Dinosaurs: Amazing Photos & Fun Facts Book For Kids Long ago, the Earth was filled with gigantic and beautiful creatures. Modern humans were not there yet, but there were trees, insects and animals. Some of these animals were dinosaurs. The word dinosaur was given by a man who studied their kind. His name was Sir Robert Owen. He coined that word from two Greek words, deinos and sauros. Deinos means fearfully-great and sauros means lizard, which is why dinosaur originally meant fearfully-great lizard," but to simplify this, the dinosaur word meaning became "terrible lizard." However, not all dinosaurs were terrible; neither were they lizards. Dinosaurs had different kinds. Some of them could be smaller than a dog, or some of them could be 2 to 3 times taller than a giraffe or wider than a killer whale. Some of them were plant-eaters, and some of them ate meat.