2.8" Iridescent Hoploscaphites Ammonite Fossil - South Dakota
This is a ribbed, 2.8" Hoploscaphities ammonite specimen collected from the Fox Hills Formation of South Dakota. The ammonite is in excellent condition, considering the difficulty (and time required) to remove it from the rock. The shell has a flashy iridescence that enhances the natural texture and white coloring. The rock it was found in is shaped and cut flat for easy, aesthetic display.
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. True ammonites appeared in the fossil record about 240 million years ago. The last lineages disappeared 65 million years ago at the end of the Cretaceous.
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.
Fox Hills Formation - Trail City Member - Hoploscaphites nicolletti Zone
Ammonite: 2.8" wide, Entire specimen: 3.6 x 2.6"