Palaeogene climate deterioration increased South American mammal turnover near the Eocene-Oligocene Transition

BUFFAN, L.; CONDAMINE, F. L.; STUTZ, N. S.; PUJOS, F.; MARIVAUX, L.; ANTOINE, P.-O.

Lisboa

Congreso; 7th European Conference of Tropical Ecology; 2024

Society for Tropical Ecology

Around 34 million years ago (Ma), the Eocene-Oligocene Transition (EOT) marked the most dramatic global climatic change episode in the last 66 million years. Palaeontological evidence suggest that this transition was associated with a major faunal remodelling among European mammal communities. In South America, concomitant biotic turnovers have been postulated at the local scale, mostly from high-latitude sites. However, to our knowledge, no integrative framework has studied the effect of the EOT on South American mammal faunas at the continent scale. In particular, little is known about the magnitude of these possible biotic changes in the Tropics, the latter often believed as being stable regarding extinction.Here, using an unprecedented fossil dataset and fossil-based Bayesian methods of diversification inference, we explore South American mammal diversification dynamics between 56 and 23.03 Ma. We distinguish diversification histories between phylogenetic orders, based on Tropical/Extra-Tropical affinities and between the main trophic classes. We then investigate the influence of abiotic (e.g. Temperature, Andes Elevation) and biotic (diversity-dependence effects) factors in the inferred patterns.We find that (1) around 38 Ma, South American mammal lineages exhibit an overall increased turnover, coinciding with (2) Late Eocene climate deterioration prior the EOT. We highlight a prominent role of temperature in shaping this diversification pattern. (3) Tropical lineages appear significantly less affected than Extra-tropical lineages by this climate transition. (4) Ecologies were unevenly affected by this climate transition, with insectivore lineages showing a sharp decline while herbivore lineages exhibit a high turnover, which can be related to a transition from closed to open habitats.Our results provide insights into how South American mammals responded to an important climate crisis, which can be of interest in the ongoing context of climate change.