Barrandeoceras

Barrandeoceras is a large, coiled, Middle Ordovician nautiloid cephalopod and part of the Tarphycerida. The shell is serpenticonic with whorls touching but not embrancing. The adult body chamber becomes freed of the preceding whorl, a rather common character among tarphyceroids. Whorl section is oval, somewhat more narrowly rounded ventrally, on the outer rim, than dorsally, on the inner rim. Prominent lateral ribs, at least on inner whorls. Grow lines show a distinct hyponomic sinus. Sutures have lateral lobes. The siphuncle is subcentral.

Barrandeoceras has been found in the Middle Ordovician of New York, Ontario, and Quebec. It is the type genus for the Barrandeoceratidae.

References

• Rousseau H Flower and Bernhard Kümmel Jr 1950. A Classification of the Nautiloidea. Journal of Paleontology Vol 24, no 5 pp 604–616, Sept 1950
• Walter C Sweet, 1964 Nautiloidea-Barrandeocerida; Treatise on Invertebrate Paleontology Part K Mollusca 3. Geological Society of America and University of Kansas Press