4.3" Ammonite (Placenticeras) Fossil - Eastern Montana
This is a 4.3" fossil ammonite (Placenticeras meeki) from the Bearpaw Shale in Eastern, Montana. This comes out of an old collection of ammonite fossils we recently acquired including some from some unusual locations. Includes an acrylic display stand.
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.