The White River Fauna are fossil animals found in the White River Group of South Dakota, North Dakota, Wyoming, Colorado and Nebraska in the United States. In southwest South Dakota and northwest Nebraska, these fossils are characteristic of the White River Badlands (including Badlands National Park), though they can be found far beyond the limits of the White River watershed. In Wyoming, the White River Group is undifferentiated, and is more commonly known as the White River Formation. Further east in Nebraska and South Dakota, the group is divided into the Chadron Formation (lower part) and Brule Formation (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 in Badlands National Park and the Arikaree Group in northwest Nebraska. Animals from the White River Group date from the Eocene and Oligocene epochs. The fauna is representative of four North American Land Mammal Ages (NALMAs):
Arikareean (late Oligocene [Chattian] - early Miocene [Burdigalian], 29.5 - 18.5 million years ago) Whitneyan ("mid-Oligocene" [Rupelian], 31.8 - 29.5 million years ago) Orellan (early Oligocene [Rupelian], 33.9 - 31.8 million years ago) Chadronian (late Eocene [Priabonian], 37 - 33.9 million years ago) Only the uppermost layers of the White River Group extend into the Arikareean (specifically, the informal "brown siltstone member" of the Brule Formation). All NALMA and Epoch information in this list refers solely to each species' distribution through the White River Group, as some species survive into later time intervals outside of the White River area.
Birds
Mammals
†Apatemyids
Artiodactyls
†Antracotheres
Camelids
†Entelodonts
†Leptochoerids Leptochoerids are an extinct and rare group of hoofed mammals. Their affinities and anatomy are nearly unknown beyond their teeth, which were generally bunodont in form.
†Merycoidodontoids Merycoidodontoids, also known as oreodonts, are an extinct yet formerly abundant group of hoofed mammals with short legs and barrel-shaped bodies. Most oreodonts were part of the family Merycoidodontidae, distinguished by hoofs and a short tail. Despite their pig-like stature, they were probably more closely related to camels.
†Protoceratids †Protoceratidae is an extinct family of deer-like hoofed mammals which would evolve elaborate horns during the Miocene. The Eocene-Oligocene species found in the White River Group were rare and had simpler skulls compared to their later (synthetoceratine) counterparts.
Ruminants Early ruminants (cud-chewing hoofed mammals) of the White River Group were very small. They were similar in appearance to modern chevrotains (mouse deer) or hornless dik-diks, though beyond this general body shape their affinities are unclear.
Suina A few suines (pig-like mammals) are rare components of the White River fauna. These species are sometimes regarded as the earliest peccaries (family Tayassuidae), though other times considered early suines which split off prior to the common ancestor between peccaries and Old World pigs (family Suidae).
Carnivorans
†Amphicyonids
Arctoids Several species of arctoids, including potential ursoids (bear relatives) are known from the White River Group.
Canids
†Nimravids Nimravids ("false saber-toothed cats") were the largest feliform predators of the White River fauna.
Other carnivorans
Chiropterans
Eulipotyphlans Modern ants often use tiny tooth fossils as grains when building their anthills, and teeth from eulipotyphlans (relatives of shrews, moles, and hedgehogs) are common at anthill sites close to the Chadronian-Orellan transition. Both erinaceomorph (hedgehog-like) and "soricomorph" (shrew and mole-like) eulipotyphlans occur in the White River fauna, though erinaceomorphs would go extinct in North America later on in the Cenozoic, near the end of the Miocene.
†Hyaenodonts
Lagomorphs
†Leptictids Leptictids are an extinct group of mammals with an insectivorous diet, a flexible snout, and hopping adaptations.
Metatherians
†Palaeanodonta
†Pantolestans
Perissodactyls
†Brontotheres
Equids
Rhinocerotoids
Tapiroids
Primates
Rodents Modern ants often use tiny tooth fossils as grains when building their anthills, and rodent teeth are common at anthill sites close to the Chadronian-Orellan transition.
Reptiles
Crocodilians
Lizards Indeterminate iguanid, skink, and diploglossine (galliwasp) fossils are also known from the White River Group.
Snakes
Turtles Indeterminate fossils of an anosteirine carettochelyid and a ptychogastrin geoemydid are also known from the White River Group.
Amphibians
See also Category:White River Fauna
Further reading Rachel Benton, Dennis O. Terry Jr., Emmett Evanoff, & H. Gregory McDonald, The White River Badlands: Geology and Paleontology, Indiana University Press 2015 Donald R. Prothero & Robert J. Emry (ed.), The Terrestrial Eocene-Oligocene Transition in North America, Cambridge University Press, 1996 William Berryman Scott, A history of land mammals in the western hemisphere, MacMillan Publishing Company, 1913
External links The Fossils of the White River Badlands, by Ryan C
References