Schizophoria ferronensis from the Silica Shale

Schizophoria is a genus of brachiopods that I have not personally collected much. I don't often find it in my preferred Middle Devonian outcrops and am aware of it mostly from the Upper Midwest portion of America.  This specimen comes from Milan, MI and is a Schizophoria ferronensis out of the Silica Shale (Devonian, Givetian stage). The large shells of Schizophoria can be identified by their oval outline, fine raidal ribs decorating the surface, wide but shallow sulcus and a shallow triangular dethyrium on the posterior of the pedicle valve.

Here are some other species: Schizophoria schnuri from Poland, Schizophoria iowaensis from Iowa.

Cyrtina hamiltonensis from the Silica Shale of Michigan

The triangular shape shell of Cyrtina is very easy to spot. It is a prolific member of many Devonian communities and is one of the more common fossils found. The specimen below is Cyrtina hamiltonensis and was found in the Silica Shale (Devonian, Givetian stage) at Milan, MI.

Brachial valve

Anterior

 Pedicle valve

Posterior

Profile

Some other examples of Cyrtina that I've blogged about are Cyrtina umbonata from Michigan, Cyrtina sp. from Iowa, Cyrtina arkonensis from Ontario, other Cyrtina species from Ontario.

Allow me a moment to explain my thought process behind this blog. The photo of the pedicle valve shown above was taken with far end of the pedicle valve in focus and so the tip closest to the camera is out of focus. Still, it gives you a view similar to those you find in older reference books with hand drawn illustrations of fossils. Imagine how frustrating it would be to try and ID your fossil when they only give you a view of the pedicle valve and brachial valve similar to my above pictures. This is part of the reason why I include anterior, posterior and profile views in my posts.

Cranaena romingeri brachiopod from the Silica Shale

The small Terebratulid brachiopod Cranaena romingeri is one of the few smooth shelled brachiopods that can be found in the Silica Shale (Devonian, Givetian stage).  It is distinctive despite it's rather mundane, unornamented appearance. The shell is oval shaped with two convex valves. The pedicle valve is a little longer than the brachial valve and is marked with an obvious circular depression (called the foramen) where the pedicle muscle would have extended outward. This specimen was collected from a quarry in Milan, MI.

Brachial valve

Anterior

Pedicle valve

Posterior

Profile

Mediospirifer audaculus brachiopod from the Silica Shale

A few months ago I posted about some Mediospirifer audaculus that I'd finally found fully articulated in the Moscow Formation of New York. Now I have a specimen of the same species from the Silica Shale of Milan, Michigan.The specimen below has a pedicle valve that is a little less deep than some of the specimens I have from New York but otherwise it looks very similar.

Brachial valve

Anterior (with some shelly debris obscuring the sulcus)

Pedicle valve

Posterior

Profile

The Silica Shale is Devonian in age and part of the Givetian stage.

Mucrospirifer mucronatus brachiopod from the Silica Shale

Here is an example of the somewhat ubiquitous Mucrospirifer mucronatus from the Silica Shale (Devonian, Givetian) at Milan, MI. Mucrospirifer is a prolific member of many mid-Devonian units and are something of a index fossil.

Brachial valve

Anterior

Pedicle valve

Posterior

Profile

M. mucronatus is noted for the somewhat ornate exterior shell surface and obvious growth lines.

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