This 10 kilometre long cliff has been the source for dozens of dinosaur skeletons since it was first discovered by railroad workers constructing the Union Pacific Railway in 1877 and excavated by teams working for America's two most famous dinosaur hunters, Othniel Charles Marsh and Edward Drinker Cope. Tons of dinosaur bones were recovered from this site and sent to museums in the eastern states including those of Triceratops, Camarasaurus, Brontosaurus (aka Apatosaurus), Troodon and Ichthyosaurus.