1. Instituto Politécnico Nacional Centro Interdisciplinario de Ciencias Marinas Av. Instituto Politécnico Nacional S/N, Playa Palo de Santa Rita, Apdo. Postal 592 CP 23096 La Paz Baja California Sur, Mexico
2. Department of Mammalogy Natural History Museum of Los Angeles County 900 Exposition Blvd Los Angeles CA 90007 USA
3. Department of Paleobiology National Museum of Natural History Smithsonian Institution Washington DC 20560 USA