1. IntroductionThe Permian to Triassic interval was a time of major perturbationsin the Earth's system. The change began with the crisis at the end ofthe Guadalupian, followed by major devastation near the Permian–Triassic boundary (PTB), and continued with several severe eventsduring the Early to Middle Triassic (Erwin, 2006; Payne et al., 2004;Isozaki et al., 2007). These events resulted in major demises of life onland and in sea, caused significant exchanges among reservoirs ofcarbon, and produced a disturbance in the way carbonate a (Payne etal., 2004; Erwin, 2006; Heydari et al., 2008). These events constitutesome of the most significant perturbations of the Phanerozoic whosecasual mechanisms remain unresolved.The most extensively studied of these events is the one at the PTB.Among many proposed scenarios, four are highly emphasized (seeHeydari et al., 2008). They include the following: suffocation oforganisms due to the lack of oxygen and in some cases the presence ofhydrogensulfide(Weidlichetal.,2003;Kumpetal.,2005),physiologicalcharacteristics of organisms in dealing with harsh environments (Knollet al., 1996), Siberian Trap volcanism-driven processes (Payne andKump, 2007), and changes in chemical composition of seawater due toinjection of massive amounts of gas hydrate methane into thehydrosphere and its consequence for the atmosphere (Heydari andHassanzadeh, 2003; Heydari et al., 2008). It is unclear whether theexplanations proposed for the PTB can also be applied to other eventsthat affected the Earth during the Permian to Triassic time interval.The aim of this contribution is to provide a close look at thesedimentology, paleontology, and geochemistry of strata ranging inage from the Permian to the Triassic in order shed additional lights onthenatureoftheprocessesthataffectedtheEarthatthattime.Articlespresented in this special issue are derived from a meeting at theGeological Society of America.S.-Z. Shen, et al. (“End-Permian mass extinction and palaeoenvir-onmental changes in Neotethys: evidence from an oceanic carbonatesection in southwestern Tibet”) studied 350 m of Upper Permian toLower Triassic carbonate strata in Tibet. They present compositeranges of brachiopods, ostracods, rugose corals, and foraminifers attheGyanyimasectionandsuggestthatevolutionanddiversificationofPermianmarineorganismscontinuedto theend-Permianprecedingamajor faunal extinction close to the PTB. The mass extinctioncoincided with a 2–3‰ PDB negative shift of δ