What is a "dinosaur"?

A dinosaur is a reptile that lived millions of years ago and dominated the Earth during the Mesozoic Era. They varied greatly in size, shape, and behavior, with some being as small as a chicken and others as large as multiple-story buildings. Dinosaurs had unique adaptations like bipedal or quadrupedal locomotion, sharp teeth, and sometimes even feathers. They ruled the land for over 160 million years before facing extinction, leaving behind a rich fossil record that continues to fascinate scientists and capture the imagination of people around the world.