PERIODICITIES IN BIODIVERSITY AND POSSIBLE CAUSAL FACTORS

Two phenomena display nearly regular timing during the Phanerozoic. There is a regular appx. 62 Myr periodicity in biodiversity driven by regularities in extinction and in origination. This was first noted by Rohde and Muller, and since confirmed with multiple data sets. It has been found to be synchronous with major fluctuations in 87Sr/86Sr, the emplacement of sedimentary packages, and the initiation ages of large igneous provinces. A second fluctuation peak in extinction exists at 27 Myr. This peak was found by Raup & Sepkoski over 250 Myr, be we have confirmed it in modern data, at higher significance, and extending backward through the Paleozoic. This signal has become stronger with the 2012 geological time scale. Geophysical explanations are suggested by the data for the 62 Myr signal. However, motions of the Solar System in the galaxy are an additional possible driving mechanism for both timings.