The Frasnian-Famennian mass extinction record in the eastern United States

Abstract

The stratigraphic record of the Frasnian-Famennian mass extinction in the eastern United States indicates that a reversal in the magnitude of extinction and speciation rates was the driving mechanism forcing the decline in species diversity in this region. Extinction rates increased sharply during the deposition of the West Falls Group in New York State, and remained high for the remainder of the Frasnian, a period of approximately 4.5 Myr. Sharp reductions in species diversity, however, only occurred during deposition of the Java Group at the very end of the Frasnian. The period of diversity loss was much more abrupt and short term than the period elevated extinction rates, and was more a function of a drop in speciation rate than a direct function of an increase in extinction rate.