THE PRESERVATION POTENTIAL OF GEOGRAPHIC RANGE SIZE DISTRIBUTIONS IN DEEP TIME

The geographic ranges of species are thought to be a strong predictor of extinction risk. By examining the relationship between species’ range size and extinction over past mass extinction events, we can potentially identify those species vulnerable to extinction in the current biodiversity crisis (the ‘6^th mass extinction’). Although this has become a central research goal in conservation paleobiology, no attempts have yet been made to establish how accurately range sizes can be preserved in the geological record, and thus whether paleo-range size data can be used as a source of predictive models for biodiversity loss. Here, we present a new analytical and simulation-based framework for quantifying the preservation potential of geographic ranges in deep time, using all 344 mammal species present in the United States and the distribution of Phanerozoic-aged sediments for geological Periods and Stages. We iteratively (and randomly) simulate fossil localities within species’ ranges: the overlap of an occurrence with a sedimentary unit produces a fossil occurrence. We then reconstruct the distribution of species ranges using four commonly-used methods for paleo-range reconstruction and quantify how the accuracy of reconstruction changes through time. Our results illustrate that accuracy in range size reconstruction is governed by a complex interplay of factors, including the area and distribution of preserved fossiliferous sediment, the number of simulated fossil localities, and the methods used to measure paleo-range size. Crucially, however, our results also suggest that range size distributions can be reconstructed reliably using relatively small areas of preserved sediment, and at stage-level temporal resolution. This, in turn, suggests that range sizes have high preservation potential, and thus paleo-range size reconstruction can become a vital tool in helping to protect vulnerable species in the face of ongoing global change.