Fossil Ammonite (Hoploscaphites) Cluster - South Dakota

This is an ammonite (Hoploscaphities) cluster from the Fox Hills Formation of South Dakota. It's been wonderfully prepared in the hard concretion it was found in. It contains three central ammonites, the top being 1.7". The total height of this cluster is 3.3" In addition to the three central ammonites, there are a number of tiny ones and fragments still partially concealed in the stone. The ammonites are iridescent and stand out nicely against the dark stone.

Ammonites were predatory mollusks that resembled a squid with a shell. These cephalopods had eyes, tentacles, and spiral shells. They are more closely related to a living octopus, though the shells resemble that of a nautilus. Ammonites appeared in the fossil record about 240 million years ago and they barely survived several major extinction events. The last lineages disappeared 65 million years ago at the end of the Cretaceous.

Hoploscaphities nodosus
South Dakota
Fox Hills Formation
1.7" top ammonite, 3.3" tall
We guarantee the authenticity of all of our
specimens. Read more about our
Authenticity Guarantee.