bivalve or brachiopod from Couvin (Be)

[2Ronalds]

I found this little shell at the site just north of Couvin.

I do not think it is a brachiopod because I do not see a peduncular opening (but that area is damaged), and both shells seem to be equally long axially. It has very prominent growth rings (appr. 0.8mm apart). There is no sign of ornamentation radiating out from the joint. Its dimensions are 10.5 x 13 x 6mm. Both shells are convex from the joint to the middle or beyond, flat to concave near the rim (less so near the axis), giving the rim one and a half wave. the material is much darker (slate grey) than the many different brachiopods I found at Couvin.

Does anyone know if this is a bivalve or a brachiopod, and which subgroup/genus/species?

[Editted by 2Ronalds on 11-09-2011 at 16:50 GMT +1]

[Editted by 2Ronalds on 11-09-2011 at 16:50 GMT +1]

[Editted by 2Ronalds on 19-09-2011 at 22:52 GMT +1]

[Frederik]

The symmetry gives away that this is a brachiopod. Often, the peduncular opening is very small, so you should not use it exclusively to discriminate between bivalves and brachiopods.

This kind of symmetry is rarely seen with bivalves.

[Juergen]

It's a devonian brachiopod of Genus Athyris or close to Athyris.
Regards, Juergen