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