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Published byDana Harris Modified over 9 years ago
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Fossils are preserved remains or traces of living things Most fossils form when living things die and are buried by sediments. The sediments slowly hardens into rock and preserves the shapes of the organisms.
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Fossils found in rock includes molds and casts, petrified fossils, carbon films and trace fossils. Other fossils form when the remains of organisms are preserved in substances such as tar, amber or ice
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Most common fossils Mold is forms when the organism is buried in a sediment, then water may deposit minerals and sediment into a mold, forming a cast. A cast is a solid copy of the shape of an organism
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Petrified means “turned into stone.” They are fossils in which minerals replace all of an organism, or a part. For example a dinosaur bone
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An extremely thin coating of carbon on rock When sediments bury an organism, some gases escape from the sediment and leave carbon behind, which eventually a thin layer of carbon remains
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Provide evidence of the activities of ancient organisms A print is buried by sediment, which slowly becomes a solid rock
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Scientists that study fossils are called paleontologists. The fossil record provides evidence about the history of life and past environments on Earth. Shows how different groups of organisms have changed over time
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The fossils found in an area tell whether the are was a shallow bay, an ocean bottom or a freshwater swamp Also shows the past climate of the region
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Fossil records reveal changes in organism Fossils show how life on Earth has evolved. Evolution is the change in living things over time
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Is a record of the geologic events and the evolution of life forms.
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Precambrian Time: Beginning of geologic time Covers 88% of Earth’s history and ended 542 years ago. Eras: 3 eras divide the time between the Precambrian time and present day. They are the Paleozoic Ear, Mesozoic Era, and the Cenozoic Era Periods: Eras are divided in subgroups called periods.
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The Cambrian Period is when many organisms evolved that had hard parts, such as shells and outer skeletons. At this time, all animals lived in the sea and many were invertebrates
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After the Cambrian Period, we go through the Ordovician Period, which the first vertebrates evolved Then during the Silurian Period, plants became more abundant but only in damp areas low in the ground Then during the Devonian Period, plants were able to grow in drier areas
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The Devonian period is also called the Age of Fishes because every main group of fish were present in the oceans at this time The Devonian period is also when animals began to spread widely on land Amphibians and reptiles began to develop during this period. At the end of the Permian Period, most species of life on Earth died out 90% of all ocean species died out 70% of all species on land died out How do you think this all happened?
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Remember that during this Era, there were three periods. Triassic Period The first dinosaurs appeared during this period Mammals first appeared during this period. A mammal is a vertebrate that can control body temp. and feed milk to its young
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Jurassic Period Dinosaurs became more common on land Cretaceous Period Reptiles, including dinosaurs, became more widespread Birds started replacing flying reptiles Flowering plants first evolved
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Toward the end of the Cretaceous period, (65 million years ago), another mass extinction occurred. Scientist believe that an asteroid from space hit Earth. Once it hit, huge amounts of dust and water vapor were thrown in the atmosphere The dust and heavy clouds blocked the sunlight for many years, which made plants die and animals that ate plants died because they had no food.
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Mammals evolved to live in many different environments- on land, water and even in the air During this era, climates started changing
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