Download The Cambrian Explosion What is the Cambrian Explosion?!?!

The Cambrian
Explosion
What is the Cambrian Explosion?!?!
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What actually happened, was a lot of complex organisms
appeared between 543 and 530 million years ago.
Organisms like brachiopods (clams, mussels), arthropods
(crabs, spiders)and echinoderms (sea stars, sea urchins)
appeared in large variations. There is a sudden increase in
fossils at the time.
Trace fossils also increased abundantly.
Soft-bodied Precambrian faunas (animals) can be preserved,
however it was difficult (too long ago and no real hardened
shells).
It is at this period, many organisms attained or improved their
shells or bones, or in lay man’s terms (simple terms), hard
parts.
Environmental Changes?
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In the Cambrian period, the super continent of Pangaea was
breaking up into smaller parts. Continents began to separate.
Many climate changes took place at this time.
Gases from this period mainly came from volcanic eruptions
(sulfur, nitrogen).
Oxygen was increasing known as the Great Oxygenation Event,
harming organisms that had evolved earlier but giving life to
even more organisms.
Temperature and rain increased leading to shallow warm seas.
Carbon Dioxide was decreasing (this caused the planet to cool
down)
There was a huge glacial movement and a very harsh ice age.
And after the ice age was finished temperatures rose to levels
higher than they are today.
Environmental Changes
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Those organisms that were able to survive these
vast changes were better adapted holding off
extinction.
Adaptation: characteristics developed over time
that help species survive in particular
environments.
Extinct: when a species dies.
Just an FYI – there was mass extinction of most
if not all species from the Cambrian period.
Why So Much Life?
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Many Theories have been created to explain this
sudden increase in life, but many contradict each
other.
One theory was that the changing climate could
have caused some of the life created in the
period.
Impact of Asteroids
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Did an impact kill the dinosaurs?
Large dips in total species diversity in the fossil
record.
The most recent was 65 million years ago,
ending the reign of the dinosaurs.
The impact caused climactic changes,
temperatures to cool, not allowing dinosaurs to
survive.
No dinosaur
fossils in these
rock layers
Thin layer
containing iridium
from impactor
Dinosaur fossils
in lower rock
layers
Iridium - evidence of an impact
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Iridium is very rare in Earth surface rocks but
often found in meteorites.
Iridium’s daughter element is Platinum.
Layers of Iridium were laid down 65 million
years ago.
Comet or
asteroid about
10km in
diameter
approaches
Earth
An iridium-rich
sediment layer and
an impact crater on
the Mexican coast
65 million years
ago.
shows that a large
impact occurred
at the time the
dinosaurs died out,
Earth’s Changing Surface
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Factors that attribute:
Thermal Energy Escaping Earths interior
(Geothermal)  Kinetic  Mechanical  Potential
 Plate tectonics
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Kinetic energy
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Some of the heat energy
in the mantle is
transformed into kinetic
energy in the form of
convection currents that
form in the mantle.
Kinetic energy  Potential
energy
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Kinetic energy of the
moving plates can be
converted into
potential energy when
two plates collide and
“stick” together.
The potential energy
builds up until it is
finally converted back
into kinetic energy and
the plates “slip”
Plate movement
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Some of the heat energy
from the earth reaches the
surface (as in a volcano.)
Some heat energy is
transformed into
mechanical energy in the
form of convection
currents, moving plates,
earthquake waves, flowing
lava, etc…
Plate movement
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As plates slide over ,
under, or past each
other, they change
the surface of the
earth.
Plate movement
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Plates that push
together can cause
the earth to
“crumple” and
form mountains.
Plate movement
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When
continental and
oceanic plates
collide, they
can produce
volcanoes.