Hello fossil experts!
I have a background in geosciences but know very little about fossils. I found the below fossils along the Rouge River near Detroit (Michigan). Doing some quick research, I think these are from the Mucrospirifer order, probably of the Thedfordensis species. Do you agree? (longest is about 1.5 inch / 4 cm)
The thing I'm most puzzled about is from what strata they are from. The interweb tells me these Mucrospirifer here are mostly from the Middle Devonian (Antrim shale, Traverse Group), while the location where I found these (as well as all of the upstream terrain) has younger bedrock, from the early Carboniferous/Mississippian (Coldwater Shale). This Coldwater Shale is a pretty thick deposit so a river/glacier can not puncture it easily. I used the Bedrock Geology map from www.esrs.wmich.edu/mgs/webmgs/migis.html
Thank you very much for your insight!
Jazz