Symmetric waxing and waning of marine invertebrate genera From: Paleobiology | Date: October 1, 2007| Author: Foote, Michael | Copyright Paleontological Society Fall 2007. Provided by ProQuest LLC.Copyright information

Abstract.-

Occurrence data from the Paleobiology Database are used to analyze the waxing and waning of genera over time. Irrespective of whether we tabulate species richness, frequency of occurrence, geographic range, or other measures, the average rise and fall of genera is remarkably symmetrical. Genera tend already to be in a state of decline when they become extinct. Genera that last appear in the major mass extinction stages, however, are more frequently truncated while they are h...

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