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 , uncoiled shell being  to over , with body chamber around . Some partial specimens may belong to shell with length around . Studies of Diplomoceras suggest that members of this genus could reach lifespans of over 200 years. References 

Turrilitoidea
Ammonite genera
Fossil taxa described in 1900