Sunday, June 21, 2015

Protoleptostrophia and Uncinulus? from the Mahantango formation of Pennsylvania

Up today are a couple of Brachiopod specimens that I collected recently from the Mahantango formation in central Pennsylvania. The first specimen is a mold of a flat valve with many thin, narrow radial ribs covering the surface. To me this looks like a specimen of Protoleptostrophia perplana because it is similar to specimens I have from the Silica Shale, and the Windom Shale which are both contemporaneous with the Mahantango formation (Devonian, Givetian stage). This specimen came from the Frame Shale member and was found in Seven Stars, PA.

Closer views of the shell show features like possible epibionts that were attached to the exterior surface and variations in the growth of the ribs (due to life events that damaged or otherwise cased growth to change)

The second brachiopod came from the Montebello mbr. north of Harrisburg, PA. It is a rynchonellid that looks very similar to the genera Uncinulus. It is rouned in the cross section and (seemingly) narrows to a point at the posterior. The problem is that there is not enough detail preserved on the anterior for me to see what the margin looks like. If it is a strong "U" shape then I would go with Unicinulus. If the margin is not as strongly shaped then it could be a variety of Camarotoechia.

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