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The earliest known fossil of a eukaryote—the term for organisms, from yeast to humans, that have a cell nucleus and usually require oxygen—is about 2 billion years old. The first fossil big enough to be seen without a microscope—the spiral-chained algae Grypania —appeared 1.9 billion years ago.
15 mar 2022 · Now, 250 years since oxygen was discovered, it is timely to revisit some of the history, the controversies and look at how oxygen has evolved during that time. Here, a few of the highlights in...
Today, around 21 percent of Earth's atmosphere is made up of oxygen. The earliest mix of gases to form a thick layer around our cooling planet some 4.6 billion years ago wasn't much different to the kind of stuff emitted by volcanoes, such […]
Geological history of oxygen. Although oxygen is the most abundant element in Earth's crust, due to its high reactivity it mostly exists in compound (oxide) forms such as water, carbon dioxide, iron oxides and silicates. Before photosynthesis evolved, Earth's atmosphere had no free diatomic elemental oxygen (O 2). [2]
1 sty 2010 · Where did oxygen come from? Remarkably, that atom of oxygen you have just breathed had its origin in the heart of an ancient star. To understand this, one has to make an imaginary journey back to the creation of the universe, the “big bang,” more than 12...
19 lut 2014 · Nature - Until about two billion years ago free oxygen was a scarce commodity in the Earth's atmosphere. For decades geochemists have been refining the story of how and when early life...
19 sie 2009 · So how did Earth end up with an atmosphere made up of roughly 21 percent of the stuff? The answer is tiny organisms known as cyanobacteria, or blue-green algae.
