8.2" Hoploscaphites Ammonite Association- Pierre Shale, Montana

Hoploscaphites Ammonite Association- Pierre Shale, Montana #209669

This is an association of multiple bumpy, Hoploscaphities ammonites collected from the Pierre Shale of Montana. There are six mostly complete Hoploscaphites ammonites in addition to some partials and a bevy of other marine fossils, including bivalves and gastropods. The association was prepared with a portion of the original rock left intact.

An acrylic stand is included for display options.

Ammonites were predatory cephalopod mollusks that resembled squids with spiral shells. They are more closely related to living octopuses, though their shells resemble that of nautilus species. True ammonites appeared in the fossil record about 240 million years ago during the Triassic Period. The last lineages disappeared 65 million years ago at the end of the Cretaceous.

What an ammonite would have looked like while alive.

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.

More about ammonites