Science Test- History of Life on Earth

- on friday

Fossilization

occurs when the remains of an animal are covered by sediment and preserved

why is fossilization so rare?

there are many processes that prevent a fossil from forming-therefore fossilization is rare

7 types of fossils-

1. **Permineralized** 
2. **Carbonized**
3. **Frozen remains**
4. **Cast and mold**
5. **Amber**
6. **Tar pit**
7. **Trace**

Radiometric dating

the method of finding the absolute age of rock based on comparing the amounts of stable +unstable particles

uniformitarianism

geologic events and phenomena that occur today, also happened in the past, and will happen in the future.

law of superposition

states that in a sequence of undisturbed rocks, the oldest layers are at the bottom; newest/youngest layers are at the top. 

absolute age

the actual age of something

half life

the amount of time needed for half of a sample of a radioactive substance to decay

extinction

when all members of a species die out

fossil record

collection of all known fossils and their placement in order from most recent

paleontologist

A person who studies fossils

geologist

A person who studies rocks; minerals

mass extinction

large numbers of species die out in different parts of Earth during a relatively short period of time

reasons for mass extinction

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**you only need 3*\*

meteor strike, climate change, overhunting, pollution, natural disasters, low oxygen levels, sea level drops, realize of methane gas

pick two trace fossils and describe what they tell us

**footprints-** tells us if the animal walked on two or four feet and how big the animal is

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**scratch marks**- tells us if the animal had claws/was a predator

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**dung stones-** tells us what the animal ate, whether it was a carnivore or herbivore.

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**burrows/nests-** tells us the type of habitat the animal liked to live in; also shows the behavior

evidence on how dinosaurs went extinct

fossils (big below, tiny above boundary)

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Iridium (In/on rocks)

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Tsunami deposits

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Crater

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Shocked quartz

rank the geologic time scales from greatest amount of years to least.

Eon, Era, Period, Epoch, Age

geologic time scale

divides Earth’s history into intervals of time defined by major events or changes on Earth