Test of sampling sufficiency in palaeontology

Abstract

Traditionally, rarefaction curves are used to test sampling sufficiency; however, such measures are not always robust. Similarly, the Pareto Principle and “90/70”rule, commonly applied to biological sampling, are also inappropriate for palaeontological data. Here, we argue that the sufficiency of sampling could be determined by the consistency between a calculated diversity and the “actual” diversity. We have applied a method introduced from biology to estimate the species richness at four localities with the early Silurian brachiopod Cathaysiorthis fauna in South China and to estimate their actual diversity using the software EstimateS. Sample size corresponding to a given diversity was calculated by means of curve fitting, which can provide important information on future sampling strategies. Diversity estimation is a relatively immature field in palaeontology that promises accurate diversity comparisons. Here, we suggest that rarefaction should be accompanied by estimation assessment to extract from samples the most comprehensive diversity information available.