Long-term cycles in the history of life: Periodic biodiversity in the Paleobiology Database

TL;DR

This study identifies a consistent approximately 62-63 million-year periodicity in marine invertebrate biodiversity from fossil records, supporting its potential significance in Earth's biological history.

Contribution

It demonstrates the robustness of the 62 My periodicity across two independent fossil datasets, despite different data treatments and potential biases.

Findings

A significant 62-63 My periodicity in fossil biodiversity.

The periodicity is consistent and in phase across datasets.

Other spectral peaks are likely artifacts, not genuine signals.

Abstract

Time series analysis of fossil biodiversity of marine invertebrates in the Paleobiology Database (PBDB) shows a significant periodicity at approximately 63 My, in agreement with previous analyses based on the Sepkoski database. I discuss how this result did not appear in a previous analysis of the PBDB. The existence of the 63 My periodicity, despite very different treatment of systematic error in both PBDB and Sepkoski databases strongly argues for consideration of its reality in the fossil record. Cross-spectral analysis of the two datasets finds that a 62 My periodicity coincides in phase by 1.6 My, equivalent to better than the errors in either measurement. Consequently, the two data sets not only contain the same strong periodicity, but its peaks and valleys closely correspond in time. Two other spectral peaks appear in the PBDB analysis, but appear to be artifacts associated with detrending and with the increased interval length. Sampling-standardization procedures implemented by the PBDB collaboration suggest that the signal is not an artifact of sampling bias. Further work should focus on finding the cause of the 62 My periodicity.