États-Unis

Chert & phosphorite in the Permian of Wyoming, USA. The Permian-aged Phosphoria Formation has a significant component of phosphorite, a scarce, phosphate-rich sedimentary rock. This material is mined in southern Idaho as a source of phosphorus for the fertilizer industry, the fireworks industry, and other uses. Phosphorites are generally considered to have >15-20% phosphate content. Texturally, phosphorites can be obviously granular, with fossil fragments or oolites or peloids or lithic fragments, or they can be composed of extremely fine-grained, phosphate-rich mud. Compositionally, the phosphate component in phosphorites is principally a mix of apatite minerals: chlorapatite (Ca5(PO4)3Cl), fluorapatite (Ca5(PO4)3F), hydroxyapatite (Ca5(PO4)3OH)), and carbonate fluorapatite (Ca10(PO4,CO3)6F2-3). Phosphorites are generally marine sedimentary rocks. They range in age from Precambrian to Holocene. In modern oceans, they tend to occur along the eastern margins of some ocean basins where deep-water upwelling occurs under areas of high biologic productivity. Stratigraphy: Rex Chert Member over Meade Peak Member, Phosphoria Formation, Roadian Stage to Wordian Stage, lower Guadalupian Series, mid-Permian Locality: roadcut on the northern side of Route 26/Route 89 at the town of Astoria Hot Springs, Snake River Canyon, southern Teton County, northwestern Wyoming, USA

Life restoration of the large, Middle Triassic Nevadan ichthyosaur Cymbopsondylus petrinus. This illustration is primarily based on specimen UCMP 9950, with much of the tail restored following UCMP 9947. The size of the eye was reconstructed based on UCMP 9954 and UCMP 9913. The unknown distal portions of the flippers, as well as some of the tail, was reconstructed after the related genus Xinminosaurus. References Merriam, J. C. (1908) Triassic Ichthyosauria: With special reference to the American forms, Berkley, California: Berkley: The University Press Klein, N.; Schmitz, L.; Wintrich, T.; Sander, P. M. (2020). "A new cymbospondylid ichthyosaur (Ichthyosauria) from the Middle Triassic (Anisian) of the Augusta Mountains, Nevada, USA". Journal of Systematic Palaeontology 18 (14): 1167-1191. DOI:10.1080/14772019.2020.1748132. Jiang, D.; Motani, R.; Hao, W.; Schmitz, L.; Rieppel, O.; Sun, Y.; Sun, Z. (2008). "New primitive ichthyosaurian (Reptilia, Diapsida) from the Middle Triassic of Panxian, Guizhou, southwestern China and its position in the Triassic biotic recovery". Progress in Natural Science 18 (10): 1315. DOI:10.1016/j.pnsc.2008.01.039.

Dinosaur National Monument is a United States National Monument located on the southeast flank of the Uinta Mountains on the border between Colorado and Utah at the confluence of the Green and Yampa Rivers. Although most of the monument area is in Moffat County, Colorado, the Dinosaur Quarry is located in Utah just to the north of the town of Jensen, Utah. The nearest communities are Jensen, Utah, and Dinosaur, Colorado. The park contains over 800 paleontological sites and has fossils of dinosaurs including Allosaurus, Deinonychus, Abydosaurus (a nearly complete skull, lower jaws and first four neck vertebrae of the specimen DINO 16488 found here at the base of the Mussentuchit Member of the Cedar Mountain Formation is the holotype for the description) and various long-neck, long-tail sauropods. It was declared a National Monument on October 4, 1915. The rock layer enclosing the fossils is a sandstone and conglomerate bed of alluvial or river bed origin known as the Morrison Formation from the Jurassic Period some 150 million years old. The dinosaurs and other ancient animals were carried by the river system which eventually entombed their remains in Utah. The pile of sediments were later buried and lithified into solid rock. The layers of rock were later uplifted and tilted to their present angle by the mountain building forces that formed the Uintas during the Laramide orogeny. The relentless forces of erosion exposed the layers at the surface to be found by paleontologists. The dinosaur fossil beds (bone beds) were discovered in 1909 by Earl Douglass, a paleontologist working and collecting for the Carnegie Museum of Natural History. He and his crews excavated thousands of fossils and shipped them back to the museum in Pittsburgh, Pennsylvania for study and display. President Woodrow Wilson proclaimed the dinosaur beds as Dinosaur National Monument in 1915. The monument boundaries were expanded in 1938 from the original 80-acre (320,000 m2) tract surrounding the dinosaur quarry in Utah, to its present extent of over 200,000 acres (800 km²) in Utah and Colorado, encompassing the spectacular river canyons of the Green and Yampa. Though lesser-known than the fossil beds, the petroglyphs in Dinosaur National Monument are another treasure the monument holds. Due to problems with vandals, many of the sites are not listed on area maps. The "Wall of Bones" located within the Dinosaur Quarry building in the park consists of a steeply tilted (67° from horizontal) rock layer which contains hundreds of dinosaur fossils. The enclosing rock has been chipped away to reveal the fossil bones intact for public viewing. In July 2006, the Quarry Visitor Center was closed due to structural problems that since 1957 had plagued the building because it was built on unstable clay. The decision was made to build a new facility elsewhere in the monument to house the visitor center and administrative functions, making it easier to resolve the structural problems of the quarry building while still retaining a portion of the historic Mission 66 era exhibit hall. It was announced in April 2009 that Dinosaur National Monument would receive $13.1 million to refurbish and reopen the gallery as part of the Obama administration's $750 billion stimulus plan. The Park Service successfully rebuilt the Quarry Exhibit Hall, supporting its weight on 70-foot steel micropile columns that extend to the bedrock below the unstable clay. The Dinosaur Quarry was reopened in Fall 2011. en.wikipedia.org/wiki/Dinosaur_National_Monument en.wikipedia.org/wiki/Wikipedia:Text_of_Creative_Commons_...

Close up of the Eulithomyrmex rugosus holotype head. Museum of Comparative Zoology specimen UCM17019. Priabonian; Florissant Formation, Colorado, USA

Outcrops of the Late Cretaceous (Campanian) aged Aguja Formation, Big Bend National Park, Texas, USA

Restored skeleton of Anzu wyliei (previously labelled as a specimen of Chirostenotes)

Ceratosaurus skeleton mount, Wisconsin

Ceratosaurus skeleton mount, Wisconsin

Anhanguera skeleton, North American Museum of Ancient Life.

The Tyrannosaurus rex, Dromaeosaurus, Triceratops, and Struthiomimus diorama in the Third Planet exhibit at the Milwaukee Public Museum in Milwaukee, Wisconsin (United States).

The Tyrannosaurus rex, Dromaeosaurus, Triceratops, and Struthiomimus diorama in the Third Planet exhibit at the Milwaukee Public Museum in Milwaukee, Wisconsin (United States).

The Tyrannosaurus rex, Dromaeosaurus, Triceratops, and Struthiomimus diorama in the Third Planet exhibit at the Milwaukee Public Museum in Milwaukee, Wisconsin (United States).

Triceratops mounted skeleton at Los Angeles Museum of Natural History, Los Angeles, United States of America

Quetzalcoatlus northropi. États-Unis

Quetzalcoatlus northropi. États-Unis

Quetzalcoatlus northropi. États-Unis