14" Baculite & Ammonite Specimen - South Dakota

This is a very aesthetic fossil association from the 75 million year old Pierre Shale of South Dakota. Preserved in the same rock are two large Baculites, one of which is 14 inches long, an ammonite of the species Hoploscaphites brevis and a partial nautiloid of the species Eutrephoceras nebrascensis. The matrix it stands on is approximately 7 inches wide and 4 inches deep.

The shells of both the baculites and ammonites shines with an opalescence that has hues of pinks and greens when the light hits it at the right angle. A truly spectacular natural association.

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.