Dryosaurus lived in the thick forests of the late Jurassic period, about 156 to 145 million years ago. It was not a very large dinosaur. It was about 10 feet long, five feet tall at the hips, and weighed about 180 pounds. That’s about as large as a big car. It had large eyes and long, thin legs with three toes on each foot. Its arms were much shorter with five long fingers on each hand. We know a lot about this dinosaur because lots of Dryosaurus skeletons have been found. It was a very common dinosaur during the Jurassic period. Paleontologists have found fossils of both adults and babies, which is helpful for studying the way the dinosaur grew.
Dryosaurus was a bipedal dinosaur, meaning that it ran on two legs. Its back legs were thin yet strong. Its tail was stiff to help it keep its balance while it was running. Dryosaurus didn’t have tough armor, sharp claws, long teeth or a whip-like tail to protect itself against predators. Instead, it used its speed and agility to escape its hunters. It could run as fast as 25 miles per hour. That was fast enough to outrun most meat-eaters. Dryosaurus was an herbivore, meaning that it only ate plants. It had no front teeth but had a sharp, hard beak that could rip the leaves off plants. It could store the food it was chewing in its cheeks. This was very handy when a dinosaur had to eat and run! It had grinding teeth in the back of its mouth. Dryosaurus means “oak tree lizard”. It got this name because of the shape of its back teeth. If you saw them from the top, they would look a little like oak leaves.
Dryosaurus laid eggs and most likely cared for its babies after the eggs hatched. Like most dinosaurs, a baby Dryosaurus was born small and grew quickly to its adult size. It might have been one of the fastest-growing dinosaurs ever. Dryosaurus was a fairly intelligent dinosaur. It had a medium-sized brain. We know this by studying the space in its skull: the bigger the space, the bigger the brain! Fossils of Dryosaurus have been found in western North America and Africa. They have also been found in England, Romania and Tanzania.