Scientists learned about the existence of dinosaurs about one hundred and fifty years ago. An English doctor and his wife first opened the door the this zoological study. Scientists thought that these reptiles were rather dangerous, and they formed the word "dinosaur" from two Greek words: "deimos" (terrible) and "sauros" (lizards).
After studying dinosaurs for many years, scientists believe that these animals lived on the Earth for millions of years and disappeared about sixty million years ago. Not all dinosaurs were meat eating; many of them were vegetarians.
Studying the bones of these beasts, scientists have reconstructed skeletons. They have learned a lot about the dinosaurs' living conditions. They have learned that dinosaurs inhabited not only land, but also water and sky.