The Triassic–Jurassic transition.: A review of environmental change at the dawn of modern life

Abstract

The Triassic–Jurassic transition, which is here broadly defined as extending from the Late Triassic through the Early Jurassic (~237 Ma to 174 Ma), was an important interval in Earth history. The end-Triassic mass extinction (ETME), at ~201 Ma, ranks among the ‘Big Five’ Phanerozoic mass extinctions. It largely completed the shift from the ‘Paleozoic Evolutionary Fauna’ to the ‘Modern Evolutionary Fauna’ that had been initiated by the end-Permian mass extinction, and may have contributed to the ‘Mesozoic Marine Revolution’ and rise of dinosaurs to dominance in terrestrial environments. In addition, the Triassic–Jurassic transition encompasses a second-order mass extinction during the early Toarcian oceanic anoxic event (T-OAE), at ~181 Ma. The ETME was triggered by Central Atlantic Magmatic Province (CAMP) magmatism, and the T-OAE by Karoo-Ferrar Large Igneous Province (KFLIP) magmatism, both associated with the stepwise disintegration of the Pangean supercontinent. These events led to major changes in continental and marine habitats, including climatic warming, ocean acidification, and widespread watermass anoxia, that produced a cascade of lethal environmental stresses. This article undertakes a review of the ETME and T-OAE mass extinctions, the large igneous province eruptions that triggered those biotic events, and the web of environmental changes that linked them together.