1.4" Iridescent, Fossil Ammonite (Scaphites) - South Dakota

Iridescent, Fossil Ammonite (Scaphites) - South Dakota #129523

This is a 1.4" ammonite (Scaphites) from the Fox Hills Formation of South Dakota. The iridescence of the outer shell creates a colorful display. This specimen has been well prepared and remains attached to the rock in which it was found.

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.

What an ammonite would have looked like while alive.

More about ammonites