Two Species Of Hoploscaphites Ammonites Back To Back - South Dakota

This is a beautiful display piece from the Fox Hills Formation of South Dakota. It features two, associated Hoploscaphities ammonites of different species in the same concretion. There is a 2.1" Hoploscaphities nebrascensis back to back with a 1.95" wide Hoploscaphites comprimus. Both fossils have been nicely prepared from the hard concretion and the base of the rock has been cut flat so it stands up nicely without the need for a display stand

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.

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.
What an ammonite would have looked like while alive.
Hoploscaphities comprimus & Hoploscaphites nebrascensis
South Dakota
Fox Hills Formation
Ammonites 2.1 & 1.95"
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