Skip to main content
    • Aa
    • Aa

A more precise speciation and extinction rate estimator

  • John Alroy (a1)

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.

Linked references
Hide All

This list contains references from the content that can be linked to their source. For a full set of references and notes please see the PDF or HTML where available.

J Alroy . 1996. Constant extinction, constrained diversification, and uncoordinated stasis in North American mammals. Palaeogeography, Palaeoclimatology, Palaeoecology 127:285 311.

J Alroy 2008. Dynamics of origination and extinction in the marine fossil record. Proceedings of the National Academy of Sciences USA 105:11,53611,542.

W. Kiessling , and C. Simpson . 2011. On the potential for ocean acidification to be a general cause of ancient reef crises. Global Change Biology 17:5667.

Recommend this journal

Email your librarian or administrator to recommend adding this journal to your organisation's collection.

  • ISSN: 0094-8373
  • EISSN: 1938-5331
  • URL: /core/journals/paleobiology
Please enter your name
Please enter a valid email address
Who would you like to send this to? *


Altmetric attention score

Full text views

Total number of HTML views: 2
Total number of PDF views: 24 *
Loading metrics...

Abstract views

Total abstract views: 121 *
Loading metrics...

* Views captured on Cambridge Core between September 2016 - 20th July 2017. This data will be updated every 24 hours.