Section Review 12-1

Section Review 9-2
Page #220: 1-8
• What is Ma?
Geologic Changes
Summarize how evolution is related
to geologic change.
Geologic changes cause changes in the
Climate, elevation, etc. can change
which can cause populations to either
evolve or become extinct.
Fossil finds and Plate Movements
Identify two characteristics of
most Precambrian rocks.
They are highly deformed and
contain few fossils.
Precambrian Rocks
Canadian Shield- Precambrian Rock
3.9 billion years old
Explain why fossils are rare in
Precambrian rocks.
Most Precambrian organisms
were small and soft bodied. The
rocks have also been highly
deformed and altered from their
original state.
Precambrian rocks in United States
Precambrian Fossils
• Stromatolites are the most intriguing fossils
that are our singular visual portal into deep time
on earth, the emergence of life, and the eventual
evolving of the beautiful life forms from
Cambrian to modern time.
• Stromatolites are laminated structures built
mainly by cyanobacteria (sometimes known as
blue-green bacteria or, less correctly, as bluegreen algae). They are still found today, but
were once much more common. They
dominated the fossil record between about 2000
million and 1000 million years ago. Nowadays
they are found mainly in saline lakes or hot
spring environments, often in environmental
niches that other organisms cannot tolerate.
Identify one life-form from each
of the six periods of the
Paleozoic Era.
Cambrian: trilobites
Ordovician: mollusks
Silurian: echinoderms (like sea stars)
Devonian: fishes
Carboniferous: amphibians
Permian: reptiles
Trilobites (Cambrian)
Ancient Precambrian sea
Echinoderms (like sea stars)
Devonian: fishes
Carboniferous: amphibians
Permian: reptiles
Explain why the Devonian
Period is commonly called the
Age of Fishes.
Many types of fossil fish have
been found in rocks from this
Devonian Fishes
Describe the kinds of life-forms
that became extinct during the
mass extinction at the end of the
Permian Period.
Many types of marine
invertebrates became extinct.
(like trilobites)
Permian mass extinctions
• A theory that an
abrupt and
dramatic rise in
levels of carbon
dioxide triggered
the massive dieoff 251 million
years ago.
Identify one way in which the
formation of Pangaea affected
Paleozoic life.
When Pangaea formed, inland seas
disappeared and organisms that
lived in those seas evolved or
became extinct.
Formation of Pangaea
• Former
oceans were
destroyed as
land masses
collided. This
trapped and
killed ocean
Why is Precambrian time ----about
88% of geologic time---- not divided
into smaller units based on the fossil
The fossil record of Precambrian
time contains few fossils so there is
not any reason (or guideline to use)
to subdivide it.
Fossil Record
The End????