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Analysis of two independent data sets with increased taxonomic resolution (genera rather than families) using the revised 2012 time scale reveals that an extinction periodicity first detected by Raup and Sepkoski (1984) for only the post-Paleozoic actually runs through the entire Phanerozoic. Although there is not a local peak of extinction every 27 million years, an excess of the fraction of genus extinction by interval follows a 27 million year timing interval and differs from a random distribution at the p ~ 0.02 level. A 27 million year periodicity in the spectrum of interval lengths no longer appears, removing the question of a possible artifact arising from it. Using a method originally developed in Bambach (2006) we identify 19 intervals of marked extinction intensity, including mass extinctions, spanning the last 470 million years (and with another six present in the Cambrian) and find that 10 of the 19 lie within 3 Myr of the maxima in the spacing of the 27 Myr periodicity, which differs from a random distribution at the p = 0.004 level. These 19 intervals of marked extinction intensity also preferentially occur during decreasing diversity phases of a well-known 62 Myr periodicity in diversity (16 of 19, p = 0.002). Both periodicities appear to enhance the likelihood of increased severity of extinction, but the cause of neither periodicity is known. Variations in the strength of the many suggested causes of extinction coupled to the variation in combined effect of the two different periodicities as they shift in and out of phase is surely one of the reasons that definitive comparative study of the causes of major extinction events is so elusive., Comment: 26 pages, 5 figures, 1 Table. To be published in Paleobiology. Updated to coincide with edits for final published version

A major revision of the geological timescale was published in 2012. We re-examine our past finding of a 27 Myr periodicity in marine extinction rates by re-assigning dates to the extinction data used previously. We find that the spectral power at this period is somewhat increased, and persists at a narrow bandwidth, which supports our previous contention that the Nemesis hypothesis is untenable as an explanation for the periodicity that was first noted by Raup and Sepkoski in the 1980s. We enumerate a number of problems in a recent study comparing extinction rates with time series models., Comment: 13 pages, 2 figures. Accepted for publication in Astrophysical Journal

We find that the marine 87Sr/86Sr record shows a significant periodicity of 59.3 \pm 3 Myr. The 87Sr/86Sr record is 171{\deg} \pm 12{\deg}out of phase with a 62 (\pm 3) Myr periodicity previously reported in the record of marine-animal diversity. These periodicities are close to 58 (\pm 4) Myr cycles found for the number of gap-bounded sedimentary carbonate packages of North America We propose that these periodicities reflect the operation of a periodic "pulse of the Earth" in large-scale, Earth processes. These may be linked to mantle or plate-tectonic events, possibly uplift, which affects Earth's climate and oceans, and so the geochemistry, sedimentation, and biodiversity of the marine realm. Alternately, they may be linked to oscillation of the solar system normal to the plane of the galaxy., Comment: 21 pages, including supplement

We investigate evolutionary dynamics related to periodicity fossil biodiversity. Coherent periodic fluctuation in origination/extinction of marine genera that survive <45 million years is the source of an observed ~62 million year periodicity analyzed in Paper I. We also show that the evolutionary dynamics of "long-lived" genera (those that survive >45 million years) do not participate in the periodic fluctuation in diversity and differ from those of "short-lived" genera. The difference between the evolutionary dynamics of these 2 genera classes indicates that the periodic pattern is not an artifact of variation in quality of the geologic record. The interplay of these two previously undifferentiated systems, together with the secular increase in abundance of "long-lived" genera, is probably the source of heretofore unexplained differences in evolutionary dynamics between the Paleozoic and post-Paleozoic as reported by others. Testing for cycles similar to the 62 Myr cycle in fossil biodiversity superimposed on the long-term trends of the Phanerozoic as described in Paper I, we find a significant (but weaker) signal in sedimentary rock packages, particularly carbonates, which suggests a connection. The presence of a periodic pattern in evolutionary dynamics of the vulnerable "short-lived" component of marine fauna demonstrates that a long-term periodic fluctuation in environmental conditions capable of affecting evolution in the marine realm characterizes our planet. Coincidence in timing is more consistent with a common cause than sampling bias. A previously identified set of mass extinctions preferentially occur during the declining phase of the 62 Myr periodicity, supporting the idea that the periodicity relates to variation in biotically important stresses. Further work should focus on finding links to physical phenomena that might reveal the causal system or systems., Comment: Paleobiology, in press. 74 pages, 13 figures

The hypothesis of a companion object (Nemesis) orbiting the Sun was motivated by the claim of a terrestrial extinction periodicity, thought to be mediated by comet showers. The orbit of a distant companion to the Sun is expected to be perturbed by the Galactic tidal field and encounters with passing stars, which will induce variation in the period. We examine the evidence for the previously proposed periodicity, using two modern, greatly improved paleontological datasets of fossil biodiversity. We find that there is a narrow peak at 27 My in the cross-spectrum of extinction intensity time series between these independent datasets. This periodicity extends over a time period nearly twice that for which it was originally noted. An excess of extinction events are associated with this periodicity at 99% confidence. In this sense we confirm the originally noted feature in the time series for extinction. However, we find that it displays extremely regular timing for about 0.5 Gy. The regularity of the timing compared with earlier calculations of orbital perturbation would seem to exclude the Nemesis hypothesis as a causal factor., Comment: 10 pages, 2 figures, accepted for publication in Monthly Notices of the Royal Astronomical Society

We use Fourier analysis and related techniques to investigate the question of periodicities in fossil biodiversity. These techniques are able to identify cycles superimposed on the long-term trends of the Phanerozoic. We review prior results and analyze data previously reduced and published. Joint time-series analysis of various reductions of the Sepkoski Data, Paleobiology Database, and Fossil Record 2 indicate the same periodicity in biodiversity of marine animals at 62 Myr. We have not found this periodicity in the terrestrial fossil record. We have found that the signal strength decreases with time because of the accumulation of apparently "resistant" long-lived genera. The existence of a 62-Myr periodicity despite very different treatment of systematic error, particularly sampling-strength biases, in all three major databases strongly argues for its reality in the fossil record., Comment: 56 pages. In press at Paleobiology. Submitted to conform with copyedited version