We re-examine the evidence for a 62 million year (Myr) periodicity in biodiversity throughout the Phanerozoic history of animal
life reported by , as well as related questions of periodicity in origination and extinction. We find that the signal is robust
against variations in methods of analysis, and is based on fluctuations in the Paleozoic and a substantial part of the Mesozoic.
Examination of origination and extinction is somewhat ambiguous, with results depending upon procedure. Origination and
extinction intensity as defined by  may be affected by an artifact at 27 Myr in the duration of stratigraphic intervals.
Nevertheless, when a procedure free of this artifact is implemented, the 27 Myr periodicity appears in origination, suggesting
that the artifact may ultimately be based on a signal in the data. A 62 Myr feature appears in extinction, when this same
procedure is used. We conclude that evidence for a periodicity at 62 Myr is robust, and evidence for periodicity at
approximately 27 Myr is also present, albeit more ambiguous.
Lieberman, B. S., and A. L. Melott. 2007. Considering the case for biodiversity cycles: reexamining the evidence for periodicity in the fossil record. PLoS One 2(8) e759:1-9. http://dx.doi.org/10.1371/journal.pone.0000759