An allosaurus skull.  Click here to go back website start. National Park Service Museum Collections presents 'Dinosaur! National Monument'
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Photo - the back bone of a dinosaur, frozen in the rock wall of Dinosaur, NM
Bones found in the Douglass Quarry belong to nine different kinds of dinosaurs. Some were very much like each other. Others were quite different. Paleontologists name, and classify or group dinosaurs according to the shape of their hip bones, teeth, feet, and other body parts.

Most of the Douglass Quarry fossils are part of the long-neck, long-tail, plant-eating group called Sauropods. They were the largest creatures ever to walk on land. This group includes Apatosaurus, Barosaurus, Camarasaurus, and Diplodocus. These animals share many common traits, and look very much alike. Other bones in the Quarry belong to different four-legged and two-legged plant-eating groups called Ornithischians.

An even smaller percentage of the bones belong to the meat-eating Theropods. Take a look at the dinosaur family tree to better understand how paleontologists classify these diverse animals.

Although originally called terrible lizards that lived millions of years ago, dinosaurs are unlike lizards in how their legs are positioned. Lizard legs sprawl out to the side. Dinosaur legs were straight under their bodies allowing them to better support tons of weight.

In order to be classified as a dinosaur, an animal must have;
· hip, knee, and ankle bones that allow it to stand with its legs directly under its body
· a ridge on the upper arm bones
· jaw muscles that attach to the top of the skull
· three bones [that make up one side of the hips] that form an open socket for the thigh bone to fit in
· the second finger is the longest digit of the hand

Go to the Dinosaur Family Tree Paleontologists divide dinosaurs into two large groups or orders, Saurichischians and Ornithischians. They are further divided into smaller groups that share certain common features.

Saurischians are dinosaurs with lizard-like hips:

Sauropods [lizard-feet] 4-legged, long-necked plant eaters
    • Apatosaurus
    • Barosaurus
    • Camarasaurus
    • Diplodocus

  • Theropods [beast feet] 2-legged, sharp-clawed meat eaters
    • Allosaurus
    • Ceratosaurus
Ornithischians are dinosaurs with bird-like hips:

Stegosaurs [plated lizards]
4-legged, plate-backed
    • Stegosaurus

  • Ornithopods [bird-feet]
    2-legged, fairly small plant eaters
    • Camptosaurus
    • Dryosaurus

Two little dinosaur drawings.

NPS Museum Management Program
Last modified: 1/21/2004
Tibia, Fibula Ribs
Scapula Radius, Ulna
Humerus Femur
Ilium Pubis
Lower Jaw Skull
Post Cranial Skull
Ilium Tooth
Diplodocus Femur