The Cedar Mountain Formation is the name given to distinctive sedimentary rocks in eastern Utah that occur between the underlying Morrison Formation and overlying Naturita Formation (sometimes incorrectly called the Dakota Formation). It is composed of non-marine sediments, that is, sediments deposited in rivers, lakes and on flood plains. Based on various fossils and radiometric dates, the Cedar Mountain Formation was deposited during the last half of the Early Cretaceous, about 127 - 98 million years ago (mya).
Dinosaurs occur throughout the formation, but their study has only occurred since the early 1990s. The dinosaurs in the lower part of the formation differ from those in the upper part. These two dinosaur assemblages, characterized by distinct dinosaurs, show the replacement of older, European-like dinosaurs with younger, Asian-like dinosaurs as the North American Continental Plate drifted westward. A middle dinosaur assemblage may be present, but the fossil record is not clear.
The formation was named for Cedar Mountain in northern Emery County, Utah, where William Lee Stokes first studied the exposures in 1944. Only recently did the 125 m (410 ft) thick formation get subdivided into smaller, distinctive beds called members. There is a debate as to whether there are five members or four depending whether the Buckhorn Conglomerate is considered to be at the top of the Morrison Formation or at the base of the Cedar Mountain Formation; most geologists and paleontologist consider it part of the Cedar Mountain Formation. In ascending order the remaining members are the Yellow Cat Member, Poison Strip Sandstone, Ruby Ranch Member, and the Mussentuchit Member. Each of these members are named after a geographic area where they were first studied.
... The Cedar Mountain Formation is proving to contain one of the richest and most diverse Early Cretaceous dinosaur faunas in the world ... of the later Cretaceous dinosaurs may lie in the Cedar Mountain, but further work is needed to understand the timing and effects the changing position of the North American Plate had on dinosaurian evolution ...
... mid-ocean ridges formed during sea-floor spreading are often referred to as undersea mountain ranges due to their bathymetric prominence ...
... Gen et sp nov Valid Perle, Norell, Clark Late Cretaceous Bayan Shireh Formation Mongolia A large dromaeosaurid Agustinia Gen et sp nov Valid Bonaparte Albian ... Microraptor Atlasaurus gen et sp nov Valid Monbaron, Russell, Taquet Middle Jurassic Tiougguit Formation Morocco A primitive sauropod Beipiaosaurus gen et sp nov Valid Xu, Tang, Wang Early ...
... were discovered in the Mussentuchit Member of the Cedar Mountain Formation in the eastern portion of the U.S ... This section of the formation is believed to represent the late Albian through early Cenomanian stages of the Late Cretaceous Period, or about 106 to 97 ... Earlier layers within the Cedar Mountain Formation contain different nodosaur species ...
... in the Poison Strip Sandstone Member of the Cedar Mountain Formation in Grand County, Utah, United States ... to the Poison Strip Sandstone Member of the Cedar Mountain Formation where the discovery was made ... venenica adds significant new information to the Barremian-Albian fauna of the Cedar Mountain Formation ...
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