The White River Fauna are

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 ...

animals found in the

White River Group The White River Formation is a geologic formation of the Paleogene Period, in the northern Great Plains and central Rocky Mountains, within the United States. It has been found in northeastern Colorado, Dawes County in western Nebraska, Badlands ...

South Dakota South Dakota (; Sioux language, Sioux: , ) is a U.S. state, state in the West North Central states, North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Dakota people, Dakota Sioux ...

North Dakota North Dakota ( ) is a U.S. state in the Upper Midwest, named after the indigenous Dakota people, Dakota and Sioux peoples. It is bordered by the Canadian provinces of Saskatchewan and Manitoba to the north and by the U.S. states of Minneso ...

Wyoming Wyoming ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States, Western United States. It borders Montana to the north and northwest, South Dakota and Nebraska to the east, Idaho t ...

Colorado Colorado is a U.S. state, state in the Western United States. It is one of the Mountain states, sharing the Four Corners region with Arizona, New Mexico, and Utah. It is also bordered by Wyoming to the north, Nebraska to the northeast, Kansas ...

and

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 ...

in the

United States The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

. In southwest South Dakota and northwest Nebraska, these fossils are characteristic of the White River Badlands (including

Badlands National Park Badlands National Park () is a List of national parks of the United States, national park of the United States in southwestern South Dakota. The park protects of sharply Erosion, eroded buttes and Pinnacle (geology), pinnacles, along with the l ...

), though they can be found far beyond the limits of the White River watershed.Scott, W. B., & Jepsen, G. L. (1940). The Mammalian Fauna of the White River Oligocene: Part IV. Artiodactyla. Transactions of the American Philosophical Society, 28(4), 363–746. https://doi.org/10.2307/1005504 In Wyoming, the White River Group is undifferentiated, and is more commonly known as the

White River Formation The White River Formation is a geologic formation of the Paleogene Period, in the northern Great Plains and central Rocky Mountains, within the United States. It has been found in northeastern Colorado, Dawes County in western Nebraska, Badland ...

. Further east in Nebraska and South Dakota, the group is divided into the

Chadron Formation Chadron Formation is a rock formation in North Dakota, South Dakota, northwestern Nebraska, and eastern Wyoming. It is named after the town of Chadron, Nebraska Chadron ( ) is a city in and the county seat of Dawes County, Nebraska, United St ...

(lower part) and

Brule Formation The Brule Formation was deposited between 34 and 30 million years ago, roughly the Rupelian age (Oligocene). It occurs as a subunit of the White River Group in South Dakota, Nebraska, Colorado, North Dakota, and Wyoming. It is a sequence of fin ...

(upper part). Exposures are less well-investigated in northeast Colorado and scattered sites across western North Dakota. The White River Group is overlain by the

Sharps Formation The Sharps Formation is a Formation (geology), geologic formation in South Dakota. It preserves fossils dating back to the Paleogene. The Sharps Formation is the namesake of the community of Sharps Corner, South Dakota. Fossil content Mammal ...

in Badlands National Park and the Arikaree Group in northwest Nebraska. Animals from the White River Group date from the

Eocene The Eocene ( ) is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (Ma). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene'' comes ...

and

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

epochs. The fauna is representative of four

North American Land Mammal Ages The North American land mammal ages (NALMA) establishes a geologic timescale for North American fauna beginning during the Late Cretaceous and continuing through to the present. These periods are referred to as ages or intervals (or stages when ref ...

(NALMAs): *

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 ...

(late Oligocene - early Miocene, 29.5 - 18.5 million years ago) *

Whitneyan The Whitneyan 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 33,300,000 to 30,800,000 years BP, a period of . It is usuall ...

(mid-Oligocene, 31.8 - 29.5 million years ago) *

Orellan The Orellan is a North American Land Mammal Age typically set from around 33,700,000 to 32,000,000 years BP, a period of . The Orellan is preceded by the Chadronian and followed by the Whitneyan NALMA stages. Relative to global geological chronolo ...

(early Oligocene, 33.9 - 31.8 million years ago) *

Chadronian The Chadronian is a North American Land Mammal Age typically set from around 37,000,000 to 33,700,000 years BP, a period of . The Chadronian is preceded by the Duchesnean and followed by the Orellan NALMA stages. Relative to global geological c ...

(late Eocene, 37 - 33.9 million years ago)

Birds

Mammals

Artiodactyls

Antracotheres

Camelids

Entelodonts

Leptomerycids

Merycoidodontids

Protoceratids

Ruminants

Creodonts

Carnivorans

Amphiconids

Canids

Nimravids

Epoicotheres

Lagomorphs

Perissodactyls

Brontotheres

Equids

Rhinocerotoids

= Amynodonts

= Hyracodontids

= Rhinocerotids

Tapirids

Rodents

Reptiles

Crocodilians

Lizards

Indeterminate

iguanid The Iguanidae is a family of lizards composed of the iguanas, chuckwallas, and their prehistoric relatives, including the widespread green iguana. Taxonomy Iguanidae is thought to be the sister group to the collared lizards (family Crotaphy ...

skink Skinks are a type of lizard belonging to the family (biology), family Scincidae, a family in the Taxonomic rank, infraorder Scincomorpha. With more than 1,500 described species across 100 different taxonomic genera, the family Scincidae is one o ...

, and diploglossine (galliwasp) fossils are also known from the White River Group.

Snakes

Turtles

Indeterminate fossils of an anosteirine carettochelyid and a ptychogastrin

geoemydid The Geoemydidae (formerly known as Bataguridae) are one of the largest and most diverse families in the order Testudines (turtles), with about 70 species. The family includes the Eurasian pond and river turtles and Neotropical wood turtles. Cha ...

are also known from the White River Group.

Amphibians

References

Paleogene animals of North America White River Formation, Fauna White River Formation, Fauna White River Formation, Fauna White River Formation, Fauna White River Formation, Fauna White River Formation, Fauna Paleontology lists Long stubs with short prose {{Paleogene-stub