Wednesday, February 12, 2014

Some gastropods from the Mahantango formation

I'm going through some boxes of findings from the Mahantango formation (Devonian, Givetian stage) and came across some decent gastropod fossils that I found at Liverpool, PA.

This is a Cyclonema mold in matrix with a little bit of the exterior shell cast intact. There is also a Nucula varicosa pelecypod just above and to the right of it.

Then there is this mold from the internal chamber of a gastropod. It's tightly coiled and the whorls stack internally rather than rise up like most snails fossils I've seen. It seems to be a fairly wide living chamber and the width of the whorls increases rapidly unlike the Goniatites of the era.

Here you can see the groove where the whorl pressed against the previous shell area.

Maybe this is a Straparoullus or Tropidodiscus? With the small amount of info that I can find online I'm leaning towards Tropidodiscus.

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