Quantifing time-averaging and the temporal resolution of the fossil record

Time-averaging is the hard limit to the resolution of the fossil record, and it is of fundamental importance to interpreting fossil assemblages, especially when comparing fossil and living assemblages. To accurately estimate time-averaging, it is essential to separate the variation in fossil ages from the uncertainties in the estimates of those individual ages. Here, I use simulations as well as ~100 previously published, dated assemblages from the Holocene of Australia to examine the effectiveness of different analytical methods used to separate dating uncertainty from the variation associated with different aged fossils (time-averaging). In the vast majority (88%) of assemblages, the variation due to time-averaging exceeds the variation associated with age-estimation error, and  time-averaging estimates that correct for age-estimation error are not different from time-averaging estimates that ignore age-estimation error. 

Despite their parametric roots, error-corrected IQR and Estimated Time Averaging (ETA) perform well across a wide range of simulated assemblage age distributions, and relatively modest sample sizes (N ~12) yield reasonable time-averaging estimates. When reporting time-averaging estimates, age-estimation error should be explicitly reported and corrected for if age-estimation error represents more than 40% of the total assemblage age variation. While ETA estimates are not directly comparable to most published time-averaging values, ETA is an effective method for removing the impact of dating uncertainty from time-averaging estimates. A consensus on the reporting of time-averaging estimates is overdue.