Lakota Formation
Stratigraphic range:
TypeGeological formation
Sub-unitsChilson Member. Fuson Member
UnderliesFall River Formation
OverliesMorrison Formation
Thickness200 to 500 feet (60 to 150 m)
Lithology
PrimarySandstone
OtherShale, Coal, Conglomerate
Location
RegionNorth America
Country United States
Type section
Named forLakota Native American tribe
Named byDarton
Year defined1899

The Lakota Formation is a sequence of rocks of early Cretaceous (Berriasian to Barremian) age from Western North America. Located in South Dakota, the name of the formation is derived from the Lakota Native American tribe.

There are two units of the Lakota Formation, the Chilson Member (upper Berriasian to Valanginian) and the underlying Fuson Member (upper Valanginian to early Barremian). A Berriasian-Valanginian age for the Chilson Member has been extrapolated by means of ostracods and charophytes.[1]

Vertebrate paleofauna

Dinosaurs

Dinosaurs reported from the Lakota Formation
Genus Species Location Stratigraphic position Material Notes Images

Dakotadon[2]

D. lakotaensis

Chilson Member

"Skull, mandible, [and] vertebrae."[3]

An ankylopollexian iguanodont

Hoplitosaurus

H. marshi

Chilson Member

"Partial postcranial skeleton [and] osteoderms."[4]

An ankylosaur belonging to Polacanthidae

Osmakasaurus[5][6]

O. depressus

Chilson Member

Portions of both ilia, anterior part of the blade of one pubis, an incomplete sacrum, centrum of the last sacro-dorsal, 12 caudal vertebrae, 1 thoracic rib and many fragments

An ankylopollexian iguanodont

Macronaria[7]

Indeterminate

Chilson Member

Left humerus and right metacarpal I

A macronarian related to Camarasaurus

Mammals

Mammals reported from the Lakota Formation
Genus Species Location Stratigraphic position Material Notes Images

Bolodon

B. hydei[8]

Chilson Member

Right M2

A plagiaulacid multituberculate

Infernolestes[8]

I. rougieri

Chilson Member

Right lower M1

A spalacotheriid trechnotherian.

Lakotalestes[8]

L. luoi

Chilson Member

Right upper molar (M5?)

A dryolestid

Passumys[8]

P. angelli

Chilson Member

Right M1

A plagiaulacid multituberculate

Turtles

Turtles reported from the Lakota Formation
Genus Species Location Stratigraphic position Material Notes Images
Lakotemys[9] L. australodakotensis Chilson Member Two shells and a partial skull A baenid paracryptodire

Other vertebrate remains found within the Lakota Formation include a fish scale from the gar Lepisosteus and a crocodile tooth [10]

References

  1. Sames, B.; Cifelli, R. L.; Schudack, M. (2010). "The nonmarine Lower Cretaceous of the North American Western Interior foreland basin: new biostratigraphic results from ostracod correlations, and their implications for paleontology and geology of the basin—an overview". Earth-Science Reviews. 101 (3–4): 207–224. doi:10.1016/j.earscirev.2010.05.001.
  2. Paul, Gregory S. (2008). "A revised taxonomy of the iguanodont dinosaur genera and species". Cretaceous Research. 29 (2): 192–216. doi:10.1016/j.cretres.2007.04.009.
  3. "Table 19.1," in Weishampel, et al. (2004). Page 416.
  4. "Table 17.1," in Weishampel, et al. (2004). Page 366.
  5. Gilmore, C.W. (1909). "Osteology of the Jurassic reptile Camptosaurus, with a revision of the species of the genus, and description of two new species". Proceedings of the U.S. National Museum. 332.
  6. McDonald, A. T. (2011). "The taxonomy of species assigned to Camptosaurus (Dinosauria: Ornithopoda)". Zootaxa. 2783 (1): 52–68. doi:10.11646/zootaxa.2783.1.4.
  7. D'Emic, M. D.; Foster, J. R. (2014). "The oldest Cretaceous North American sauropod dinosaur". Historical Biology. 28 (4): 470–478. doi:10.1080/08912963.2014.976817.
  8. 1 2 3 4 Cifelli, R. L.; Davis, B. M.; Sames, B. (2014). "Earliest Cretaceous mammals from the western United States". Acta Palaeontologica Polonica. 59 (1): 31–52. doi:10.4202/app.2012.0089.
  9. Joyce, Walter G.; Rollot, Yann; Cifelli, Richard L. (2020-02-12). "A new species of baenid turtle from the Early Cretaceous Lakota Formation of South Dakota". Fossil Record. 23 (1): 1–13. doi:10.5194/fr-23-1-2020. ISSN 2193-0066.
  10. Darton, Nelson Horatio (1904). "Comparison of the Stratigraphy of the Black Hills, Bighorn Mountains, and Rocky Mountain Front Range". Geological Society of America Bulletin. 15: 379–448.


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