The History of Life
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Transcript of The History of Life
![Page 1: The History of Life](https://reader036.fdocuments.us/reader036/viewer/2022062301/5681303b550346895d95d367/html5/thumbnails/1.jpg)
The History of Life
Chapter 14
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How the Earth Was Made:The Birth of the Earth Video
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I. Paleontologists
A. Scientists who study ancient life
1. Kinds of organisms
2. Ancient climate
3. Geography
![Page 4: The History of Life](https://reader036.fdocuments.us/reader036/viewer/2022062301/5681303b550346895d95d367/html5/thumbnails/4.jpg)
II. Early History of Earth
A.Very hotB. Volcanoes
spewing lava and gases
C. Little oxygen in the atmosphere but lots of CO2, nitrogen and water vapor
![Page 5: The History of Life](https://reader036.fdocuments.us/reader036/viewer/2022062301/5681303b550346895d95d367/html5/thumbnails/5.jpg)
II. Early History of Earth
Earth Cools
-lava cools (forms lands)
-rains for millions of years (forms oceans
-3.8 bya
![Page 6: The History of Life](https://reader036.fdocuments.us/reader036/viewer/2022062301/5681303b550346895d95d367/html5/thumbnails/6.jpg)
III. FossilsA. Sedimentary rocks contain fossils- clues to the
past
B. Oldest rocks 3.9 BILLION years old.
![Page 7: The History of Life](https://reader036.fdocuments.us/reader036/viewer/2022062301/5681303b550346895d95d367/html5/thumbnails/7.jpg)
III. Fossils
C. The Fossilization process
http://www.enchantedlearning.com/subjects/dinosaurs/dinofossils/Fossiltypes.html
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III. FossilsD. Mold (empty space)
E. Casts (minerals fill a space left by decayed organism)
F. Trace fossils (indirect
G. Petrified (hardened/permineralized)
H. Amber preserved (quickly trapped in sap & hardened)
I. Frozen (preserved in ice)
![Page 9: The History of Life](https://reader036.fdocuments.us/reader036/viewer/2022062301/5681303b550346895d95d367/html5/thumbnails/9.jpg)
V. The Age of a Fossil
A. Relative Dating
1. Determined by dating the rocks in the layer above and below the fossil
a. Newspaper example
2. An estimate of age
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V. The Age of a FossilB. Radiometric Dating
1. Determination of how many of the original atoms are left in the rock.
a. Atoms decay at a steady rate
2. Half-life- Time needed for ½ the atoms to decay
a. If the fossil’s half-life is 2 million years, when ½ of its atoms are gone it will be 2 million years old.
![Page 11: The History of Life](https://reader036.fdocuments.us/reader036/viewer/2022062301/5681303b550346895d95d367/html5/thumbnails/11.jpg)
V. The Age of a Fossil3. Scientists use potassium-40 to date the oldest rocks and carbon-14 to date younger fossils
a. Draw example on board
4. Errors can occur if the rock has been heated (atoms are lost or gained).
![Page 12: The History of Life](https://reader036.fdocuments.us/reader036/viewer/2022062301/5681303b550346895d95d367/html5/thumbnails/12.jpg)
VI. The Geologic Time Scale
A. Four Eras
1. Precambrian
2. Paleozoic
3. Mesozoic
4. Cenozoic
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VII. Life in the Precambrian (4600-543 MYA)
A. Earth’s formation
B. Prokaryotes
1. Cynobacteria-like
2. Stromatolites
C. 1.8 BYA eukaryotes evolve
D. 87% of Earth’s history
1.(January-October)
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VIII. The Paleozoic Era 543 MYA – 245 MYA
A. Cambrian explosion of life!
1. Worms, sea stars, arthropods, fishes
2. 400 MYA, ferns & early seed plants
3.Amphibians, reptiles
![Page 15: The History of Life](https://reader036.fdocuments.us/reader036/viewer/2022062301/5681303b550346895d95d367/html5/thumbnails/15.jpg)
End of the PaleozoicB. Largest mass
extinction
1. 90% of marine species extinct
2. 70% of land species extinct
30%
70%
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IX. Mesozoic 245 MYA – 66 MYA
A. Triassic period
1. Mammals (small)
2. Dinosaurs
3. Fern forest
B. Jurassic period
1. Dinosaurs
2. Modern birds evolved from birds of this period
![Page 17: The History of Life](https://reader036.fdocuments.us/reader036/viewer/2022062301/5681303b550346895d95d367/html5/thumbnails/17.jpg)
End of the Mesozoic
C. Cretaceous Period
1. New Mammals
2. Flowering Plants
D. Mass extinction of the dinosaurs
1. 66% of all living species extinct
2. Evidence of meteorite collision (Mexico)
E. Pangaea broke apart
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66% died
34% survived
![Page 18: The History of Life](https://reader036.fdocuments.us/reader036/viewer/2022062301/5681303b550346895d95d367/html5/thumbnails/18.jpg)
End of the Mesozoic
See “Owen’s Dinosaur Video”
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X. The Cenozoic Era66 MYA – present
A. Mammals flourish
B. 30 MYA- primates
C. 200,000 years ago, modern humans