Period: Late Jurassic


Order, Suborder, Family: Ornithischia, Ornitbopoda, Dryosauridae

Location: North America, Africa (Tanzania)

Length: 10-13 feet (3-4 meters)

Dryosaurus is the most important member of the family Dryosauridae. This is a group of small plant-eating dinosaurs from the Late Jurassic and Early Cretaceous of North America, eastern Africa, and Europe.

Dryosaurus had long, powerful back legs. Its foot was slim and had three toes. Its arms were strong and had five-fingered hands; the animal probably used its hands to grasp leaves and branches when feeding. Its stiff tail balanced the body while it was standing or running across the countryside.

Dryosaurus had no teeth at the front of its mouth. It used its horny beak to nip plants from the ground, shrubs, and low-level branches. Dryosaurus had chewing teeth, located toward the back of the jaws, which ground up leaves and shoots before the animal swallowed them.

Workers found Dryosaurus in Late Jurassic rocks in the western United States. Also, a spectacular fossil site of the same age is in Tanzania, Africa. W. Janensch from Berlin, Germany, collected hundreds of Dryosaurus bones from Tanzania in the early part of the 20th century. Many of these fossils were young, even hatchling, dryosaurs. This will tell scientists a great deal about how these dinosaurs grew up.

Othniel Charles Marsh coined the name Dryosaurus in 1894. The name means "oak reptile." Dryosaurus, along with its close relative Valdosaurus, was one of the earliest members of a large group of important ornithopods known as iguanodontians. Other members of this group included Tenontosaurus, Camptosaurus, and the later iguanodontids and hadrosaurids.