Geological Museum

Department of Geology and Geophysics

Apatosaurus

Geologic Age: Late Jurassic, ~145 to 155 million years ago

Rock Unit: Morrison Formation

Geographic range: Wyoming, Colorado, Utah, Montana, Oklahoma

Adult size: Up to 80 ft (25 m) in length

Adult weight: Up to 30 tons

Diet: plants

Habitat: Lowland floodplains

Apatosaurus belongs to a group of dinosaurs called the sauropods. This group of herbivorous (plant-eating) dinosaurs consists of the largest animals that ever lived on land. An animal this size probably needed to eat more than a ton of vegetation each day just to stay alive!

This specimen on display in the museum is about 75 feet long and weighed about 25 tons in life. It is approximately 60-percent complete. The darker-colored bones are the actual fossil bones, and the lighter gray bones are casts, copies made from other Apatosaurus specimens or from this animal itself.

This specimen was excavated from the Morrison Formation at Sheep Creek in Albany County, Wyoming, in 1901 by the Carnegie Museum of Natural History in Pittsburgh, PA. The skeleton was obtained for the University of Wyoming by Samuel "Doc" Knight in 1956, and he built the mount between 1959 and 1961. It was recently taken down, cleaned, and updated.