Triassic climate and the rise of the dinosaur empire in South America

The Triassic period (251.9 to 201.4 Ma) is the first period of the Mesozoic Era, initiating after the Permian-Triassic mass extinction and ending at the Triassic-Jurassic mass extinction. This period witnessed the origin of modern ecosystems, and also the rise of the dinosaurs. This influence on both geological and ecological history of the Earth has prompted close attention to the paleoclimate and paleoecology of the Triassic period over the last 60 years. This review builds on past work to summarize knowledge of Triassic climate and ecology, especially focusing on data acquired over the last decade for key South American strata. The main climatic events that occurred in the Triassic period can be subdivided in three key intervals, from the base to top: pre-, syn- and post-Carnian Pluvial Episode (CPE). Each of these three intervals corresponds with major climatic events or episodes, positioned relative to the Permian-Triassic mass extinction, CPE, and Triassic-Jurassic mass extinction. The pre-CPE interval of the Early and Middle Triassic represents relatively warm and dry conditions. The CPE of the earliest Late Triassic marks a global increase in effective precipitation (precipitation minus evaporation) for at least 1-2 Myr, causing major floristic and faunal turnovers and possibly triggering the rise of the dinosaurs. The post-CPE interval of the Late Triassic represents a return to warm and dry conditions. Triassic deposits in Brazil and Argentina represent windows for investigating the interrelationship(s) between changes in climate, floras, and faunas. Alternate triggers for dinosaur diversification are also evaluated, including classical considerations of competition, opportunism, and body temperature, in addition to more novel and subtle factors.