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The history of life on Earth traces the processes by which living and extinct organisms evolved, from the earliest emergence of life to the present day. Earth formed about 4.5 billion years ago (abbreviated as Ga, for gigaannum) and evidence suggests that life emerged prior to 3.7 Ga. [1] [2] [3] The similarities among all known present-day species indicate that they have diverged through the ...
End Triassic: 200 million years ago, 80% of species lost, including all conodonts; 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.
Co-based superalloys depend on carbide precipitation and solid solution strengthening for mechanical properties. While these strengthening mechanisms are inferior to gamma prime (γ') precipitation strengthening, [1] cobalt has a higher melting point than nickel and has superior hot corrosion resistance and thermal fatigue. As a result, carbide ...
Throughout the fossil record, many species that appear at an early stratigraphic level disappear at a later level. This is interpreted in evolutionary terms as indicating the times when species originated and became extinct. Geographical regions and climatic conditions have varied throughout Earth's history.
The evolutionary history of the primates can be traced back 57-90 million years. [1] One of the oldest known primate-like mammal species, Plesiadapis, came from North America; [2] another, Archicebus, came from China. [3] Other similar basal primates were widespread in Eurasia and Africa during the tropical conditions of the Paleocene and Eocene.
As for life on land, in 2019 scientists reported the discovery of a fossilized fungus, named Ourasphaira giraldae, in the Canadian Arctic, that may have grown on land a billion years ago, well before plants are thought to have been living on land. [100] [101] [102] The earliest life on land may have been bacteria 3.22 billion years ago. [103]
"Evolution of Evolution – 150 Years of Darwin's "On the Origin of Species" ". National Science Foundation; Human Timeline (Interactive) – Smithsonian, National Museum of Natural History (August 2016). Experiments concerning the process of biological evolution. Lenski RE. "Experimental Evolution – Michigan State University"
This includes fields such as paleobiology, where paleobiologists and evolutionary biologists, including Thomas Halliday and Anjali Goswami, studied the evolution of early mammals going far back in time during the Mesozoic and Cenozoic eras (between 299 million to 12,000 years ago).