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History of the Earth

History of the Earth. Chapter 12. How Old is the Earth?. Early Earth 4.5 Billion Years Old Before then it was a fiery ball of molten rock. The water vapor from the atmosphere cooled and formed vast oceans. How Old is the Earth?. How do we know?

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History of the Earth

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  1. History of the Earth Chapter 12

  2. How Old is the Earth? • Early Earth • 4.5 Billion Years Old • Before then it was a fiery ball of molten rock. • The water vapor from the atmosphere cooled and formed vast oceans.

  3. How Old is the Earth? • How do we know? • Evidence of the earth’s age can be found in rock. • Radiometric Dating • The estimation of age of an object by measuring its content of radioactive isotopes.

  4. Radioactive Decay • Radioactive Decay • Radioactive isotopes are unstable isotopes that break down giving off energy in the form of radiation.

  5. The Evidence of Evolution • Fossils • Preserved or mineralized remains or imprint of organism that lived long ago • Show a pattern of development form early ancestors to now

  6. Evidence of Evolution • Most scientists agree that: • Earth is about 4.5 billion years old • Organisms have inhabited Earth for most of its history • All organisms living today share common ancestry with earlier, simpler life-forms.

  7. Evolution of Cellular Life • Precambrian Era • The first bacteria have been found to have lived 2.5 billion years ago during this era • Cyanobacteria • First prokaryotes • First organisms to live on earth • Photosynthetic bacteria • Released oxygen into the atmosphere • Protists • First Eukaryotes • Large group of unicellular and multicellular organisms

  8. Evolution of Cellular Life • Cambrian Period • About 1 billion years ago • The first animals probably originated from this period • This great diversification of animals is called the “Cambrian Explosion”

  9. Evolution of Cellular Life • Ordovician Period • About 505 to 438 million years ago • This is the time when animal diversity abounds and the first jawless fishes swam the seas • The appearance of more sea animals occurs during this period • Mass Extinction • During this period a large percentage life on earth went extinct

  10. Evolution of Cellular Life • Silurian Period (437 million years ago) • During this period Plants, arthropods, and fungi invade the land • May have been the first multicellular organisms to actually live on land. • Jawed fishes appear in the seas • Devonian Period (405 million years ago) • During this period bony fishes become abundant • Amphibians • The first vertebrates to leave the sea • Second Mass Extinction

  11. Evolution of Cellular Life • Carboniferous Period (360 million years ago) • Reptiles who evolved from amphibians have begun to inhabit the earth • Permian Period (290 million years ago) • Third Mass Extinction • Triassic Period (250 million years ago) • The first dinosaurs and Mammals appear • Fourth Mass Extinction

  12. Evolution of Cellular Life • Jurassic Period (210 million years ago) • Cretaceous Period (150 million years ago) • This period is marked by the appearance of flowering plants • Fifth mass extinction

  13. Evolution of Life • Tertiary Period (65 million years ago) • Due to the continents drifting birds and Mammals spread • Major mammal groups evolve and become abundant on land • Appearance of Australopithecus

  14. Evolution of Cellular Life • Quarternary Period (5 million years ago–today) • During this period the first Homo sapiens walked the land and continue to this day.

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