The fate of South America's endemic mammalian fauna in response to the most dramatic Cenozoic climate disruption

Around 34 Mya, the Eocene-Oligocene transition (EOT) marked the most dramatic global climatic cooling of the Cenozoic. On a planetary scale, paleontological evidence suggests that this transition was associated with major faunal turnovers, sometimes even regarded as a mass extinction crisis. In Sout...

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Published in:Proceedings of the National Academy of Sciences - PNAS Vol. 122; no. 20; p. e2419520122
Main Authors: Buffan, Lucas, Condamine, Fabien L, Stutz, Narla S, Pujos, François, Antoine, Pierre-Olivier, Marivaux, Laurent
Format: Journal Article
Language:English
Published: United States 20.05.2025
Subjects:
Animals
Bayes Theorem
Biodiversity
Biological Evolution
Climate Change
Extinction, Biological
Fossils
Mammals - classification
Mammals - physiology
Paleontology
South America
South America
multivariate analyses
Eocene−Oligocene transition
diversification dynamics
Bayesian inference
Biological crisis
ISSN:1091-6490, 1091-6490
Online Access:Get more information
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Summary:Around 34 Mya, the Eocene-Oligocene transition (EOT) marked the most dramatic global climatic cooling of the Cenozoic. On a planetary scale, paleontological evidence suggests that this transition was associated with major faunal turnovers, sometimes even regarded as a mass extinction crisis. In South America, there is no consensus on the response of the endemic mammals to this transition. Here, using a vetted fossil dataset and cutting-edge Bayesian methods, we analyzed the dynamics of South American mammal (SAM) diversification and their possible drivers across latitude (tropical vs. extratropical), taxonomic groups, and trophic guilds throughout the Eocene-Oligocene ( 56 to 23 Ma). Our results did not evidence any mass extinction among SAM at the EOT. Instead, they experienced a gradual and long-term diversity decline from the middle Eocene to the early Oligocene, followed by a sudden waxing-and-waning diversity associated with a large taxonomic-but not ecological-turnover. Tropical and extratropical lineages have had very distinct macroevolutionary histories. No effective change in the pace at which tropical lineages diversify was found, thus favoring the tropical stability hypothesis proposed by Wallace. Diversity-dependent effects, temperature, and Andean uplift were recovered as probable drivers of SAM diversification across the period. Contrasting evidence casts doubt on the common hypothesis primarily linking Oligocene faunal changes to grassland expansion. Our findings illustrate the uniqueness of the deep-time interplay between endemic SAM and their physical environment in a context of climatic shift, highlighting the need to consider regional idiosyncrasies for understanding the coevolution of life and climate.
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ISSN:1091-6490
1091-6490
DOI:10.1073/pnas.2419520122