The History of Life Chapter 14. How the Earth Was Made: The Birth of the Earth Video.

The History of Life

Chapter 14

How the Earth Was Made:The Birth of the Earth Video

I. Paleontologists

A. Scientists who study ancient life

1. Kinds of organisms

2. Ancient climate

3. Geography

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

II. Early History of Earth

Earth Cools

-lava cools (forms lands)

-rains for millions of years (forms oceans

-3.8 bya

III. FossilsA. Sedimentary rocks contain fossils- clues to the

past

B. Oldest rocks 3.9 BILLION years old.

III. Fossils

C. The Fossilization process

http://www.enchantedlearning.com/subjects/dinosaurs/dinofossils/Fossiltypes.html

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)

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

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.

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).

VI. The Geologic Time Scale

A. Four Eras

1. Precambrian

2. Paleozoic

3. Mesozoic

4. Cenozoic

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)

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

End of the PaleozoicB. Largest mass

extinction

1. 90% of marine species extinct

2. 70% of land species extinct

30%

70%

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

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

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