Drawing maps in the dark: Devonian palaeomagnetic uncertainty and the illusion of robust palaeogeography

Palaeomagnetic data are the most important quantitative basis for palaeogeographic models on which a significant proportion of geoscientific research depends. Many of the key palaeomagnetic datasets were collected between the 1970s and 1990s; despite persistent gaps, the last 20 years brought few new data for global palaeogeographic reconstructions. Some intervals, notably the Devonian, remain particularly poorly constrained. This strongly affects palaeogeographic reconstructions, which are now commonly used to model palaeoclimate and investigate mass extinctions and other biotic crises. Although the scarcity of reliable Devonian palaeomagnetic data is well known within palaeomagnetism, its implications are less appreciated by users of global plate models and dependent palaeoclimate models. Here, we highlight these implications, examine problems with Devonian palaeomagnetic data, compare alternative palaeogeographic models for this interval and evaluate how these models influence climate reconstructions. We show that sparse palaeomagnetic constraints and often non-transparent datasets promote artificial convergence among reconstructions, obscuring large underlying uncertainties. We encourage explicit recognition of the substantial uncertainties within Devonian palaeogeographic models, particularly in climate simulations, and we outline how expanded, FAIR (Findable, Accessible, Interoperable, Reusable) palaeomagnetic datasets and transparent model construction can improve future palaeogeographic reconstructions and research.