The Ophidioceratidae is a family of closely coiled tarphycerids, represented solely by the Upper Silurian genus, Ophioceras, characterized by an evolute shell with narrow, subrounded, annulated whorls and a subcentral siphuncle composed of thin connecting rings that show no evidence of layering. The mature body chamber is strongly divergent and is the longest proportionally of any tarphycerid

Tarphycerida

The Tarphycerida were the first of the coiled cephalopods. They are found in marine sediments from the Lower Ordovician to the Middle Devonian. Some like Aphetoceras and Estonioceras are loosely coiled, gyroconic, others like Campbelloceras, Tarphyceras, and Trocholites are tightly coiled, but...

. The aperture has a deep hyponomic sinus and occular sinuses, and so resembles some lituitids

Lituitida

The Lituitida are the Lituitidae of the Treatise , reranked as an order and combined with other orthoceratoids.. They are considered to be more closely related to the Orthocerida than to the Ascocerida or Pseudorthocerida which are also included.Lituitids are characterized by smooth to annulate...

.

The Ophidioceratidae seems to have its origin in the Trocholitidae

Trocholitidae

The Trocholitidae are Tarphycerida with whorls in close contact as with the Tarphyceratidae, but in which the siphuncle, similar in structure, becomes dorsal. The Trocholitidae are derived from the Tarphyceratidae, perhaps from different tarphyceratids....

, possibly in Graftonoceras.

References

• Furnish, W. M, and Glenister, Brian F. 1964. Nautiloidea - Tarphycerida, Treatise on Invertebrate Paleontology, Part K, Geo Soc. of America. Teichert and Moore (eds.)