Download Evolution of Life and Mass Extinctions

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Comparing fossils with similar life forms alive
today make it possible to infer facts about
Earth’s past environments.
Ex. most present-day corals live in shallow,
warm ocean waters, so we can assume that
coral fossils formed in an environment that
was the same
The movements of the plates and their
associated landmasses have changed the
Earth’s environment over time
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Environmental Evolution and Rock Types: As
Earth’s environments changed over time,
specific rocks and minerals formed, as well as
deposits of fossil fuels. (ex. worldwide coal
deposits of today were formed from swamps
formed during the hot and humid conditions
of the Carboniferous Period)
Deposits of salt and gypsum are found in
western NYS because old oceans that covered
the state evaporated during the hot and dry
Silurian Period (noted on reference tables)
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Most organisms decompose or are eaten after
they die, so only a small percent leave fossils
Fossils found in Africa suggest that we have
evolved over the past 4 million years from
apelike animals
This is only about 1/10 of 1% of Earth’s age
Humans are a very recent life-form
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Mass Extinction: Points in geologic time
where a large number of species become
extinct
Although not certain, scientists link many of
these mass extinctions to asteroid, comet or
meteoroid impact events
It is believed that an object from outer space
that left a crater in southern Mexico wiped
out the dinosaurs and many other species
about 65 million years ago
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Extinction was more likely a result of global
climatic change that resulted from the debris
thrown into the air by the impact, rather than
the impact itself
The debris would have stopped sunlight from
reaching Earth’s surface.
This would have disrupted the whole food
chain