Centroceratidae
| Centroceratidae Temporal range: M Devonian - L Permian |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Mollusca |
| Class: | Cephalopoda |
| Subclass: | Nautiloidea |
| Order: | Nautilida |
| Superfamily: | Trigonocerataceae |
| Family: |
Centroceratidae Hyatt in Zittel, 1900 |
| Genera | |
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The Centroceratidae is the ancestral family of the Trigonocerataceae and of the equivalent Centroceratina; extinct shelled cephalopods belonging to the order Nautilida
The Centroceratidae, which range from the Middle Devonian to the Lower Permian, are characterized by gyroconic, evolute tarphyceraconic, and involute nautiliconic shells with compressed whorls, typically with a quadrangular whorl section in which the flanks converge on venter that is much narrower than the dorsum and ventral and umbilical shoulders are sharply angular, or rarely rounded. In some, e.g. Centroceras, the flanks are divided by a ridge that runs along the middle. Sutures have ventral and lateral lobes but are transverse dorsally. The siphuncle is tubular and close to but not on in contact with the venter (Kummel 1964).
The Centroceratidae are thought probably to be derived from the stock (Flower 1950, 1988, Kummel 1964) Earliest are Centroceras, Homaloceras, and Strophiceras .from the Middle Devonian; Centroceras and Homaloceras from North America, Strophiceras from Europe. Next is Carlloceras from the Upper Devonian of North America, followed by Diorugoceras from the Lower Carboniferous of Europe. Last is Phacoceras, found in the Lower Carboniferous of Europe and Lower Permian of Australia. (Kummel 1964)
Homaloceras is the most primitive, with a laterally compressed, cyrtoconic to gyronic shell with a narrow, concave venter, broadly convex flanks, and rounded dorsum, The suture is only slightly sinuous, the siphuncle tubular and near the venter.
Centroceras, the type genus, is evolute with only a few, rapidly expanding whorls and wide, perforate umbilicus. The cross section may be faintly hexagonal from the effect of a median ridge on either flank, otherwise is tetragonal. Flanks converge from a broad dorsum to a narrow, barely convex venter. Ventral and umblical shoulders are sharp. The suture is with a shallow ventral lobe and broad lateral lobes with subacute saddles on the shoulders; the siphuncle is tubular, near the venter; the living chamber half a volution in length. The surface is covered with alternating striae and lirae; fine, parallel "scratches" and "wires"
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