Benefits and pitfalls of quantitative biostratigraphy

Quantitative methods are now entering biostratigraphy with full force, reflecting general trends in science. Reconstructing a temporal sequence from fossil data that are both heterogenous and sparse both in space and time is a challenging problem. It is easy to get incorrect results that are seemingly clean and robust. Several methods are now in relatively common use, including Ranking-Scaling, Constrained Optimization and Unitary Associations, and other promising approaches are under development. The biostratigrapher needs to understand the quite different philosophies behind these methods before making a choice. Particularly important is the distinction between global ("evolutionary") and local ("ecological") solutions. It may be productive to use several methods and compare the results. Another pivotal question is the selection of taxa and sites to include in the analysis. Removal of presumably noisy data involves a trade-off between objectivity and apparent quality of the result.