A Humboldtian approach to life and climate of the geological past: Estimating palaeotemperature from dental traits of mammalian communities

Aim The links between geo- and biodiversity, postulated by Humboldt, can now be made quantitative. Species are adapted to their environments and interact with their environments by having pertinent functional traits. We aim to improve global ecometric models using functional traits for estimating palaeoclimate and apply models to Pleistocene fauna for palaeoclimate interpretation. Location Global at present day, Pleistocene of Europe for fossil data analysis. Taxa Artiodactyla, Perissodactyla, Proboscidea and Primates. Methods We quantify functional traits of large mammal communities and develop statistical models linking trait distributions to local climate at present day. We apply these models to the fossil record, survey functional traits, and quantitatively estimate climates of the past. This approach to analysing functional relationships between faunal communities and their environments is called ecometrics. Results and main conclusions Here, we present new global ecometric models for estimating mean annual and minimum temperature from dental traits of present day mammalian communities. We also present refined models for predicting net primary productivity. Using dental ecometric models, we produce palaeoclimate estimates for 50 Pleistocene fossil localities in Europe and show that the estimates are consistent with trends derived from other proxies, especially for minimum temperatures, which we hypothesize to be ecologically limiting. Our new temperature models allow us to trace the distribution of freezing and non-freezing ecosystems in the recent past, opening new perspectives on the evolution of cold-adaptive biota as the Pleistocene cooling progressed.