Comment--Contrasting Deep-water Records from the Upper Permian and Lower Triassic of South Tibet and British Columbia: Evidence for a Diachronous Mass Extinction (Wignall and Newton, 2003)

Abstract

“Happy families are all alike, but every unhappy family is unhappy in its own way” Tolstoy (1878). As in this famous first line of Anna Karenina, each Permian–Triassic boundary section is unhappy in its own way. Wignall and Newton (2003) are to be commended for showing that this great mass extinction had different effects at different localities, such as deep oceanic warming in Tibet, but they have not demonstrated their chief claims that (1) mass extinction was globally diachronous by a half million years, or (2) due to dysoxia from oceanic stagnation. Furthermore, their foraminiferal disaster taxa are better explained by a methane-outburst hypothesis (Krull and Retallack, 1999; Berner, 2002), which they fail to mention. There is a difference between diachronous mass extinction, where most species become extinct at different times in different places, and selective survival, where some species survive the mass extinction. Wignall and Newton's (2003) claim for diachroneity comes from range truncation of foraminifera assigned to …