title: Repeated mass strandings of Miocene marine mammals from Atacama Region of Chile point to sudden death at sea.
abstract: Marine mammal mass strandings have occurred for millions of years, but their origins defy singular explanations. Beyond human causes, mass strandings have been attributed to herding behaviour, large-scale oceanographic fronts and harmful algal blooms (HABs). Because algal toxins cause organ failure in marine mammals, HABs are the most common mass stranding agent with broad geographical and widespread taxonomic impact. Toxin-mediated mortalities in marine food webs have the potential to occur over geological timescales, but direct evidence for their antiquity has been lacking. Here, we describe an unusually dense accumulation of fossil marine vertebrates from Cerro Ballena, a Late Miocene locality in Atacama Region of Chile, preserving over 40 skeletons of rorqual whales, sperm whales, seals, aquatic sloths, walrus-whales and predatory bony fish. Marine mammal skeletons are distributed in four discrete horizons at the site, representing a recurring accumulation mechanism. Taphonomic analysis points to strong spatial focusing with a rapid death mechanism at sea, before being buried on a barrier-protected supratidal flat. In modern settings, HABs are the only known natural cause for such repeated, multispecies accumulations. This proposed agent suggests that upwelling zones elsewhere in the world should preserve fossil marine vertebrate accumulations in similar modes and densities.
authors.affiliation: Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, , PO Box 37012, Washington, DC 20013, USA, Department of Mineral Sciences, National Museum of Natural History, Smithsonian Institution, , PO Box 37012, Washington, DC 20013, USA, Department of Mammalogy, Burke Museum of Natural History and Culture, , Seattle, WA 98195, USA, Department of Paleontology, Burke Museum of Natural History and Culture, , Seattle, WA 98195, USA, Red Paleontológica, Laboratorio de Ontogenia y Filogenia, Departamento de Biología, Facultad de Ciencias, Universidad de Chile, Las Palmeras, Santiago 3425, Chile, John D. Cooper Archaeological and Paleontological Center, Department of Geological Sciences, California State University, , Fullerton, CA 92834, USA, Departamento de Geología, Facultad de Ciencias Físicas y Matemáticas and Andean Geothermal Center of Excellence, Universidad de Chile, , Plaza Ercilla 803, Santiago, Chile, Digitization Program Office 3D Lab, Office of the Chief Information Officer, Smithsonian Institution, , Landover, MD 20785, USA, Laboratorio de Ecofisiología, Departamento de Ecología, Facultad de Ciencias, Universidad de Chile, , Las Palmeras, Santiago 3425, Chile, Florida Museum of Natural History, University of Florida, , Gainesville, FL 32611, USA, Área Paleontología, Museo Nacional de Historia Natural, , Casilla 787, Santiago, Chile, Departamento de Zoologia, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, , Belo Horizonte, Minas Gerais, Brazil.
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Pyenson
authors.forename: Carolina S
authors.initials: CS
authors.lastname: Gutstein
authors.forename: James F
authors.initials: JF
authors.lastname: Parham
authors.forename: Jacobus P
authors.initials: JP
authors.lastname: Le Roux
authors.forename: Catalina Carreño
authors.initials: CC
authors.lastname: Chavarría
authors.forename: Holly
authors.initials: H
authors.lastname: Little
authors.forename: Adam
authors.initials: A
authors.lastname: Metallo
authors.forename: Vincent
authors.initials: V
authors.lastname: Rossi
authors.forename: Ana M
authors.initials: AM
authors.lastname: Valenzuela-Toro
authors.forename: Jorge
authors.initials: J
authors.lastname: Velez-Juarbe
authors.forename: Cara M
authors.initials: CM
authors.lastname: Santelli
authors.forename: David Rubilar
authors.initials: DR
authors.lastname: Rogers
authors.forename: Mario A
authors.initials: MA
authors.lastname: Cozzuol
authors.forename: Mario E
authors.initials: ME
authors.lastname: Suárez
mesh_terms: D000818:Animals; D059001:Aquatic Organisms; D002677:Chile; D005580:Fossils; D057097:Harmful Algal Bloom; D008322:Mammals; D008855:Microscopy, Electron, Scanning; D010140:Pacific Ocean; D013045:Species Specificity; D013057:Spectrum Analysis
keywords: fossil record; harmful algal blooms; strandings; taphonomy