The Middle Permian (Capitanian) mass extinction on land and in the oceans

Abstract

A Middle Permian mass extinction, first discovered in 1994, has become known as the "end-Guadalupian event" in the literature. However, recent studies of foraminifera- and brachiopod-range truncations in conodont-dated sections on the South China Block have shown that the losses occur below this level, in the middle of the Capitanian Stage. Extinctions were suffered by several other groups, notably the corals, whilst the mollusc record is more enigmatic. A major bivalve crisis has been reported in some studies, the giant alatoconchids being notable victims, but not others. Gastropods were unaffected by the crisis whilst a roughly contemporaneous ammonoid mass extinction may have occurred in the Early Wuchiapingian, a few million years after the main marine losses. Compilation of data from plant species in South China reveals a significant 24% loss, suggesting that the Capitanian crisis also occurred on land. An intra-Capitanian extinction of 56% of plant species in North China Block sequences may also have coincided with these losses. Correlation of these marine and terrestrial extinction events, using the palaeomagnetic record, provides two alternatives: either turnover amongst plant species is contemporaneous with the marine extinction (and the eruption of the Emeishan flood basalt province in southwest China); or plant losses post-date the marine extinction and instead coincide with the waning phase of the igneous province. Current understanding of the major dinocephalian extinction suggests this event occurred during the preceding stage (the Wordian), but future improvements in both sampling and dating this tetrapod crisis may reveal a synchronicity of plant, animal and marine invertebrate extinctions. The clear temporal link of the Capitanian marine extinction with Emeishan volcanism suggests that these flood basalt eruptions triggered the crisis. A contemporaneous, major negative C isotope excursion suggests that, like many other mass extinction events, methane release from hydrates may also be implicated. However, in the best-dated Chinese sections the main excursion is found to slightly post-date the extinction which occurs at the end of an unusual (and unexplained) interval of exceptionally heavy δ 13C values. Other "usual suspects" for mass extinctions either lack geological and palaeontological evidence (e.g. marine anoxia and global cooling) or do not precisely correlate with the extinction (e.g. major, eustatic regression). © 2010 Elsevier B.V.