Agate Fossil Beds National Monument is a

U.S. National Monument In the United States, a national monument is a protected area that can be created from any land owned or controlled by the federal government by proclamation of the President of the United States or an act of Congress. National monuments pr ...

near

Harrison, Nebraska Harrison is a village in Sioux County, Nebraska, United States. The population was 239 at the 2020 census. It is the county seat of Sioux County. History Harrison was originally called Bowen, and under that name was platted in 1886, when the Fr ...

. The main features of the monument are a

valley A valley is an elongated low area often running between Hill, hills or Mountain, mountains, which will typically contain a river or stream running from one end to the other. Most valleys are formed by erosion of the land surface by rivers ...

of the

Niobrara River The Niobrara River (; oma, Ní Ubthátha khe, , literally "water spread-out horizontal-the" or "The Wide-Spreading Water") is a tributary of the Missouri River, approximately long,U.S. Geological Survey. Many early settlers, such as Mari Sando ...

and the fossils found on Carnegie Hill and University Hill. The area largely consists of grass-covered

plain In geography, a plain is a flat expanse of land that generally does not change much in elevation, and is primarily treeless. Plains occur as lowlands along valleys or at the base of mountains, as coastal plains, and as plateaus or uplands ...

s. Plants on the site include prairie sandreed,

blue grama ''Bouteloua gracilis'', the blue grama, is a long-lived, warm-season ( C4) perennial grass, native to North America. It is most commonly found from Alberta, Canada, east to Manitoba and south across the Rocky Mountains, Great Plains, and U.S. ...

little bluestem ''Schizachyrium scoparium'', commonly known as little bluestem or beard grass, is a species of North American prairie grass native to most of the contiguous United States (except California, Nevada, and Oregon) as well as a small area north of t ...

and needle and thread grass, and the wildflowers

lupin ''Lupinus'', commonly known as lupin, lupine, or regionally bluebonnet etc., is a genus of plants in the legume family Fabaceae. The genus includes over 199 species, with centers of diversity in North and South America. Smaller centers occur ...

spiderwort ''Tradescantia'' () is a genus of 85 species of herbaceous perennial wildflowers in the family Commelinaceae, native to the Americas from southern Canada to northern Argentina, including the West Indies. Members of the genus are known by many co ...

, western wallflower and

sunflower The common sunflower (''Helianthus annuus'') is a large annual forb of the genus ''Helianthus'' grown as a crop for its edible oily seeds. Apart from cooking oil production, it is also used as livestock forage (as a meal or a silage plant), as ...

History

Entering Agate Fossil Beds National Monument

Originally the Agate Springs Ranch, a working cattle ranch, was owned by Capt. James Cook. The monument's museum collection also contains more than 500 artifacts from the Cook Collection of

Plains Indians Plains Indians or Indigenous peoples of the Great Plains and Canadian Prairies are the Native American tribes and First Nation band governments who have historically lived on the Interior Plains (the Great Plains and Canadian Prairies) of N ...

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 The National Register of Historic Places (NRHP) is the United States federal government's official list of districts, sites, buildings, structures and objects deemed worthy of preservation for their historical significance or "great artistic v ...

in 1977. Agate Fossil Beds is maintained by the

National Park Service The National Park Service (NPS) is an agency of the United States federal government within the U.S. Department of the Interior that manages all national parks, most national monuments, and other natural, historical, and recreational propertie ...

Paleontology

The site is best known for a large number of well-preserved

Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s, many of which were found at dig sites on Carnegie and University Hills. Fossils from the

Harrison Formation The Harrison Formation is a geologic group in South Dakota and Nebraska. It preserves fossils from the Miocene. See also * List of fossiliferous stratigraphic units in South Dakota * Paleontology in South Dakota Paleontology in South Dakota r ...

and Anderson Ranch Formation, which date to the

Arikareean The Arikareean North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 30,600,000 to 20,800,000 years BP, a period of . It is usuall ...

in the North American land mammal classification, about 20 to 16.3 million years ago, are among some of the best specimens of Miocene

mammal Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...

s. Species found in Agate include: * ''

Miohippus ''Miohippus'' (meaning "small horse") was a genus of prehistoric horse existing longer than most Equidae. ''Miohippus'' lived in what is now North America from 32 to 25 million years ago, during the late Eocene to late Oligocene. ''Miohippus'' w ...

'', ''

Merychippus ''Merychippus'' is an extinct proto-horse of the family Equidae that was endemic to North America during the Miocene, 15.97–5.33 million years ago. It had three toes on each foot and is the first horse known to have grazed. Discovery and nami ...

'' and ''

Parahippus ''Parahippus'' ("near to horse"), is an extinct equid, a relative of modern horses, asses and zebras. It lived from 24 to 17 million years ago, during the Miocene epoch. It was very similar to ''Miohippus'', but slightly larger, at around tall, ...

'',

ancestors An ancestor, also known as a forefather, fore-elder or a forebear, is a parent or (recursively) the parent of an antecedent (i.e., a grandparent, great-grandparent, great-great-grandparent and so forth). ''Ancestor'' is "any person from whom ...

of the modern day horse. * ''

Diceratherium ''Diceratherium'' (meaning "two horned beast") is an extinct genus of rhinoceros endemic to North America, Europe, and Asia during the Oligocene through Miocene living from 33.9 to 11.6 mya, existing for approximately . Mass estimates for the ...

'', two-horned

rhinoceros A rhinoceros (; ; ), commonly abbreviated to rhino, is a member of any of the five extant species (or numerous extinct species) of odd-toed ungulates in the family Rhinocerotidae. (It can also refer to a member of any of the extinct species o ...

. * ''

Menoceras ''Menoceras'' ("Crescent Horns") is a genus of extinct, small rhinoceros endemic to most of southern North America and ranged as far south as Panama during the early Miocene epoch. It lived from around 30.7—19.7 Ma, existing for approximately ...

'', pony-sized

, the most common animal found in the fossil beds. * ''

Daphoenodon ''Daphoenodon'' is an extinct genus of terrestrial carnivore, which lived in the early Miocene and belonged to the family Amphicyonidae ("bear dogs") of the suborder Caniformia Caniformia is a suborder within the order Carnivora consistin ...

'', a

bear dog Amphicyonidae is an extinct family of terrestrial carnivorans belonging to the suborder Caniformia. They first appeared in North America in the middle Eocene (around 45 mya), spread to Europe by the late Eocene (35 mya), and appear in Asia, a ...

. * ''

Promerycochoerus ''Promerycochoerus'' ("Before '' Merycochoerus''" or "Before Ruminating Hog") is an extinct genus of hippopotamus-like oreodont artiodactyl that lived in Central North America during the Early Miocene. The 1 m (3 ft 4 in) long c ...

'', a semiaquatic hippo-like

oreodont Merycoidodontoidea, sometimes called "oreodonts" or "ruminating hogs", is an extinct superfamily of prehistoric cud-chewing artiodactyls with short faces and fang-like canine teeth. As their name implies, some of the better known forms were gen ...

. * ''

Daeodon ''Daeodon'' is an extinct genus of entelodont even-toed ungulates that inhabited North America about 23 to 20 million years ago during the latest Oligocene and earliest Miocene. The type species is ''Daeodon shoshonensis'', described by a very ...

'', the largest

Entelodont Entelodontidae, the entelodonts, are an extinct family of pig-like artiodactyls (even-toed ungulates) which inhabited the Northern Hemisphere (Asia, Europe, and North America) from the late Eocene to the Middle Miocene epochs, about 38-19 million ...

(giant pig-like ungulate). * ''

Stenomylus ''Stenomylus'' is an extinct genus of miniature camelid native to North America that died out around 30 million years ago. Its name is derived from the Greek (, "narrow") and (, "molar"). ''Stenomylus'' was extremely diminutive compared to ...

'' , gazelle-like

camelids Camelids are members of the biological family Camelidae, the only currently living family in the suborder Tylopoda. The seven extant members of this group are: dromedary camels, Bactrian camels, wild Bactrian camels, llamas, alpacas, vicuñas, ...

. * ''

Oxydactylus ''Oxydactylus'' is an extinct genus of camelid endemic to North America. It lived from the Late Oligocene to the Middle Miocene (28.4–13.7 mya), existing for approximately . The name is from the Ancient Greek οξύς (oxys, "sharp")and δ ...

'', giraffe-like

. * ''

Palaeocastor ''Palaeocastor'' ('prehistoric beaver') is an extinct genus of beavers that lived in the North American Badlands during the late Oligocene period to early Miocene. ''Palaeocastor'' was much smaller than modern beavers. There are several specie ...

'', land beavers that dug large corkscrew-shaped burrows (''Daemonelix''). * ''

Moropus ''Moropus'' (meaning "slow foot") is an extinct genus of large perissodactyl ("odd-toed" ungulate) mammal in the chalicothere family. They were endemic to North America during the Miocene from ~20.4—13.6 Mya, existing for approximately . ...

'', a

chalicothere Chalicotheres (from Greek '' chalix'', "gravel" and '' therion'', "beast") are an extinct clade of herbivorous, odd-toed ungulate (perissodactyl) mammals that lived in North America, Eurasia, and Africa from the Middle Eocene until the Early Plei ...

which are relatives of rhinos and horses. * ''

Merychyus ''Merychyus'' is an extinct genus of oreodont of the family Merycoidodontidae, endemic to North America. It lived during the Miocene, 20.4—10.3 mya, existing for approximately .oreodont Merycoidodontoidea, sometimes called "oreodonts" or "ruminating hogs", is an extinct superfamily of prehistoric cud-chewing artiodactyls with short faces and fang-like canine teeth. As their name implies, some of the better known forms were gen ...

. * ''

Syndyoceras ''Syndyoceras'' is a small extinct genus of Artiodactyla, of the family Protoceratidae, endemic to central North America from the Miocene epoch (24.8—20.6 Ma), existing for approximately . Taxonomy ''Syndyoceras'' was named by Barbour (1 ...

'', antelope-like mammal and extinct relatives of

artiodactyls The even-toed ungulates (Artiodactyla , ) are ungulates—hoofed animals—which bear weight equally on two (an even number) of their five toes: the third and fourth. The other three toes are either present, absent, vestigial, or pointing poster ...

Gallery

References

External links

* Official NPS website
Agate Fossil Beds National Monument
{{authority control Federal lands in Nebraska National Park Service National Monuments in Nebraska Cenozoic paleontological sites of North America Miocene paleontological sites Natural history of Nebraska Protected areas established in 1997 Dinosaur museums in the United States Natural history museums in Nebraska Museums in Sioux County, Nebraska Protected areas of Sioux County, Nebraska 1997 establishments in Nebraska Fossil parks in the United States Paleontology in Nebraska Paleontological protected areas in the United States 1997 in paleontology National Register of Historic Places in Sioux County, Nebraska