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Science 28 August 2009:
Vol. 325. no. 5944, pp. 1118 - 1121
DOI: 10.1126/science.1174638
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Reports

Good Genes and Good Luck: Ammonoid Diversity and the End-Permian Mass Extinction

Arnaud Brayard,1,* Gilles Escarguel,2,* Hugo Bucher,3,4 Claude Monnet,3 Thomas Brühwiler,3 Nicolas Goudemand,3 Thomas Galfetti,3 Jean Guex5

The end-Permian mass extinction removed more than 80% of marine genera. Ammonoid cephalopods were among the organisms most affected by this crisis. The analysis of a global diversity data set of ammonoid genera covering about 106 million years centered on the Permian-Triassic boundary (PTB) shows that Triassic ammonoids actually reached levels of diversity higher than in the Permian less than 2 million years after the PTB. The data favor a hierarchical rather than logistic model of diversification coupled with a niche incumbency hypothesis. This explosive and nondelayed diversification contrasts with the slow and delayed character of the Triassic biotic recovery as currently illustrated for other, mainly benthic groups such as bivalves and gastropods.

1 UMR-CNRS 5561 Biogéosciences, Université de Bourgogne, 6 Boulevard Gabriel, F-21000, Dijon, France.
2 UMR-CNRS 5125 PEPS, Université Lyon 1, Campus de la Doua, Bât. Géode, 2 Rue Dubois, F-69622 Villeurbanne Cedex, France.
3 Paläontologisches Institut und Museum, Universität Zürich, Karl-Schmid Strasse 4, CH-8006 Zürich, Switzerland.
4 Department of Earth Sciences, ETH Zürich, Switzerland.
5 Department of Geology and Paleontology, University of Lausanne, l’Anthropole, Lausanne, Switzerland.

* To whom correspondence should be addressed. E-mail: arnaud.brayard{at}u-bourgogne.fr (A.B.); gilles.escarguel{at}univ-lyon1.fr (G.E.)

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THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Flourishing After the End-Permian Mass Extinction.
C. R. Marshall and D. K. Jacobs (2009)
Science 325, 1079-1080
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