triassic

The Triassic is the first period of the Mesozoic Era, lasting from about 252 to 201 million years ago. It follows the Permian-Triassic extinction event and precedes the Jurassic. During much of the Triassic, the supercontinent Pangaea dominated Earth, producing extreme climates with hot temperatures and arid to semiarid interiors while shallow seas played a key role along continental margins. Global ecosystems gradually recovered from the end-Permian crisis, paving the way for new groups of land and marine life.

The Triassic is divided into Early, Middle, and Late subdivisions, with stages including the Induan and Olenekian in the Early Triassic; the Anisian and Ladinian in the Middle Triassic; and the Carnian, Norian, and Rhaetian in the Late Triassic. After the early recovery, ecosystems diversified more fully, particularly among reptiles. The first true dinosaurs appeared toward the end of the Triassic, alongside early crocodile relatives and other archosaurs. On land, gymnosperms such as conifers, cycads, and ginkgo-like plants were common, while deserts and seasonal climates were widespread. In the seas, ammonoids, conodonts, and various marine reptiles such as ichthyosaurs and early plesiosaurs occupied ecological niches.

The end of the Triassic is marked by a mass extinction, roughly 201 million years ago, which affected many marine and terrestrial groups and is linked to large-scale volcanic activity, including the breakup of Pangaea and the associated climate changes. This event paved the way for the rise of dinosaurs as the dominant terrestrial vertebrates in the Jurassic.