Cyclostomiceratidae is an extinct family of Early Ordovician, (Cassinian), ellesmerocerid cephalopods characterized by short, essentially straight shells...

the order includes the Ellesmeroceratidae, Protocycloceratidae, Cyclostomiceratidae, Bassleroceratidae, Eothinoceratidae, Bathmoceratidae, and Cyrtocerinidae...

Ordovician (Floian) Valhallfonna Formation  Norway A member of the family Cyclostomiceratidae. Deltoceras beluga Sp. nov Valid Kröger & Pohle Ordovician (Floian)...