2.8" Hoploscaphities Comprimus Ammonite - SD

This is a Hoploscaphities comprimus ammonite from the Fox Hills Formation of South Dakota. It's been wonderfully prepared from the hard concretion it was found in, and stands up on it's own. There is a second smaller ammonite specimen in the matrix right behind it.

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.