First European record of Homiphoca (Phocidae: Monachinae: Lobodontini) and its bearing on the paleobiogeography of the genus

ABSTRACT

Marine mammal fossils (except pinnipeds) have commonly been found in Pliocene marine siliciclastic layers of the Neogene Guadalquivir Basin in Southwest Spain. A few Neogene phocid innominate bones are known from the Western Paratethys and Western Atlantic. Here we describe a new innominate bone from the early Pliocene (5.3–3.6 Ma) of the Western Paratethys (Spain), which is typical of the subfamily Monachinae, and has a flattened ilium similar to representatives of the tribe Lobodontini, particularly Leptonychotes weddellii. Comparison with other fossil monachine innominates from North America, South America and South Africa reveals that this specimen represents the genus Homiphoca, but species classification remains premature. This is the first European record of the genus Homiphoca and has paleobiogeographic implications, questioning the geological age of the Varswater Formation ‘E’ Quarry, Langebaanweg, Cape Province of South Africa. This discovery from the eastern North Atlantic further implies a more regular transatlantic gene flow in Miocene and Pliocene times than today. We argue that during the Messinian-Zanclean crisis, monachines became isolated and retreated southward to lower latitudes, possibly due to climatic deterioration (during glacial stages) and competition from the cold-adapted phocines from the north.

Abbreviations: NMNH: National Museum of Natural History, Smithsonian Institution, Washington, DC., USA; CMM: Calvert Marine Museum, Solomons, Maryland (USA); UTM: Universal Transverse Mercator Coordinate system

KEYWORDS:

• Innominate
• pliocene
• mediterranean
• Spain
• Huelva sands formation

Acknowledgments

We wish to thank Dr. Daryl Domning, Howard University, USA for his support and assistance during this study. Thanks to Research Group RNM 293 “Geomorfología Ambiental y Recursos hídricos”of Junta de Andalucia (Spanish government) and Miguel Ángel Bernal,who found the fossil. Also, we want to thank Dr. C. de Muizon (National Museum of Natural History, Paris, France) for his valuable critique of an earlier version of this manuscript. We want to thank the reviewers and editor for helpful suggestions that strengthened our manuscript.

Disclosure statement

No potential conflict of interest was reported by the authors.