Nautiloid, Eutrephoceras elegans

Nautiloid, Eutrephoceras elegans, Pierre Shale Formation, South Dakota. This rare and beautiful 73 million year old Nautiloid specimen is a must for any serious ammonite collector. This 3.5 inch Nautiloid is mounted on its original concretion fossil ball base, with internal septa showing and a calcite lining. Collected within the past decade and part of the Artist’s personal collection. Comes with label and color brochure.

The Order Nautiloidea is distinguished by a curved to coiled external aragonitic shell containing a phragmocone and a body chamber. The phragmocone is segmented into many chambers by nearly straight septa and sutures. The Nautiloids had a thicker shell than that of their relatives, the ammonites, which may have enabled them to withstand crushing at deep oceanic depths and pressures. Cretaceous Age Nautiloids appear to have inhabited water of 100 meters or less during most of their lifespan laying ten to fifty eggs per year.

This extinct Cephalopod swam the warm oceans during the Cretaceous Period 75 million years ago and had coiled shells with chambers that filled with gas and provided both buoyancy and propulsion in the water. Although Nautiloids are found all over the world, limited supplies of colorful iridescent quality Nautilus are only found in protective, shell preserving septarian concretions and fossil balls, in the Pierre Shale Formation and marine equivalents of the Western Interior Seaway of Montana, and South Dakota. These amazing Cephalopod specimens from Elk Creek, South Dakota are found in, and carefully collected from, large fossil ball concretions in the ancient Pierre Shale Seaway. All specimens Fluoresce brightly under UV Light.