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Greenhouse−icehouse transition in the Late Ordovician marks a step change in extinction regime in the marine plankton

Authors :
Michael Foote
Peter M. Sadler
Roger A. Cooper
James S. Crampton
Source :
Proceedings of the National Academy of Sciences of the United States of America, vol 113, iss 6
Publication Year :
2016
Publisher :
Proceedings of the National Academy of Sciences, 2016.

Abstract

Two distinct regimes of extinction dynamic are present in the major marine zooplankton group, the graptolites, during the Ordovician and Silurian periods (486−418 Ma). In conditions of “background” extinction, which dominated in the Ordovician, taxonomic evolutionary rates were relatively low and the probability of extinction was highest among newly evolved species (“background extinction mode”). A sharp change in extinction regime in the Late Ordovician marked the onset of repeated severe spikes in the extinction rate curve; evolutionary turnover increased greatly in the Silurian, and the extinction mode changed to include extinction that was independent of species age (“high-extinction mode”). This change coincides with a change in global climate, from greenhouse to icehouse conditions. During the most extreme episode of extinction, the Late Ordovician Mass Extinction, old species were selectively removed (“mass extinction mode”). Our analysis indicates that selective regimes in the Paleozoic ocean plankton switched rapidly (generally in

Details

ISSN :
10916490 and 00278424
Volume :
113
Database :
OpenAIRE
Journal :
Proceedings of the National Academy of Sciences
Accession number :
edsair.doi.dedup.....166dab78a12ba729f332f0e81c6fa912