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The Hirnantian Ice Age had a significant impact on marine invertebrate biota at the end of the Ordovician due to drastic cooling and falling sea levels. The Parnaíba Basin (NE Brazil) was located closer to the South Pole during the Hirnantian and exhibits significant ichnofaunal turnover in the Serra Grande Group deposits, which represent the filling of the basin during the Late Ordovician to the Early Silurian. The benthic biota inhabiting the Parnaíba Basin during the Hirnantian is represented by the glacial paleoichnocenosis, preserved in the diamictites of the upper portion of the Ipú Formation. The local occurrence and low ichnodiversity of the glacial assemblage indicate harsh conditions during the Hirnantian cooling. Resting/dwelling traces of large burrowing sea anemones ( Conichnus isp.) and burrows of potential commensal or scavenger organisms ( Palaeophycus tubularis ) are the main components of the ichnofossil assemblage, suggesting severe restrictions on the ecological space occupation by endobenthic organisms. In contrast, the postglacial deposits of the Tianguá and Jaicós formations exhibit greater ichnodiversity, as evidenced by the 27 ichnotaxa and several unidentified ichnofossils that form distinct suites preserved in delta plain, tidal flats, prodelta, and delta front settings. The glacial paleoichnocenosis of the Serra Grande Group is convergent with the few Hirnantian ichnofauna found in Gondwanan deposits, whereas the Llandovery postglacial paleoichnocenosis resembles those documented worldwide since the early Llandovery. Despite the abrupt decrease in ichnodiversity in Gondwana terranes throughout the Hirnantian, ichnodisparity remained high, indicating that the main ecological niches continued to be active and were occupied by tolerant species. The preponderance of plug-shaped burrows, likely produced by soft-bodied cnidarians in Gondwana’s Hirnantian ichnofauna, supports the idea that these organisms tolerated the significant physicochemical variations generated by glaciation in shallow seas. In contrast, postglacial deposits exhibit greater ichnodiversity, suggesting that the ichnofauna was substantially renewed as a result of the worldwide eustatic sea-level rise during the Llandovery stage.