Evolution of Multicellular Life

1
Evolution of Multicellular Life

• Section 173
• This section describes how multicellular life
  evolved from its earliest forms to its
  present-day diversity.

2
Precambrian Time

• Is the following sentence true or false?
• Almost 90 percent of Earths history occurred
  during the Precambrian.
• TRUE

3
Precambrian Time

• Circle the letter of each sentence that is true
  about life in the Precambrian.
• Anaerobic and photosynthetic forms of life
  appeared.

4
Precambrian Time

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

5
Precambrian Time

• Life existed on the land and in the sea.

6
Precambrian Time

• Why do few fossils exist from the Precambrian?
• The animals were all soft-bodied.

7
Paleozoic Era

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

8
Paleozoic Era

• Is the following sentence true or false?
• Life was not very diverse during the Cambrian
  Period.
• false

9
Paleozoic Era

• Circle the letter of each sentence that is true
  about the Cambrian Period.
• a. Organisms with hard parts first appeared.
• b. Most animal phyla first evolved.
• d. Brachiopods and trilobites were common.

10
Paleozoic Era

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

11
Paleozoic Era

• Animals first begin to invade the land during the
  ______Period.
• Devonian

12
The History of Life

• Where does the Carboniferous Period get its
  name?
• Vast swampy forests, giant ferns and other
  plants that grew during that time formed thick
  deposits of sediment that changed into coal over
  millions of years.

13
The History of Life

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

14
The History of Life

• Is the following sentence true or false?
• The mass extinction at the end of the Paleozoic
  affected only land animals.
• false

15
Mesozoic Era

• Complete the compare-and-contrast table.
• PERIODS OF THE MESOZOIC ERA

16
The History of Life

• The Mesozoic Era is called the Age of .
• REPTILES

17
The History of Life

• The first dinosaurs appeared in the___
  Period.
• Triassic

18
The History of Life

• Is the following sentence true or false?
• The mammals of the Triassic Period were very
  small.
• true

19
The History of Life

• Is the following sentence true or false?
• Many paleontologists think that birds are
  close relatives of dinosaurs.
• true

20
The History of Life

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

21
The History of Life

• What advantage do flowering plants have over
  conifers?
• Their seeds are enclosed in a fruit, which
  protects the seed and aids in dispersing it to
  new locations.

22
The History of Life

• Describe the mass extinction that occurred at the
  end of the Cretaceous Period.
• More than half of all plant and animals groups
  were wiped out, including all of the dinosaurs.

23
Cenozoic Era

• Is the following sentence true or false?
• During the Cenozoic Era, mammals evolved
  adaptations that allowed them to live on land, in
  water, and in the air.
• true

24
Cenozoic Era

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

25
Cenozoic Era

• What were Earths climates like during the
  Tertiary Period?
• They were really warm and mild.

26
Cenozoic Era

• How did Earths climate change during the
  Quaternary Period?
• First it cooled causing a series of ice ages.
  Then, it began to warm again.

27
Cenozoic Era

• Is the following sentence true or false?
• The very earliest ancestors of our species
  appeared about 100,000 years ago.
• FALSE