Triassic Period Facts. The Triassic Period was the first period of the Mesozoic Era. A lot happened to Earth and its life-forms during the Triassic but the most celebrated event was the evolution of dinosaurs.The Triassic Period was the first period of the Mesozoic Era, and ran from 248 to 200 million years ago.A lot happened to Earth and its life-forms during the Triassic but the most celebrated event was the evolution of dinosaurs.These remarkable creatures emerged around 230 MYA and dominated the planet throughout the Mesozoic Era. lot happened to Earth and its life-forms during the Triassic but the most celebrated event was the evolution of dinosaurs. These remarkable creatures emerged around 230 MYA and dominated the planet throughout the Mesozoic Era.