Abstract #302236

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JSM 2003 Abstract #302236
Activity Number: 472
Type: Contributed
Date/Time: Thursday, August 7, 2003 : 10:30 AM to 12:20 PM
Sponsor: Biometrics Section
Abstract - #302236
Title: Statistical Modeling of Mass Extinctions
Author(s): Steve C. Wang*+
Companies: Swarthmore College
Address: Math & Statistics Dept., Swarthmore, PA, 19081-1306,
Keywords: Poisson process ; uniform distribution ; likelihood ratio test ; paleontology
Abstract:

Mass extinctions have played a major role in the history of life. The end-Cretaceous extinction 65 million years ago, for instance, killed the dinosaurs and opened the way for many new mammal species. A much-debated question is whether mass extinctions are sudden or gradual. We address this question by presenting a model for the mass extinction of a group of S species. Occurrences of the ith fossil species are modeled as a Poisson process defined over time 0 to theta_i, where theta_i represents the extinction time of the ith species. We then use a likelihood ratio statistic to test hypotheses of the form theta_i = k_i for I = 1.S. Equal k_i correspond to a simultaneous (sudden) extinction; unequal k_i correspond to a gradual extinction. We also calculate confidence intervals for max(theta_i-theta_j), the duration of the extinction event. Such information provides important evidence for inferring whether the extinction was sudden and caused by factors such as asteroid impact, or gradual and caused by factors such as climate change.

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