Ozarkian and Canadian Cephalopods: Part I: Nautilicones
E. O. Ulrich, Aug. F. Foerste, A. K. Miller, W. M. Furnish, 1942. "Ozarkian and Canadian Cephalopods: Part I: Nautilicones", Ozarkian and Canadian Cephalopods: Part I: Nautilicones, E. O. Ulrich, Aug. F. Foerste, A. K. Miller, W. M. Furnish
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Coiled nautiloids are not known to occur in the Ozarkian but are widespread in the Upper Canadian of North America. The best preserved and most diversified faunas are from the Lake Champlain region. Also, numerous specimens have been collected at several localities in western Newfoundland and the Mingan Island area. The Southern Appalachian and the Ozark regions have yielded a sequence of faunas which are locally well represented. These few areas constitute all the important occurrences, and only a very small number of questionable specimens are known outside of North America.
All the Canadian nautilicones are rather unspecialized forms with orthochoanitic siphuncles. They vary chiefly in the shape of the conch and the position of the siphuncle. Primarily on the basis of these features, they have been placed in four families: the Deltoceratidae, Plectoceratidae, Tarphyceratidae, and Trocholitidae. Altogether about 75 species are now known, and these are being referred to 17 genera.