Didymoceras

Didymoceras
Didymoceras
Temporal range: 83.5–70.6 Ma
Upper Campanian
D. stevensoni, D. nebrascensis, and D. cheyennese
Scientific classification
Kingdom: Animalia
Phylum: Mollusca
Class: Cephalopoda
Subclass: Ammonoidea
Suborder: Ancyloceratina
Wiedmann, 1966
Superfamily: Turrilitaceae
Family: ?Didymoceratidae
Genus: Didymoceras
Hyatt, 1894
Species

D. platycostatum
D. stevensoni
D. nebrascense
D. saxonicum
D. cheyennese

Synonyms

Helicoceras
Emperoceras
Didymoceratoides

Didymoceras ("Paired Horns") is an extinct genus of ammonite cephalopod. It is one of the most bizarrely shaped genera, with a shell that spirals upwards into a loose, hooked tip. It is thought to have drifted in the water vertically, moving up and down.

D. stevensoni fossil

Its taxonomic place is often in flux, being placed in either Turrilitidae, Nostoceratidae, or its own family, "Didymoceratidae."