The Ashfall Fossil Beds of Antelope County in northeastern

Nebraska Nebraska ( ) is a landlocked U.S. state, state in the Midwestern United States, Midwestern region of the United States. It borders South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Ka ...

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 preserve ...

sites of the type called

lagerstätte A Fossil-Lagerstätte (, from ''Lager'' 'storage, lair' '' Stätte'' 'place'; plural ''Lagerstätten'') is a sedimentary deposit that preserves an exceptionally high amount of palaeontological information. ''Konzentrat-Lagerstätten'' preserv ...

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 eruption 10-12 million years ago created these fossilized

bone bed A bone bed is any Geology, geological stratum or deposition (geology), deposit that contains bones of whatever kind. Inevitably, such deposits are Sedimentary rock, sedimentary in nature. Not a formal term, it tends to be used more to describe esp ...

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

mammals A mammal () is a vertebrate animal of the class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three middle e ...

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 geochronolo ...

. The Ashfall Fossil Beds are stratigraphically part of the

Serravallian The Serravallian is, in the geologic timescale, an List of time periods, age or a stage (stratigraphy), stage in the middle Miocene epoch (geology), Epoch/series (stratigraphy), Series, which spans the time between 13.82 annum, Ma and 11.63 Ma (m ...

-age Ogallala Group, within the

Ash Hollow Formation The Ash Hollow Formation of the Ogallala Group is a geological formation found in Nebraska and South Dakota. It preserves fossils dating back to the Neogene Period (geology), period. It was named after Ash Hollow, Nebraska and can be seen in Ash ...

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 landlocked U.S. state, state in the Pacific Northwest and Mountain states, Mountain West subregions of the Western United States. It borders Montana and Wyoming to the east, Nevada and Utah to the south, and Washington (state), ...

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

camel A camel (from and () from Ancient Semitic: ''gāmāl'') is an even-toed ungulate in the genus ''Camelus'' that bears distinctive fatty deposits known as "humps" on its back. Camels have long been domesticated and, as livestock, they provid ...

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

fetus A fetus or foetus (; : fetuses, foetuses, rarely feti or foeti) is the unborn offspring of a viviparous animal that develops from an embryo. Following the embryonic development, embryonic stage, the fetal stage of development takes place. Pren ...

, 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) biome and ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach th ...

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 In geology and related fields, a stratum (: strata) is a layer of rock or sediment characterized by certain lithologic properties or attributes that distinguish it from adjacent layers from which it is separated by visible surfaces known as ...

of more erosion-resistant

sandstone Sandstone is a Clastic rock#Sedimentary clastic rocks, clastic sedimentary rock composed mainly of grain size, sand-sized (0.0625 to 2 mm) silicate mineral, silicate grains, Cementation (geology), cemented together by another mineral. Sand ...

has acted as "caprock" to preserve the strata beneath.

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 e ...

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

paleontologists Paleontology, also spelled as palaeontology or palæontology, is the scientific study of the life of the past, mainly but not exclusively through the study of fossils. Paleontologists use fossils as a means to classify organisms, measure geolo ...

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 The Hemphillian North American Stage on the geologic ...

'', '' Pseudhipparion'', ''

Neohipparion ''Neohipparion'' (Greek: "new" (neos), "pony" (hipparion)) is an extinction, extinct genus of equid, from the Neogene (Miocene to Pliocene) of North America and Central America. Fossils of this horse have been found in Texas, Florida, Kansas, ...

'' and '' Pliohippus'' *three

camelid Camelids are members of the biological family (biology), family Camelidae, the only currently living family in the suborder Tylopoda. The seven extant taxon, extant members of this group are: dromedary, dromedary camels, Bactrian camels, wild Bac ...

genera: '' Procamelus'', '' Aepycamelus'' and '' Protolabis'' *three

canid Canidae (; from Latin, ''canis'', "dog") is a family (biology), biological family of caniform carnivorans, constituting a clade. A member of this family is also called a canid (). The family includes three subfamily, subfamilies: the Caninae, a ...

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 o ...

'' 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 early Clarendonian age of the Late Miocene to the late Hemphil ...

'' *one rhinoceros genus: '' Teleoceras'' *one saber-toothed

musk deer Musk deer can refer to any one, or all eight, of the species that make up ''Moschus'', the only extant genus of the family (biology), family Moschidae. Despite being commonly called deer, they are not true deer belonging to the family Cervidae, b ...

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 bird of prey that is Endemism, endemic to Africa. It is mostly terrestrial, spending most of its time on the ground, and is usually found in the open grasslands and s ...

), 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'' (a large

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

), ''

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 US and southeast Ontario, Canada. Musk glands p ...

'' (a musk turtle) and ''

Chrysemys ''Chrysemys'' is a genus of turtles in the family Emydidae. They are found throughout most of North America. Reproduction Chrysemys have temperature dependent sex determination. During egg incubation, lower temperatures produce males while higher ...

'' (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