Lakota Formation
Stratigraphic range: Berriasian-Barremian

PreЄ

Type| Geological formation
Sub-units| Chilson Member. Fuson Member
Underlies| Fall River Formation
Overlies| Morrison Formation
Thickness| 200 to 500 feet (60 to 150 m)
Lithology
Primary| Sandstone
Other| Shale, Coal, Conglomerate
Location
Region| North America
Country| United States
Type section
Named for| Lakota Native American tribe
Named by| Darton
Year defined| 1899

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]

The Fuson Member takes its name from rock exposures in Fuson Canyon, a valley on the eastern side of the Black Hills.[2]

## Contents

* 1 Vertebrate paleofauna
* 1.1 Dinosaurs
* 1.2 Mammals
* 1.3 Turtles
* 2 References

## Vertebrate paleofauna

### Dinosaurs

Dinosaurs reported from the Lakota Formation

Genus  | Species  | Location  | Stratigraphic position  | Material  | Notes  | Images

Dakotadon[3]

D. lakotaensis

|  |

Chilson Member

"Skull, mandible, [and] vertebrae."[4]

An ankylopollexian iguanodont

Hoplitosaurus

H. marshi

|  |

Chilson Member

"Partial postcranial skeleton [and] osteoderms."[5]

An ankylosaur belonging to Polacanthidae

Osmakasaurus[6][7]

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[8]

| 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[9]

|  |

Chilson Member

Right M2

A plagiaulacid multituberculate

Infernolestes[9]

I. rougieri

|  |

Chilson Member

Right lower M1

A spalacotheriid trechnotherian.

Lakotalestes[9]

L. luoi

|  |

Chilson Member

Right upper molar (M5?)

A dryolestid

Passumys[9]

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[10] | 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 [11]

## 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. ↑ "Geolex — Fuson publications". https://ngmdb.usgs.gov/Geolex/UnitRefs/FusonRefs_8218.html.
3. ↑ 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.
4. ↑ "Table 19.1," in Weishampel, et al. (2004). Page 416.
5. ↑ "Table 17.1," in Weishampel, et al. (2004). Page 366.
6. ↑ 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.
7. ↑ 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. https://www.mapress.com/j/zt/article/view/zootaxa.2783.1.4.
8. ↑ 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.
9. ↑ 9.0 9.1 9.2 9.3 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.
10. ↑ 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" (in English). Fossil Record 23 (1): 1–13. doi:10.5194/fr-23-1-2020. ISSN 2193-0066. https://fr.copernicus.org/articles/23/1/2020/.
11. ↑ Darton, Nelson Horatio (1904). "Comparison of the Stratigraphy of the Black Hills, Bighorn Mountains, and Rocky Mountain Front Range" (in English). Geological Society of America Bulletin 15: 379-448. https://archive.org/details/sim_geological-society-of-america-bulletin_1904_15/.

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