This is the "Fossil Friday" post #205. 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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Asterophyllites equisetiformis is a part of the Calamites plant (to learn more see Mazon Monday #103). An extinct species of horsetail that lived during the Pennsylvanian Period. A. equisetiformis is the terminal end of the Calamites foliage.
Our Fossil Friday specimen was found in the fossil deposits near Terre Haute, Indiana, which date to about 305.5 million years ago. That's a little younger than the Mazon Creek fossil deposit at 307-308 million years ago. The concretions is the Terre Haute area come from the Dugger Formation, which sits atop the Springfield coal member. The Dugger Formation is the uppermost formation in the Carbondale Group. The Springfield coal member has been correlated with the Danville coal in Illinois and is now referred to by the same name. We did a post about the fossils of Terre Haute in Mazon Monday #36. The spoil piles to the south of Terre Haute in Fowler Park come from the Chieftain #20 mine, which closed in 1969. The plant and animal fossils found in this locality are very similar to what is found in the Mazon Creek area.
This particular specimen is special because it's bifurcated, which is a pretty rare condition.
