Hostname: page-component-cd4964975-ppllx Total loading time: 0 Render date: 2023-03-30T02:40:49.699Z Has data issue: true Feature Flags: { "useRatesEcommerce": false } hasContentIssue true

A more precise speciation and extinction rate estimator

Published online by Cambridge University Press:  07 October 2015

John Alroy*
Department of Biological Sciences, Macquarie University, New South Wales 2109, Australia. E-mail:


A new turnover rate metric is introduced that combines simplicity and precision. Like the related three-timer and gap-filler equations, it involves first identifying a cohort of taxa sampled in the time interval preceding the one of interest (call the intervals i0 and i1). Taxa sampled in i0 and i1 are two-timers (t2); those sampled in i0 and i2 but not i1 are part-timers (p); and taxa sampled only in either i1, i2, or i3 are newly notated here as either s1, s2, or s3. The gap-filler extinction proportion can be reformulated as (s1s3)/(t2+p). The method proposed here is to substitute s3 with the second-highest of the three counts when the expected ordering s1s2s3 is violated. In simulation, this new estimator yields values that are highly correlated with those produced by the gap-filler equation but more precise. In particular, it rarely produces highly negative values even when sample sizes are quite small. It is mildly upwards biased when sampling is extremely poor and turnover rates are extremely low, but it is otherwise highly accurate. Examples of Phanerozoic extinction rates for four major marine invertebrate groups are given to illustrate the method’s improved precision. Based on the results, the procedure is recommended for general use.

Paleobiology , Volume 41 , Issue 4 , September 2015 , pp. 633 - 639
Copyright © 2015 The Paleontological Society. All rights reserved 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)


Literature Cited

Alroy, J. 1996. Constant extinction, constrained diversification, and uncoordinated stasis in North American mammals. Palaeogeography, Palaeoclimatology, Palaeoecology 127:285 311.CrossRefGoogle Scholar
Alroy, J 2008. Dynamics of origination and extinction in the marine fossil record. Proceedings of the National Academy of Sciences USA 105:11,53611,542.CrossRefGoogle ScholarPubMed
Alroy, J 2014. Accurate and precise estimates of origination and extinction rates. Paleobiology 40:374397.CrossRefGoogle Scholar
Foote, M. 1994. Temporal variation in extinction risk and temporal scaling of extinction metrics. Paleobiology 20:424444.CrossRefGoogle Scholar
Foote, M 1999. Morphological diversity in the evolutionary radiation of Paleozoic and post-Paleozoic crinoids. Paleobiology Memoirs No. 1. Paleobiology 25(Suppl. to No. 2).Google Scholar
Foote, M 2000. Origination and extinction components of taxonomic diversity: general problems. In D. H. Erwin and S. L. Wing, eds. Deep time: Paleobiology’s perspective. Paleobiology 26(Suppl. to No. 4), 74102.Google Scholar
Gould, S. J., and Calloway, C. B.. 1980. Clams and brachiopods–ships that pass in the night. Paleobiology 6:383396.CrossRefGoogle Scholar
Kiessling, W., and Simpson, C.. 2011. On the potential for ocean acidification to be a general cause of ancient reef crises. Global Change Biology 17:5667.CrossRefGoogle Scholar
Miller, A. I., and Sepkoski, J. J. Jr. 1988. Modelling bivalve diversification: the effect of interaction on a macroevolutionary system. Paleobiology 14:364369.CrossRefGoogle Scholar
Sepkoski, J. J. Jr. 1981. A factor analytic description of the Phanerozoic marine fossil record. Paleobiology 7:3653.CrossRefGoogle Scholar