1. Department of Integrative Biology, University of Texas, 2415 Speedway #C0930, Austin, TX 78712, USA
2. Department of Biology University of Washington, Box 351800, Seattle, WA 98105, USA
3. Richard Gilder Graduate School, Department of Mammalogy, and Division of Paleontology, American Museum of Natural History, 200 Central Park West, New York, NY 10024, USA