5.3" Placenticeras Ammonite - Free Of Matrix

This is 5 inch wide Placenticeras meeki ammonite from the Pierre Shale of South Dakota. The beautiful suture pattern of this ammonite can easily be seen on the surface. There are several areas of restoration on this ammonite to fill in gaps.

It's Late Cretaceous in age (Upper Campanian Stage) or approximately 75 million years old. Back at this time South Dakota was covered by a shallow inland sea. These ammonites are found in hard concretions, or balls of rock which form around the fossil. These concretions are split open to reveal the ammonites which then must be expertly prepared from the surrounding rock, a very time consuming task requiring a lot of skill.