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Earth’s History Geological time Scale
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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.
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Scientist calculate Earth to be 4.54 billion years old.
How old is Earth? Scientist calculate Earth to be 4.54 billion years old.
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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
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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)
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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
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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
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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
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Brain Pop
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