Earth formed roughly 4.6 billion years ago as a molten sphere of rock clouded with “choking fumes” (Appenzeller 2006). With time, the young planet cooled, and, as it became more hospitable, life slowly emerged, triumphing over several extinctions in order to achieve its current state of a flourishing, diverse environment. Earth is at an ideal distance from the sun, so that it retained water while it cooled; water is a critical ingredient in life. Three point eight billion years ago, the first life emerged as photosynthesizing cyanobacteria. It took another 3.256 billion years until the Cambrian explosion, the time period where most fossils originate from. With the beginning of the Paleozoic era came a time of dramatic geological, climatic, and evolutionary change. Interspersed with various advancements in the sophistication of life were five extinctions--the Ordovician (445 million years ago), Late Devonian (360 million years ago), Permian (251 million years ago), Triassic (205 million years ago), and K-T (65 million years ago). During each extinction, huge percentages of life were eliminated. However, that which was left (at times only 5%) rebounded, shaping today’s world after the first hominids appeared 4 million years ago.
For a more in-depth exploration of Earth’s History, please view our Prezi here.
Our bibliography is here.
Our bibliography is here.
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