ABSTRACT
Plicathyridines, a group of short lived, dynamically evolving, Old World and northern Eurasian athyrids of the Middle and Late Devonian, vanished in stepwise fashion during the Frasnian-Famennian mass extinction. Plicathyridine genera, as a rule, have short stratigraphic ranges, with regional differences in their occurrence, radiation and extinction. Two major innovations occurred, one in the Emsian-Eifelian (serotinus-partitus conodont zones) of the Rheno-Ardennian province, and the other in the Early to Late Frasnian (transitans-linguiformis conodont zones) of the Altai-Sayan province in the Kuznetsk Basin. Their disappearance coincides with the base of the Famennian lower triangularis Zone and is correlated westward with the Upper Kellwasser event.
