Actinocamax cobbani n. sp. from the Coniacian of Montana and Wyoming and the occurrence of Late Cretaceous belemnites in North America and Greenland

• Published in: Journal of Paleontology
• Main Author: Christensen, Walter Kegel
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 1993
• Subjects: Paleontology; Greenland; Bayle
• Online Access: http://dx.doi.org/10.1017/s0022336000036891; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022336000036891

Actinocamax cobbani , a new belemnitellid species from the middle Coniacian of Montana and Wyoming, is described, including univariate and bivariate biometric analyses. The species is stout and medium sized, lanceolate or strongly lanceolate in ventral view, and has adorally a low cone-shaped alveolar fracture. It may be granulated. It is compared to species of Actinocamax Miller and Gonioteuthis Bayle from the North American and North European paleobiogeographic provinces. The importance of various morphological characters, such as the shape of the guard and the structure of the adoral end, are discussed. The majority of the belemnitellids of the North American Province are endemic and the stratigraphic distribution is punctuated during the Late Cretaceous, suggesting short-lived migrations of populations from the North European Province.