Evolution of Multicellular Life Section 17–3 This section describes how multicellular life evolved from its earliest forms to its present-day diversity.

Evolution of Multicellular Evolution of Multicellular Life Life

Section 17–3Section 17–3This section describes how This section describes how multicellular life evolved from its multicellular life evolved from its earliest forms to its present-day earliest forms to its present-day diversity. diversity.

Precambrian Time Precambrian Time

Is the following sentence true or false? Is the following sentence true or false?

Almost 90 percent of Earth’s history Almost 90 percent of Earth’s history occurred during the Precambrian.occurred during the Precambrian.

TRUE TRUE

Precambrian TimePrecambrian Time

Circle the letter of each sentence Circle the letter of each sentence that is true about life in the that is true about life in the Precambrian. Precambrian.

Anaerobic and photosynthetic forms Anaerobic and photosynthetic forms of life appeared.of life appeared.

Precambrian TimePrecambrian Time

Aerobic forms of life evolved, and Aerobic forms of life evolved, and eukaryotes appeared.eukaryotes appeared.

Multicellular life forms evolved.Multicellular life forms evolved.

Precambrian TimePrecambrian Time

Life existed on the land and in the Life existed on the land and in the sea. sea.

Precambrian TimePrecambrian Time

Why do few fossils exist from the Why do few fossils exist from the Precambrian?Precambrian?

The animals were all soft-bodied. The animals were all soft-bodied.

Paleozoic Era Paleozoic Era

The first part of the Paleozoic Era is The first part of the Paleozoic Era is the _____Period. the _____Period.

Cambrian EraCambrian Era

Paleozoic EraPaleozoic Era

Is the following sentence true or false?Is the following sentence true or false?

Life was not very diverse during the Life was not very diverse during the Cambrian Period.Cambrian Period.

false false

Paleozoic EraPaleozoic Era

Circle the letter of each sentence that Circle the letter of each sentence that is true about the Cambrian Period. is true about the Cambrian Period.

a.a. Organisms with hard parts first Organisms with hard parts first appeared. appeared.

b.b. Most animal phyla first evolved. Most animal phyla first evolved. d.d. Brachiopods and trilobites were Brachiopods and trilobites were

common. common.

Paleozoic EraPaleozoic Era

Match the periods of the Paleozoic Match the periods of the Paleozoic Era with the evolutionary events that Era with the evolutionary events that occurred during them. occurred during them.

Paleozoic EraPaleozoic Era

Animals first begin to invade the land Animals first begin to invade the land during the ______during the ______Period. Period.

DevonianDevonian

The History of Life The History of Life

Where does the Carboniferous Period Where does the Carboniferous Period get its name?get its name?

Vast swampy forests, giant ferns Vast swampy forests, giant ferns and other plants that grew during and other plants that grew during that time formed thick deposits of that time formed thick deposits of sediment that changed into coal over sediment that changed into coal over millions of years. millions of years.

The History of LifeThe History of Life

When many types of living things When many types of living things become extinct at the same time, it become extinct at the same time, it is called a(an) is called a(an)

mass extinctionmass extinction

The History of LifeThe History of Life

Is the following sentence true or false?Is the following sentence true or false?

The mass extinction at the end of The mass extinction at the end of the Paleozoic affected only land the Paleozoic affected only land animals.animals.

false false

Mesozoic Era Mesozoic Era

Complete the compare-and-contrast Complete the compare-and-contrast table. table.

PERIODS OF THE MESOZOIC ERA PERIODS OF THE MESOZOIC ERA

The History of LifeThe History of Life

The Mesozoic Era is called the Age ofThe Mesozoic Era is called the Age of . .

REPTILESREPTILES

The History of LifeThe History of Life

The first dinosaurs appeared in The first dinosaurs appeared in the___the___ Period. Period.

TriassicTriassic

The History of LifeThe History of Life

Is the following sentence true or false? Is the following sentence true or false?

The mammals of the Triassic Period The mammals of the Triassic Period were very small.were very small.

true true

The History of LifeThe History of Life

Is the following sentence true or false? Is the following sentence true or false?

Many paleontologists think that Many paleontologists think that birds are close relatives of dinosaurs.birds are close relatives of dinosaurs.

true true

The History of LifeThe History of Life

The dominant vertebrates throughout The dominant vertebrates throughout the Cretaceous Period were ____. the Cretaceous Period were ____.

reptilesreptiles

The History of LifeThe History of Life

What advantage do flowering plants What advantage do flowering plants have over conifers? have over conifers?

Their seeds are enclosed in a Their seeds are enclosed in a fruit, fruit, which protects the seed and aids in which protects the seed and aids in dispersing it to new locations.dispersing it to new locations.

The History of LifeThe History of Life

Describe the mass extinction that Describe the mass extinction that occurred at the end of the occurred at the end of the Cretaceous Period. Cretaceous Period.

More than half of all plant and More than half of all plant and animals groups were wiped out, animals groups were wiped out, including all of the dinosaurs. including all of the dinosaurs.

Cenozoic Era Cenozoic Era

Is the following sentence true or false? Is the following sentence true or false?

During the Cenozoic Era, mammals During the Cenozoic Era, mammals evolved adaptations that allowed them evolved adaptations that allowed them to live on land, in water, and in the air. to live on land, in water, and in the air.

true true

Cenozoic EraCenozoic Era

The Cenozoic Era is called the Age of The Cenozoic Era is called the Age of _______. _______.

MammalsMammals

Cenozoic EraCenozoic Era

What were Earth’s climates like What were Earth’s climates like during the Tertiary Period? during the Tertiary Period?

They were really warmThey were really warm and mild. and mild.

Cenozoic EraCenozoic Era

How did Earth’s climate change How did Earth’s climate change during the Quaternary Period?during the Quaternary Period?

First it cooled causing a series of ice First it cooled causing a series of ice ages. Then, it began to warm again. ages. Then, it began to warm again.

Cenozoic EraCenozoic Era

Is the following sentence true Is the following sentence true or false? or false?

The very earliest ancestors of The very earliest ancestors of our species appeared about our species appeared about 100,000 years ago. 100,000 years ago.

FALSEFALSE