Comment on 'Fusiline biotic turnover across the Guadalupian-Lopingian (middle-upper Permian) boundary in mid-oceanic carbonate build-ups: Biostratigraphy of accreted limestone in Japan' by Ayano Ota and Yukio Isozaki

摘要

The recent paper by Ota and Isozaki (2006) is an important contribution to ongoing studies of the Permian world and the mass extinctions marking the ends of the Middle (～260 Ma) and Late Permian (～251 Ma). Both events were considerably larger than the Cretaceous-Tertiary boundary episode (e.g., Sepkoski, 1996), and their separation in time of just nine million years suggests that the environmental system of Permian Earth was particularly vulnerable to stress. Thus, a detailed understanding of the two extinctions, including their causal mechanisms, as well as the background state of the intervening interval would tell us much about the planet's biological development over this key period.