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

Abstract

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.

Ecometrics and the paleoecological implications of Pleistocene faunas from the western coastal plains of the Cape Floristic Region, South Africa

“…Of course, the value of these relationships as a tool for paleoenvironmental reconstruction depends in part on understanding the causal mechanisms underpinning them (Faith and Lyman, 2019). In the context of our analyses, the positive regression coefficients for hypsodonty (Table 6) are consistent with a large body of previous ecometric work showing that mean hypsodonty increases in more arid environments (Eronen et al ., 2010b; Liu et al ., 2012; Fortelius et al ., 2016; Žliobaitė et al ., 2016; Faith et al ., 2019a; Oksanen et al ., 2019). This is thought to reflect the importance of hypsodonty for extending the functional lifespan of the dentition in open and arid environments, where plant foods are often tough, fibrous and siliceous, and coated in exogenous grit and dust (e.g.…”

“…Janis, 1988; Fortelius et al ., 2002; Damuth and Janis, 2011). The hypsodonty of ungulates from the CFR does not predict aridity as well as it does in other present‐day contexts (Table 5), where it is often a very strong predictor of aridity (Eronen et al ., 2010b; Liu et al ., 2012; Fortelius et al ., 2016; Žliobaitė et al ., 2016; Faith et al ., 2019a; Oksanen et al ., 2019), probably because the CFR lacks faunal communities dominated by brachydont taxa associated with humid, forested environments (i.e. the present‐day CFR has a limited range of mean hypsodonty scores).…”

“…Ecometric approaches to paleoenvironmental reconstruction typically involve exploring how the distribution of traits in modern biotic communities varies across environmental gradients, which then facilitates interpretation of the fossil record (Eronen et al ., 2010a; Vermillion et al ., 2018; Faith and Lyman, 2019). With respect to herbivore dental traits, strong ecometric relationships with climate have been demonstrated across a variety of spatial scales, ranging from regional (Žliobaitė et al ., 2016), continental and sub‐continental (Fortelius et al ., 2016; Žliobaitė et al ., 2018; Faith et al ., 2019a), to global (Eronen et al ., 2010b; Liu et al ., 2012; Oksanen et al ., 2019). With respect to African faunas, however, previous work has shown global‐scale ecometric relationships to be inadequate (Fortelius et al ., 2016; Žliobaitė et al ., 2018).…”

Revisiting biogeography of livestock animal domestication

“…If information about the behaviour now and in the past diverged, we assigned the value for the past. We characterized dental traits following the functional crown type scoring scheme described by with one modification allowing selenodonts have acute lophs, following the reasoning of Oksanen et al (2019).…”

“…Scoring is typically done on the second upper molar, except for suids, where functionally dominant tooth is the third upper molar. Dental trait scores come from publications , Galbrun et al 2018, Zliobaite et al 2018and Oksanen et al 2018. Pseudoryx teeth are scored by the nearest living relative (Bubalus or Syncerus, as per Bibi 2013).…”