Dinosaurs are a diverse group of reptiles that first appeared during the Triassic period, about 245 million years ago. They were the dominant terrestrial vertebrates for over 180 million years, until their extinction at the end of the Cretaceous period, about 65 million years ago. Dinosaurs were a highly successful group of animals, and they adapted to a wide range of habitats, from forests to deserts to swamps. They were also the ancestors of birds, which are the only living dinosaurs today.
Dinosaurs are often depicted as large, fearsome creatures, but they actually came in a wide range of sizes, from the tiny Microraptor, which was about the size of a pigeon, to the enormous Argentinosaurus, which was over 100 feet long and weighed over 100 tons. Dinosaurs were also incredibly diverse in their diets, with some being herbivores, some being carnivores, and some being omnivores. They played a major role in the Earth’s ecosystems, and their extinction had a profound impact on the planet’s history.