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Geologic Time. Add this unit to your Table of contents!. A timeline of your education . If we made a timeline of your education, where would you fall?? What would we use as the scale? Grade level. Where would you fall on the timeline of the Earth ’ s history??. Fossils and Geologic Time.
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Geologic Time Add this unit to your Table of contents!
A timeline of your education • If we made a timeline of your education, where would you fall?? • What would we use as the scale? • Grade level • Where would you fall on the timeline of the Earth’s history??
Fossils and Geologic Time • The geologic time scale organizes geologic and evolutionary events. • It is based on evidence in the fossil record and has been shaped by mass extinctions.
How do extinctions shape Geologic Time? • Mass extinction- A large number of species become extinct • After a mass extinction, opportunities open for new life-forms to emerge.
Geologic Time Scale • Divisions of the Geologic Time Scale • Precambrian Era • Paleozoic Era • Mesozoic Era • Cenozoic Era
The Precambrian Era • 4.6 billion years ago – 542 million years ago • ~88% of the earth’s history
Major Events • Formation of the Earth’s crust from molten rock • First appearance of life ---bacteria! • First organisms could photosynthesize---- • Oxygenated atmosphere • First multi-cellular organisms
Major Events • MASS Extinction- widespread glaciation • Geologists compared the Earth to a giant snowball during this time
DOMINATE ORGANISMS Cyanobacteria and stromatolites • Bacteria • Multicellular organisms Fossils found in South Australia
The Paleozoic Era • 542 million years ago - 251 million years ago
Major Events • Cambrian explosion (of life)! • Primitive fishes appear • Mass EXTINCTION
Major Events • Plants colonize land • Insects and amphibians appear • ANOTHER Mass EXTINCTION
Major Events • Seed plants dominate land • Reptiles become dominate
DOMINATE ORGANISMS • Plants • Fishes • Insects • Amphibians • Reptiles
Warm-up 10/16/13 1. What years did the Precambrian Era span? 4.6 billion years ago – 542 million years ago 2. What percentage of Earth’s history does the Precambrian Era account for? 88%
The Mesozoic Era • 251 million years ago – 65.5 million years ago
Major Events • Dinosaurs appear • Mammals appear • Birds appear • Flowering Plants appear
Major Events • MASS EXTINCTION! - Hypothesized that the extinction occurred abruptly when a 10 km meteorite hit the Earth.
DOMINATE ORGANISMS • Reptiles • Dinosaurs • Conifer trees • Flowering Plants
The Cenozoic Era • 65.5 million years ago – Present day
Major Events • Mammals diversify (age of the mammals) • Forests dominate land • Grasslands appear
DOMINATE ORGANISMS • Wooly Mammoth • Primates • Mammals • Early humans