Add this unit to your Table of contents! 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 K 12 K 1 2 3 4 5 6 7 8 9 10 11 12 4.6 billion years ago Present day 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 Bacteria Multicellular organisms Cyanobacteria and stromatolites DOMINATE ORGANISMS Bacteria Multicellular organisms Fossils found in South Australia

Pictures of Precambrian Era Life and Fossils

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

Pictures of Paleozoic life and fossils

4.6 billion years ago – 542 million years ago 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

Mesozoic Era pictures and fossils

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

Cenozoic Era pictures and fossils