Published online by Cambridge University Press: 13 October 2009
Both before and after the biologic events near the Permian–Triassic boundary, large-scale extinctions and new appearances of organisms occurred at higher taxonomic levels. Each taxonomic unit has its own terminal phylogenetic history, showing a distinctive disappearance pattern in various ways. Permian corals have been reported from many regions of the world, but the Rugosa became extinct at the end of the Permian (Oliver, 1980; Ezaki, 1989), first disappearing in the Boreal province arid finally in the Tethys province at the latest Changxingian. Although the local disappearance events of rugose corals obviously were heterochronous, all Rugosa had disappeared by the time of formation of the mixed-fauna beds described by Yin (1985). There were no Triassic representatives, which makes positive biostratigraphic determination of the Permian–Triassic boundary using Rugosa impossible. The occurrences of late Permian corals were restricted geographically, but specific groups survived in conditions that were suitable for them. Permian Rugosa provide important case examples of the patterns and processes of the end-Permian extinction and their relationships to environments.
Upper Permian stratigraphy and interregional correlations have been intensively studied in each Tethyan region. Stratigraphic schemes for the Upper Permian have been proposed, for example, by Kotlyar et al. (1989) and Nakazawa (1993), and the standard Permian stratigraphy is based on detailed biostratigraphic analyses, especially using fusulinids, conodonts, and ammonoids.