This is the "Fossil Friday" post #31. Expect this to be a somewhat regular feature of the website. We will post any fossil pictures you send in to [email protected]. Please include a short description or story. Check the #FossilFriday Twitter hash tag for contributions from around the world!
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Fossil Friday #31 highlights Pennsylvanian Period ferns from St. Clair, PA. Yes, that's Pennsylvanian ferns from Pennsylvania! The Llewellyn Formation, from whence these ferns come, dates to 308 to 300 million years ago. Remember, the fossils of Mazon Creek date to about 307 million years, so these plants were contemporaries. It should not be surprising that the species found in this deposit are very similar if not the same as those found in Mazon Creek. The fern fossils of this formation were formed in a low oxygen muddy swamp bottom, which is why they are in black shale.
The Fossil Guy has good web page that describes a trip to the locality. Here is what it looks like. Unfortunately, the site has new owners and is currently closed to collecting.
And, here are some plates with Alethopteris serlii and Neuropteris fossils. Fossils from St. Clair can be very striking in silver, white, and orange on black.
