Unexpected pampatheriid from the early Oligocene of Peruvian Amazonia: insights into the tropical differentiation of cingulate xenarthrans
- 1. Instituto Argentino de Nivología, Glaciología y Ciencias Ambientales (IANIGLA), CONICET-UNCUYO-Mendoza, Mendoza, Argentina
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2.
National Scientific and Technical Research Council
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3.
Institut des Sciences de l'Evolution de Montpellier
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4.
National University of Jujuy
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5.
Cayetano Heredia University
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6.
National University of San Marcos
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7.
California Institute of Technology
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8.
University of Namur
Abstract
Cingulates (armoured xenarthrans) constitute one of the most peculiar endemic clades of South American mammals. Their first occurrence in the fossil record can be traced back to the early Eocene. However, their Palaeogene remains are scarce, especially in tropical regions. Here, we report an isolated molariform tooth of xenarthran from the early Oligocene of Peruvian Amazonia. This tooth is small and bilobed, with slightly marked apicobasal sulci, more compatible with a cingulate dental pattern than that of folivorans (the only toothed pilosans). High-resolution microtomography of this specimen reveals an inner layer highly vascularised suggestive of osteodentine, encircled by a middle layer of orthodentine with densely S-curved dentinal tubules, and a thin outer layer. There is no clear evidence regarding the presence of cement, otherwise typically present in tree sloths. Although its external appearance cannot fully discard an assignment to a sloth, the microstructural pattern, such as well-developed osteodentine arranged in a row without ramifications, suggests that this tooth belongs to an early pampatheriid. The presence of Oligocene Pampatheriidae in Western Amazonia, previously suggested by isolated osteoderms, is substantiated by this dental remain, which underlines the importance of tropical areas for the differentiation of cingulate xenarthrans.
Acknowledgement
We are particularly indebted to M. Ciancio for providing the pictures of Yuruatherium tropicalis. We thank the editor and the two anonymous reviewers for their substantial corrections.
Data Availability
All data are included herein or in the Supplementary Figures S1 and S2 or in Pujos et al. (Citation2025).
Contributions
L.H. and F.P. designed and performed research and wrote the manuscript, J.Y. conducted the chemostratigraphy analyses, and B.M. generated most of the 3D models; L.M. and P.-O.A. have acquired funding for fieldwork and analyses; L.M., M.B., J.V.T.-L., R.S.-G., R.M.V.M., J.Y., P.-O.A., and F.P. performed fieldwork. All authors reviewed the manuscript and provided edits; they have given their final approval for publication and agreed to be held accountable for the work performed in this study.
Supplemental Material
Supplemental data for this article can be accessed online at https://doi.org/10.1080/08912963.2025.2481525
- Electronic Supplementary Material – Figure S1: S1 Pujos et al.doc
- Electronic Supplementary Material – Figure S2: S2 Pujos et al R1.doc
Funding
This study is part of the ongoing EMERGENCE strategic project of the LabEx CEBA (Centre d’Étude de la Biodiversité Amazonienne; ANR-10-LABX-25-01). Field and labwork were supported by the LabEx CEBA, the Leakey Foundation, the National Geographic Society, and the Institut des Sciences de l’Évolution de Montpellier (ISE-M). Palaeontological investigations in Peruvian Amazonia are carried out in the framework of an ongoing collaboration agreement between the Museo de Historia Natural de la Universidad Nacional Mayor San Marcos (Lima, Peru) and the Institut des Sciences de l’Évolution de Montpellier-Université de Montpellier, France. This is ISE-M publication 2025–054 SUD.
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Additional details
- LabEx CEBA
- ANR-10-LABX-25-01
- Leakey Foundation
- National Geographic Society
- Institut des Sciences de l'Evolution de Montpellier
- Accepted
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2025-03-14Accepted
- Available
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2025-03-28Published online
- Caltech groups
- Division of Geological and Planetary Sciences (GPS)
- Series Name
- ISE-M publication
- Series Volume or Issue Number
- 2025–054 SUD
- Publication Status
- In Press