Racki and Wignall have questioned “whether the mechanism proposed by Murphy et al. (2000a) can account for the [Late Devonian] marine extinctions” and cite three main points of contention with our interpretations. Before addressing their arguments we must correct some inaccuracies in their synopsis. First, we did not conclude that euxinic conditions developed during deposition of the New York Kellwasser equivalents. Redox-sensitive trace element data actually indicate depositional conditions similar to those of the late Givetian Geneseo Formation (Murphy, 2000). Second, enhanced N release from organic matter does not necessarily represent a “background” state. Aller's (1994) experiments showed...

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