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Download Notes: Fossils
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Dinosaur Fossil Phenomenon • How were these fossils made? • What can they tell us about life’s history? NOTES: FOSSILS Essential Questions: What are fossils and how are they formed? What are the different kinds of fossils? What do fossils tell about how organisms have changed over time? How do we determine the age of fossils? Fossils • Fossils are the preserved remains or traces of living things • Fossils provide evidence of how life has changed over time • Fossils also help scientists infer how Earth’s surface has changed • Fossils are clues to what past environments were like TYPES OF FOSSILS • Permineralization: minerals carried by water are deposited around or replace the hard structure • Casts: form when flowing water removes all of the original bones, leaving impression in sediment; minerals fill in the mold • Trace fossils: record activity of organism. Include nests, burrows, imprints of leaves, and footprints TYPES OF FOSSILS • Amber-preserved fossils: organisms trapped in tree resin that hardens into amber • Preserved remains: form when entire organism becomes encased in material such as ice, volcanic ash, or immersed in bogs How are Fossils Formed? • Fossils form when living things die and are buried by sediments. The sediments slowly harden into rock and preserve the shapes of the organisms. • Most fossils form in sedimentary rock • Only 1% of life on Earth becomes a fossil due to natural processes (earthquakes, volcanoes, etc) The Fossil Record • Provides evidence about the history of life on Earth • Shows that different groups of organisms have changed over time • Shows that fossils occur in a particular pattern • Older rocks contain fossils of simpler organisms • Younger rocks contain fossils of more complex organisms • In other words, the fossil record shows that life on Earth has evolved, or changed
