Dinosaurs were a diverse group of prehistoric reptiles that ruled the Earth for over 160 million years. These ancient creatures varied greatly in size, from small, bird-like predators to massive, long-necked herbivores. They thrived during the Mesozoic Era, divided into the Triassic, Jurassic, and Cretaceous periods, before facing extinction around 65 million years ago. Fossils discovered worldwide provide evidence of their existence, revealing fascinating details about their anatomy, behavior, and habitats. Some dinosaurs, like the mighty Tyrannosaurus rex and the horned Triceratops, continue to captivate imaginations through books, films, and museum exhibits. Their evolutionary legacy lives on in modern birds, which scientists believe descended from theropod dinosaurs. The study of dinosaurs, paleontology, helps us understand Earth’s ancient ecosystems and the forces that shaped life on our planet.