The Agate Fossil Beds are in western Nebraska about an hours drive north of Scottsbluff. A large fossilizes leg bone was found by James Cook on his land in 1887. Since then large numbers of fossilized bones and complete skeletons of prehistoric animals have been found in the vicinity. The bones were found around ancient waterholes. It is thought the waterholes dried up in a time of drought and the animals died in the shallow waters of a few remaining ponds.