A new marine mammal assemblage from central Chile reveals the Pliocene survival of true seals in South America

ABSTRACT

The fossil record of marine mammals from the upper Pliocene of the western coast of South America is poorly known, hindering our knowledge about how and when marine mammal faunas attained their modern distribution in the area. Here, we describe a new marine mammal assemblage from the Horcón Formation (upper Pliocene), located in the Valparaíso Region of central Chile. The material reported comprises postcranial remains of an indeterminate seal (Phocidae), Delphinoidea vertebrae, and mysticete elements (still in the field). The Phocidae remains constitute the youngest pre-Pleistocene record of this family in South America, providing new information regarding the timing for the establishment of the modern diversity and distribution of pinnipeds in the Southern Hemisphere. Furthermore, the pinniped and cetacean remains reported indicate that the marine mammal assemblage from the upper Pliocene along central Chile was composed of a mixture of modern and extinct taxa.

KEYWORDS:

• Fossil marine mammals
• faunal turnovers
• Phocidae
• cetacea
• late Pliocene
• South America
• Chile

Acknowledgments

We would like to thank David Rubilar-Rogers and Sergio Soto-Acuña for their comments and suggestions, which improved preliminary versions of the manuscript; and Robert W. Boessenecker and Mario Cozzuol for their comments and revision of a previous version of this work. We extend our gratitude to editor Gareth Dyke and reviewers Morgan Churchill, Sulman Rahmat for their thorough and helpful review. The authors especially wish to thank Mauricio F. Landaeta, María Verónica Andrade, Marco Cisternas, Marcelo Stucchi, Manuel J. Laime, Rodolfo Salas-Gismondi, Mario Urbina, Gabriel Aguirre-Fernandez, Marcelo Sanchez-Villagra, Andrés Varas, Leroy Quiroz and Hernán Vergara for their generous and important counselling and collaboration. We thank Nicholas D. Pyenson (USNM), Paulo Simões-Lopes (UFSC), Loic Costeur (M. Basel) David Rubilar-Rogers (MNHN), John Ossosky (USNM), James Rule (M. Victoria) and Rodolfo Salas-Gismondi (MUSM) for access to collections and assistance. This work benefited from financial support through CONICYT-PCHA, Master Fellowship (Grant No. 2013–221320410), ANID PCHA/Becas Chile, Doctoral Fellowship (Grant No. 2016–72170286), and National Geographic Society Committee on Research Exploration Young Explorer Grant 9391–13 to A.V.T., and U-REDES (Domeyko II UR-C12/1, Universidad de Chile, PI: A. Vargas) to A.V.T., C.F.B and C.S.G. also received funds from Fondecyt Nº 3160710; ACT 172099 PIA-Conicyt and REDES 190190 (PI: A. Vargas). Permit to collecting Nº 4703/2010 was granted by the Consejo de Monumentos Nacionales to J.C.B.

Disclosure statement

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