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End-Cretaceous marine mass extinction not caused by productivity collapse

  1. Kyger C Lohmanne
  1. aDepartamento de Ciencias de la Tierra, Universidad Zaragoza, 50009 Zaragoza, Spain;
  2. bInstituto Universitario de Investigación en Ciencias Ambientales de Aragón, Universidad Zaragoza, 50009 Zaragoza, Spain;
  3. cDepartment of Geology and Geophysics, Yale University, New Haven, CT 06520-8109;
  4. dDepartment of Earth and Environmental Sciences, Wesleyan University, Middletown, CT 06459; and
  5. eDepartment of Geological Sciences, University of Michigan, Ann Arbor, MI 48109-1063

  1. Edited by* Karl K. Turekian, Yale University, North Haven, CT, and approved November 22, 2011 (received for review June 30, 2011)

Abstract

An asteroid impact at the end of the Cretaceous caused mass extinction, but extinction mechanisms are not well-understood. The collapse of sea surface to sea floor carbon isotope gradients has been interpreted as reflecting a global collapse of primary productivity (Strangelove Ocean) or export productivity (Living Ocean), which caused mass extinction higher in the marine food chain. Phytoplankton-dependent benthic foraminifera on the deep-sea floor, however, did not suffer significant extinction, suggesting that export productivity persisted at a level sufficient to support their populations. We compare benthic foraminiferal records with benthic and bulk stable carbon isotope records from the Pacific, Southeast Atlantic, and Southern Oceans. We conclude that end-Cretaceous decrease in export productivity was moderate, regional, and insufficient to explain marine mass extinction. A transient episode of surface ocean acidification may have been the main cause of extinction of calcifying plankton and ammonites, and recovery of productivity may have been as fast in the oceans as on land.

Footnotes

  • ↵1To whom correspondence should be addressed. E-mail: laia{at}unizar.es.

  • Author contributions: L.A. and E.T. designed research; L.A., E.T., and K.C.L. performed research; L.A. and E.T. analyzed data; and L.A. and E.T. wrote the paper.

  • The authors declare no conflict of interest.

  • *This Direct Submission article had a prearranged editor.

  • This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1110601109/-/DCSupplemental.

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