Help on identifying species, age, and region of this pelecypod found in Michigan, US?

[Zippy.Shrimp.Feet]

I recently found a large stone hosting many of these pelecypods.

I assume this is a limestone, as it has a slight reaction to acid, and there didn't seem to be any other super identifiable fossils, aside from some possible crinoid remnants.

 

Its hinge is located far off to the side. These were found from rock placed along the Saginaw River in a small park in Michigan, so I can't say they were naturally from this area, but are local to Michigan.

 

The ones I found range in size from about 25mm to 57mm. I would appreciate it greatly if anyone has any insight on the possible species, geological age, and where they might have originated from in the state?

 

Thanks in advance for any help that can be provided.

 

 

[Fredmo]

Looks like it's probably some kind of Allorisma.

 

http://michiganbasinfossils.org/viewrecord/363

[cngodles]

I would call this Wilkingia. I'm not sure about which species.

 

https://fossil.15656.com/catalog/search-for/Wilkingia

 

I'm not sure how valid the name Allorisma is today: https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=63202&is_real_user=1

Edited May 3 by cngodles

[Fredmo]

1 hour ago, cngodles said:

I would call this Wilkingia. I'm not sure about which species.

 

https://fossil.15656.com/catalog/search-for/Wilkingia

 

I'm not sure how valid the name Allorisma is today: https://paleobiodb.org/classic/checkTaxonInfo?taxon_no=63202&is_real_user=1

Thanks for that. I've seen both names used on similar fossils, but didn't know that Wilkingia had actually replaced Allorisma.

[cngodles]

If I had to name two other commonly misused names today, they would be:

 

Pteronites. The book Pennsylvanian Marine Bivalvia and Rostroconchia of Ohio uses this name for late Pennsylvanian pinnids. Some late Pennsylvanian pinnids will soon get a new name.
Mooreoceras: This was long used for large straight-shelled nautiloids, but Kroger and Mapes (2005) did an extensive investigation and determined they are just the bigger Pseudorthoceras Girty, 1911

 

To add one more, the gastropod Strobeus is often called Ianthinopsis, Macrochilina, Sphaerodoma, and more. But it's not surprising; one species has been called seven different names over the past 185 years. There was even a funny goof in an 1884 White publication where they reversed the genus and subgenus names on the plate! Soleniscus (Macrocheilus) vs  Macrocheilus (Soleniscus). The former is correct.