Manitoulinoceras

Manitoulinoceras is a genus of Late Ordovician oncocerid nautiloid cephalopods, found in North America (Kentucky, Ohio, Indiana, and Ontario). The shell is cyrtoconic, exogastric, more strongly curved than in Kindleoceras. The cross section is somewhat wider than high, with a somewhat flattened upper side, known as the dorsum. Actinosiphonate deposits in the siphuncle are confined to early part of phragmocone.

Staufferoceras, a valcuouroceratid from the Middle and Upper Ordovician of Minnesota and Ohio named by Foeste, 1932, is much like Manitoulinoceras but with a living chamber that is swollen in the middle, narrowing toward the aperture.

References

• Walter C Sweet, 1964 Nautiloidea-Oncocerida. Treatise on Invertebrate Paleontology Part K Mollusca 3. Geological Society of America and University of Kansas Press.