Megastrophia concava from the Silica Shale

One of the largest Brachiopods found within the Silica Shale is Megastrophia concava. Superficially it looks like an overgrown Strophodonta, but the size is the key. No other Strophomenids grow this large within the Silica Shale and the thin radiating ribs on the surface are spaced farther apart than on any Strophodonta.



This is an partial brachial valve that shows the two kidney bean shaped muscle attachement scars.



This is a very easy shell to ID as Megastrophia concava based on the 1975 book by Robert V. Kesling & Ruth B. Chilman: Strata and Megafossils of the Middle Devonian Silica Formation: Museum of Paleontology, Papers on Paleontology, No. 8, pg. 96, pl. 26.