Using Confidence Intervals to Quantify the Uncertainty in the End-Points of Stratigraphic Ranges

Abstract

One of the many contributions paleontology makes to our understanding of the biosphere and its evolution is a direct temporal record of biotic events. However, assuming fossils have been correctly identified and accurately dated, stratigraphic ranges underestimate true temporal ranges: observed first occurrences are too young, and observed last occurrences are too old. Here I introduce the techniques developed for placing confidence intervals on the end-points of stratigraphic ranges. I begin with the analysis of single taxa in local sections – with the simplest of assumptions – random fossilization. This is followed by a discussion of the methods developed to handle the fact that the recovery of fossils is often non-random in space and time. After discussion of how confidence intervals can be used to test for simultaneous origination and extinctions, I conclude with an example application of confidence intervals to unravel the relative importance of background extinction, environmental change and mass extinction of ammonite species at the end of the Cretaceous in western Tethys.