ESTIMATING THE DURATION OF A MASS EXTINCTION ACCOUNTING FOR SIGNOR-LIPPS EFFECT
Wang et al (2012) described a method for answering the question “How gradual could the extinction have been?” by developing a confidence interval for the duration of a mass extinction. For example, the method can be used to estimate with 90% confidence that an extinction took place over a duration of 0.3 to 1.1 million years, or 24 to 57 meters of stratigraphic thickness. However, their method assumed uniform preservation and recovery, which is unrealistic. Here we describe a new method for estimating the duration of an extinction event that does not assume uniform recovery. We also implement a binary search algorithm to speed up the computation time by an order of magnitude. The method incorporates the Adaptive Beta Method of Wang et al (2016) to allow for increasing or decreasing fossil recovery potential. We illustrate its use with data from Late Cretaceous ammonites from Seymour Island, Antarctica.