Dinosaurs: The Rise and Fall

The first dinosaurs lived around 200 million years ago with a large reptile population. There were enormous creatures that resembled crocodiles, hefty plant-eating animals, and even four-legged runners with vicious, tyrannosaur-like heads.

However, as the Triassic era was drawing to an end, something unexpected occurred. All those competing lineages were finally wiped out when the planet underwent a series of catastrophic transformations. The dinosaurs that were the size of chickens and dogs endured, thrived, and developed into the enormous creatures we know today.

The biggest extinction catastrophe to ever affect life on Earth (252-201 million years ago) marked the start of the Triassic Period. One of the most important catastrophes in the history of our planet was the Permian-Triassic extinction event, sometimes referred to as the Great Dying, which occurred around 252 million years ago. The difference between the Palaeozoic and Mesozoic eras is symbolised by it.

It is still unclear what caused the Permian-Triassic extinction catastrophe. Many hypotheses have been put out, including an unidentified asteroid impact, large-scale volcanic eruptions in what is now Siberia, the release of methane from the ocean's depths, sea level change, rising aridity, or a combination of many of these.

Whatever the cause of the extinction event, the outcome was disastrous for a sizable portion of life. According to some estimates, up to 90% of all species went extinct as a result of the Great Dying. It wiped out several insect species, a sizable population of reptiles that resembled mammals, and the whole population of trilobites, a species that had lived in the waters for for 300 million years.

Extinction events dominate the definition of the Triassic, although the continents' locations at that time also play a significant role. Pangea was the lone supercontinent that existed. The conifers first began to proliferate in the early Triassic. Conifers developed enormous forests with individual trees reaching heights of up to 30 metres since blooming plants and grasses had not yet evolved. Other conifer growth forms, including shrubs and woody vines, that do not exist now would have been abundant in the understory.

What appeared on land when animal life started to rebound wasn't much that different from what had been there before. The little Lystrosaurus, a herbivorous synapsid or mammal-like reptile, was the most prevalent vertebrate on land.

The earliest sphenodonts arose at the same time as ichthyosaurs began to diverge. They are the sister group of lizards and snakes and are currently only represented by one species, the tuatara. Despite having a very similar appearance to lizards, they belong to a different ancestry. The Triassic lizards were more diversified than their modern-day counterparts, yet they served the same ecological functions.

Similar to how it started, the Triassic ended. By 201.3 million years ago, the climate had begun to alter, causing another major extinction to occur on Earth. Massive volcanic activity occurred in what is now the Atlantic Ocean for reasons that are still not fully understood. These eruptions, which are collectively referred to as the Central Atlantic Magmatic Province (CAMP), are likely to have caused significant climate changes because they emitted so much carbon dioxide or sulphur dioxide.

The seas started to get more acidic, and sea levels started to rise. The severe extinctions in the seas, including the entire extinction of conodonts, are likely to have been caused by this. There was a lot of change on the ground since terrestrial life likewise suffered greatly. Aside from dinosaurs, pterosaurs, and crocodiles, no Triassic archosaurs survived.

This allowed the remaining dinosaurs to take over many of the settings that the archosaurs had previously occupied, while their tiny mammalian cousins continued to scurry around the forest floors.