Apatosaurus

Apatosaurus excelsius (Jurassic period, about 140 million years ago) was a Sauropod dinosaur, one of the largest land animals that ever existed, about 15 feet (4.6 m) tall at the hips, with a length of up to 35 m. Until recently it was called Brontosaurus, but the name "Apatosaurus" became authoritative after it was discovered that the skull used to construct the brontosaurus skeleton actually belonged to Camarasaurus.

Like its relative Diplodocus, Apatosaurus was a grazing animal with a very long neck, and a long tail as a counterweight. To aid in processing tough plant fibers, Apatosaurus swallowed gizzard stones (gastroliths)

Fossils of this animal have been found in Nine Mile Quarry and Bone Cabin Quarry in Wyoming at sites in Utah and in Oklahoma..

Other Apatosaurus species:

• A. ajax - found in Colorado
• A. louisae - found in Colorado
• A. yahnahpin - found in Wyoming