The other two epochs of the Triassic were the Lower and Middle Triassic.
Many early dinosaur species appeared for the first time during the Upper Triassic, including Plateosaurus, Coelophysis, and Eoraptor. Pterosaurs were common in the air, and Ichthyosaurs dominated the seas.
At the end of the Upper Triassic some event or events caused the extinction of many animal species worldwide. Known as the end–Triassic extinction event, it was similar to the more famous event that lead to the extinction of the dinosaurs, except no one knows for sure what caused the event.
Carnian pluvial event
Although the Triassic was, in general, a dry period with inland areas often deserts, the Upper Triassis saw a big change.
The Carnian Pluvial Event (CPE) was a major global climate change and biotic turnover (many extinctions) early in the Upper Triassic, ~ 230 million years ago. Shifts in carbon and oxygen isotopes suggest a global warming.
Major changes in organisms responsible for calcium carbonate production occurred during the CPE. Carbonate sedimentation stopped in deep water settings of Southern Italy. High extinction rates occurred among ammonoids, conodonts, bryozoa and crinoids. Major evolutionary innovations followed the CPE, as the first occurrence of dinosaurs, calcareous nannofossils and scleractinian corals.
Upper Triassic Facts for Kids. Kiddle Encyclopedia.