Cloverly Formation
Cloverly Formation | |
---|---|
Stratigraphic range: | |
Type | Geological formation |
Sub-units | Pryor Conglomerate, Little Sheep Member, Himes Member |
Underlies | Thermopolis Shale |
Overlies | Morrison Formation |
Thickness | 150–400 ft (46–122 m) |
Lithology | |
Primary | Mudstone |
Other | Conglomerate, sandstone |
Location | |
Region | Wyoming, Montana, Utah |
Country | USA |
Type section | |
Named for | Cloverly post office, Wyoming |
Named by | Nelson Horatio Darton, 1904[1] |
The Cloverly Formation is a
Stratigraphy
The Cloverly Formation rests disconformably on the Morrison Formation and is conformably overlain by the Thermopolis Shale. It is subdivided into a variety of members, depending on the location.[2][4] In the Bighorn Basin along the Montana-Wyoming border, Moberly (1960) divided the Cloverly into the following three members:
- The Pryor Conglomerate lies at the base and contains abundant black chert. It is named from thick beds exposed on the west side of the Pryor Mountains.
- The Little Sheep Member lies in the middle and is composed of pale-purple, gray to almost white, bentonitic mudstone.
- The uppermost unit is the Himes Member, which contains some coarse-grained channel sandstone deposits, but consists primarily of brightly multicolored (variegated) mudstones.
In contrast, Ostrom (1970) divided the formation into four units, which he named Units IV-VII:
- Unit IV equates to the Pryor Conglomerate of Moberly and consists of a conglomerate or conglomeratic sandstone.
- Unit V, overlaying Unit IV, consists of a lower grey-to-purple claystone with abundant fist-sized chalcedony and barite concretions; the unit is highly bentonitic and contains occasional channel sands.
- Unit VI is a discontinuous "salt and pepper" cross-stratified channel sandstone with occasional conglomerate, considered by Moberly to be part of the Himes Member.
- Unit VII, the uppermost, is a maroon to orange claystone with occasional highly rounded and polished pebbles of silica.[5]
Age
A stratigraphic revision of the Cloverly Formation using new uranium lead dates reinterpret the formation as spanning the Valanginian-Cenomanian stages of the Cretaceous period. The individual ages of the members are listed below:[6]
- Pryor Conglomerate; 140-130 Ma (Valanginian-Hauterivian)
- Little Sheep Member; 130-124 Ma (marine section) (Hauterivian-Barremian) and 124-109 Ma (terrestrial section) (Barremian-Albian)
- Himes Member; 109-98 Ma (Albian-Cenomanian)
Depositional environment
The sediments of the Cloverly Formation were deposited in
Vertebrate fauna
Animals recovered include the dinosaurs
References for data: Ostrom 1970; Cifelli et al. 1998; Cifelli 1999; Nydam and Cifelli 2002. Possible
Ornithischians
Ornithischians reported from the Cloverly Formation
| ||||||
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Genus | Species | State | Stratigraphic position | Material | Notes | Images |
A. americanus |
|
Cloverly VII; Himes Member[10] |
A basal neoceratopsian .
|
|||
S. edwardsorum[11] |
Known from "several articulated skeletons" and common armor plates.[11] Only one partial skull is known.[12] |
Articulated skeletons are often encased in carbonate caliche deposits that require acid to be removed safely.[11] | ||||
Tatankacephalus[13] | T. cooneyorum[13] |
|
Cloverly VII[13] | Partial cranium, rib fragments, and osteoderms.[13] | Originally described as an ankylosaurid but has since been reclassified as a nodosaurid.[14] | |
T. tilleti[11] |
Its remains are the most common of any dinosaur of the formation.[11] |
Juvenile remains are sometimes found together, suggesting that young Tenontosaurus lived in sibling groups. Deinonychus teeth are sometimes associated with Tenontosaurus remains suggesting a predator–prey relationship between the two.[11] | ||||
Z. schaffi[11] |
|
Himes Member |
Its remains are "very rare."[11] |
Saurischians
Theropod eggshell fragments are known from the formation. Unidentifiable ornithomimid remains are present and most commonly represented by toe bones. have also been found here as well.
Color key
|
Notes Uncertain or tentative taxa are in small text; |
Saurischians reported from the Cloverly Formation
| ||||||
---|---|---|---|---|---|---|
Genus | Species | State | Stratigraphic position | Material | Notes | Images |
Acrocanthosaurus[16] | A. atokensis[16] |
|
Cloverly VII; Himes Member[16] | |||
D. antirrhopus[11] |
Its remains are "very rare."[11] |
Tenontosaurus remains have been recovered in association with Deinonychus teeth on several occasions suggesting a predator–prey relationship between the two.[11] | ||||
M. celer[11] |
Himes Member |
Its remains are "extremely rare."[11] Known only from a "[p]artial skeleton with partial skull."[17] The specimen lacks feet and is catalogued as AMNH 3041.[18] |
The type specimen AMNH 3041[11] was recovered by Barnum Brown from Cloverly strata in Montana in 1933. | |||
O. velox[19] |
Later found to be indeterminate ornithomimid remains.[19] | |||||
R. cooneyi[20] |
|
Cloverly VII; Himes Member[20] | ||||
Sauroposeidon[21] | S. proteles |
|
Cloverly VII; Himes Member[16] |
Mammals
Mammals reported from the Cloverly Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | State | Stratigraphic position | Material | Notes | Images |
A. sp.[22] |
Previously referred as "Cloverly triconodont" | |||||
cf. Atokatheridium |
Indeterminate | |||||
B. sp. |
||||||
C. montanensis |
||||||
G. ostromi |
||||||
J. sp. |
||||||
M. keeblerorum |
||||||
cf. Oklatheridium |
Indeterminate | |||||
cf. Paracimexomys |
Indeterminate |
|||||
Spalacotheriidae | Indeterminate |
Crocodyliforms
Crocodyliforms reported from the Cloverly Formation
| ||||||
---|---|---|---|---|---|---|
Genus | Species | State | Stratigraphic position | Material | Notes | |
cf. Atoposauridae |
Indeterminate | |||||
cf. Bernissartidae |
Indeterminate | |||||
cf. Goniopholididae |
Indeterminate| |
|||||
cf. Pholidosauridae |
Indeterminate |
Turtles
Turtles reported from the Cloverly Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | State | Stratigraphic position | Material | Notes | |
Indeterminate | ||||||
"G". pervicax[11] |
||||||
N. speciosa[11] |
||||||
Indeterminate |
Lepidosaurs
Lepidosaurs reported from the Cloverly Formation
| ||||||
---|---|---|---|---|---|---|
Genus | Species | State | Stratigraphic position | Material | Notes | |
P. keebleri |
||||||
Indeterminate | ||||||
P. wilsoni |
Also known from the Antlers Formation | |||||
Indeterminate |
Amphibians
Amphibians reported from the Cloverly Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | State | Stratigraphic position | Material | Notes | Images |
A. ektopistikon[23] |
||||||
Anura
|
Indeterminate |
|||||
Batrachosauroididae |
Indeterminate |
|||||
Indeterminate |
||||||
cf. Scotiophryne |
Indeterminate |
Bony fish
Osteichthyes reported from the Cloverly Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | State | Stratigraphic position | Material | Notes | Images |
|
C. frazieri[11] |
|||||
C. nirumbee[24] |
||||||
aff. Lepidotes |
Indeterminate |
|||||
aff. Pycnodontidae |
Indeterminate |
|||||
Vidalamiinae
|
Indeterminate |
Cartilaginous fish
Chondrichthyes reported from the Cloverly Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | State | Stratigraphic position | Material | Notes | |
E. sp. |
||||||
H. parvidens | ||||||
L. sp. |
||||||
P. sp. | ||||||
P. sp. |
See also
- List of dinosaur-bearing rock formations
- Cloverly Fauna
Footnotes
- ^ a b Darton, N.H. 1904. Comparison of the stratigraphy of the Black Hills, Bighorn Mountains, and Rocky Mountain Front Range. Geological Society of America Bulletin, v. 15, p. 379-448.
- ^ a b c U.S. Geological Survey (1993). "Geologic Unit: Cloverly". Retrieved 2014-12-23.
- ^ "National Natural Landmarks - National Natural Landmarks (U.S. National Park Service)". www.nps.gov. Retrieved 2019-03-22.
Year designated: 1973
- ^ a b Moberly, R.M., Jr., 1960, Morrison, Cloverly, and Sykes Mountain formations, northern Bighorn basin, Wyoming and Montana: Geological Society of America Bulletin, v. 71, no. 8, p. 1137-1176.
- OCLC 258060311.
- S2CID 132032611.
- ^ May, M.T. 1992. Intra- and extrabasinal tectonism, climate and intrinsic threshold cycles as possible controls on Early Cretaceous fluvial architecture, Wind River basin, Wyoming. In: Sundell, K.A., and Anderson, T.C., eds., Rediscover the Rockies: Wyoming Geological Association Field Conference Guidebook, 43rd Annual Field Conference, Casper, WY, September 12–19, 1992, no. 43, p. 61-74.
- ISSN 0272-4634.
- ^ a b "3.11 Montana, United States; 1. Cloverly Formation," in Weishampel, et al. (2004). Page 556.
- ^ PMID 25494182.
- ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac ad ae af ag Horner. Pp. 93-100.
- ^ "Table 17.1," in Weishampel, et al. (2004). Page 365.
- ^ doi:10.1139/E09-045.
- S2CID 86002282.
- ^ a b c d "3.12 Wyoming, United States; 2. Cloverly Formation," in Weishampel, et al. (2004). Page 556.
- ^ .
- ^ "Table 8.1," in Weishampel, et al. (2004). Page 167.
- ^ "Table 5.1," in Varricchio (2001). Page 44.
- ^ a b c "3.11 Wyoming, United States; 1. Cloverly Formation" and "3.12 Montana, United States; 2. Cloverly Formation," in Weishampel, et al. (2004). Page 556.
- ^ .
- ^ D'Emic, M.D., and B.Z. Foreman. (2012). The beginning of the sauropod dinosaur hiatus in North America: insights from the Lower Cretaceous Cloverly Formation of Wyoming. Journal of Vertebrate Paleontology 32(4):883–902.
- ISSN 1573-7055.
- ISSN 0272-4634.
- ^ Frederickson J.A. and Cifelli R.L. (2016) New Cretaceous lungfishes (Dipnoi, Ceratodontidae) from western North America. Journal of Paleontology.
References
- Burton, D., Greenhalgh, B.W., Britt, B.B., Kowallis, B.J., Elliott, W.S., and Barrick, R. 2006. New radiometric ages from the Cedar Mountain Formation, Utah and the Cloverly Formation, Wyoming: implications for contained dinosaur faunas. Geological Society of America Abstracts with Programs 38(7): 52.
- Chen, Z.-Q. and Lubin, S. 1997. A fission track study of the terrigenous sedimentary sequences of the Morrison and Cloverly Formations in northeastern Bighorn Basin, Wyoming. The Mountain Geologist 34:51-62.
- Cifelli, R.L. 1999. Tribosphenic mammal from the North American Early Cretaceous. Nature 401:363-366.
- Cifelli, R.L., Wible, J.R., and Jenkins, F.A. 1998. Triconodont mammals from the Cloverly Formation (Lower Cretaceous), Montana and Wyoming. Journal of Vertebrate Paleontology 18: 237-241.
- Horner, John R. Dinosaurs Under the Big Sky (Cloverly Formation). Mountain Press Publishing Company. pp. 93–100. ISBN 0-87842-445-8.
- Nydam, R.L., and Cifelli, R.L. 2002. Lizards from the Lower Cretaceous (Aptian-Albian) Antlers and Cloverly Formations. Journal of Vertebrate Paleontology 22: 286-298.
- Ostrom, J. H. 1970. Stratigraphy and paleontology of the Cloverly Formation (Lower Cretaceous) of the Bighorn Basin area, Wyoming and Montana. Peabody Museum Bulletin 35:1-234
- Varricchio, D. J. 2001. Late Cretaceous oviraptorosaur (Theropoda) dinosaurs from Montana. pp. 42–57 in D. H. Tanke and K. Carpenter (eds.), Mesozoic Vertebrate Life. Indiana University Press, Indianapolis, Indiana.
- Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. 861 pp. ISBN 0-520-24209-2.