The Cloverly Formation are Lower Cretaceous strata located in Montana

Montana

Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...

 and Wyoming

Wyoming

Wyoming is a state in the mountain region of the Western United States. The western two thirds of the state is covered mostly with the mountain ranges and rangelands in the foothills of the Eastern Rocky Mountains, while the eastern third of the state is high elevation prairie known as the High...

, in the western United States

United States

The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. The term now includes strata that had formerly been called the Dakota Formation

Dakota Formation

The Dakota Formation is a geologic formation composed of sedimentary rocks deposited on the western side of the Late Cretaceous Western Interior Seaway. F.B. Meek and F.V. Hayden named it for exposures along the Missouri River near Dakota City, Nebraska...

 in central and southern Wyoming.

Members

In the Bighorn Basin

Bighorn Basin

The Bighorn Basin is a plateau region and intermontane basin, approximately 100 miles wide, in north-central Wyoming in the United States. It is bounded by the Absaroka Range on the west, the Bighorn Mountains on the east, and the Owl Creek Mountains and Bridger Mountains on the south...

 region along the Montana - Wyoming border, the Cloverly is divided into several members.

• 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. A radiometric date of 115 +/- 10 MA has been obtained from low in the member (Chen and Lubin 1997), and other near the top at 108.5 +/- 0.2 MA (Burton et al. 2006). These dates confirm that the Cloverly is Aptian-Albian in age.
• The uppermost member is the Himes Member contains some coarse grained channel deposits, but is primarily brightly, multicolored (variegated) mudstones.

Vertebrate fauna

Animals recovered include the dinosaurs Deinonychus

Deinonychus

Deinonychus was a genus of carnivorous dromaeosaurid dinosaur. There is one described species, Deinonychus antirrhopus. This 3.4 meter long dinosaur lived during the early Cretaceous Period, about 115–108 million years ago . Fossils have been recovered from the U.S...

, Microvenator

Microvenator

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 living length of about four feet. The adult size of...

Tenontosaurus

Tenontosaurus

Tenontosaurus is a genus of medium- to large-sized ornithopod dinosaur. The genus is known from the late Aptian to Albian ages of the middle Cretaceous period sediments of western North America, dating between 115 to 108 million years ago...

, Zephyrosaurus

Zephyrosaurus

Zephyrosaurus is a genus of hypsilophodont ornithopod dinosaur. It is based on a partial skull and postcranial fragments discovered in the Aptian-Albian-age Lower Cretaceous Cloverly Formation of Carbon County, Montana...

and Sauropelta

Sauropelta

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...

as well as fragmentary remains of Titanosaurs and Ornithomimids. As well, two genera of turtle
Naomichelys and Glyptops and the lungfish Ceratodus

Ceratodus

Ceratodus was a wide-ranging genus of extinct sarcopterygiian lungfish. Fossil evidence dates back to the Middle Triassic 228 million years ago. A wide range of fossil species from different time periods have been found around the world in places such as the United States, Argentina, England,...

.

Dinosaur eggs have been found in Montana.

References for data: Ostrom 1970; Cifelli et al. 1998; Cifelli 1999; Nydam and Cifelli 2002. Possible goniopholidid remains are known from the formation.

Ornithischians

Ornithischians reported from the Cloverly Formation
Genus	Species	State	Stratigraphic position	Material	Notes	Images
Sauropelta Sauropelta 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...	S. edwardsorum	Montana Wyoming		Known from "several articulated skeletons" and its armor plates are common fossils. Only one partial skull is known."."	Articulated skeletons are often encased in carbonate caliche deposits that require acid to be removed safely.
Tenontosaurus Tenontosaurus Tenontosaurus is a genus of medium- to large-sized ornithopod dinosaur. The genus is known from the late Aptian to Albian ages of the middle Cretaceous period sediments of western North America, dating between 115 to 108 million years ago...	T. tilleti	Montana Wyoming		Its remains are the most common of any dinosaur of the formation.	Juvenile remains are sometimes found together, suggesting that young Tenontosaurus lived in sibling groups. Deinonychus Deinonychus Deinonychus was a genus of carnivorous dromaeosaurid dinosaur. There is one described species, Deinonychus antirrhopus. This 3.4 meter long dinosaur lived during the early Cretaceous Period, about 115–108 million years ago . Fossils have been recovered from the U.S... teeth are sometimes associated with Tenontosaurus remains suggesting a predator-prey relationship between the two.
Zephyrosaurus Zephyrosaurus Zephyrosaurus is a genus of hypsilophodont ornithopod dinosaur. It is based on a partial skull and postcranial fragments discovered in the Aptian-Albian-age Lower Cretaceous Cloverly Formation of Carbon County, Montana...	Z. schaffi	Montana		Its remains are "very rare."

Saurischians

Theropod eggshell fragments are known from the formation. A partial titanosaurid skeleton catalogued as MOR 334 and possible gastroliths are known from the formation. Unidentifiable ornithomimmid remains are present and most commonly represented by toe bones. Indeterminate allosauroid remains are known from the formation. Remains identified by John Ostrom

John Ostrom

John H. Ostrom was an American paleontologist who revolutionized modern understanding of dinosaurs in the 1960s, when he demonstrated that dinosaurs are more like big non-flying birds than they are like lizards , an idea first proposed by Thomas Henry Huxley in the 1860s, but which had garnered...

 as Ornithomimus are suspected by Jack Horner to be of a new ornithomimid genus.

Saurischians reported from the Cloverly Formation
Genus	Species	State	Stratigraphic position	Material	Notes	Images
Deinonychus Deinonychus Deinonychus was a genus of carnivorous dromaeosaurid dinosaur. There is one described species, Deinonychus antirrhopus. This 3.4 meter long dinosaur lived during the early Cretaceous Period, about 115–108 million years ago . Fossils have been recovered from the U.S...	D. antirrhopus	Montana Wyoming		Its remains are "very rare."	Tenontosaurus Tenontosaurus Tenontosaurus is a genus of medium- to large-sized ornithopod dinosaur. The genus is known from the late Aptian to Albian ages of the middle Cretaceous period sediments of western North America, dating between 115 to 108 million years ago... remains have been recovered in association with Deinonychus teeth on several occasions suggesting a predator-prey relationship between the two.
Microvenator Microvenator 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 living length of about four feet. The adult size of...	M. celer	Montana Wyoming		Its remains are "extremely rare." Known only from a "[p]artial skeleton with partial skull." The specimen lacks feet and is catalogued as AMNH 3041.	The type specimen AMNH 3041 was recovered by Barnum Brown Barnum Brown Barnum Brown , a paleontologist born in Carbondale, Kansas, and named after the circus showman P.T. Barnum, discovered the second fossil of Tyrannosaurus rex during a career that made him one of the most famous fossil hunters working from the late Victorian era into the early 20th century.Sponsored...  from Cloverly strata in Montana in 1933 1933 in paleontology -Dinosaurs:* Barnum Brown prospected the Two Medicine Formation, but found nothing significant.* Lull published a mongraph wherein he discusses AMNH 5244, a ceratopsian braincase.-Newly named dinosaurs:... .
Ornithomimus Ornithomimus Ornithomimus is a genus of ornithomimid dinosaur from the Late Cretaceous Period of what is now North America.In 1890 Ornithomimus velox was named by Othniel Charles Marsh on the basis of a foot and partial hand from the Maastrichtian Denver Formation. Another seventeen species have been named since...	O. velox	Montana Wyoming			Later found to be indeterminate ornithomimid remains.
Pleurocoelus	Indeterminate	Montana Wyoming

Lizards

Lizard Lizard Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains... s reported from the Cloverly Formation
Genus	Species	State	Stratigraphic position	Material	Notes
Paramacellodus Paramacellodus Paramacellodus was a genus of prehistoric lizard of the Late Jurrasic Morrison Formation of Western North America.Present in stratigraphic zones 4 and 5....	P. keebleri

Mammals

Mammal Mammal Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young... s reported from the Cloverly Formation
Genus	Species	State	Stratigraphic position	Material	Notes	Images
Corviconodon	C. montanensis
Gobiconodon Gobiconodon Gobiconodon is an extinct genus of carnivorous mammal. It weighed 10–12 pounds and measured 18-20 inches, and might have resembled a large and robust opossum.-Species:...	G. ostromi
Montanalestes Montanalestes Montanalestes is an extinct mammal known from the Cretaceous in North America....	M. keebleri

Turtles

Possible goniopholidid remains are known from the formation.

Turtle Turtle Turtles are reptiles of the order Testudines , characterised by a special bony or cartilaginous shell developed from their ribs that acts as a shield... s reported from the Cloverly Formation
Genus	Species	State	Stratigraphic position	Material	Notes
Glyptops Glyptops Glyptops is an extinct genus of cryptodire turtle dating from the Late Jurassic and Early Cretaceous periods 155 to 99 m.y.a. Fossils have been found in South Dakota, Wyoming, Colorado, Utah, New Mexico, Oklahoma, and Texas from both the Morrison and Cedar Mountain formations. The type species is G...	G. pervicax
	G. plicatulus
Naomichelys	N. speciosa

Bony fish

Indeterminate amiiformes

Amiiformes

Amiiformes is an order of fish, of which only one species, the Bowfin, Amia calva, is still extant.-Taxonomy:Amiiformes Hay 1929*Superfamily Amioidea Bonaparte 1838**Family Amiidae Bonaparte 1837***Subfamily Amiinae Bonaparte 1837...

 are known from the formation.

Osteichthyes Osteichthyes Osteichthyes , also called bony fish, are a taxonomic group of fish that have bony, as opposed to cartilaginous, skeletons. The vast majority of fish are osteichthyes, which is an extremely diverse and abundant group consisting of over 29,000 species...  reported from the Cloverly Formation
Genus	Species	State	Stratigraphic position	Material	Notes	Images
Ceratodus Ceratodus Ceratodus was a wide-ranging genus of extinct sarcopterygiian lungfish. Fossil evidence dates back to the Middle Triassic 228 million years ago. A wide range of fossil species from different time periods have been found around the world in places such as the United States, Argentina, England,...	C. frazieri