White River Fauna

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.^[1]

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 - early Miocene, 29.5 - 18.5 million years ago)
• Whitneyan (mid-Oligocene, 31.8 - 29.5 million years ago)
• Orellan (early Oligocene, 33.9 - 31.8 million years ago)
• Chadronian (late Eocene, 37 - 33.9 million years ago)

Birds

Genus	Species	Clade	Epoch	Image	Notes
†Bathornis	†B. veredus (type) †B. celeripes †B. cursor †B. fricki †B. geographicus †B. grallator †B. fax? †B. minor	†Bathornithidae	Eocene-Miocene		The type genus of the Bathornithidae, large predatory birds related to seriemas.[2]
†Paracrax		†Bathornithidae			Closely related and similar to the conspecific Bathornis; however, it seems to have occupied more arid environments.[3]

Mammals

Artiodactyls

Antracotheres

Genus	Species	Clade	Epoch	Image	Notes
†Bothriodon	†B. sp.	†Anthracotheriidae
†Elomeryx	†E. brachyrhynchus	†Anthracotheriidae

Camelids

Genus	Species	Clade	Epoch	Image	Notes
†Poebrotherium	†P. wilsoni (type) †P. chadronensis †P. eximium †P. franki †P. labratum	Camelidae

Entelodonts

Genus	Species	Clade	Epoch	Image	Notes
†Archaeotherium	†A. mortoni (type)	†Entelodontidae	Oligocene
†Daeodon	†D. shoshonensis (type) †D. humerosum?	†Entelodontidae	Miocene

Leptomerycids

Genus	Species	Clade	Epoch	Image	Notes
†Leptomeryx		†Leptomerycidae			The most common fossil found in the area.[4]

Merycoidodontids

Genus	Species	Clade	Epoch	Image	Notes
†Eporeodon	†E. major (type) †E. occidentalis †E. pygmyus	†Merycoidodontidae	Oligocene
†Leptauchenia		†Merycoidodontidae
†Merycoidodon		†Merycoidodontidae
†Miniochoerus		†Merycoidodontidae

Protoceratids

Genus	Species	Clade	Epoch	Image	Notes
†Protoceras		†Protoceratidae

Ruminants

Genus	Species	Clade	Epoch	Image	Notes
†Hypertragulus		†Hypertragulidae

Creodonts

Genus	Species	Clade	Epoch	Image	Notes
†Hyaenodon	†H. horridus	†Hyaenodontidae	Eocene - Miocene

Carnivorans

Amphiconids

Genus	Species	Clade	Epoch	Image	Notes
†Daphoenus	†D. vetus (type) †D. hartshorianus †D. lambei †D. ruber †D. socialis †D. transversus	†Amphicyonidae	Eocene-Miocene
†Parictis		†Amphicynodontinae

Canids

Genus	Species	Clade	Epoch	Image	Notes
†Archaeocyon	†A. leptodus (type) †A. pavidus †A. falkenbachi	†Borophaginae	Oligocene
†Osbornodon		Canidae

Nimravids

Genus	Species	Clade	Epoch	Image	Notes
†Dinictis	†D. felina (type)	†Nimravidae	Eocene-Miocene
†Hoplophoneus	H. primaevus (type) H. occidentalis H. strigidens H. cerebralis H. dakotensis H. oharrai H. sicarius	†Nimravidae	Eocene-Oligocene
†Nimravus		†Nimravidae

Epoicotheres

Genus	Species	Clade	Epoch	Image	Notes
†Xenocranium	†X. pileorivale (type)	†Epoicotheriidae	Oligocene

Lagomorphs

Genus	Species	Clade	Epoch	Image	Notes
†Palaeolagus		Leporidae

Perissodactyls

Brontotheres

Genus	Species	Clade	Epoch	Image	Notes
†Megacerops		†Brontotheriidae	Eocene - Oligocene

Equids

Genus	Species	Clade	Epoch	Image	Notes
†Mesohippus		Equidae
†Miohippus		Equidae

Rhinocerotoids

Amynodonts

Genus	Species	Clade	Epoch	Image	Notes
†Metamynodon		†Amynodontidae

Hyracodontids

Genus	Species	Clade	Epoch	Image	Notes
†Hyracodon		†Hyracodontidae	Eocene - Oligocene

Rhinocerotids

Genus	Species	Clade	Epoch	Image	Notes
†Subhyracodon		Rhinocerotidae

Tapirids

Genus	Species	Clade	Epoch	Image	Notes
†Protapirus		Tapiridae

Rodents

Genus	Species	Clade	Epoch	Image	Notes
†Agnotocastor	†A. praeteredens (type) †A. coloradensis †A. galushai †A. readingi	Castoridae	Eocene-Miocene
†Ischyromys		†Ischyromyidae

Reptiles

Crocodilians

Genus	Species	NALMA	Age	Notes	Image
Alligator	†A. prenasalis	Chadronian	late Eocene	The earliest known species of alligator.

Lizards

Indeterminate iguanid, skink, and diploglossine (galliwasp) fossils are also known from the White River Group.^[5]

Genus	Species	NALMA	Epoch	Notes	Image
†Aciprion	†A. formosum	Orellan	early Oligocene	An iguanian related to crotaphytids (collared lizards).[6][7]
†Cremastosaurus	†C. carinicollis	Chadronian	late Eocene	A rare and enigmatic squamate based on vertebrae.[6]
	†"C". rhambastes
†Cypressaurus	†C. sp.	Chadronian	late Eocene	A rare iguanid based on jaw fragments.[5]
†Exostinus	†E. serratus	Orellan	early Oligocene	A rare xenosaurid known from skull fragments.[6][8]
†Helodermoides	†H. tuberculatus	Chadronian to Orellan	late Eocene to early Oligocene	A glyptosaurine anguid (an armored lizard related to glass lizards and alligator lizards). Previously considered a species of Glyptosaurus.[6][9][5]
†Hyporhina	†H. antiqua	Orellan to Whitneyan	early-mid Oligocene	An amphisbaenian (worm lizard).[6]
	†H. tertia	Chadronian	late Eocene
†Lowesaurus	†L. matthewi	Orellan to Arikareean	Oligocene	A rare helodermatid (beaded lizard).[6]
†Palaeoxantusia	†P. cf. P. borealis	Chadronian	late Eocene	A xantusiid (night lizard).[6][5]
†Paraphrynosoma	†P. greeni	Orellan	early Oligocene	A rare iguanian known from a single jaw.[6]
†Parophisaurus	†P. pawneensis	Orellan	early Oligocene	An anguid related to Ophisaurus (eastern glass lizards).[6]
†Peltosaurus	†P. granulosus	Chadronian to Arikareean	late Eocene to late Oligocene	A common glyptosaurine anguid (an armored lizard related to glass lizards and alligator lizards).[6][9][5]
Polychrus	†P. charisticus[5]	Chadronian	late Eocene	A rare polychrotine (bush anole) based on jaw fragments.[5]
Rhineura	†R. coloradoensis	Chadronian	late Eocene	A rhineurid amphisbaenian closely related to the Florida worm lizard (Rhineura floridana).[6][9][5]
	†R. hatcherii	Orellan to Whitneyan	early-mid Oligocene
†Saniwa	†S. edura[5]	Chadronian	late Eocene	A rare varanid based on jaw fragments.[5]
†Spathorhynchus	†S. natronicus	Chadronian	late Eocene	A rare rhineurid based on a single skull.[6][5]
†Tinosaurus	†T. sp.	Chadronian	late Eocene	A rare acrodontan based on jaw fragments.[5]
†Tuberculacerta[5]	†T. pearsoni	Chadronian	late Eocene	A rare phrynosomatine (relative of fence lizards) based on jaw fragments.[5]

Snakes

Genus	Species	NALMA	Epoch	Notes	Image
†Boavus	†B. cf. occidentalis	Chadronian to Orellan	late Eocene to early Oligocene	A boine boid (true boa).[6]
†Calamagras	†C. angulatus	Orellan to Arikareean	Oligocene	An erycine boid (sand boa).[6][9]
	†C. murivorus	Orellan	early Oligocene
†Coprophis	†C. dakotaensis	Orellan	early Oligocene	A rare booid based on eroded fossils found within a mammal coprolite.[6]
†Geringophis	†G. vetus	Orellan	early Oligocene	An erycine boid (sand boa).[6][9]
†Helagras	†H. orellanensis	Orellan	early Oligocene	An erycine boid (sand boa).[6]
†Hibernophis[10]	†H. breithaupti	Orellan	early Oligocene	A booid based on complete skeletons.[10]
†Texasophis	†T. galbreathi	Orellan	early Oligocene	A colubrid.[6]

Turtles

Indeterminate fossils of an anosteirine carettochelyid and a ptychogastrin geoemydid are also known from the White River Group.^[11]

Genus	Species	NALMA	Epoch	Notes	Image
Apalone	†A. leucopotamica	Chadronian to Orellan	late Eocene to early Oligocene	A trionychid (softshell turtle).[11]
Chrysemys	†C. antiqua	Chadronian to Whitneyan	late Eocene to mid-Oligocene	An emydid (pond turtle), sometimes known as "Trachemys" antiqua. A potential relative of modern painted turtles (Chrysemys).[11]
cf. †Echmatemys	cf. †E. sp.	Chadronian	late Eocene	A "batagurid" (geoemydid) similar to Echmatemys.[11]
Gopherus	†G. laticuneus	Chadronian to Whitneyan	late Eocene to mid-Oligocene	A gopher tortoise in the subgenus Oligopherus. Gopherus fossils are also known from the Whitneyan.[11]
†Hesperotestudo	†H. brontops	Chadronian	late Eocene	A testudinid (tortoise). Hesperotestudo-like fossils are also known from the Whitneyan.[11]
†Pseudograptemys[11]	†P. inornata	Chadronian	late Eocene	An emydid (pond turtle) closely related to Graptemys (map turtles).[11]
†Stylemys	†S. amphithorax	Chadronian	late Eocene	A common testudinid (tortoise) related to gopher tortoises (Gopherus). Probably survived into the Whitneyan in the White River area.[11]
	†S. nebrascensis	Chadronian to Orellan	late Eocene to early Oligocene
†Xenochelys	†X. formosa	Chadronian	late Eocene	A kinosternid (mud turtle).[11]

Amphibians

Genus	Species	NALMA	Epoch	Notes	Image
†Eopelobates	†E. grandis	Chadronian	late Eocene	A pelobatid frog related to Pelobates (the European spadefoot toads).[12]

See also

• Category:White River Fauna

Further reading

• Rachel Benton, The White River Badlands: Geology and Paleontology, Indiana University Press 2015
• William Berryman Scott, A history of land mammals in the western hemisphere, MacMillan Publishing Company, 1913