Anisian

The Anisian is a stage of the Middle Triassic epoch in the International Chronostratigraphic Chart (ICS). It spans roughly 247 to 242 million years ago, following the Olenekian stage and preceding the Ladinian. The Anisian is defined by global fossil markers, with boundaries typically marked at Global Boundary Stratotype Sections and Points (GSSPs) or other reference sections where available.

Stratigraphy and paleontology during the Anisian reflect ongoing recovery after the Permian–Triassic extinction event. Fossil assemblages from Anisian rocks include ammonoids and conodonts that help correlate rocks across regions. Terrestrial faunas show diversification of early reptiles and archosauriforms, while marine ecosystems exhibit broad invertebrate radiations and reef development in suitable regions. The interval records a shift toward more complex ecosystems that would persist into the Late Triassic.

Geography and climate of the Anisian were influenced by the late Paleozoic supercontinent configuration, with landmasses largely joined in the supercontinent Pangaea. The climate is generally interpreted as warm, with seasonal variability and episodic aridity, though regional conditions varied and fluctuated over the stage's span.

Overall, the Anisian marks a middle-phase of Triassic recovery and diversification, bridging earlier post-extinction fauna with the later radiations that characterize the Late Triassic. It is a core unit for correlating Triassic rocks and fossil assemblages across continents.