Dinosaurs, the gigantic creatures that ruled the Earth for more than 160 million years, have captured the imagination of mankind since the discovery of their first fossils. To understand how these fascinating creatures emerged, it is essential to go back to the Paleozoic era, when life on Earth began to diversify significantly. The story of the dinosaurs begins at the end of the Permian, about 252 million years ago, just after the largest mass extinction our planet has ever known, which wiped out almost 96% of all marine species and 70% of terrestrial vertebrate species. This mass extinction created an ecological vacuum, leaving fertile ground for the emergence of new life forms during the following period, the Triassic. At the beginning of the Triassic, the Earth offered a radically different landscape: a single supercontinent called Pangaea, characterized by extreme climates. In these harsh conditions, a group of vertebrates called archosaurs began to evolve and diversify. These archosaurs, which shared a common ancestor with modern crocodiles and birds, were the precursors to the dinosaurs. Toward the end of the Triassic Period, about 245 million years ago, the first true dinosaurs appeared. Scientists generally agree that the distinctive features of dinosaurs, such as their upright stance with their legs held vertically under their bodies and an antorbital window (an opening in the skull in front of the eye sockets) marked a significant evolution from their archosaur ancestors. These adaptations allowed dinosaurs to become the dominant land animals because they were so efficient at moving and hunting that they had a considerable advantage over other land animals of their time. Early dinosaurs included creatures like Eoraptor and Herrerasaurus, which were relatively small but extremely agile, allowing them to hunt effectively in the arid and often inhospitable environments of Pangaea. As the Triassic progressed, dinosaurs began to diversify into two main groups: the saurischians, or lizard-pelvis dinosaurs, which included ferocious carnivores and giant bipedal herbivores, and the ornithischians, or bird-pelvis dinosaurs, which were primarily herbivorous. This diversification was accompanied by an increasing variety of shapes and sizes, allowing dinosaurs to colonize a wide range of habitats across Pangaea. The transition from the Triassic to the Jurassic, about 201 million years ago, was marked by another mass extinction, albeit less devastating than that of the Permian. This extinction again reshaped Earth's ecosystems, allowing dinosaurs to consolidate their dominance over the continents. During the Jurassic, many of the existing dinosaur groups diversified further, and new ones appeared, such as the brachiosaurs and stegosaurs. The Mesozoic, often referred to as the Age of the Dinosaurs, was a period of undisputed reign for these creatures, whose diversity reached its peak during the Cretaceous, the final period of the Mesozoic Era. During this period, iconic dinosaurs such as Tyrannosaurus rex and Triceratops roamed the Earth, while others, such as pterosaurs, conquered the skies. The dinosaurs' dominance came to an abrupt end about 66 million years ago, when a mass extinction, likely triggered by an asteroid impact, marked the end of the Cretaceous and Mesozoic Eras. This catastrophic event ended the dinosaurs' reign, allowing other life forms, particularly mammals, to take over and evolve into the diversity we see today. This channel is an official affiliate of the ORBINEA STUDIO network.