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The Precambrian includes approximately 90% of geologic time. It extends from 4.6 billion years ago to the beginning of the Cambrian Period (about 539 Ma).It includes the first three of the four eons of Earth's prehistory (the Hadean, Archean, and Proterozoic) and precedes the Phanerozoic eon.
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.
The Triassic (/ t r aɪ ˈ æ s ɪ k / try-ASS-ik; sometimes symbolized 🝈) [8] is a geologic period and system which spans 50.5 million years from the end of the Permian Period 251.902 million years ago (), to the beginning of the Jurassic Period 201.4 Mya. [9]
At long irregular intervals, Earth's biosphere suffers a catastrophic die-off, a mass extinction, [9] often comprising an accumulation of smaller extinction events over a relatively brief period. [10] The first known mass extinction was the Great Oxidation Event 2.4 billion years ago, which killed most of the planet's obligate anaerobes ...
2024 marks 200 years since the first dinosaur, Megalosaurus, was formally identified. Here’s what we’ve learned about the prehistoric creatures over the past two centuries.
The Precambrian is an informal unit of geologic time, [3] subdivided into three eons (Hadean, Archean, Proterozoic) of the geologic time scale. It spans from the formation of Earth about 4.6 billion years ago to the beginning of the Cambrian Period, about 538.8 million years ago , when hard-shelled creatures first appeared in abundance.
Dinosaurs evolved from more primitive reptiles in the aftermath of Earth's biggest mass-extinction event caused by extreme volcanism at the end of the Permian Period about 252 million years ago.
The discovery, made public Wednesday, includes well-preserved footprints of reptiles and amphibians that scientists say date back 280 million years to a geologic period known as the Permian period ...