An early Oligocene age for the oldest known monkeys and rodents of South America

Campbell, KE; O'Sullivan, PB; Fleagle, JG; de Vries, D; Seiffert, ER

Abstract

The Santa Rosa fossil locality in eastern Perú produced the first Paleogene vertebrate fauna from the Amazon Basin, including the oldest known monkeys from South America. This diverse paleofauna was originally assigned an Eocene age based largely on the stage of evolution of the site's caviomorph rodents and marsupials. Here, we present detrital zircon dates that indicate that the maximum composite age of Santa Rosa is 29.6 ± 0.08 Ma (Lower Oligocene), although several zircons from Santa Rosa date to the Upper Oligocene. The first appearance datum for Caviomorpha in South America is purported to be the CTA-27 site in the Contamana region of Perú, which is hypothesized to be ∼41 Ma (Middle Eocene) in age. However, the presence of the same caviomorph species and/or genera at both CTA-27 and at Santa Rosa is now difficult to reconcile with a >11-My age difference. To further test the Middle Eocene age estimate for CTA-27, we ran multiple Bayesian tip-dating analyses of Caviomorpha, treating the ages of all Paleogene species from Perú as unknown. These analyses produced mean age estimates for Santa Rosa that closely approximate the maximum 29.6 ± 0.08 Ma composite date provided by detrital zircons, but predict that CTA-27 is much younger than currently thought (∼30 Ma). We conclude that the ∼41 Ma age proposed for CTA-27 is incorrect, and that there are currently no compelling Eocene records of either rodents or primates in the known fossil record of South America.

Citation

Campbell, K., O'Sullivan, P., Fleagle, J., de Vries, D., & Seiffert, E. (2021). An early Oligocene age for the oldest known monkeys and rodents of South America. Proceedings of the National Academy of Sciences, 118(37), e2105956118. https://doi.org/10.1073/pnas.2105956118

• Journal Article Type: Article
• Acceptance Date: Jul 8, 2021
• Publication Date: Sep 14, 2021
• Deposit Date: Nov 18, 2021
• Publicly Available Date: Mar 14, 2022
• Journal: Proceedings of the National Academy of Sciences (PNAS)
• Electronic ISSN: 1091-6490
• Publisher: National Academy of Sciences
• Volume: 118
• Issue: 37
• Pages: e2105956118
• DOI: https://doi.org/10.1073/pnas.2105956118
• Publisher URL: https://doi.org/10.1073/pnas.2105956118
• Related Public URLs: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8449332/; http://www.pnas.org/
• Additional Information: Additional Information : ** From PubMed via Jisc Publications Router **Journal IDs: eissn 1091-6490 **Article IDs: pubmed: 34493667; pii: 2105956118 **History: submitted 21-07-2021; accepted 08-07-2021; Access Information : Edits were made following acceptance, so please to refer to the published or PubMed versions for the final version of the paper