Autor(es)

Varejao, Filipe Giovanini ; Warren, Lucas Verissimo ; Rodrigues, Mariza Gomes ; Assine, Mario Luis ; Simoes, Marcello Guimaraes

• Tipo de documento: Artigo Científico
• Fonte: SEDIMENTARY GEOLOGY; v. 470, p. 16-pg., 2024-06-22.

Resumo

The Crato Konservat-Lagerstiitte is one of the main Mesozoic fossil sites from Gondwana, recording a wide diversity of terrestrial and non-marine aquatic fossils of great paleobiological and evolutionary signi ficance. This conservation deposit is recorded in a 9 m-thick interval of laminite, microbialite, and grainstone deposited in a lake system with variable water level, alternating moments of hypersaline and freshwater conditions. Despite numerous studies describing new species of plants, arthropods, fish, pterosaurs, birds, and many others, there remains a signi ficant gap in our understanding of the most common and archetypal fossils, which are the rod-shaped macrofossils found on bedding surfaces in distinct stratigraphic intervals of the Crato Konservat-Lagerstiitte . The rodshaped macrofossils are up to 1.6 cm-long and 0.1 cm-wide, straight to curved compressions that preserve pyritized microfossils. Here we interpret the rod-shaped macrofossils as macroscopic organic aggregates that sank into the lakebed in a process called lake snow. During high organic productivity periods in the epilimnion, planktonic organisms thrived and produced exopolymers responsible for aggregation. Their concentrations in the limestone bedding planes re flect intensity of lake snow and environmental seasonality. Aggregates are prolate particles that are commonly oriented, suggesting their transport as bedload for short distances, which was facilitated by biostabilization by microbes and their exopolymers. Finally, pyritization was mediated by microbial communities living in the lakebed. (c) 2024 Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies. (AU)

• Processo FAPESP: 16/13214-7 - Abordagem multi-indicadores do sistema misto carbonático-siliciclástico da Formação Crato: evolução sedimentar, paleogeografia e tectônica
• Beneficiário: Filipe Giovanini Varejão
• Modalidade de apoio: Bolsas no Brasil - Doutorado