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 geological formation of Early and Late Cretaceous age (Valanginian to Cenomanian stage) that is present in parts of Montana, Wyoming, Colorado and Utah in the western United States. It was named for a post office on the eastern side of the Bighorn Basin in Wyoming by N.H. Darton in 1904. [1] [2] The sedimentary rocks of formation were deposited in floodplain environments and contain vertebrate fossils, including a diverse assemblage of dinosaur remains. In 1973, the Cloverly Formation Site was designated as a National Natural Landmark by the National Park Service. [3]
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:
In contrast, Ostrom (1970) divided the formation into four units, which he named Units IV-VII:
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]
The sediments of the Cloverly Formation were deposited in alluvial and floodplain environments. The basal conglomerates probably represent braided river deposits, while the sandstones were deposited in fluvial channels. The mudstones that contain most of the fossils represent overbank, lacustrine, and pedogenic deposits. [2] [4] [7]
Animals recovered include the dinosaurs Deinonychus , Microvenator , Tenontosaurus , Zephyrosaurus and Sauropelta as well as fragmentary remains of Titanosaurs, Ankylosaurs and Ornithomimids. As well, two genera of turtle Naomichelys and Glyptops and the lungfish Ceratodus . [8] Dinosaur eggs have been found in Montana. [9]
References for data: Ostrom 1970; Cifelli et al. 1998; Cifelli 1999; Nydam and Cifelli 2002. Possible goniopholidid remains are known from the formation.
Ankylosaurs reported from the Cloverly Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | State | Stratigraphic position | Material | Notes | Images |
S. edwardsorum [10] | Known from "several articulated skeletons" and common armor plates. [10] Only one partial skull is known. [11] | Articulated skeletons are often encased in carbonate caliche deposits that require acid to be removed safely. [10] | ||||
Tatankacephalus [12] | T. cooneyorum [12] |
| Cloverly VII [12] | Partial cranium, rib fragments, and osteoderms. [12] | Originally described as an ankylosaurid but has since been reclassified as a nodosaurid. [13] | |
Ceratopsians reported from the Cloverly Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | State | Stratigraphic position | Material | Notes | Images |
A. americanus |
| Cloverly VII; Himes Member [14] | A basal neoceratopsian. | |||
Ornithopods reported from the Cloverly Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | State | Stratigraphic position | Material | Notes | Images |
T. tilleti [10] | Its remains are the most common of any dinosaur of the formation. [10] | Juvenile remains are sometimes found together, suggesting that young Tenontosaurus lived in sibling groups. Deinonychus teeth are sometimes associated with Tenontosaurus, suggesting a predator-prey relationship between the two. [10] | ||||
Z. schaffi [10] |
| Himes Member | Its remains are "very rare." [10] | An orodromine ornithopod. | ||
Theropod eggshell fragments are known from the formation. Unidentifiable ornithomimid remains are present and most commonly represented by toe bones. [10] Indeterminate allosauroid remains are known from the formation. Remains identified by John Ostrom as Ornithomimus are suspected by Jack Horner to be of a new ornithomimid genus. [10] Possible remains of a microraptorian, a troodontid, and a basal tyrannosauroid similar to Moros have also been found here as well.
Color key
| Notes Uncertain or tentative taxa are in small text; |
Sauropods reported from the Cloverly Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | State | Stratigraphic position | Material | Notes | Images |
R. cooneyi [16] |
| Cloverly VII; Himes Member [16] | ||||
Sauroposeidon [17] | S. proteles |
| Cloverly VII; Himes Member [18] |
Theropods reported from the Cloverly Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | State | Stratigraphic position | Material | Notes | Images |
Acrocanthosaurus [18] | A. atokensis [18] |
| Cloverly VII; Himes Member [18] | |||
D. antirrhopus [10] | Its remains are "very rare." [10] | Tenontosaurus remains have been recovered in association with Deinonychus teeth, suggesting a predator-prey relationship between the two. [10] | ||||
M. celer [10] | Himes Member | Its remains are "extremely rare." [10] Known only from a "[p]artial skeleton with partial skull." [19] The specimen lacks feet and is catalogued as AMNH 3041. [20] | The type specimen AMNH 3041 [10] was recovered by Barnum Brown from Cloverly strata in Montana in 1933. | |||
O. velox [21] | Later found to be indeterminate ornithomimid remains. [21] | |||||
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 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 reported from the Cloverly Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | State | Stratigraphic position | Material | Notes | |
Indeterminate | ||||||
"G". pervicax [10] | ||||||
N. speciosa [10] | ||||||
Indeterminate | ||||||
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 reported from the Cloverly Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | State | Stratigraphic position | Material | Notes | Images |
A. ektopistikon [23] | ||||||
Anura | Indeterminate | |||||
Batrachosauroididae | Indeterminate | |||||
Indeterminate | ||||||
cf. Scotiophryne | Indeterminate | |||||
Osteichthyes reported from the Cloverly Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | State | Stratigraphic position | Material | Notes | Images |
C. frazieri [10] | ||||||
C. nirumbee [24] | ||||||
aff. Lepidotes | Indeterminate | |||||
aff. Pycnodontidae | Indeterminate | |||||
Indeterminate | ||||||
Chondrichthyes reported from the Cloverly Formation | ||||||
---|---|---|---|---|---|---|
Genus | Species | State | Stratigraphic position | Material | Notes | |
E. sp. | ||||||
H. parvidens | ||||||
L. sp. | ||||||
P. sp. | ||||||
P. sp. |
Year designated: 1973
Sauroposeidon is a genus of sauropod dinosaur known from several incomplete specimens including a bone bed and fossilized trackways that have been found in the U.S. states of Oklahoma, Wyoming, and Texas.
Tenontosaurus is a genus of iguanodontian ornithopod dinosaur. It had an unusually long, broad tail, which like its back was stiffened with a network of bony tendons.
The Lance (Creek) Formation is a division of Late Cretaceous rocks in the western United States. Named after Lance Creek, Wyoming, the microvertebrate fossils and dinosaurs represent important components of the latest Mesozoic vertebrate faunas. The Lance Formation is Late Maastrichtian in age, and shares much fauna with the Hell Creek Formation of Montana and North Dakota, the Frenchman Formation of southwest Saskatchewan, and the lower part of the Scollard Formation of Alberta.
Sauropelta is a genus of nodosaurid dinosaur that existed in the Early Cretaceous Period of North America. One species has been named although others may have existed. Anatomically, Sauropelta is one of the most well-understood nodosaurids, with fossilized remains recovered in the U.S. states of Wyoming, Montana, and possibly Utah. It is also the earliest known genus of nodosaurinae; most of its remains are found in a section of the Cloverly Formation dated to 108.5 million years ago.
Microvenator is a genus of dinosaur from the Early Cretaceous Cloverly Formation in what is now south central Montana. Microvenator was an oviraptorosaurian theropod. The holotype fossil is an incomplete skeleton, most likely a juvenile with a length of 1.3 m (4.3 ft), and consequently, the adult size remains uncertain. Microvenator celer is primitive and may be the "sister taxon to all other oviraptorosaurs."
Astrodon is a genus of large herbivorous sauropod dinosaur, measuring 20 m (66 ft) in length, 9 m (30 ft) in height and 20 metric tons in body mass. It lived in what is now the eastern United States during the Early Cretaceous period, and fossils have been found in the Arundel Formation, which has been dated through palynomorphs to the Albian about 112 to 110 million years ago.
The Lakota Formation is a sequence of rocks of early Cretaceous age from Western North America. Located in South Dakota, the name of the formation is derived from the Lakota Native American tribe.
The Tendaguru Formation, or Tendaguru Beds are a highly fossiliferous formation and Lagerstätte located in the Lindi Region of southeastern Tanzania. The formation represents the oldest sedimentary unit of the Mandawa Basin, overlying Neoproterozoic basement, separating by a long hiatus and unconformity. The formation reaches a total sedimentary thickness of more than 110 metres (360 ft). The formation ranges in age from the late Middle Jurassic to the Early Cretaceous, Oxfordian to Hauterivian stages, with the base of the formation possibly extending into the Callovian.
The Laramie Formation is a geologic formation of the Late Cretaceous (Maastrichtian) age, named by Clarence King in 1876 for exposures in northeastern Colorado, in the United States. It was deposited on a coastal plain and in coastal swamps that flanked the Western Interior Seaway. It contains coal, clay and uranium deposits, as well as plant and animal fossils, including dinosaur remains.
Ceratodus is an extinct genus of lungfish. It has been described as a "catch all", and a "form genus" used to refer to the remains of a variety of lungfish belonging to the extinct family Ceratodontidae. Fossil evidence dates back to the Early Triassic. A wide range of fossil species from different time periods have been found around the world in places such as the United States, Argentina, Greenland, England, Germany, Egypt, Madagascar, China, and Australia. Ceratodus is believed to have become extinct sometime around the beginning of the Eocene Epoch.
The Cedar Mountain Formation is the name given to a distinctive sedimentary geologic formation in eastern Utah, spanning most of the early and mid-Cretaceous. The formation was named for Cedar Mountain in northern Emery County, Utah, where William Lee Stokes first studied the exposures in 1944.
The Antlers Formation is a stratum which ranges from Arkansas through southern Oklahoma into northeastern Texas. The stratum is 150 m (490 ft) thick consisting of silty to sandy mudstone and fine to coarse grained sandstone that is poorly to moderately sorted. The stratum is cemented with clay and calcium carbonate. In places the sandstone may be conglomeratic or ferruginous.
The Arundel Formation, also known as the Arundel Clay, is a clay-rich sedimentary rock formation, within the Potomac Group, found in Maryland of the United States of America. It is of Aptian age. This rock unit had been economically important as a source of iron ore, but is now more notable for its dinosaur fossils. It consists of clay lenses within depressions in the upper part of the Patuxent Formation that may represent oxbow swamp facies. It is named for Anne Arundel County, Maryland.
The Wonthaggi Formation is an informal geological formation in Victoria, Australia whose strata date back to the Early Cretaceous. It is part of the Strzelecki Group within the Gippsland Basin. Dinosaur remains are among the fossils that have been recovered from the formation. It is partially equivalent to the Eumeralla Formation.
The Wapiti Formation is a geological formation of the Western Canada Sedimentary Basin in northwestern Alberta, and northeastern British Columbia, Canada. Its deposition spanned the time interval from the lower Campanian through to the upper Maastrichtian, between approximately 80 and 68 Ma. It was named by G.M. Dawson in 1881, presumably for exposures along the lower part of the Wapiti River and downstream along the Smoky River in Alberta.
The North Horn Formation is a widespread non-marine sedimentary unit with extensive outcrops exposed in central and eastern Utah. The formation locally exceeds 3,600 feet (1,100 m) in thickness and is characterized by fluvial, lacustrine, and floodplain dominated systems, representing a terrestrial, high energy, depositional environment. The sediments date from Late Cretaceous (Maastrichtian) to early Paleocene in age and include the K-Pg extinction event boundary; however, this boundary is extremely difficult to locate and there is no strong stratigraphic evidence available that indicates a specific marker bed such as an iridium rich clay layer. Thus far, the only visible evidence is represented in the form of faunal turnover from dinosaur to mammal-dominated fossil assemblages. Taxa from the Cretaceous part of the formation include squamates, testudines, choristoderes, crocodyliforms, sharks, bony fishes, amphibians, mammals, dinosaurs, eggshell fragments, trace fossils, mollusks, plant macrofossils, such as wood fragments, and palynomorphs.
The Ferris Formation is a Late Cretaceous to Paleocene, fluvial-deltaic geological formation in southern Wyoming. It contains a variety of trace and body fossils, preserved in sandy fluvial channel deposits and overbank units. Dinosaur remains are fragmentary, but include Triceratops, Tyrannosaurus, dromaeosaurids, Paronychodon, Ricardoestesia, Edmontosaurus, Edmontonia, Ankylosaurus, and Pachycephalosaurus.
The Mowry Shale is an Early Cretaceous geologic formation. The formation was named for Mowrie Creek, northwest of Buffalo in Johnson County, Wyoming.
Rugocaudia is a potentially dubious genus of basal titanosauriform sauropod dinosaur known from the Early Cretaceous of Montana, United States.
The Thermopolis Shale is a geologic formation which formed in west-central North America in the Albian age of the Late Cretaceous period. Surface outcroppings occur in central Canada, and the U.S. states of Montana and Wyoming. The rock formation was laid down over about 7 million years by sediment flowing into the Western Interior Seaway. The formation's boundaries and members are not well-defined by geologists, which has led to different definitions of the formation. Some geologists conclude the formation should not have a designation independent of the formations above and below it. A range of invertebrate and small and large vertebrate fossils and coprolites are found in the formation.