Brule Formation

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Brule Formation
Stratigraphic range: Rupelian
~33–30 Ma
Brule Formation Badlands NP.jpg
Brule Formation in Badlands National Park
Type Geological formation
Unit of White River Formation
Underlies Sharps Formation, Arikaree Formation
Overlies Chadron Formation
Thickness 6–65 metres (20–213 ft)[1]
Lithology
Primary Fine grained clastic rocks
Other Freshwater limestone, Tuff, Sandstone
Location
Region Nebraska, North Dakota, South Dakota, Colorado, Wyoming
Country United States

The Brule Formation was deposited between 33 and 30 million years ago, roughly the Rupelian age (Oligocene).[2] It occurs as a subunit of the White River Formation in Nebraska, Colorado, North Dakota, South Dakota, and Wyoming.

It is a sequence of fine grained clastic rocks (claystones, mudstones, siltstones) interbeded with freshwater carbonates, volcanic ash (tuff), and sandstone.[1]

The sandstones layers, which are up to 3 metres (9.8 ft) thick, can contain mammalian fossils (e.g. the Fitterer bed). The most important fossils sites are:[1]

Fossil record[edit]

Prehistoric catfish, several mammals such as nimravids and hesperocyon and sunfish fossils are known from the Brule Formation in Badlands National Park.[3]

Notable among the local fauna are Bathornithid birds, ranging from the highly varied wetland-dwelling Bathornis species to the gigantic Paracrax.

Fauna[edit]

Fauna reported from the Brule Formation
Genus Species Location Stratigraphic position Material Description Images

Proscalops[4]

Proscalps tertius[4] Numerous, including upper incisor and molar.[4] Species holotype likely located here.[4]
Hyracodon
  • H. nebracensis
SD, ND, NE Jaw fragments, skulls Early rhinoceros
Subhyracodon
  • S. occidentalis
NE, SD, ND, WY Teeth and skulls Early rhinocers
Eporeodon
  • E. major
SD Incredibly rare Large oredodont
Leptauchenia
  • L. decora
SD, NE Teeth and skulls Small Oreodont
Merycoidodon
  • M. culbertsoni
  • M. gracilis
SD, ND, NE, WY Skulls, limb bones, and skeletons Oreodont
Poebrotherium
  • P. wilsoni
SD, ND, NE, WY Bones, jaw fragments Early camel
Leptomeryx SD, NE, WY Teeth Deer-like mammal
Archaeotherium
  • A. mortoni
WY Teeth and skulls Entelodont

See also[edit]

References[edit]

  1. ^ a b c "Lithostratigraphy, Paleontology, and Biochronology of the Chadron, Brule, and Arikaree Formations in North Dakota". Retrieved 28 February 2013.
  2. ^ "Geologic Formations". nps.gov.
  3. ^ Hunt, ReBecca K., Vincent L. Santucci and Jason Kenworthy. 2006. "A preliminary inventory of fossil fish from National Park Service units." in S.G. Lucas, J.A. Spielmann, P.M. Hester, J.P. Kenworthy, and V.L. Santucci (ed.s), Fossils from Federal Lands. New Mexico Museum of Natural History and Science Bulletin 34, pp. 63-69.
  4. ^ a b c d Bjork, Philip R. (1975). "Observations on Proscalops tertius (Mammalia: Insectivora) of the Upper Oligocene of South Dakota". Journal of Paleontology. 49 (5): 808–813. JSTOR 1303274.