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Research-paper

Base of the Upper Devonian in the Conodont Zonation

Johnson, J. G.

Newsletters on Stratigraphy Volume 21 Number 1 (1989), p. 11 - 14

published: 8/30/1989

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Abstract

The base of the Lower asymmetrica Zone has been displaced backward in time as the early evolution of its definer, Ancyrodella rotundiloba, has been made known. Assertions that the base of the zone can remain stable, without redefinition, lack a viable basis such as location in a stratotype.