A statistically significant long term characteristic time-scale of test size variation of Calcareous Trochospiral Benthic Foraminifera (CTBF) during the past 120 m.y

Geo‐marine records are faithful recorders of the earth's evolutionary history and hence are most suitable for identifying long‐term cyclic patterns. Although a remarkable synchronism among Calcareous Trochospiral Benthic Foraminifera (CTBF) test size variation, ocean productivity, dissolved oxygen and global climate exists, global “geospectroscopy” is essential for understanding the wider ramification of significant physical linkages of the various terrestrial and extra‐terrestrial processes. Earlier claims of a quasi‐periodicity of 26–36 m.y. in various geo‐bio‐ocean‐atmospheric records sparked a major controversy. Here, we examine spectral characteristics of the latest available time series representing fluctuations in test size of CTBF for the past 120 m.y. using the Multi‐Taper Method (MTM) and Maximum Entropy Method (MEM) of spectral analyses. The analyses of test size variations of CTBF time series reveal, hitherto unidentified, a statistically significant and stable harmonic component of 35 ± 5 m.y. against a robust “red background noise”. Further, wavelet spectral analysis of this record exhibits a strong stationary power in the above frequency band suggesting temporal persistence of spectral peak through the entire evolutionary period. This finding renders credible support to the concept of cyclic geo‐marine processes and will provide stimulus for further quantitative research into the coupling of marine geo‐bio‐chemical cycles.