Dinosaurs were animals that lived millions of years ago.
Many dinosaurs were very big. But some were as small as chickens are today.
Most dinosaurs ate only plants. Some dinosaurs ate other animals. They were meat eaters.
Scientists aren't sure what color dinosaurs were. Some think dinosaurs might have been as colorful as many birds are today.
In 1902, part of a huge skeleton was uncovered in Montana. Later, another was found in Wyoming. From these bones the American paleontologist Henry Fairfield Osborn drew up the first pictures of this giant creature. He named it Tyrannosaurus Rex (meaning 'king of the tyrant reptiles') because it was the biggest meat - eating dinosaur then known to have lived on Earth.
Scientists in Argentina, South America, claim to have found the world's oldest dinosaur. This creature, called Herrarasaurus, is said to be 230 million years old.
Dinosaurs sometimes had accidents, and fossil bones have been found with fractures in them.
The most complete skeleton of a Stegosaurus ever found has been dug up at the foot of the Rocky Mountains in Colorado. It had to be hauled out of the earth by an army helicopter.
Your dentist's drill has other uses. In the laboratory, scientists often use dental drills to clear and prepare dinosaur bones.
Tracks left in the mud by dinosaurs provide clues as to how quickly they moved. By measuring the distance between footprints, experts have worked out that some dinosaurs could have reached speeds up to 25 mph.
Velociraptor was probably very fierce. A fossil found in Utah, shows its claws may have been up to 15 inches in length--as long as a three-year-old child's arm. These claws formed very effective hooks with which to hold prey.