title: The oldest known fur seal.
abstract: The poorly known fossil record of fur seals and sea lions (Otariidae) does not reflect their current diversity and widespread abundance. This limited fossil record contrasts with the more complete fossil records of other pinnipeds such as walruses (Odobenidae). The oldest known otariids appear 5-6 Ma after the earliest odobenids, and the remarkably derived craniodental morphology of otariids offers few clues to their early evolutionary history and phylogenetic affinities among pinnipeds. We report a new otariid, Eotaria crypta, from the lower middle Miocene 'Topanga' Formation (15-17.1 Ma) of southern California, represented by a partial mandible with well-preserved dentition. Eotaria crypta is geochronologically intermediate between 'enaliarctine' stem pinnipedimorphs (16.6-27 Ma) and previously described otariid fossils (7.3-12.5 Ma), as well as morphologically intermediate by retaining an M2 and a reduced M1 metaconid cusp and lacking P2-4 metaconid cusps. Eotaria crypta eliminates the otariid ghost lineage and confirms that otariids evolved from an 'enaliarctine'-like ancestor.
authors: Department of Geology, University of Otago, Dunedin 9010, New Zealand Museum of Paleontology, University of California, Berkeley, CA 94720, USA boessenecker@gmail.com.
authors: Robert W
authors: RW
authors: Boessenecker
authors: Department of Geology and Geophysics, University of Wyoming, Laramie, WY, USA Program in Ecology, University of Wyoming, Laramie, WY, USA.
authors: Morgan
authors: M
authors: Churchill
mesh_terms: D000818:Animals; D005075:Biological Evolution; D002140:California; D005580:Fossils; D046069:Fur Seals / Q000033:anatomy & histology* / Q000145:classification*; D010802:Phylogeny
keywords: Miocene; North Pacific; Otariidae; Pinnipedia