Morphological Disparity of Ammonoids and the Mark of Permian Mass Extinctions

doi:10.1126/science.1102127

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Morphological Disparity of Ammonoids and the Mark of Permian Mass Extinctions

Loïc Villier¹^,2^* and Dieter Korn²

The taxonomic diversity of ammonoids, in terms of the numberof taxa preserved, provides an incomplete picture of the extinctionpattern during the Permian because of a strongly biased fossilrecord. The analysis of morphological disparity (the varietyof shell shapes) is a powerful complementary tool for testinghypotheses about the selectivity of extinction and permits therecognition of three distinct patterns. First, a trend of decreasingdisparity, ranging for about 30 million years, led to a minimumdisparity immediately before the Permian-Triassic boundary.Second, the strongly selective Capitanian crisis fits a modelof background extinction driven by standard environmental changes.Third, the end-Permian mass extinction operated as a random,nonselective sorting of morphologies, which is consistent witha catastrophic cause.

¹ Centre de Sédimentologie–Paléontologie, FRE CNRS 2761, Université de Provence, 3 place Victor-Hugo, F-13331 Marseille Cedex 3, France.
² Museum für Naturkunde, Humboldt-Universität zu Berlin, Invalidenstraße 43, D-10115 Berlin, Germany.

^* To whom correspondence should be addressed. E-mail: lvillier{at}up.univ-mrs.fr

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