Desafiando a Nomenklatura Científica: Preservação de fósseis de baleias implica em uma taxa alta de acumulação de diatomito na Formação Pisco do Mioceno-Plioceno do Peru

terça-feira, janeiro 17, 2012

Fossil whale preservation implies high diatom accumulation rate in the Miocene–Pliocene Pisco Formation of Peru

Leonard R. Brand*1, Raúl Esperante*2, Arthur V. Chadwick*3, Orlando Poma Porras*4 and Merling Alomía*4

Author Affiliations

1Department of Natural Sciences, Loma Linda University, Loma Linda, California 92350, USA

2Geoscience Research Institute, Loma Linda, California 92350, USA

3Biology Department, Southwestern Adventist University, Keene, Texas 76059, USA

4 Universidad Peruana Unión, Carretera Central, km. 19, Ñaña, Lima, Peru

Abstract

Diatomaceous deposits in the Miocene–Pliocene Pisco Formation contain abundant whales preserved in pristine condition (bones articulated or at least closely associated), in some cases including preserved baleen. The well-preserved whales indicate rapid burial. The 346 whales within ∼1.5 km2 of surveyed surface were not buried as an event, but were distributed uninterrupted through an 80-m-thick sedimentary section. The diatomaceous sediment lacks repeating primary laminations, but instead is mostly massive, with irregular laminations and speckles. There is no evidence for bioturbation by invertebrates in the whale-bearing sediment. Current depositional models do not account for the volume of diatomaceous sediments or the taphonomic features of the whales. These taphonomic and sedimentary features suggest that rapid burial due to high diatom accumulation, in part by lateral advection into protected, shallow embayments, is responsible for the superb preservation of these whales, leading to a higher upper limit on phytoplankton accumulation rates than previously documented.