Dinosaur

Dinosaurs were reptiles that lived through three periods of Earth's geologic history: Triassic (208-245 million years ago), Jurassic (145-208 million years ago), and Cretaceous (65-145 million years ago). Different species of dinosaurs flourished and then became extinct throughout these three periods. All dinosaurs were reptiles, but not all reptiles were dinosaurs. Even though the name "dinosaur" means "terrible lizard," dinosaurs were not lizards at all.