Elephant seal (Mirounga sp.) from the Pleistocene of the Antofagasta Region, northern Chile

ABSTRACT

The genus Mirounga is the largest living member of the Phocidae family (true seals) and includes two species: M. angustirostris and M. leonina. These species exhibit a noticeable antitropical distribution in the Northern and Southern hemispheres, respectively. The evolutionary history of elephant seals, especially in regard to establishing this antitropical pattern, is poorly known. Nearly all fossils of the genus are isolated remains from the Pleistocene of California (M. angustirostris) and South Africa (M. leonina). Here, we describe new fossil material of Mirounga sp. (incomplete maxilla, dentary, and humerus), from the middle to late Pleistocene of Antofagasta Region, northern Chile. This material constitutes the first fossil occurrence of this species in South America and suggests that during part of the Pleistocene, phocids coexisted with otariids along the eastern edge of the South Pacific Ocean, which contrasts with the current biogeographic pattern in this ocean basin, providing new information about the structure of the pinniped community during the Pleistocene of South America.

ACKNOWLEDGMENTS

A.V.T. was funded by CONICYT-PCHA/ Magister Nacional/ 2013-221320410 and for Young Explorer Grant (9391-13) from National Geographic Society Committee on Research Exploration to A.V.T. Additional funding for this work comes from a National Museum of Natural History Small Grant Award, discretionary funding from NMNH Office of the Director, the Smithsonian Institution's Remington Kellogg Fund, a NGS CRE grant (8903-11) to N.D.P, and by U-REDES (Domeyko II UR-C12/1, Universidad de Chile) to the rest of the authors. Excavations were financed by Sociedad GNL Mejillones. We would like to thank C. Loch (University of Otago, Dunedin, New Zealand) for providing information about dentition of Elephant seals. We also thank S. Fuentes Tamblay (Museo Paleontológico de Caldera) and S. Soto Acuña (Museo Nacional de Historia Natural, Santiago, Chile) for the preparation and photography, respectively. Also, R. E. Yury-Yáñez (Universidad de Chile) and D. Rubilar-Rogers (Museo Nacional de Historia Natural, Santiago, Chile) provided comments and suggestions that improved a preliminary version of the manuscript. We appreciate the useful and detailed comments from the editor Erich Fitzgerald, as well as those from R.W. Boessenecker and an anonymous reviewer, which substantially improved the manuscript.