The story
The Morrison Formation is a band of sandstone, mudstone and limestone spread across Colorado, Wyoming, Utah, Montana and neighboring states, laid down about 157 to 150 million years ago on broad river floodplains with seasonal droughts. It holds the best-known Late Jurassic fauna in the world: the sauropods Diplodocus, Apatosaurus, Camarasaurus and Brachiosaurus, the plated Stegosaurus, and the predators Allosaurus, Ceratosaurus and Torvosaurus. Small mammals, frogs, pterosaurs and crocodile relatives lived beside them.
The formation has been dug since 1877 at sites such as Como Bluff in Wyoming, Dinosaur National Monument on the Utah-Colorado border (worked by Earl Douglass from 1909) and the Cleveland-Lloyd Quarry. Elmer Riggs found Brachiosaurus in western Colorado in 1900. Andrew Carnegie sponsored the Diplodocus found in Wyoming in 1899, and plaster casts of the skeleton were sent to museums across Europe and the Americas from 1905. For many people, this is the first picture of what a dinosaur world looks like.
Why it mattered
- The Morrison dig sites set off the Bone Wars and shaped how the public pictures dinosaurs.
- Its sauropod diversity shows how many giant plant eaters could share one landscape.
- Its casts of Diplodocus helped spread dinosaur science across the world.
Sources
- The Morrison Formation National Park Service
- Dippy Casts Abroad Carnegie Museum of Natural History
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