Hoploscaphites Ammonite Cluster - South Dakota

This is a displayable cluster of iridescent Hoploscaphities nicolletii and Discoscaphites gulosus ammonites from the Fox Hills Formation of South Dakota. It's been wonderfully prepared from the hard concretion it was found in. The cluster has many other small fossils like fossil clams.

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.