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In geology, a debate remains open concerning the use of Myr (duration) plus Mya (million years ago) versus using only the term Ma. [1] [2] In either case, the term Ma is used in geology literature conforming to ISO 31-1 (now ISO 80000-3) and NIST 811 recommended practices.
1600 Mya – 2500 Mya: all GSSA points Eras in the Archean Eon 2500 Mya – years > 3600 Mya rocks older than 2.5 Billion years – rocks older than 3.6 Billion years [1] [2] Neoarchean: 2500 Mya – 2800 Mya (only GSSA points) Mesoarchean: 2800 Mya – 3200 Mya: Paleoarchean: 3200 Mya – 3600 Mya: Eoarchean: 3600 Mya – 4000 Mya: Earth's ...
Approximate extent of the Karoo Glaciation (in blue), over the Gondwana supercontinent during the Carboniferous and Permian periods. The late Paleozoic icehouse, also known as the Late Paleozoic Ice Age (LPIA) and formerly known as the Karoo ice age, was an ice age that began in the Late Devonian and ended in the Late Permian, [1] occurring from 360 to 255 million years ago (Mya), [2] [3] and ...
It is commonly used as a unit of time to denote length of time before the present in 10 9 years. This initialism is often used in the sciences of astronomy , geology , and paleontology . The "billion" in bya is the 10 9 "billion" of the short scale of the U.S. , [ 1 ] not the long-scale 10 12 "billion" of some European usage.
KNM-ER 1813 reconstructed skull and jaw. The first recognised remains—OH 7, partial juvenile skull, hand, and foot bones dating to 1.75 million years ago (mya)—were discovered in Olduvai Gorge, Tanzania, in 1960 by Jonathan Leakey, with other native Africans who digged into Olduvai Gorge, and who worked for Jonathan Leakey.
The Cretaceous (IPA: / k r ɪ ˈ t eɪ ʃ ə s / krih-TAY-shəss) [2] is a geological period that lasted from about 143.1 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 77 million years, it is the ninth and longest geological period of the entire Phanerozoic.
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The Norian is the second age of the Late Triassic, covering the time interval from about 227 to 208.5 million years ago. [11] During this age, herbiverous sauropodomorphs diversified and began to displace the large herbivorous therapsids , perhaps because they were better able to adapt to the increasingly arid climate. [ 20 ]