2.9" Cut & Polished Fossil Nautilus (Eutrephoceras) - South Dakota

This is a beautiful fossil nautilus (Eutrephoceras nebrascensis) from the Pierre Shale of South Dakota. It was prepared completely free from the hard concretion it was found in. The nautilus is cut in half and polished, revealing the inner chamber structure of this ancient marine animal.

A display stand is included for each half of the specimen.

A nautilus's shell is made up of two layers. The inner layer has the iridescent shine, while the outer layer provides protection from external forces. Inside the shell are septa that divide the living area of the shell into compartments and help the animal maintain balance and position in the water column.

Nautilus are "living fossils": species similar to this one still exist in our oceans!

These 70 million year old ammonites lived when South Dakota was a shallow inland sea. They were found preserved in concretions when split open. They then had to be hand-prepared to remove the hard rock surrounding them from their shells, a very time consuming task.
Eutrephoceras nebrascensis
Meade County, South Dakota
Pierre Shale
Nautilus: 2.9" wide
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