Possible bivalve that looks like a tooth?

[Pleuromya]

Hi,

I found this ironstone fossil inside a rock that I split earlier. It was full of some very nice fossils. I was wondering what this could be? It looks like a tooth, as it has many small upward facing points on one edge, but I imagine it is something else as there isn't enamel. Found in Northamptonshire, UK. I believe it is from the early Jurassic. It measures 1.8cm lengthways. Sorry the photos are quite zoomed out, the quality of the picture gets worse the closer I go.

 

Many thanks.

[Thomas.Dodson]

Not one tooth but multiple teeth, if you count hinge teeth.

 

You're correct in it being a bivalve. The general shape and comb like hinge teeth are consistent with Nuculanids from what I can see but I'd like to see more closeups. If you can narrow down the formation or group it might help too.

[Pleuromya]

7 minutes ago, Thomas.Dodson said:

Not one tooth but multiple teeth, if you count hinge teeth.

 

You're correct in it being a bivalve. The general shape and comb like hinge teeth are consistent with Nuculanids from what I can see but I'd like to see more closeups. If you can narrow down the formation or group it might help too.

Thanks.  I think it may be from the Dyrham formation, or possibly the Whitby Mudstone formation.