The Ashfall Fossil Beds of Antelope County in northeastern

Nebraska Nebraska () is a state in the Midwestern region of the United States. It is bordered by South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Kansas to the south; Colorado to the sout ...

are rare

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 ...

sites of the type called

lagerstätte A Lagerstätte (, from ''Lager'' 'storage, lair' '' Stätte'' 'place'; plural ''Lagerstätten'') is a sedimentary deposit that exhibits extraordinary fossils with exceptional preservation—sometimes including preserved soft tissues. These f ...

n that, due to extraordinary local conditions, capture an ecological "snapshot" in time of a range of well-preserved fossilized organisms. Ash from a

Yellowstone hotspot The Yellowstone hotspot is a volcanic hotspot in the United States responsible for large scale volcanism in Idaho, Montana, Nevada, Oregon, and Wyoming, formed as the North American tectonic plate moved over it. It formed the eastern Snake Riv ...

eruption 10-12 million years ago created these fossilized bone beds. The ash depth was up to 1 foot. The site is protected as Ashfall Fossil Beds State Historical Park, a park that includes a visitor center with interpretive displays and working fossil preparation laboratory, and a protected ongoing excavation site, the Hubbard Rhino Barn, featuring fossil ''

Teleoceras ''Teleoceras'' (Greek: "perfect" (teleos), "horn" (keratos)) is an extinct genus of grazing rhinoceros. It lived in North America during the Miocene and Pliocene epochs during the Hemingfordian to the end of Hemphillian from around 17.5 to 4. ...

'' (native hippo-like ancestral rhinoceros) and ancestral horses. The Ashfall Fossil Beds are especially famous for fossils of

mammals 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 o ...

from the middle

Miocene The Miocene ( ) is the first epoch (geology), 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 mea ...

geologic epoch The geologic time scale, or geological time scale, (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochrono ...

. The Ashfall Fossil Beds are stratigraphically part of the

Serravallian The Serravallian is, in the geologic timescale, an age or a stage in the middle Miocene Epoch/Series, which spans the time between 13.82 Ma and 11.63 Ma (million years ago). The Serravallian follows the Langhian and is followed by the Tortonian ...

-age Ogallala Group.

Bruneau-Jarbidge event

The Ashfall deposit preserves the fossilized remains of ancient animals that perished in a dense volcanic ash fall which occurred during the late

, approximately 12 million years ago; the animals had come to a waterhole seeking relief. The fall of ash drifted downwind from the Bruneau-Jarbidge supervolcano eruption (in present-day

Idaho Idaho ( ) is a state in the Pacific Northwest region of the Western United States. To the north, it shares a small portion of the Canada–United States border with the province of British Columbia. It borders the states of Montana and Wyomi ...

), nearly west of the Ashfall site. A large number of very well preserved fossil ''

'' (extinct hippo-like relatives of rhinos), small three-toed and one-toed

horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 million yea ...

s, camels, and birds have been excavated. Many animals were preserved with their bones articulated; one rhino still bears her unborn

fetus A fetus or foetus (; plural fetuses, feti, foetuses, or foeti) is the unborn offspring that develops from an animal embryo. Following embryonic development the fetal stage of development takes place. In human prenatal development, fetal dev ...

, while others retain the contents of their last meal. The bones of the animals show features that indicate that the animals died of lung failure induced by inhaling volcanic ash. The smaller animals with smaller lung capacity were the first to die, and the larger animals were the last. Bite-marks on some bones show that local predators (the carnivorous bone-crunching dog '' Aelurodon'') scavenged some of the carcasses, but no predator remains have yet surfaced. There are also abundant clues to the region's ecology, indicating a

savanna A savanna or savannah is a mixed woodland- grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to ...

of grassland interspersed with trees that luxuriated in a warmer, milder climate than today's. The rapidly accumulating ash, windblown into deep drifts at low places like the waterhole site, remained moderately soft. The ash preserved the animals in three dimensions; not even the delicate bones of birds or the carapaces of turtles were crushed. Above the layer of ash, a stratum of more erosion-resistant

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates ...

has acted as "caprock" to preserve the strata beneath. Ashfall fossil beds - Baby rhino

Preservation

The first hint of the site's richness was the skull of a juvenile rhinoceros noticed in 1971 eroding out of a gully at the edge of a cornfield. In 1971, University of Nebraska State Museum paleontologist Michael Voorhies was walking with his wife Jane through a series of gullies on Melvin Colson's farm in northeastern Nebraska and made this discovery. The Nebraska Game and Parks Foundation purchased the Ashfall site in 1986. Ashfall Fossil Beds State Historical Park opened in 1991. The site was declared a

National Natural Landmark The National Natural Landmarks (NNL) Program recognizes and encourages the conservation of outstanding examples of the natural history of the United States. It is the only national natural areas program that identifies and recognizes the best ...

on May 9, 2006. The park's Hubbard Rhino Barn opened in 2009. The pavilion lets visitors observe as

paleontologists Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of foss ...

carry out excavations of new discoveries exactly where the fossilized remains lie preserved. Specially constructed walkways afford visitors an unobstructed close-up view of paleontologists at work during the summer field season.

Species

The remains of ''Teleoceras'' are so numerous and concentrated that the main section of Ashfall is called the "Rhino Barn". Other fossils at the "Rhino Barn" include the remains of horses and camels. Taxa discovered in the Ashfall deposits include: *five

genera: '' Cormohipparion'', ''

Protohippus ''Protohippus'' is an extinct three-toed genus of horse. It was roughly the size of a modern donkey. Fossil evidence suggests that it lived during the Late Miocene (Clarendonian to Hemphillian), from about 13.6 Ma to 5.3 Ma. Analysis of ''Proto ...

'', '' Pseudhipparion'', ''

Neohipparion ''Neohipparion'' (Greek: "new" (neos), "pony" (hipparion)) is an extinct genus of equid, from the Neogene (Miocene to Pliocene) of North America and Central America Central America ( es, América Central or ) is a subregion of the Ameri ...

'' and ''

Pliohippus ''Pliohippus'' (Greek (, "more") and (, "horse")) is an extinction, extinct genus of Equidae, the "horse family". ''Pliohippus'' arose in the middle Miocene, around 15 million years ago. The long and slim limbs of ''Pliohippus'' reveal a quick- ...

'' *three

camelid 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, ...

genera: ''

Procamelus ''Procamelus'' is an extinct genus of Camelini, camel endemic to North America. It lived from the Middle to Late Miocene 16.0—5.3 Annum, mya, existing for approximately . The name is derived from the Greek πρό, meaning "before" or denoting p ...

'', ''

Aepycamelus ''Aepycamelus'' is an extinct genus of camelids that lived during the Miocene 20.6–4.9 million years ago, existing for about . Its name is derived from the Homeric Greek , "high and steep" and κάμηλος – "camel"; thus, "high camel"; ''a ...

'' and '' Protolabis'' *three

canid Canidae (; from Latin, '' canis'', " dog") is a biological family of dog-like carnivorans, colloquially referred to as dogs, and constitutes a clade. A member of this family is also called a canid (). There are three subfamilies found withi ...

genera: '' Leptocyon'', ''

Cynarctus ''Cynarctus'' is an extinct genus of the Borophaginae subfamily of canids native to North America. The genus was first founded by W. D. Matthew in 1901, based from a pair of lower jaws, ''Cynarctus saxitilis,'' found in the Pawnee Creek Beds of ...

'' and evidence of scavenging from a bone-crushing canid, possibly ''

Epicyon ''Epicyon'' ("more than a dog") is a large, extinct, canid genus of the subfamily Borophaginae ("bone-crushing dogs"), native to North America. ''Epicyon'' existed for about from the Hemingfordian age of the Early Miocene, to the Hemphillian o ...

'' *one rhinoceros genus: ''

'' *one saber-toothed musk deer genus: '' Longirostromeryx'' *three bird species: '' Balearica exigua'' (a crowned crane), '' Apatosagittarius'' (a hawk resembling the living

secretarybird The secretarybird or secretary bird (''Sagittarius serpentarius'') is a large, mostly terrestrial bird of prey. Endemic to Africa, it is usually found in the open grasslands and savanna of the sub-Saharan region. John Frederick Miller describe ...

), and '' Anchigyps'' (a scavenger related to

Old World vultures Old World vultures are vultures that are found in the Old World, i.e. the continents of Europe, Asia and Africa, and which belong to the family Accipitridae, which also includes eagles, buzzards, kites, and hawks. Old World vultures are not clo ...

) *three turtle species: ''

Hesperotestudo ''Hesperotestudo'' ("Western turtle") is an extinct genus of tortoise native to North and Central America from the Oligocene to the Late Pleistocene. Species of ''Hesperotesudo'' varied widely in size, with the largest unnamed species from El Sal ...

'' (a large

tortoise Tortoises () are reptiles of the family Testudinidae of the order Testudines (Latin: ''tortoise''). Like other turtles, tortoises have a shell to protect from predation and other threats. The shell in tortoises is generally hard, and like oth ...

), ''

Sternotherus ''Sternotherus'' is a genus of turtles in the family Kinosternidae including six species commonly known as musk turtles. The genus is endemic to North America, occurring in the eastern third of the USA and southeast Ontario, Canada. Musk glands ...

'' (a musk turtle) and ''

Chrysemys ''Chrysemys'' is a genus of turtles in the family Emydidae. They are found throughout most of North America. Species There are two extant species: * ''Chrysemys dorsalis'' Agassiz, 1857 – Southern painted turtle * ''Chrysemys picta'' Schneider ...

'' (a painted turtle)

References

External links

Ashfall Fossil Beds State Historical Park
Nebraska Game and Parks Commission
Ashfall Fossil Beds State Historical Park
University of Nebraska State Museum
Ashfall Fossil Beds Skeleton Map
University of Nebraska State Museum
Cenozoic Geology of Idaho: "The Bruneau-Jarbidge Eruptive Center, Southwestern Idaho" by Bill Bonnichsen (pages 251-268)
Idaho Bureau of Mines and Geology {{authority control State parks of Nebraska Museums in Antelope County, Nebraska Protected areas of Antelope County, Nebraska Protected areas established in 1986 Fossil parks in the United States National Natural Landmarks in Nebraska Natural history museums in Nebraska Paleontology in Nebraska Miocene paleontological sites of North America Lagerstätten 1991 establishments in Nebraska 1991 in paleontology 2006 in paleontology Volcanic eruptions in the United States

Bruneau-Jarbidge event

Preservation

Species

See also

References

External links