The Triassic Period (252-201 million years ago) began after Earth's worst-ever extinction event devastated life.
The Permian-Triassic extinction event, also known as the Great Dying, took place roughly 252 million years ago and was one of the most significant events in the history of our planet. It represents the divide between the Palaeozoic and the Mesozoic Eras.
The cause of the Permian-Triassic extinction event is not fully understood. Various theories have been proposed, such as an unknown asteroid impact, massive volcanic eruptions in what is now Siberia, the release of methane from the depths of the oceans, sea level change, increasing aridity, or a combination of many of these.
By some estimates, it may have taken up to 10 million years for the planet to recover from the devastation caused by the Great Dying.