The organic walled microfossils were found in 15 different outcrops distributed along the Brazilian states of Minas Gerais, Paraná, Santa Catarina and Rio Grande do Sul (Fig. This suggests that specific physical–chemical processes related to the peperite formation have contribute to improved preservation of microfossils. Unexpectedly, the studied peperite deposits yielded a higher microfossiliferous content in terms of diversity and abundance relative to the volcanoclastic sandstones. They are critically the first case of paleontological remains known from Mesozoic wet peperite deposits, as previous findings have exclusively recorded at the Palaeogene Staffa Formation 23. Although there have been few mentions of ostracods in this province before 22, these organic walled microfossils represent the first documented fossil recovered from this LIP. In this study, we report an assemblage of organic walled microfossils extracted from wet peperite rocks, sandstones and interpillow sandstones from the PE-LIP in Brazil. Despite the availability of sedimentological and geochemical data, the PE-LIP lavas have not been investigated in terms of their paleobiological significance because igneous rocks are typically considered as non-conducive to the preservation of fossilized biological remains. Recent data from sedimentary and volcaniclastic rocks interbedded with PE-LIP lavas in Brazil suggests that the SO 2 degassing process from volcanism caused a climate cooling and restructured the precipitation pattern 8, resulting in more humid conditions at the Paraná Basin. Alternatively, it has also been proposed that the PE-LIP might have caused a cooling phenomenon at the end of the volcanism 19, 20, 21. Although the correlation between the PE-LIP and the WE 13, 17, 18 remains uncertain, it has been suggested that CO 2 degassing processes triggered global warming and affected the hydrological cycle 10, 15, 18.

In particular, the WE is marked by a positive δ 13C excursion, and is often linked to a minor biotic crisis 13, 14, 15, 16, 17, 18.

This volcanic activity is related with the opening of the South Atlantic Ocean, and thought to have contributed to the Weissert Anoxic Event (WE) 9, 10, 11, 12, 13, 14, and to the proliferation of more humid climate conditions in Paraná Basin of Brazil during the Valanginian (c. The Paraná-Etendeka Large Igneous Province (PE-LIP) is a well-known magmatic event 1, 2, 3, 4, 5, 6, 7, 8 from the Early Cretaceous. We corroborate the potential of wet peperite rocks as a valuable source of paleobiological data and emphasize the importance of sampling volcaniclastic units that have been traditionally considered with lower fossiliferous potential due to their igneous origin. Our findings represent the first insight into the biodiversity of the Paraná Basin during the Early Cretaceous during a period of intense magmatism, and the microfossil assemblages corroborate a regional paleoclimatic transition from arid to more humid conditions that were likely induced by the volcanic activity. In addition to the peperites, organic walled microfossils were also found in heterolithic sandstones and interpillow sandstones. The organic walled microfossils recovered from the Paraná-Etendeka peperites include pollen grains, spores, acritarchs, and other remains of unidentifiable organic matter. 132 Ma) as a continental flood basalt in present day South America and Namibia, and released enormous amounts of carbon dioxide, sulfur dioxide, methane and hydrogen fluoride into the atmosphere.

Wet peperites are a volcaniclastic rock formed by the interaction of lava and subaqueous sediments.The Paraná-Etendeka was formed during the Valanginian (ca. Here, we provide the first paleontological evidence for organic walled microfossils extracted from wet peperites from the Early Cretaceous Paraná-Etendeka intertrappean deposits of the Paraná basin in Brazil. LIPs provide an excellent sedimentological and geochemical record of short but intense periods of geological activity in the past, but their contribution towards understanding ancient life is much more restricted due to the destructive nature of their igneous origin. Large igneous provinces (LIPs) are major magmatic events that have a significant impact on the global environment and the biosphere, for example as triggers of mass extinctions.

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