The Triassic Period began after the devastating Permian-Triassic extinction event also known as the Great Dying, the largest mass extinction in Earth's history. During this time entire life on planet earth almost went extinct with 96% of sea and 70% of all land life forms disappearing in a timeline of 60000 years. It took almost 50 million years for life to recover from this event, with new evolutionary experiments appearing across land and sea.
During this time, Earth's continents were still united as the supercontinent Pangaea. Reptiles diversified, with the first dinosaurs and mammals making their appearance. Climate was hot and dry, shaping desert-like environments across vast regions.
The Triassic ecosystem was characterized by recovery and innovation. With most of Earth's landmass consolidated into Pangaea, interior regions experienced extreme seasons and arid conditions. Flora was dominated by drought-resistant plants like conifers, cycads, and ferns. River systems and oases provided crucial habitats for emerging reptiles. The first coral reefs began forming in warm shallow seas, creating new marine habitats. This period saw the establishment of modern-style ecosystems with complex food webs, though they were less diverse than in later periods. The emergence of the first dinosaurs represented a major shift in terrestrial ecosystems that would define the rest of the Mesozoic Era. During this period roughly 80% of all species were marine, with the rest being terrestrial. The dominant land animals were archosaurs, which included the ancestors of crocodiles and dinosaurs. The first true dinosaurs appeared in the late Triassic, but they were not yet dominant. Instead, large amphibians and crocodile-like reptiles called phytosaurs were among the top predators. In the oceans, marine reptiles like ichthyosaurs and plesiosaurs thrived, along with ammonites and other invertebrates. During the middle Triassic roughly 234-232 million years ago, Earth went through another mini extinction event, the Carnian Pluvial Event, a 2 million year period of non-stop raining. This was likely caused by volcanic activity and climate change. This event led to significant changes in ecosystems and may have paved the way for the rise of dinosaurs in the late Triassic.
The end of the Triassic period is marked by the Triassic–Jurassic extinction event. This event was caused by different, massive volcanic activity—the Central Atlantic Magmatic Province (CAMP)—which released huge volumes of carbon dioxide and caused global warming and ocean acidification. It wiped out about 76% of all marine and terrestrial species This event opened the door for dinosaurs to dominate in the following Jurassic Period.