| Autor: |
Becker-Kerber B; Programa de Pós-Graduação em Ecologia e Recursos Naturais, Universidade Federal de São Carlos, Washington Luiz, 325 km, São Carlos (SP) 13565-905, Brazil.; Unité Mixte de Recherche (UMR), Centre National de la Recherche Scientifique (CNRS), IC2MP 7285, University of Poitiers, 86073 Poitiers, France., de Barros GEB; Programa de Pós-Graduação em Biologia Comparada, Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto (FFCLRP), Universidade de São Paulo (USP), Avenue Bandeirantes, 3900-Vila Monte Alegre, 14049-900, Ribeirão Preto, São Paulo, Brazil., Paim PSG; Programa de Pós-Graduação em Geologia, Universidade do Vale do Rio dos Sinos, 93.022-750, São Leopoldo (RS), Brazil., Prado GMEM; Programa de Pós Graduação em Geoquímica e Geotectônica, Instituto de Geociências, Universidade de São Paulo (USP), Avenue Bandeirantes, 3900-Vila Monte Alegre, 14049-900, Ribeirão Preto, São Paulo, Brazil., da Rosa ALZ; Petrobras, Santos (SP), Brazil., El Albani A; Unité Mixte de Recherche (UMR), Centre National de la Recherche Scientifique (CNRS), IC2MP 7285, University of Poitiers, 86073 Poitiers, France., Laflamme M; Department of Chemical and Physical Sciences, University of Toronto Mississauga, 3359 Mississauga Road, Mississauga, Ontario, Canada L5 L 1C6. |
| Abstrakt: |
Precambrian filamentous microfossils are common and diverse. Nevertheless, their taxonomic assignment can be difficult owing to their overall simple shapes typically lacking in diagnostic features. Here, we report in situ communities of well-preserved, large filamentous impressions from the Ediacaran Itajaí Basin ( ca 563 Ma) of Brazil. The filaments are uniserial (unbranched) and can reach up to 200 µm in width and up to 44 mm in length. They occur as both densely packed or sparsely populated surfaces, and typically show a consistent orientation. Although simple in shape, their preferred orientation suggests they were tethered to the seafloor, and their overall flexibility (e.g. bent, folded and twisted) supports a biological (rather than sedimentary) affinity. Biometric comparisons with modern filamentous groups further support their biological affinity, suggesting links with either large sulfide-oxidizing bacteria (SOB) or eukaryotes. Other morphological and palaeoecological characteristics further corroborates their similarities with modern large filamentous SOB. Their widespread occurrence and association with complex Ediacaran macrobiota (e.g. frondose organisms, Palaeopascichnus ) suggest that they probably played an important role in the ecological dynamics of these early benthic communities by providing firm substrates for metazoans to inhabit. It is further hypothesized that the dynamic redox condition in the latest Ediacaran, with the non-continuous rise in oxygen concentration and periods of hypoxia, may have created ideal conditions for SOB to thrive. |
