Discoscaphites & Sphenodiscus Ammonites - South Dakota

This is a displayable association of Discoscaphites gulosus (thick bumpy one) & Sphenodiscus ammonites. specimen from the Fox Hills Formation of South Dakota. It's been wonderfully prepared from the hard concretion it was found in. The base has been cut flat so that is shows nicely on a flat surface.

These 70 million year old ammonites lived when South Dakota was a shallow inland sea. It was found preserved in a concretion that was split open. It then had to be hand prepared to remove the hard rock surrounding it from the shell, a very time consuming task.