Dinosaurs were a diverse group of reptiles that roamed the Earth during the Mesozoic Era, approximately 230 to 65 million years ago. They varied greatly in size, shape, and habitat, ranging from the towering Brachiosaurus to the small, bird-like Velociraptor. Dinosaurs are often classified into two main groups: the Saurischia and the Ornithischia. These fascinating creatures are known for their unique adaptations and evolutionary significance. Some dinosaurs, like the Tyrannosaurus rex, were fierce predators, while others, such as the Triceratops, were herbivores with distinctive features. The extinction of dinosaurs around 65 million years ago remains a subject of scientific study and intrigue.