Section Review 9-2Section Review 9-2

Page #220: 1-8Page #220: 1-8

• What is Ma?

Geologic ChangesGeologic Changes

#1#1

Summarize how evolution is related to geologic change.

Geologic changes cause changes in the environment.

Climate, elevation, etc. can change which can cause populations to either evolve or become extinct.

Fossil finds and Plate MovementsFossil finds and Plate Movements

#2#2Identify two characteristics of most

Precambrian rocks.

They are highly deformed and contain few fossils.

Precambrian RocksPrecambrian Rocks

Canadian Shield- Precambrian Rock 3.9 billion years old

#3#3

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 StatesPrecambrian rocks in United States

Precambrian FossilsPrecambrian 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 blue-green 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.

StromatolitesStromatolites

#4#4Identify one life-form from each of the

six periods of the Paleozoic Era.

Cambrian: trilobites

Ordovician: mollusks Silurian: echinoderms (like sea stars)Devonian: fishesCarboniferous: amphibiansPermian: reptiles

Trilobites (Trilobites (Cambrian)

Ancient Precambrian sea

MollusksMollusks ( (Ordovician)

Echinoderms (like sea stars) (Silurian)

Devonian: fishes

Carboniferous: amphibians

Permian: reptiles

#5#5Explain why the Devonian Period is commonly called the Age of Fishes.

Many types of fossil fish have been found in rocks from this period.

Devonian FishesDevonian Fishes

#6#6Describe 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 extinctionsPermian mass extinctions

• A theory that an abrupt and dramatic rise in atmospheric levels of carbon dioxide triggered the massive die-off 251 million years ago.

#7#7Identify 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 PangaeaFormation of Pangaea

• Former oceans were destroyed as land masses collided. This trapped and killed ocean life.

#8#8Why is Precambrian time ----about 88% of geologic time---- not divided into smaller units based on the fossil record?

The fossil record of Precambrian time contains few fossils so there is not any reason (or guideline to use) to subdivide it.

Fossil RecordFossil Record

The End????The End????