Mind the uncertainty: Global plate model choice impacts deep-time palaeobiological studies

Abstract

Global plate models (GPMs) aim to reconstruct the tectonic evolution of the Earth by modelling the motion of the plates and continents through time. These models enable palaeobiologists to study the past distribution of extinct organisms. However, different GPMs exist that vary in their partitioning of the Earth's surface and the modelling of continental motions. Consequently, the preferred use of one GPM will influence palaeogeographic reconstruction of fossil occurrences and any inferred palaeobiological and palaeoclimatic conclusion. Here, using five open-access GPMs, we reconstruct the palaeogeographic distribution of cell centroids from a global hexagonal grid and quantify palaeogeographic uncertainty across the entire Phanerozoic (540–0 Ma). We measure uncertainty between reconstructed coordinates using two metrics: (1) palaeolatitudinal standard deviation and (2) mean pairwise geodesic distance. Subsequently, we evaluate the impact of GPM choice on palaeoclimatic reconstructions when using fossil occurrence data. To do so, we use two climatically sensitive entities (coral reefs and crocodylomorphs) to infer the palaeolatitudinal extent of subtropical climatic conditions for the last 240 million years. Our results indicate that differences between GPMs increase with the age of reconstruction. Specifically, cell centroids rotated to older intervals show larger differences in palaeolatitude and geographic spread than those rotated to younger intervals. However, high palaeogeographic uncertainty is also observed in younger intervals within tectonically complex regions (i.e. in the vicinity of terrane and plate boundaries). We also show that when using fossil data to infer the distribution of subtropical climatic conditions across the last 240 Ma, estimates vary by 6–7° latitude on average, and up to 24° latitude in extreme cases. Our findings confirm that GPM choice is an important consideration when studying past biogeographic patterns and palaeoclimatic trends. We recommend using GPMs that report true palaeolatitudes (i.e. use a palaeomagnetic reference frame) and incorporating palaeogeographic uncertainty into palaeobiological analyses.