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Regardless, dinosaurs existed alongside non-dinosaurian ornithodirans for a period of time, with estimates ranging from 5–10 million years [116] to 21 million years. [ 112 ] When dinosaurs appeared, they were not the dominant terrestrial animals.
The Mesozoic Era [3] is the era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Periods.It is characterized by the dominance of archosaurian reptiles such as the dinosaurs, and of gymnosperms such as cycads, ginkgoaceae and araucarian conifers; a hot greenhouse climate; and the tectonic break-up of Pangaea.
End Cretaceous: 66 million years ago, 76% of species lost, including all ammonites, mosasaurs, plesiosaurs, pterosaurs, and nonavian dinosaurs; Smaller extinction events have occurred in the periods between, with some dividing geologic time periods and epochs. The Holocene extinction event is currently under way. [12]
Mounted skeletons of Tyrannosaurus (left) and Apatosaurus (right) at the AMNH. Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago, although the exact origin and timing of the evolution of dinosaurs is the subject of active research.
Geologic Time – Period prior to humans. 4.6 billion to 3 million years ago. (See "prehistoric periods" for more detail into this.) (See "prehistoric periods" for more detail into this.) Primatomorphid Era – Period prior to the existence of Primatomorpha
Footprints dating back 120 million years show where dinosaurs were able to cross between land that's now part of two different continents. Matching dinosaur footprints found more than 3,700 miles ...
Scientists have unearthed nearly 200 dinosaur footprints, dating back 166 million years to the Middle Jurassic Period, at Dewars Farm Quarry in Oxfordshire, England.
List of Asian dinosaurs; List of Australian and Antarctic dinosaurs; List of dinosaurs and other Mesozoic reptiles of New Zealand; List of European dinosaurs; List of Indian and Madagascan dinosaurs; List of North American dinosaurs. List of Appalachian dinosaurs; List of archosaurs of the Chinle Formation; List of dinosaurs of the Morrison ...