Originally mounted in 1907, the Carnegie specimen is the best example of the sauropod dinosaur Diplodocus, and perhaps the most famous dinosaur skeleton in the world. Casts of the specimen, including the London example known as "Dippy", were distributed around the world during the early 1900s, and a final concrete cast was even created in 1957 for the Utah Field House at Vernal.

Although the moulds used to create these casts were lost sometime during the 1960's, new ones created from the concrete skeleton have allowed second generation casts to be made, with some elements being incorporated into other iconic mounts.