Diplomoceras

Diplomoceras is a genus of ammonites included in the family Diplomoceratidae. Fossils of species within this genus have been found in the Late Cretaceous sediments (age range: Campanian-Maastrichtian). D. maximum had coiled shell length about 1.5 m, uncoiled shell being 3 m to over 4 m, with body chamber around 2 m.  Some partial specimens may belong to shell with length around 1.7 m. Studies of Diplomoceras suggest that members of this genus could reach lifespans of over 200 years.