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Wayan Formation
The Wayan Formation is a geological formation in Idaho whose strata date back to the latest Early Cretaceous and the earliest Late Cretaceous. Dinosaur, other reptile, mammal, and micro and macro-floral remains are among the fossils that have been recovered from the formation. The lack of extensive outcrops, limited geographic extent, and extreme structural deformation have limited paleontological explorations of the Wayan. Geology and age The Wayan occurs in the Caribou Mountains of eastern Idaho. Sediments are dominantly floodplain mudstones (many having undergone extensive pedogenic processes) with some fluvial sandstones and minor conglomerates, limestones, and tuffs. Carbonate nodules in pedogenic mudstones suggest a semi-arid, seasonal climate during deposition. Radiometric U-Pb dates from detrital zircons indicate a latest Albian to early to middle Cenomanian age. Detrital zircon U-Pb dating within one stratigraphic meter of an '' Oryctodromeus'' locality yielded an a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geological Formation
A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exposed in a geographical region (the stratigraphic column). It is the fundamental unit of lithostratigraphy, the study of strata or rock layers. A formation must be large enough that it can be mapped at the surface or traced in the subsurface. Formations are otherwise not defined by the thickness (geology), thickness of their rock strata, which can vary widely. They are usually, but not universally, tabular in form. They may consist of a single lithology (rock type), or of alternating beds of two or more lithologies, or even a heterogeneous mixture of lithologies, so long as this distinguishes them from adjacent bodies of rock. The concept of a geologic formation goes back to the beginnings of modern scientific geology. The term was used by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fluvial
In geography and geology, fluvial processes are associated with rivers and streams and the deposits and landforms created by them. When the stream or rivers are associated with glaciers, ice sheets, or ice caps, the term glaciofluvial or fluvioglacial is used. Fluvial processes Fluvial processes include the motion of sediment and erosion or deposition on the river bed. The movement of water across the stream bed exerts a shear stress directly onto the bed. If the cohesive strength of the substrate is lower than the shear exerted, or the bed is composed of loose sediment which can be mobilized by such stresses, then the bed will be lowered purely by clearwater flow. In addition, if the river carries significant quantities of sediment, this material can act as tools to enhance wear of the bed ( abrasion). At the same time the fragments themselves are ground down, becoming smaller and more rounded ( attrition). Sediment in rivers is transported as either bedload (the coar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Theropods
Theropoda (; ), whose members are known as theropods, is a dinosaur clade that is characterized by hollow bones and three toes and claws on each limb. Theropods are generally classed as a group of saurischian dinosaurs. They were ancestrally carnivorous, although a number of theropod groups evolved to become herbivores and omnivores. Theropods first appeared during the Carnian age of the late Triassic period 231.4 million years ago ( Ma) and included all the large terrestrial carnivores from the Early Jurassic until at least the close of the Cretaceous, about 66 Ma. In the Jurassic, birds evolved from small specialized coelurosaurian theropods, and are today represented by about 10,500 living species. Biology Diet and teeth Theropods exhibit a wide range of diets, from insectivores to herbivores and carnivores. Strict carnivory has always been considered the ancestral diet for theropods as a group, and a wider variety of diets was historically considered a characte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Macroelongatoolithus
''Macroelongatoolithus'' is an oogenus of large theropod dinosaur eggs, representing the eggs of giant caenagnathid oviraptorosaurs. They are known from Asia and from North America. Historically, several oospecies have been assigned to ''Macroelongatoolithus'', however they are all now considered to be a single oospecies: ''M. carlylensis''. History of discovery ''" Oolithes" carlylensis'' was described in 1970 by James Jensen.Jensen J. 1970. Fossil eggs in the lower cretaceous of Utah. ''Brigham Young University research studies. Geology Series. Geology Studies'' 17: 51-65. In 1998, ''O. carlylensis'' was moved to a new oogenus, ''Boletuoolithus'', which was then classified as a Spheroolithid.Bray, E. S. 1998. Dinosaur eggshell ''Boletuoolithus carlylensis'', oogen. nov. from the Lower Cretaceous Cedar Mountain Formation of Utah; pp. 221–223 in S. G. Lucas, J. I. Kirkland, and J. W. Estep (eds.), Lower and Middle Cretaceous Terrestrial Ecosystems. New Mexico Museum of Nat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oviraptorosaur
Oviraptorosaurs ("egg thief lizards") are a group of feathered maniraptoran dinosaurs from the Cretaceous Period of what are now Asia and North America. They are distinct for their characteristically short, beaked, parrot-like skulls, with or without bony crests atop the head. They ranged in size from ''Caudipteryx'', which was the size of a turkey, to the 8-meter-long, 1.4-ton ''Gigantoraptor''. The group (along with all maniraptoran dinosaurs) is close to the ancestry of birds. Some researchers such as Maryanska ''et al'' (2002) and Osmólska ''et al.'' (2004) have proposed that they may represent primitive flightless birds.Osmólska, Halszka, Currie, Philip J., Brasbold, Rinchen (2004) "The Dinosauria" Weishampel, Dodson, Osmólska. "Chapter 8 Oviraptorosauria" University of California Press. The most complete oviraptorosaur specimens have been found in Asia. The North American oviraptorosaur record is sparse.Varricchio, D. J. 2001. Late Cretaceous oviraptorosaur (Theropod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neovenatorid
Neovenatoridae is a proposed clade of carcharodontosaurian dinosaurs uniting some primitive members of the group such as ''Neovenator'' with the Megaraptora, a group of theropods with controversial affinities. Other studies recover megaraptorans as basal coelurosaurs unrelated to carcharodontosaurs. Other theropods with uncertain affinities such as ''Gualicho'', ''Chilantaisaurus'' and ''Deltadromeus'' are also sometimes included. Classification Phylogenetic studies conducted by Benson, Carrano and Brusatte (2010) and Carrano, Benson and Sampson (2012) recovered the group Megaraptora as members of the Neovenatoridae. This would make neovenatorids the latest-surviving allosauroids; at least one megaraptoran, '' Orkoraptor'', lived near the end of the Mesozoic era, dating to the early Maastrichtian stage of the latest Cretaceous period, about 70 million years ago. On the other hand, Novas ''et al.'' (2012), while confirming that ''Neovenator'' was closely related to carcharodontos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tyrannosauroid
Tyrannosauroidea (meaning 'tyrant lizard forms') is a superfamily (or clade) of coelurosaurian theropod dinosaurs that includes the family Tyrannosauridae as well as more basal relatives. Tyrannosauroids lived on the Laurasian supercontinent beginning in the Jurassic Period. By the end of the Cretaceous Period, tyrannosauroids were the dominant large predators in the Northern Hemisphere, culminating in the gigantic ''Tyrannosaurus''. Fossils of tyrannosauroids have been recovered on what are now the continents of North America, Europe and Asia, with fragmentary remains possibly attributable to tyrannosaurs also known from South America and Australia. Tyrannosauroids were bipedal carnivores, as were most theropods, and were characterized by numerous skeletal features, especially of the skull and pelvis. Early in their existence, tyrannosauroids were small predators with long, three-fingered forelimbs. Late Cretaceous genera became much larger, including some of the largest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dromaeosaurs
Dromaeosauridae () is a family of feathered theropod dinosaurs. They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period. The name Dromaeosauridae means 'running lizards', from Greek ('), meaning 'runner', and ('), meaning 'lizard'. In informal usage, they are often called raptors (after ''Velociraptor''), a term popularized by the film ''Jurassic Park''; a few types include the term "raptor" directly in their name and have come to emphasize their bird-like appearance and speculated bird-like behavior. Dromaeosaurid fossils have been found across the globe in North America, Europe, Africa, Asia, South America and Antarctica, with some fossils giving credence to the possibility that they inhabited Australia as well. They first appeared in the mid-Jurassic Period (late Bathonian stage, about 167 million years ago) and survived until the end of the Cretaceous (Maastrichtian stage, 66 ma), existing until the Cretaceous–Paleogene ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hadrosaurid
Hadrosaurids (), or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The ornithopod family, which includes genera such as ''Edmontosaurus'' and ''Parasaurolophus'', was a common group of herbivores during the Late Cretaceous Period. Hadrosaurids are descendants of the Upper Jurassic/Lower Cretaceous iguanodontian dinosaurs and had a similar body layout. Hadrosaurs were among the most dominant herbivores during the Late Cretaceous in Asia and North America, and during the close of the Cretaceous several lineages dispersed into Europe, Africa, South America and Antarctica. Like other ornithischians, hadrosaurids had a predentary bone and a pubic bone which was positioned backwards in the pelvis. Unlike more primitive iguanodonts, the teeth of hadrosaurids are stacked into complex structures known as dental batteries, which acted as effe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iguanodontid
Iguanodontidae is a family of iguanodontians belonging to Styracosterna, a derived clade within Ankylopollexia. Characterized by their elongated maxillae, they were herbivorous and typically large in size. This family exhibited locomotive dynamism; there exists evidence for both bipedalism and quadrupedalism within iguanodontid species, supporting the idea that individual organisms were capable of both locomoting exclusively with their hind limbs and locomoting quadrupedally. Iguanodontids possess hoof-like second, third, and fourth digits, and in some cases, a specialized thumb spike and an opposable fifth digit. Their skull construction allows for a strong chewing mechanism called a transverse power stroke. This, paired with their bilateral dental occlusion, made them extremely effective as herbivores. Members of Iguanodontidae are thought to have had a diet that consisted of both gymnosperms and angiosperms, the latter of which co-evolved with the iguanodontids in the C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tenontosaurus
''Tenontosaurus'' ( ; ) is a genus of medium- to large-sized ornithopod dinosaur. It was a relatively medium sized ornithopod, reaching in length and in body mass. It had an unusually long, broad tail, which like its back was stiffened with a network of bony tendons. The genus is known from the late Aptian to Albian ages of the Early Cretaceous period sediments of western North America, dating between 115 and 108 million years ago. It contains two species, ''Tenontosaurus tilletti'' (described by John Ostrom in 1970) and ''Tenontosaurus dossi'' (described by Winkler, Murry, and Jacobs in 1997). Many specimens of ''T. tilletti'' have been collected from several geological formations throughout western North America. ''T. dossi'' is known from only a handful of specimens collected from the Twin Mountains Formation of Parker County, Texas. History of discovery The first ''Tenontosaurus'' fossil was found in Big Horn County, Montana by an American Museum of Natural ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ankylosaur
Ankylosauria is a group of herbivorous dinosaurs of the order Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms, similar to turtles. Ankylosaurs were bulky quadrupeds, with short, powerful limbs. They are known to have first appeared in the Middle Jurassic, and persisted until the end of the Cretaceous Period. The two main families of Ankylosaurs, Nodosauridae and Ankylosauridae are primarily known from the Northern Hemisphere, but the more basal Parankylosauria are known from southern Gondwana during the Cretaceous. Ankylosauria was first named by Henry Fairfield Osborn in 1923.Osborn, H. F. (1923). "Two Lower Cretaceous dinosaurs of Mongolia." ''American Museum Novitates'', 95: 1–1/ref> In the Linnaean classification system, the group is usually considered either a suborder or an infraorder. It is contained within the group Thyreophora, which also includes the stegosaurs, armored dinosaurs known for their combination of plat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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