Cyrtocerinidae

Cyrtocerinidae; Temporal range: Ordovician
Scientific classification
Kingdom:	Animalia
Phylum:	Mollusca
Class:	Cephalopoda
Subclass:	Nautiloidea
Order:	†Cyrtocerinida
Family:	†Cyrtocerinidae; Flower, 1946
Genera
	Centrocyrtocerina; Cyrtocerina; Rummoceras?;

Cyrtocerinidae is a family of nautiloid cephalopods in the Order Cyrtocerinida, previously considered ellesmerocerids. Members of the family have slightly endogastric (inwardly curved) breviconic shells with ventral siphuncles that have connecting rings thickened as lobes that project straight into the interior.

Cyrtocerinidae was established by Flower 1964 for the genus Cyrtocerina Billings 1865, found at various locations across North America. The shells are generally small, laterally compressed, and dorsum more narrowly rounded than the venter.

References

↑ Mutvei, Harry (2015-07-03). "Characterization of two new superorders Nautilosiphonata and Calciosiphonata and a new order Cyrtocerinida of the subclass Nautiloidea; siphuncular structure in the Ordovician nautiloid Bathmoceras (Cephalopoda)". GFF. 137 (3): 164–174. doi:10.1080/11035897.2015.1061592. ISSN 1103-5897. S2CID 41162554.
1 2 3 4 Flower, Rousseau H. (1964). "The nautiloid order Ellesmeroceratida (Cephalopoda)" (PDF). New Mexico Bureau of Mines and Mineral Resources Memoir. 12: 1–164.

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[:0-1] Mutvei, Harry (2015-07-03). "Characterization of two new superorders Nautilosiphonata and Calciosiphonata and a new order Cyrtocerinida of the subclass Nautiloidea; siphuncular structure in the Ordovician nautiloid Bathmoceras (Cephalopoda)". GFF. 137 (3): 164–174. doi:10.1080/11035897.2015.1061592. ISSN 1103-5897. S2CID 41162554.

[:1-2] 1 2 3 4 Flower, Rousseau H. (1964). "The nautiloid order Ellesmeroceratida (Cephalopoda)" (PDF). New Mexico Bureau of Mines and Mineral Resources Memoir. 12: 1–164.