Placenticeras planum Hyatt 1903

Cretaceous

Eagle Sandstone

Billings, Montana, USA.

73mm ammonite on 153mm concretion.

Ammonite. Cephalopod.

Placenticeras is a genus of ammonite that lived during the Late Cretaceous – right up to the end.  It has been found at numerous localities in the North America as well as Europe, India, Iran, and Papua New Guinea.