Geological Society of America

76 Paleontology, Diversity, Extinction, Origination (Posters)

Sunday, 25 September 2016
9:00 AM - 5:30 PM
Exhibit Hall E/F

ACCOUNTING FOR THE SIGNOR-LIPPS EFFECT IN ESTIMATING THE DURATION AND NUMBER OF PULSES IN THE CAMBRIAN EXPLOSION

Paper number: 76-41
Program: Technical Sessions
Time: 9:00 AM – 5:30 PM

Authors

Tuan Nguyen Presenting Author
Swarthmore College, Swarthmore, PA
Linda Gai
Johns Hopkins University, Baltimore, MD
Chengying Wang
Swarthmore College, Swarthmore, PA
Katrina M. Midgley
Swarthmore College, Swarthmore, PA
Jason Z. Lin
Swarthmore College, Swarthmore, PA
Steve Wang
Swarthmore College, Swarthmore, PA
Susannah Porter
University of California Santa Barbara, Santa Barbara, CA
John L. Moore
University of California, Santa Barbara, Santa Barbara, CA
Adam Maloof
Princeton University, Princeton, NJ
Heather J. Zhou
Swarthmore College, Swarthmore, PA
Daniel Wang
Swarthmore College, Swarthmore, PA

Abstract

Although the Signor-Lipps effect is most often associated with mass extinctions, it also plays a role in “mass origination” events. The Cambrian explosion is arguably the most important such example and a pivotal event in the history of life. The general timeline of the Cambrian explosion is well established, but details about the duration and pattern of origination events remain unclear. Maloof et al. (2010) found that a dataset of small shelly fossils through the earliest Cambrian showed three pulses of fossil appearances over approximately 16 million years. Here we attempt to provide a statistically rigorous estimate for the duration and number of pulses in the Cambrian explosion using novel methods that account for Signor-Lipps-type effects.

We used a revised dataset of fossil occurrences of 166 genera of small shelly fossils from Mongolia, Siberia, and China, dating from the earliest part of the Cambrian (Nemakit-Daldynian and Tommotian, or Terreneuvian). To estimate the duration of the origination event, we construct a confidence interval for the time span between the earliest and latest originations, by inverting a hypothesis test for whether a given duration is consistent with the observed fossil record. To estimate the number of pulses, we use a k-Nearest Neighbor classifier, which takes in a vector of Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) weights and outputs a vector indicating the posterior probability for each possible number of pulses.

Geological Society of America Abstracts with Programs. Vol. 48, No. 7

doi: 10.1130/abs/2016AM-287039

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