This ammonite from Elk Creek, South Dakota showcases the texture and shape of fossils from the Pierre Shale Formation beautifully. Specimens from the nodusus species are frequently found with damaged nodes (bumps on the shell), with this example in a better condition than most. The shell measures 3.6" across.
Fossils found in the Pierre Shale Formation (83-69 million years ago) are part of the Western Interior Seaway which stretched across the Great Plains and much of the Rocky Mountain region, connecting the Arctic Ocean to the Gulf of Mexico. This stretch of the Cretaceous Period between 113-66 million years ago is responsible for many aquatic fossils found in North America.
Locality: Elk Creek, Pierre Shale Formation, South Dakota, USA
Species: Hoploscaphites nodosus
