1. Evolution “The History of Life”
Edwin P. Davis, M.Ed.
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2. History of the Earth Formed 4.6 billion year ago
Started as hot ball of rock
Earth cooled 4.4 billion years ago
First life began between 3.9 and 3.4 bya
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3. Fossils Evidence of an organism that lived long ago Paleontologists
Study ancient life
Uses fossils to:
understand events that happened long ago
Determine the kinds of organisms that lived during the past and their behaviors
Study ancient climate and geography
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4. How fossils form Organisms are buried in mud, sand, or clay
Sediments cover the organism, slows decomposition
Minerals from sediments seep into body
Over time, sedimentary layers compressed into rock
Mineral replace the body’s bone material
Earth’s movement or erosion expose the body
Rocks form at relatively low temperatures and pressure
Prevent damage of organism
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5. Types of Fossils Trace fossils An indirect evidence left by an animal
Include a footprint, a trail, or a burrow
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6. Casts
A replica or cast
Minerals in rocks fill a space left by a decayed organism
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7. Molds An empty space left by an organisms after it decays 8/1/2019
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8. Minerals penetrate and replace the hard parts of an organism
Petrified
Minerals penetrate and replace the hard parts of an organism
Permineralized
Void spaces in original organism is filled by minerals
Petrified
Permineralized
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9. Amber-preserved or frozen
An entire organism quickly trapped in ice or tree sap and hardens
Amber preserved
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Frozen

10. Dating fossils Relative dating
uses the position of fossils in sediment layers
oldest fossil at the bottom layer, youngest on top
Can only determine whether one fossil is older than another
Cannot determine the actual age
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11. Radiometric dating
use radioactive isotopes (atoms with unstable nuclei that break down or decay)
decay of each radioactive element is known and continues at a steady rate
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12. Half-life
the time it takes a radioactive element to get to half its original amount
Potassium billion yrs
Carbon years
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13. Geologic Time Scale
a type of calendar based on the different types of living organisms that have appeared on Earth
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14. Precambrian Era Starts 4.7 bya Accounts for 87% of Earth’s history
Oldest rock dates 3.4 bya
Unicellular prokaryotes appeared
Eukaryotes appeared 2.1 bya
Ended 345 mya
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Oldest rock from Yukon, 4 byo

15. Paleozoic Era
345 to 248 mya
Appearance of plants and animals including fishes, reptiles, amphibians and ferns
90% of Earth’s marine species and 70% of land species disappeared
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16. Mesozoic Era 248 to 65 mya Triassic Jurassic Cretaceous Oldest
Mammals appeared
Dinosaurs first appeared
Jurassic
Age of dinosaurs
Cretaceous
Mammals and flowering plants
Dinosaurs and 2/3 of living species became extinct
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17. Theory of Continental Drift
Continents were joined in a landmass known as Pangaea
Pangaea broke apart resulting in two large masses
At the end of the Mesozoic, most of the continents had taken on their modern shapes
Explained by plate tectonics
Movement of the continents
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19. The Origin of Life
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20. The Early Ideas Spontaneous generation
Nonliving material can produce life
Experiments to disprove this theory
Francesco Redi
Used maggots in covered and uncovered jars
Louis Pasteur
Used curved flasks with heated broth
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21. Francesco Redi
1668
Showed that rotting meat kept away from flies would not produce new flies
Maggots appeared only on meat that had been exposed to flies
Eggs laid on meat
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22. Louis Pasteur Mid- 1800s Used curve-necked flasks
Microorganisms were prevented from entering the flask
When curved necks were broken, broth became cloudy with microorganims
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23. Biogenesis All living things come from other living things
Became cornerstone of biology after Pasteur’s experiment
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24. The Modern Ideas Alexander Oparin
Life began in the oceans that formed on early Earth
Energy from sun + lightning+ Earth’s heat = simple compounds (eg. amino acids)
Earth cooled, water vapor condensed to form lakes and seas, compounds collected in the water
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25. Stanley Miller and Harold Urey
Used Oparin’s hypothesis to setup experiment
Produced amino acids and other organic compounds
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26. Formation of Protocells
Sidney Fox
Produced protocells
Large, ordered structure, enclosed by a membrane
Carries out some life activities (growth and division)
Heated amino acids
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27. The First True Cells Prokaryotes evolved from a protocell
Heterotrophs
Anaerobic
Archaebacteria
Prokaryotic
Autotrophs
Made glucose by chemosynthesis
Lived in harsh environments
Deep-sea vents and hot springs
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28. Photosynthesizing prokaryotes Eukaryotes evolved from prokaryotes
Increased oxygen in atmosphere
Eukaryotes evolved from prokaryotes
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29. Endosymbiont Theory Eukaryote provided beneficial environment
Prokaryote provided method of energy synthesis
Endosymbiotic, aerobic prokaryotes evolved into modern mitochondria
Photosynthetic cyanobacteria evolved into chloroplasts
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