This Specimen has been sold.
2.6" Red Iridescent Ammonite (Hoploscaphites) - South Dakota
This is a 2.6" Hoploscaphities comprimus ammonite specimen collected from the Fox Hills Formation of South Dakota. It's been wonderfully prepared free from the concretion it was found in. A portion of the concretion has been left with the specimen, allowing for removal and replacement of the ammonite.
These 70 million year old ammonites lived when South Dakota was a shallow inland sea. It was found preserved in a concretion that was split open. It then had to be hand prepared to remove the hard rock surrounding it from the shell, a very time consuming task.
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. The last lineages disappeared 65 million years ago at the end of the Cretaceous.