Cyclostomiceratidae

Cylostomiceratidae Temporal range: Early Ordovician
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Subclass:	Nautiloidea
Order:	Ellesmerocerida
Family:	Cylostomiceratidae Foerse, 1925
Genera
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Cylostomiceratidae is a family of Early Ordovician, (Cassinian), ellesmerocerid cephalopods characterized by short, essentially straight shells, a fairly rapidly expanding phragmocone and a ventral siphuncle in which septal necks are almost non-existent and connecting rings are thick and layered. As typical of the Ellesmerocerida, chambers are short, septa close spaced.

Five genera are recognized; Cyclostomiceras, Eocyclostomiceras, Microstomiceras, Paracyclostomiceras, and Pictetoceras. Cyclostomiceras and Paracyclostomiceras were described in Flower (1964).

Microstomiceras and Pictetoceras come from the Middle Ordovician Hälludden cliff section, Oland Island, Sweden, associated with such as Paldoceras.

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