Middle eocene rodents from peruvian amazonia reveal the pattern and timing of caviomorph origins and biogeography

Pierre Olivier Antoine, Laurent Marivaux, Darin A. Croft, Guillaume Billet, Morgan GanerØd, Carlos Jaramillo, Thomas Martin, Maëva J. Orliac, Julia Tejada, Ali J. Altamirano, Francis Duranthon, Grégory Fanjat, Sonia Rousse, Rodolfo Salas Gismondi

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236 Scopus citations


The long-term isolation of South America during most of the Cenozoic produced a highly peculiar terrestrial vertebrate biota, with a wide array of mammal groups, among which caviomorph rodents and platyrrhine primates are Mid-Cenozoic immigrants. In the absence of indisputable pre-Oligocene South American rodents or primates, the mode, timing and biogeography of these extraordinary dispersals remained debated. Here, we describe South America's oldest known rodents, based on a new diverse caviomorph assemblage from the late Middle Eocene (approx. 41 Ma) of Peru, including five small rodents with three stem caviomorphs. Instead of being tied to the Eocene/Oligocene global cooling and drying episode (approx. 34 Ma), as previously considered, the arrival of caviomorphs and their initial radiation in South America probably occurred under much warmer and wetter conditions, around the Mid-Eocene Climatic Optimum. Our phylogenetic results reaffirm the African origin of South American rodents and support a trans-Atlantic dispersal of these mammals during Middle Eocene times. This discovery further extends the gap (approx. 15 Myr) between first appearances of rodents and primates in South America.
Original languageAmerican English
Pages (from-to)1319-1326
Number of pages8
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1732
StatePublished - 7 Apr 2012


  • Hystricognathi
  • Mid-eocene climatic optimum
  • Phylogeny
  • Platyrrhini
  • South america


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