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

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 alveol...

Full description

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