The end-Guadalupian (259.8 Ma) biodiversity crisis: the sixth major mass extinction?

The modern loss of species diversity has been labelled the 'sixth extinction' subsequent to the five major mass extinctions widely recognised in the Phanerozoic geologic record - the end-Ordovician (443.8 Ma), the Late Devonian (372.2 Ma), end-Permian (251.9 Ma), end-Triassic (201.4 Ma) and end-Cretaceous (66 Ma) events. Rankings in terms of numbers of genera suffering extinction, and especially in terms of ecological impact, however, put the end-Guadalupian (end-Capitanian) (259.8 Ma) extinction event in the same category with the other major mass extinctions. Thus, there were apparently six major Phanerozoic mass extinctions, and the current loss of species should perhaps be called the 'seventh extinction'.

Automated summary

The modern loss of species diversity is labeled as the 'sixth extinction', following five major mass extinctions recognized in the Phanerozoic geologic record. However, the impact of the end-Guadalupian (end-Capitanian) extinction event is similar to the other major mass extinctions, suggesting there may have been a 'seventh extinction' instead.