Post-Paleozoic concretion fossils in Ohio?

[pefty]

Came across this specimen on an Ohio Fossils group. It was apparently found in south-central Ohio (Serpent Mound area) in 1958. What’s bothering me is that it seems to be a marine pelecypod with aragonitic preservation. All of Ohio’s exposed rocks are either Paleozoic or Pleistocene, and with vanishingly few exceptions, Paleozoic aragonite is simply not preserved. I know there are mollusks in pleistocene marine concretions, notably from Newfoundland, but not in the sediments representing Pleistocene Ohio’s terrestrial&freshwater environments. This is a marine clam, and there was no marine environment in pleistocene Ohio. Nor were there marine environments producing concretionary fossils in any nearby source area for glacial debris that ended up in Ohio, as far as I am aware. Nor in any of the Ohio River’s past source areas to the south during the Pleistocene. 
 

So....is this concretion then an object moved long distances by ancient humans? Does anyone recognize the concretion as similar to ones they’ve seen in some particular Formation? Or am I way off in terms of my preservational logic?
 

Original post:

“I collected this 60+ years ago from a tributary stream to the Miami River in SW Ohio - what is it and how old?  Opinions please!”

[GemCityHippie]

I would posit that it's likely far older than the Pleistocene. Pelecypod specimens dating as far back as the Ordovician have been found in neighboring Indiana. Ohio during the Ordovician, Silurian, and Devonian was in fact a tropical sea. The area in SW Ohio that's spoken of, the Miami River; I know is well within the bounds of the Silurian era Brassfield Formation. It stands to reason that this would likely be a pelecypod concretion from that era and most likely that formation as well.

 

As for exact identification of the specimen you would need to consult with someone more experienced than I. However I hope that does give you some idea as to a likely age or timeframe.

Edited September 14, 2020 by GemCityHippie

[Fossildude19]

Glacial erratic?

[GemCityHippie]

42 minutes ago, Fossildude19 said:

Glacial erratic?

I suppose it might be possible but being a native of the area where this was supposedly found I can tell you that I've never seen an erratic that small. We actually have a fairly decent number of glacial remnants etc. (one city near me is literally named Moraine). Pretty much all the glacial erratics you see around here are large or very large boulders of rock; much larger than the few inches of scale that the picture suggests the specimen is.

[erose]

My guess would be this was brought in by those early native peoples. They traded from areas far and wide. I seem to remember an abalone shell that came out of a SW Ohio mound site.  

 

PS you can find small "erratics" in the glacial gravels of the area.  I have a Petoskey Stone from the gravels that were adjacent to some glacial striations in Silurian limestone near Huber Heights.  

 

[doushantuo]