphella sigmoidalis (although there could be an arguement that it's E. projecta). I collected this from eroded residue of the Silica Shale (Devonian, Givetian stage) near Sylvania, Ohio.