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, 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 and Brule Formation. 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 :

Mammals

Perissodactyls

Rhinocerotoids

Amynodonts

Hyracodontids

Rhinocerotids

Reptiles

Lizards

Indeterminate iguanid, skink, and diploglossine fossils are also known from the White River Group.

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

Turtles

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

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