Skip to Main Content
Book Chapter

Reshuffling the cards in the photic zone at the Eocene/Oligocene boundary

By
Marie-Pierre Aubry
Marie-Pierre Aubry
Department of Geological Sciences, Rutgers University, 610 Taylor Road, Piscataway, New Jersey 08854-8066, USA
Search for other works by this author on:
David Bord
David Bord
Department of Geological Sciences, Rutgers University, 610 Taylor Road, Piscataway, New Jersey 08854-8066, USA
Search for other works by this author on:
Published:
April 01, 2009

Patterns of diversification and longevity in Paleogene coccolithophorids are analyzed by combining the temporal history of selected genera, families, and orders with the number of discrete morphospecies in them. The coccolithophorids underwent an abrupt mass extinction at the Cretaceous/Paleogene boundary, and a rapid (~1 m.y.-long) global turnover at the Paleocene/Eocene boundary. In contrast, they underwent a diachronous turnover at the Eocene/Oligocene boundary that spread over 6–7 m.y. at mid- and low-latitudes. The turnover included sequential extinctions and speciations of short-lived taxa, beginning slightly before 37 Ma, and losses of taxa that dominated mid- and low latitudes at 34.2 Ma and high latitudes at 32.3 Ma. It is also marked by a few evolutionary appearances, in particular, that of the Family Syracosphaeraceae, which is the most diversified of the living coccolithophorids. Most importantly, the turnover resulted in a shift in the balance between families across several orders, such that families that dominated during the Eocene dwindled during the turnover, and, conversely, families that were little diversified during the Eocene became dominant. Thus, members of Family Coccolithaceae and the genus Heliodiscoaster typify Eocene communities; members of the Family Calcidiscaceae and the genus Eudiscoaster characterize Neogene communities. This shift was accompanied by a decrease in the robustness of coccoliths, suggesting that the Eocene/Oligocene event had a marked effect on the physiology of Eocene coccolithophorids. Bolide impacts and the emplacement of large basaltic provinces provide mechanisms to explain large biotic events. Such mechanisms, however, can be ruled out in the case of the Eocene/Oligocene turnover, which was undoubtedly related to climatic cooling and glaciation. The filtering effect of environmental stress on late Eocene diversity remains to be explained.

You do not currently have access to this article.
Don't already have an account? Register

Figures & Tables

Contents

GSA Special Papers

The Late Eocene Earth—Hothouse, Icehouse, and Impacts

Christian Koeberl
Christian Koeberl
Search for other works by this author on:
Alessandro Montanari
Alessandro Montanari
Search for other works by this author on:
Geological Society of America
Volume
452
ISBN print:
9780813724522
Publication date:
April 01, 2009

References

Related

A comprehensive resource of eBooks for researchers in the Earth Sciences

This Feature Is Available To Subscribers Only

Sign In or Create an Account

This PDF is available to Subscribers Only

View Article Abstract & Purchase Options

For full access to this pdf, sign in to an existing account, or purchase an annual subscription.

Subscribe Now