AP BIOLOGY 24 MASS EXTRICTIONS POGIL
KEY
Why?
Mass Extinctions
What is the biological significance of mass extinctions?
Evidence suggests that five mass extinctions have occurred throughout the history of the Earth—the most
famous of which led to the extinction of the dinosaurs. Scientists ...
key why mass extinctions what is the biological significance of mass extinctions evidence suggests that five mass extinctions have occurred throughout the histor
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KEY
Mass Extinctions
What is the biological significance of mass extinctions?
Why?
Evidence suggests that five mass extinctions have occurred throughout the history of the Earth—the most
famous of which led to the extinction of the dinosaurs. Scientists are still studying the causes of these
catastrophic events. What can we learn from mass extinctions, and what is their impact on the diversity of
life forms found on Earth?
Model 1 – Extinction Over Time
30
Total Extinction Rate (families per million years)
25
20
15
10
5
0
Paleozoic Mesozoic Cenozoic
E O S D C P Tr J C P N
542 488 444 416 359 299 251 200 145 65.5 23.5 0
Time (millions of years ago)
1. What are the names of the three eras identified on the x-axis in Model 1?
The names of the three eras identified in Model 1 are Paleozoic, Mesozoic and Cenozoic.
2. To what does the y-axis on the graph in Model 1 refer? (Include the unit of this variable.)
The y-axis in the graph represents the total number of families that have gone extinct over time.
3. According to Model 1, approximately how long did each of these eras last?
a. Paleozoic 291 million years
b. Mesozoic 185.5 million years
c. Cenozoic 65.5 million years
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, 4. The letters below each era refer to discrete time periods that are listed in the table below. Com-
plete the columns to indicate the approximate length of time each period lasted.
Era Period Length of time (in millions of years)
Paleozoic Edicaran 54 million
Ordovician 44 million
Silurian 28 million
Devonian 57 million
Carboniferous 60 million
Permian 48 million
Mesozoic Triassic 51 million
Jurassic 55 million
Cretaceous 79.5 million
Cenozoic Paleogene 45 million
Neogene 23.5 million
5. Circle the five major mass extinctions on the graph in Model 1.
6. List the period in which each mass extinction begins and ends.
Mass Extinction 1 begins in Ordovician and ends inSilurian.
Mass Extinction 2 begins in Devonian and ends in Carboniferous.
Mass Extinction 3 begins in Permian and ends in Triassic.
Mass Extinction 4 begins in Triassic and ends in Jurassic.
Mass Extinction 5 begins in Cretaceous and ends in Paleogene.
7. What appears to be one criterion that scientists use when defining the timing of geologic periods?
Scientists use mass extinctions as a way to define the timing of geologic time periods.
8. Scientists name mass extinctions using the name of the time period during which the extinction
began. Using this information, with your group name each of the five mass extinctions.
Ordovician Mass Extinction, Devonian Mass Extinction, Permian Mass Extinction, Triassic Mass Extinction,
and Cretaceous Mass extinction.
9. Carefully study the graph in Model 1.
a. The line on the graph is never flat. What does this tell you about the rate of extinctions over
time?
b. The line never reaches zero. What does this tell you?
Since the line never reaches zero, this tells us that there is always life on Earth.
2 POGIL™ Activities for AP* Biology
This study source was downloaded by 100000835361505 from CourseHero.com on 02-02-2022 14:31:43 GMT -06:00
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