Evidence for periodicity and nonlinearity in a high-resolution fossil record of long-term evolution

The application of new signal analysis techniques provides increased insigh t into the study of the fossil record and processes of evolution. The fossi l record of 622 planktic foraminifera contains data from 200 stratigraphic stages of the past 127 m.y. Time-series analyses (wavelet and Fourier trans form) of the planktic foraminifera fossil record were used to discern perio dic components in long-term evolution. The correlation function analysis wa s used to distinguish between random and deterministic behavior of the foss il record. The analyses show that stationary similar to 30 m.y. periodicity and complex deterministic patterns occur in the long-term planktic foramin ifera evolution, in particular in the extinction record. Our results sugges t that the occurrence of intense diversity fluctuations with 3-10 m.y. peri odicity after major extinction events may be attributed to nonlinear, self organized evolutionary response to the availability of new ecospace. This c oupled nonlinear-periodic scenario mag explain the repetitive appearance of similar morphotypes in similar to 30 m.y. intervals.