A new pachyrukhine (Notoungulata: Typotheria) from the late Early Miocene of south-central Chile

ABSTRACT

Here, we studied several Pachyrukhinae (Mammalia: Notoungulata: Typotheria: Hegetotheriidae) fossils recovered from the late Early Miocene (Santacrucian SALMA) beds of the Cura-Mallín Formation at the Laguna del Laja (Biobío Region, Chile). The specimens are referred to a new species of the genus Pachyrukhos Ameghino, 1885, P. ngenwinkul sp. nov. The holotype of this taxon is a relatively well-preserved articulated skull and mandibles, which was investigated using 3D X-ray Microscopy. The new taxon is distinguished from other Pachyrukhos species by having a p2 smaller than p3, M3 mesiodistally shorter (around 30%) than M1, and upper premolars of a rather subtriangular contour. Pachyrukhos ngenwinkul is the most common mammal and the smallest-sized (with ~2 kg of body mass) notoungulate found in the Santacrucian assemblage at the Laguna del Laja. The discovery of this new taxon improves our understanding of the Neogene pachyrukhine diversity in southern South America and highlights the potential of the Chilean Andean Cenozoic deposits in revealing a hidden diversity of extinct continental mammals.

https://zoobank.org:pub:9B23EF16-2085-49E8-AE8E-7EBEBB9261ED

KEYWORDS:

• Paleodiversity
• cladistic analysis
• santacrucian
• Cura-Mallín formation
• hegetotheriids

Acknowledgments

We thank the Consejo de Monumentos Nacionales (CMN, Chile) and the Corporación Nacional Forestal (CONAF) for authorising palaeontological prospections in the Laguna del Laja area. Furthermore, Karina Buldrini (MNHN), Katherine Cisterna (MHNC), Laura Chornogubsky (MACN), Martín Ezcurra (MACN), and Marcelo Reguero (MLP) for granting access to the vertebrate palaeontological collections under their care; to Paz Butikofer, Francisca Riffo, Gabriel Arriagada, Hernán Arriagada and Aníbal Anavalón for their help and camaraderie during the field trips at Laguna del Laja, and María José Salas for their assistance and support in obtaining CT-scan images. We thank the editor Gareth Dyke, and the four anonymous reviewers for their comments and suggestions that significantly improved the final version of this manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by the Fondo Nacional de Desarrollo Científico y Tecnológico [1151146]. Finally, the authors would like to acknowledge the financial support of the Agencia Nacional de Investigación y Desarrollo (Chile) through FONDECYT projects 3220078 (to AS), 1151146 (to AE) and FONDEQUIP project EQM 130028.