Originations and extinctions: Analyses of fossil data and simulations

We analyse the fossil data of Benton(1) with and without interpolation sche mes. By Fourier transform analysis, we find a frequency dependence of the a mplitude of 1/f for the various interpolation schemes used in the past. We illustrate that shuffling the interpolated data changes the spectra only sl ightly. On the other hand, an identical analysis performed on the raw (unin terpolated) fossil data gives a flat frequency spectrum. We conclude that t he 1/f behavior is an artifact of the interpolation schemes. We next introd uce a simulation of extinctions driven only by interactions between two tro phic levels. Fourier transform analysis of the simulation data shows a freq uency dependence of 1/f. When the data are grouped into a form resembling t he fossil record the frequency dependence vanishes, giving a Bat spectrum. Our simulation produces a frequency spectrum that agrees with the observed fossil record.