Agate Fossil Beds National Monument

Most of the land that is now the National Monument was part of the Agate Springs Ranch, a working cattle ranch, owned by James and Kate Cook, who bought the ranch in 1887. Another is that animal carcasses were swept down the ancient rivers and deposited there due to the particular geometry of the river bends and eddies. Another is that animals became trapped in quicksand there. The monument's museum collection also contains more than 500 artifacts from the Cook Collection of Plains Indians artifacts. The national monument was authorized on June 5, 1965, but was not established until June 14, 1997. The Harold J. Cook Homestead (Bone Cabin Complex) was listed on the National Register of Historic Places in 1977. Agate Fossil Beds is maintained by the National Park Service. == Paleontology ==

The site is best known for a large number of well-preserved Miocene fossils, many of which were found at dig sites on Carnegie and University Hills. Fossils from the Harrison Formation and Anderson Ranch Formation, which date to the Arikareean in the North American land mammal classification, about 20 to 16.3 million years ago, are among some of the best specimens of Miocene mammals. Species found in Agate include: • Merychippus and Parahippus, ancestors of the modern day horse. • Diceratherium, two-horned rhinoceros. • Menoceras, pony-sized rhinoceros, the most common animal found in the fossil beds. • Daphoenodon and Ysengrinia, two types of mid-sized bear dogs. • Promerycochoerus, a semiaquatic hippo-like oreodont. • Daeodon, the largest Entelodont (giant pig-like ungulate). • Stenomylus, gazelle-like camelids. • Oxydactylus, giraffe-like camelids. • Palaeocastor, land beavers that dug large corkscrew-shaped burrows (Daemonelix). • Moropus, a chalicothere which are relatives of rhinos and horses. • Merychyus, a sheep-like oreodont. • Syndyoceras, antelope-like mammal and extinct relatives of artiodactyls. ==Gallery==