Cretaceous Fossil Ammonite Cluster - South Dakota
There are crack repairs through the Hoploscaphities nicolletii and both the Hoploscaphites spedeni and Discoscaphites gulosus ammonites were removed from the rock, prepped and then remounted to the original portion of the rock they were found in.
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.