Taphonomy of marine vertebrates of the Pisco Formation (Miocene, Peru): Insights into the origin of an outstanding Fossil-Lagerstätte

PLoS One. 2021 Jul 15;16(7):e0254395. doi: 10.1371/journal.pone.0254395. eCollection 2021.

Abstract

The Miocene Pisco Formation, broadly exposed in the Ica Desert of southern Peru, is among the most outstanding Cenozoic marine Fossil-Lagerstätten worldwide. It is renowned for its exceptional preservation and abundance of vertebrate fossils, including a rich assemblage of whales and dolphins (Cetacea). Here, we integrate taphonomic data on 890 marine vertebrate fossils, gathered through 16 different localities. Our observations range from the taxonomic distribution, articulation, completeness, disposition and orientation of skeletons, to the presence of bite marks, associations with shark teeth and macro-invertebrates, bone and soft tissue preservation, and the formation of attendant carbonate concretions and sedimentary structures. We propose that the exceptional preservation characterising many Pisco vertebrates, as well as their exceptionally high abundance, cannot be ascribed to a single cause like high sedimentation rates (as proposed in the past), but rather to the interplay of several favourable factors including: (i) low levels of dissolved oxygen at the seafloor (with the intervention of seasonal anoxic events); (ii) the early onset of mineralisation processes like apatite dissolution/recrystallisation and carbonate mineral precipitation; (iii) rapid burial of carcasses in a soupy substrate and/or a novel mechanism involving scour-induced self-burial; and (iv) original biological richness. Collectively, our observations provide a comprehensive overview of the taphonomic processes that shaped one of South America's most important fossil deposits, and suggest a model for the formation of other marine vertebrate Fossil-Lagerstätten.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Fossils*
  • Invertebrates
  • Paleontology
  • Peru

Grants and funding

This study was supported by grants from the Italian Ministero dell’Istruzione dell’Università e della Ricerca to (PRIN Project 2012YJSBMK to G.B.), by the University of Pisa (PRA_2015_0028; PRA_2017_0032 to G.B.), by the Università di Camerino (FAR 2019, STI000102 to C.D.C.), and by National Geographic Society Committee for Research Exploration grants (9410-13 to G.B.; GEFNE 177-16 to O.L.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.