1. Earth’s History
Geological time Scale

2. How do we know about our planet’s history?
8.E.2 Understand the history of Earth and its life forms based on evidence of change recorded in fossil records and landforms.
I will explore the geologic timescale of Earth.

3. Scientist calculate Earth to be 4.54 billion years old.
How old is Earth?
Scientist calculate Earth to be 4.54 billion years old.

4. Geologic Time Scale
system of chronological measurements used to describe the timing & relationships between events that have occurred throughout Earth's history.
Different ages of Earth; ends when a mass extinction
beginning when Earth was formed goes to present
Using fossils, Paleontologists determine which common organisms fit in which age
Chronological= arranged in order of time

6. Precambrian Era 4600 to 542 million years ago(mya)
First era; began with creation of Earth, around 4.6 billion years ago
5 events (creation) )sun 2)Earth 3)atmosphere 4)oceans 5) life(simple- bacteria & algae)
Organisms became more complex (jellyfish & sea worms)
Few fossils- soft bodied & no hard skeleton
Extinction-stromatolites and acritarchs (microorganisms)

7. Paleozoic Era 542 to 251 mya
Begins with early invertebrates (lacking a backbone) develops into early vertebrate
(fish arachnids & insects amphibians ending with reptiles)
Land plants begin to grow
(simple mosses & ferns cone-bearing plants ending with seed plants)
The Age of Trilobite
Pangea formed about 270mya
Extinction- most invertebrates & amphibians begin to disappear, 95% of marine species

8. Mesozoic Era 251 to 65 mya ‘Age of the Dinosaur’
Pangea broke apart about 200 mya.
Dominant animals include reptiles & dinosaurs
Small mammals & birds appeared
Toward end of era more varieties of mammals and flowering plants appeared (life became more diverse)
Era ended due to mass extinction of dinosaurs

9. Cenozoic Era 65 mya- Present
Age of Mammals and Humans
Mammals – new organisms appeared(more diversity, appearance of humans) & others extinct
Flowering plants become more common & diverse

11. Brain Pop