Expanding the ichnological record of the Late Paleozoic Ice Age: A new and diverse trace fossil assemblage from the upper Itararé Group (NE Paraná Basin, Brazil)

The Itararé Group (Paraná Basin) provides crucial evidence of environmental changes during the Late Paleozoic Ice Age (LPIA) in southwest Gondwana. While body fossils are scarce, trace fossils are abundant, offering valuable insights into glacial and deglacial ecosystems. Most studies have focused on the basin’s southern deposits, leaving its northern areas largely unexplored. This work documents a newly discovered trace fossil assemblage from São Paulo State, located in the northeastern Paraná Basin, and in the upper part of the Itararé Group, significantly expanding the local ichnological record and shedding light on unexplored northeastern and upper Itararé Group deposits. The ichnoassemblage occurs on heterolithic bedding planes deposited by turbidity currents in a prograding deltaic system, with sparse evidence of direct glacial influence. It comprises two distinct trace fossil suites: (i) a simple trail-dominated suite and (ii) an arthropod trackway-dominated suite. They represent a mixed Mermia-Scoyenia ichnofacies, likely within a freshwater setting. With twenty-one ichnotaxa and six architectural designs, this assemblage exhibits a much higher diversity and complexity than previous records from glacially influenced deposits in the northern side of the Paraná Basin, and comparable with the most studied sections of the southern Itararé Group. These findings suggest that climate amelioration during a deglaciation phase influenced substrate conditions and benthic community structures, supporting the idea that environmental shifts played a key role in shaping LPIA ecosystem structures. This enhanced record strengthens our understanding of how life responded to climatic transitions during the LPIA and underscores the potential of southwestern Gondwana for further paleoenvironmental research