“…The extrinsic causal mechanism for the mass extinction remains a topic of ongoing debate, with rapid afforestation, volcanism, global cooling, and transgression among the most speculated triggers (Algeo et al, 1995;Bond & Wignall, 2008;Joachimski & Buggisch, 2002;Lu et al, 2019;Racki et al, 2018). Ongoing discussion also continues around the direct kill mechanism, bringing forward multiple hypotheses such as sulfide poisoning (Chen et al, 2013) and ocean acidification (Kabanov et al, 2023;Zeng et al, 2011). However, there is a broad consensus that the Late Devonian marine environment is overall reducing, leading to prolonged oxygen stress that is considered to be a significant contributing factor to taxonomic and ecological turnovers of marine organisms (Boyer et al, 2021;Carmichael et al, 2019;Lu, Lu, Ikejiri, Sun, et al, 2021).…”