Lakota Formation

Lakota Formation
Stratigraphic range: Berriasian-Barremian
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]

Vertebrate paleofauna

Archosaurs

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

Dakotadon

D. lakotaensis

Chilson Member

"Skull, mandible, [and] vertebrae."[2]

An ankylopollexian iguanodont

Hoplitosaurus

H. marshi

Chilson Member

"Partial postcranial skeleton [and] osteoderms."[3]

An ankylosaur belonging to Polacanthidae

Osmakasaurus[4][5]

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

Unnamed basal macronarian[6]

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[7]

Chilson Member

Right M2

A plagiaulacid.

Infernolestes[7]

I. rougieri

Chilson Member

Right lower M1

A spalacotheriid trechnotherian.

Lakotalestes[7]

L. luoi

Chilson Member

Right upper molar (M5?)

A dryolestid

Passumys[7]

P. angelli

Chilson Member

Right M1

References

  1. ↑ Sames, B., Cifelli, R.L., and 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: 207–224.
  2. ↑ "Table 19.1," in Weishampel, et al. (2004). Page 416.
  3. ↑ "Table 17.1," in Weishampel, et al. (2004). Page 366.
  4. ↑ 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 36: 197-332.
  5. ↑ McDonald, A.T., 2011. The taxonomy of species assigned to Camptosaurus (Dinosauria: Ornithopoda). Zootaxa 2783: 52-68.
  6. ↑ M.D. D'Emic & J.R. Foster (2014) The oldest Cretaceous North American sauropod dinosaur. Historical Biology (advance online publication) DOI:10.1080/08912963.2014.976817 http://www.tandfonline.com/doi/full/10.1080/08912963.2014.976817#.VGofevnF_To
  7. 1 2 3 4 Cifelli, R.L., Davis, B.M., and Sames, B. 2014. Earliest Cretaceous mammals from the western United States. Acta Palaeontologica Polonica 59 (1): 31–52.


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