Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

Geological Magazine

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by RICKARDS, R. B. Search for Related Content GeoRef GeoRef Citation

The significance of the graptoloid Amphigraptus divergens from the (mid-Rawtheyan) type section of the Ashgill Series, Ordovician

Department of Earth Sciences, University of Cambridge, Downing Street, Cambridge CB2 3EQ, UK

^* e-mail: wagreen{at}esc.cam.ac.uk

Amphigraptus divergens Lapworth is known to be restricted, in Britain, to the linearis Biozone, and its occurrence in the type Ashgill Series reinforces Rickards’ prior independent attribution of that part of the type Ashgill to the linearis Biozone. The thecal structure revealed in this paper allies A. divergens to the dicellograptids rather than the leptograptids, hence it is placed in the family Dicranograptidae. The evolutionary origin of Amphigraptus is almost certainly rooted in Dicellograptus.

Key Words: Ashgill Series • Ordovician • graptolites

This article has been cited by other articles:

				T. R. A. VANDENBROUCKE, M. WILLIAMS, J. A. ZALASIEWICZ, J. R. DAVIES, and R. A. WATERS Integrated Upper Ordovician graptolite-chitinozoan biostratigraphy of the Cardigan and Whitland areas, southwest Wales Geological Magazine, March 1, 2008; 145(2): 199 - 214. [Abstract] [Full Text] [PDF]