Dinosaurs roamed our planet around 150 million years ago. They are now extinct but you can visit there bones that archeologist have found throughout the world at the Natural History Museum in New York City. You will see the Diplodocus who is a plant eating dinosaur. It is the longest of its kind and uses his long lashing tail to fight off predators. This animal walked on four legs, but it had the ability to stand or rear up on its two legs.