Global Triassic tetrapod biostratigraphy and biochronology

Eight, temporally successive assemblage zones of tetrapod fossils provide the basis for dividing Triassic time into eight land-vertebrate faunachrons. These land-vertebrate faunachrons, their type assemblage zones, and their approximate correlation to the standard global chronostratigraphic scale are (ascending order): (1) Lootsbergian (Lystrosaurus Assemblage Zone, Balfour, Katberg and Burgersdorp formations, Karoo basin, South Africa) = late Dorashamian–Induan; (2) Nonesian (Cynognathus Assemblage Zone, Burgersdorp Formation, Karoo basin, South Africa) = Olenikian; (3) Perovkan (Shansiodon Assemblage Zone, Donguz Formation, Russian Urals) = Anisian; (4) Berdyankian (Mastodonsaurus Assemblage Zone, Bukobay Formation, Russian Urals) = Ladinian–early Carnian; (5) Otischalkian (Paleorhinus Assemblage Zone, Chinle Group, Chinle basin, USA) = late-early to early-late Carnian; (6) Adamanian (Rutiodon Assemblage Zone, Chinle Group, Chinle basin, USA) = latest Carnian; (7) Revueltian (Pseudopalatus Assemblage Zone, Chinle Group, Chinle basin, USA) = Norian; (8) Apachean (Redondasaurus Assemblage Zone, Chinle Group, Chinle basin, USA), = Rhaetian. The Triassic land-vertebrate faunachrons provide a framework for the correlation of Triassic nonmarine deposits with a temporal resolution comparable to the seven Triassic Stage/Ages of the standard global chronostratigraphic scale.