Mazon Creek Bivalve ID

[Nimravis]

Ok fellow Mazon Creek collectors and admirers, I am looking for confirmation on a bivalve that I have in my collection. I think is is either Edmondia ovata or Grammysiodea hayi, i am leaning towards the latter. If you think I am wrong on both choices please let me know what you think.

Thanks

[RCFossils]

I am pretty sure that your specimen is Edmondia ovata.

To my knowledge, there are only 2 known examples of Grammysiodea hayi. One is the holotype, the other is a specimen in my collection that is pictured in the Mazon Creek Fauna book by Jack Wittry.

My Grammysoidea comes more to a point at the hinge and has a more oval shape. Also the growth rings are spaced further apart.

Nice specimen!

[Nimravis]

I am pretty sure that your specimen is Edmondia ovata.

To my knowledge, there are only 2 known examples of Grammysiodea hayi. One is the holotype, the other is a specimen in my collection that is pictured in the Mazon Creek Fauna book by Jack Wittry.

My Grammysoidea comes more to a point at the hinge and has a more oval shape. Also the growth rings are spaced further apart.

Nice specimen!

Thanks much- I will go with your ID. This was collected back in "93" and I am in the process of re-mounting some specimens so I thought I would put it out for ID.

[doushantuo]

Thanks for the info,Nim,RCF.

Given the inadequate sampling of the taxon hayi ,it SHOULD be abondoned,I think.