Late middle Eocene caviomorph rodents from Contamana, Peruvian Amazonia
Abstract
Caviomorph rodents represent one of the most successful groups of placental mammals from South America. Despite their modern, Neogene and late Paleogene high diversity, their early evolutionary history has long remained obscure. Recent field expeditions in Peruvian Amazonia have yielded among the earliest representatives of that group, in deposits dating from the late middle Eocene (Contamana, CTA-27 locality, ~41 Ma). Here, we provide an exhaustive analysis of the rodent material from CTA27 and from new sub-coeval localities discovered in the same area and geological formation (Pozo Formation): CTA-47, CTA-51, CTA-73, CTA-66, and CTA-29. A total of 20 rodent taxa are identified in these localities, among which one from CTA-29 (Pozomys ucayaliensis gen. et sp. nov.) remains with uncertain suprafamilial affinities. Additionally, the material of CTA-27 previously attributed to Eobranisamys sp. is assigned here to the new species Eobranisamys javierpradoi. In terms of taxonomic composition, Eocene localities from Contamana area have many taxa in common (Cachiyacuy, Canaanimys, Eobranisamys, and Eoespina, or very close relatives). These Eocene assemblages are clearly distinct from Oligocene ones, mostly documented at mid and high latitudes. In contrast, they share some affinities with the late Eocene-earliest Oligocene Santa Rosa locality (Peruvian Amazonia), from which the two genera Eobranisamys and Eoespina were originally described. This faunal closeness might more reflect biogeographic affinities than contemporaneity. In addition, the occlusal pattern of some upper molars of Eosallamys from Santa Rosa recalls that of Cachiyacuy and Canaanimys. These low-latitude caviomorph assemblages provide new insights into the early evolutionary history, biogeography, and paleodiversity of that group.
Additional Information
© April 2017 Palaeontological Association. Submission: 3 November 2016. Acceptance: 5 April 2017. We especially thank the Canaan Shipibo Native Community and Maple Gas Peru S.A. for granting access to the field and the IRD-Peru-Petro Convention Programme for logistic support. We are particularly grateful to our guides Manuel and Manuel, for their long standing help in the forest during the field seasons. Many thanks to S. Adnet (ISEM, Montpellier, France), A.J. Altamirano-Sierra (MUSM, Lima, Peru), G. Billet (MNHN, Paris, France), A. Boada-Saña (Spain), F. Duranthon (Muséum de Toulouse, France), and whoever helped us in the field and in the lab. We are much indebted to M.E. Pérez (MPEF, Trelew, Argentina), M.G. Vucetich, and A. Candela (MLP, La Plata, Argentina), and A.G. Kramarz (MACN, Buenos Aires, Argentina) for discussing on rodent affinities, and providing crucial bibliographic references. C. Argot (MNHN), A.G. Kramarz, and M. Reguero (MLP) kindly granted access to the collections under their care. We gratefully thank M.G. Vucetich, who kindly provided casts of fossil rodents from Argentinean Patagonia. We warmly thank C. Cazevieille (Montpellier RIO Imaging, Institut des Neurosciences de Montpellier, France) and D. Cot (Institut Européen des Membranes [IEM], Montpellier, France) for access to a scanning electron microscope facility. We thank J. Louys, K. Claeson, and C. Grohé (members of the Palaeontologia Electronica Editorial Board), as well as the anonymous reviewers, who provided formal reviews of this manuscript that enhanced the final version. This work was supported by CNRS "Eclipse 2", CNRS "Paleo2", Toulouse University "SPAM" programs, by the L. S. B. Leakey Foundation, the ANR PALASIAFRICA (ANR-08-JCJC-0017, ANR-ERC), the National Geographic Society (grant 9679-15), an "Investissements d'Avenir" grant managed by the "Agence Nationale de la Recherche" (CEBA, ANR-10-LABX-0025-01), and by the COOPINTEER CNRS/CONICET and the ECOS-SUD/FONCyT international collaboration programs. This is ISEM publication 2017-013-Sud.Additional details
- Eprint ID
- 116202
- DOI
- 10.26879/742
- Resolver ID
- CaltechAUTHORS:20220810-751609000
- Centre National de la Recherche Scientifique (CNRS)
- Toulouse University
- Leakey Foundation
- ANR-08-JCJC-0017
- Agence Nationale de la Recherche (ANR)
- 9679-15
- National Geographic Society
- ANR-10-LABX-0025-01
- Agence Nationale de la Recherche (ANR)
- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET)
- Fondo para la Investigación Científica y Tecnológica (FONCYT)
- Created
-
2022-08-11Created from EPrint's datestamp field
- Updated
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2023-03-14Created from EPrint's last_modified field
- Caltech groups
- Division of Geological and Planetary Sciences
- Other Numbering System Name
- ISEM
- Other Numbering System Identifier
- 2017-013-Sud