First occurrence of Helicotoma Salter (Gastropoda) from the Ordovician of Alaska

• Published in: Journal of Paleontology
• Main Authors: Rohr, David M., Blodgett, Robert B.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1988
• Subjects: Paleontology; Arctic; Alaska
• Online Access: http://dx.doi.org/10.1017/s0022336000029966; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022336000029966

Middle and lower Ordovician gastropods have not previously been described from Alaska, and the genus Helicotoma Salter has not been reported from western and arctic North America with the exception of one locality in California (Rohr, 1980). Like many other Paleozoic gastropod genera, Helicotoma has several species assigned to it, but the species are often based on poor material and, in some cases, on a single specimen. This lack of knowledge of variation within the species as well as the detailed features of the shell make further interpretations of the gastropods difficult. The occurrence of relatively abundant, well-preserved Helicotoma specimens in Alaska is important for biogeographic and biostratigraphic studies of lower Paleozoic mollusks.