Intriguing Hoploscaphites Ammonite Cluster - South Dakota

This is a cluster of Hoploscaphities nicolletii ammonites collected from the Fox Hills Formation of South Dakota. It's been wonderfully prepared in the hard concretion it was found in. Along with the ammonite, there are lots of other micro fossils in this cluster such as clams, gastropods, and other small ammonites. There are about a dozen beautiful ammonites in this cluster.

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.