First Ediacaran Fauna Occurrence in Northeastern Brazil (Jaibaras Basin, ?Ediacaran-Cambrian): Preliminary Results and Regional Correlation

Abstract

This study reports the first known occurrence of the Ediacaran fauna in northeastern Brazil (at Pacujá Municipality, northwestern state of Ceará) and presents preliminary interpretations of its significance. Regional correlation indicates that the fossils originated in the Jaibaras Basin and that they may represent a new geological system. The depositional environment can be attributed to a fluviomarine system. Nine Ediacaran species can be identified, including members of pandemic groups (e.g., Charniodiscus arboreus Glaessner, 1959; ?Charniodiscus concentricus Ford, 1958; Cyclomedusa davidi Sprigg, 1947; Ediacaria flindersi Sprigg, 1947; and Medusinites asteroides Sprigg, 1949) and endemic groups (e.g., Kimberella quadrata Glaessner & Wade, 1966; Palaeophragmodictya reticulata Gehling & Rigby, 1996; Parvancorina minchami Glaessner, 1958; and Pectinifrons abyssalis Bamforth, Narbonne, Anderson, 2008). Three ichnogenera are also present: Arenicolites Salter, 1857; Palaeophycus Hall, 1987; and Planolites Nicholson, 1873. The relative age of the deposits is between ?Ediacaran and Cambrian, and the fauna resembles the White Sea Assemblage. The bioturbation presents typical unbranched Ediacaran ichnogenera with little depth in the substrate. This previously unknown occurrence of the Ediacaran fauna reinforces the importance of the state of Ceará to Brazilian and global palaeontology.

Ediacaran discs from South America: probable soft-bodied macrofossils unlock the paleogeography of the Clymene Ocean

“…Apart of skeletal records of acritarchs 16 18 , calcified or organic-walled macroscopic Cloudina lucianoi 14 , Corumbella werneri 13 and extremely rare conulariids 17 recorded in the Ediacaran Corumbá Group, Mato Grosso do Sul, Brazil, impressions of macroscopically complex, soft-bodied organisms are scarce in South American deposits of this age 22 23 24 . Siliciclastic sedimentary strata preserved in the Neoproterozoic Itajaí Basin, southern Brazil, record poorly preserved impressions assigned to Parvancorina sp., Charniodiscus ?…”

“…and Cyclomedusa sp 23 . On the other hand, supposed impressions of soft-bodied specimens were reported from a fluvio-marine succession in the probably Cambrian Jaibaras Basin, northeastern Brazil 24 . However, the nature of those “impressions” is still controversial, mainly due to: (a) their extremely poor preservation, (b) the deep weathering of structures and rock matrix, (c) their preservation within a fluvio-marine succession, (d) the low number of structures in the same bedding plane (except for the Jaibaras Basin), in clear contrast with their large abundance in the best known Ediacaran occurrences 4 , (e) their much larger sizes when compared with other well-accepted records, and (f) unreliable depositional ages of the units containing the dubious structures or fossils (especially in the case of the Jaibaras Basin).…”

Correlations of some Neoproterozoic carbonate-dominated successions in South America based on high-resolution chemostratigraphy

“…There, limestone-marl rhythmites occur at the base, which pass into dark gray to black, finely laminated, organic-rich limestones, at the top. Barroso et al (2014) reported the occurrence of probable soft-bodied Ediacaran fossils in the overlying Jaibaras Group, similar to the White Sea assemblage, which could assure an Ediacaran age to this unit (560 -542 Ma, Narbonne 2005; Chiglino et al (2015). Fedonkin et al 2007).…”

Astrobiologia: uma ciência emergente

“…Por exemplo, a bactéria Acidithiobacillus ferrooxidans, além de ser capaz de crescer a partir da oxidação de enxofre elementar, consegue crescer através da oxidação de Fe +2 , fixando CO 2 e produzindo atp. Devido a esse metabolismo, é um importante organismo modelo para quimiolitotróficos e tem sido estudada e aplicada nas áreas de biotecnologia e bioprospecção (Nemati et al, 1998;Yang et al, 2009). Porém, é um metabolismo extremamente pouco eficiente, uma vez que produz muito pouco atp (diferença muito pequena entre o potencial de redução do par redox Fe +2 /Fe +3 e o aceptor final de elétrons, O 2 /H 2 O) e gasta uma grande quantidade de atp para gerar poder redutor (grande diferença entre o potencial de redução do par redox Fe +2 /Fe +3 e o aceptor final nadp +/ nadph).…”