Abstract: A brief historical review of ammonoid-based Permian biostratigraphy is performed. Changes in ammonoid associations are shown for each of nine Permian stages. The major correlation problems were discussed. A renewed ammonoid zonal scale is proposed.

Abstract: Conchostracans are one of the most common fossil animal groups of continental deposits from late Palaeozoic to modern times. Their habitats have ranged from perennial lakes of the Carboniferous and Early Permian to seasonal playa lakes and temporary ponds from the late Early Permian into the Triassic, where they could form mass occurrences. This, together with relatively high speciation rates, makes them ideal guide fossils, especially in otherwise fossil-poor wet and dry red beds. Based on material and data collected since the 1980s from both surface outcrops and well cores in central Europe, a preliminary conchostracan zonation is proposed. We used a conservative approach, erecting assemblage zones comprising two or three species instead of species-range zones with only one or, sometimes, two forms. Assemblage zones are more robust and provide more reliability for each delineated time interval. Isotopically dated occurrences of conchostracan zone species, or co-occurrences of conchostracans, insect zone species and marine index fossils such as conodonts and fusulinids, allow us to correlate our assemblage zones with the marine Standard Global Chronostratigraphic Scale.

Abstract: The most extensive Permian tetrapod (amphibian and reptile) fossil records from the western USA (New Mexico to Texas) and South Africa have been used to define 11 land vertebrate faunachrons (LVFs). These are, in ascending order, the Coyotean, Seymouran, Mitchellcreekian, Redtankian, Littlecrotonian, Kapteinskraalian, Gamkan, Hoedemakeran, Steilkransian, Platbergian and Lootsbergian. These faunachrons provide a biochronological framework with which to assign ages to, and correlate, Permian tetrapod fossil assemblages. Intercalated marine strata, radioisotopic ages and magnetostratigraphy were used to correlate the Permian LVFs to the standard global chronostratigraphic scale with varying degrees of precision. Such correlations identified the following significant events in Permian tetrapod evolution: a Coyotean chronofaunal event (end Coyotean); Redtankian events (Mitchellcreekian–Littlecrotonian); Olson’s gap (late Littlecrotonian); a therapsid event (Kapteinskraalian); a dinocephalian extinction event (end Gamkan); and a latest Permian extinction event (Platbergian–Lootsbergian boundary). Problems of incompleteness, endemism and taxonomy, and the relative lack of non-biochronological age control continue to hinder the refinement and correlation of a Permian timescale based on tetrapod biochronology. Nevertheless, the global Permian timescale based on tetrapod biochronology is a robust tool for both global and regional age assignment and correlation. Advances in Permian tetrapod biochronology will come from new fossil discoveries, more detailed biostratigraphy and additional alpha taxonomic studies based on sound evolutionary taxonomic principles.