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.
| Lakota Formation | |
|---|---|
| Stratigraphic range: | |
| 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 |
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
editDinosaurs
edit| Dinosaurs reported from the Lakota Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
|
D. lakotaensis |
Chilson Member |
"Skull, mandible, [and] vertebrae."[3] |
||||
|
H. marshi |
Chilson Member |
"Partial postcranial skeleton [and] osteoderms."[4] |
An ankylosaur belonging to Polacanthidae |
|||
|
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 |
|||
| Indeterminate |
Chilson Member |
Left humerus and right metacarpal I |
A macronarian related to Camarasaurus |
|||
Mammals
edit| Mammals reported from the Lakota Formation | ||||||
|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images |
|
B. hydei[8] |
Chilson Member |
Right M2 |
||||
|
I. rougieri |
Chilson Member |
Right lower M1 |
||||
|
L. luoi |
Chilson Member |
Right upper molar (M5?) |
||||
|
P. angelli |
Chilson Member |
Right M1 |
A plagiaulacid multituberculate | |||
Turtles
edit| 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
edit- ^ 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.
- ^ 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.
- ^ "Table 19.1," in Weishampel, et al. (2004). Page 416.
- ^ "Table 17.1," in Weishampel, et al. (2004). Page 366.
- ^ 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.
- ^ 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.
- ^ 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.
- ^ a b c d 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.
- ^ 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.
- ^ 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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