Evolution 3e TE v5

7 Origins of Species

view and reflect
1–2 class sessions

ACTIVITY OVERVIEW

NGSS CONNECTIONS

Students explore and explain how one species of finch arriving on the Galapagos
Islands 3 million years ago evolved into the current 13 species. They also explore
how recent changes in the environment have selected for different beak shapes and
sizes within a species, reinforcing cause-and-effect relationships. Students learn
that evidence from the Galapagos finches supports scientists’ assumptions that the
same processes that operated in the past are operating today; thus, the same cause-
and-effect relationships happening in Galapagos finches today also happened in
the past.

NGSS CORRELATIONS

Performance Expectations

Working towards MS-LS4-1: Analyze and interpret data for patterns in the fossil
record that document the existence, diversity, extinction, and change of life forms
throughout the history of life on Earth under the assumption that natural laws
operate today as in the past.

Working towards MS-LS4-2: Apply scientific ideas to construct an explanation for
the anatomical similarities and differences among modern organisms and between
modern and fossil organisms to infer evolutionary relationships.

Applying MS-LS4-4: Construct an explanation based on evidence that describes
how genetic variations of traits in a population increase some individuals’
probability of surviving and reproducing in a specific environment.

Applying MS-LS4-6: Use mathematical representations to support explanations
of how natural selection may lead to increases and decreases to specific traits in
populations over time.

Applying MS-LS3-1: Develop and use a model to describe why structural changes
to genes (mutations) located on chromosomes may affect proteins and may result
in harmful, beneficial, or neutral effects to the structure and function of the
organism.

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ACTIVITY 7  ORIGINS OF SPECIES

Disciplinary Core Ideas

MS-LS4.A Evidence of Common Ancestry and Diversity:
The collection of fossils and their placement in chronological order (e.g., through
the location of the sedimentary layers in which they are found or through radio-
active dating) is known as the fossil record. It documents the existence, diversity,
extinction, and change of many life forms throughout the history of life on Earth.
Anatomical similarities and differences between various organisms living today
and between them and organisms in the fossil record, enable the reconstruction of
evolutionary history and the inference of lines of evolutionary descent.
MS-LS3.BVariation of Traits: In addition to variations that arise from sexual
reproduction, genetic information can be altered because of mutations. Though
rare, mutations may result in changes to the structure and function of proteins.
Some changes are beneficial, others harmful, and some neutral to the organism.

MS-LS4.B Natural Selection: Natural selection leads to the predominance of
certain traits in a population, and the suppression of others.

MS-LS4.C Adaptation: Adaptation by natural selection acting over generations
is one important process by which species change over time in response to
changes in environmental conditions. Traits that support successful survival and
reproduction in the new environment become more common; those that do not
become less common. Thus, the distribution of traits in a population changes.

Science and Engineering Practices

Constructing Explanations and Designing Solutions:

Construct an explanation that includes qualitative or quantitative relationships
between variables that predict or describe phenomena.

Apply scientific ideas to construct an explanation for real-world phenomena,
examples, or events.

Crosscutting Concepts

Cause and Effect: Phenomena may have more than one cause, and some cause and
effect relationships in systems can only be described using probability.

Patterns:
Patterns can be used to identify cause and effect relationships.
Graphs, charts, and images can be used to identify patterns in data.

Connections to Nature of Science: Science Is a Human Endeavor: Scientists and
engineers rely on human qualities such as persistence, precision, reasoning, logic,
imagination and creativity.

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ORIGINS OF SPECIES ACTIVITY 7

Common Core State Standards—ELA/Literacy
RST.6-8.9: Compare and contrast the information gained from experiments,
simulations, video, or multimedia sources with that gained from reading a text on
the same topic.
WHST.6-8.2: Write informative/explanatory texts to examine and convey ideas,
concepts, and information through the selection, organization, and analysis of
relevant content.

WHAT STUDENTS DO
Students watch a video segment on the evolution of Galapagos finches. They learn
about Darwin’s original discovery of the finches and how the birds contributed to
his ideas about natural selection. They also learn about recent research done by
Peter and Rosemary Grant over several decade, who documented the phenomenon
of evolving beak size. They use a viewing guide to help them understand speciation
and natural selection in the Galapagos finches.

MATERIALS AND ADVANCE PREPARATION

■■ For the teacher

1 Scoring Guide: constructing explanations (exp)
access to video, Galapagos Finch Evolution

■■ For each student

1 Student Sheet 7.1, “Viewing Guide: Galapagos Finch Evolution”
1 Scoring Guide: constructing explanations (exp) (optional)
1 Literacy Student Sheet 4a, “Constructing Explanations” (optional)
For a link to the video, see the teacher page of the SEPUP Third Edition Evolution
website at www.sepuplhs.org/middle/third-edition. Preview the video, and decide
whether you will have the students watch the video once or twice.

TEACHING SUMMARY

GET STARTED

1. Students consider what might happen if natural selection occurs over a long
period of time.
a. Ask students, “What would happen if another kind of food became
available to the forkbirds?”
b. Let students know that they will watch a video segment to explore this
question in a group of real bird species, Galapagos finches.

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ACTIVITY 7  ORIGINS OF SPECIES

DO THE ACTIVITY

2. (literacy) Students prepare to watch the video segment.
Instruct students to preview the statements on Student Sheet 7.1, “Viewing

Guide: Galapagos Finch Evolution.”
3. Students watch the video and complete Student Sheet 7.1.

a. Play the video for students.
b. (literacy) Instruct students to complete Student Sheet 7.1.

BUILD UNDERSTANDING

4. The class discusses the answers to Student Sheet 7.1.
a. Facilitate a class discussion about the statements on the Viewing Guide.
b. Come to a class consensus on the statements.

5. Students answer the Analysis.
a. (exp assessment) Direct students to Analysis item 1.
b. Direct students to Analysis item 2, and elicit their responses.
c. Direct students to Analysis item 3 about evolutionary trees.
d. Discuss Analysis item 4 about the nature of science as a class.

TEACHING STEPS

GET STARTED

1. Students consider what might happen if natural selection occurs over a long
period of time.

This is a good place to reintroduce the third driving question for this sequence
of learning. Revisit and add to or revise students' ideas as needed.

a. Ask students, “What would happen if another kind of food became
available to the forkbirds?”150151

Students are likely to say that birds with other beak shapes might be able
to feed on that different food source. Ask them, “What would happen over
a long period of time? Would there be more than one type of forkbird?”
Accept all responses at this point.

b. Let students know that they will watch a video segment to explore this
question in a group of real bird species, Galapagos finches.

Explain that this video highlights the work of Peter and Rosemary Grant,
who have been studying this group of birds for over 40 years. In addition

150 NGLS4C1
151 NGLS4B1

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ORIGINS OF SPECIES ACTIVITY 7

to presenting their research, the video also highlights the Connections
to the Nature of Science: Science Is a Human Endeavor: Scientists
and engineers rely on human qualities such as persistence, precision,
reasoning, logic, imagination and creativity.

DO THE ACTIVITY

2. (literacy) Students prepare to watch the video segment.152

Instruct students to preview the statements on Student Sheet 7.1, “Viewing
Guide: Galapagos Finch Evolution.”

A Viewing Guide is a literacy strategy that focuses students on processing
content from visual or auditory sources. The guide contains a series of
statement from two levels of understanding: literal and interpretive. Explain
to students the types of statements in each of the two levels. The first set of
statements requires students to look and listen for ideas that are explicitly in
the video. The second set of statements requires students to draw a conclusion
from what they saw or heard.

Students should read the statements on Student Sheet 7.1 before watching
the video. By getting a sense of some of the video’s concepts and ideas, they
are better prepared to recognize key information in it. After viewing the video,
students should place a check mark next to those statements they agree with.

3. Students watch the video and complete Student Sheet 7.1.

a. Play the video for students.

Break the video into three segments, pausing for the first time at 5:42. The
first segment focuses on the evidence that all of the Galapagos finches
evolved from one single species. 153154155

When you pause the video, have students look at the statements on the
Viewing Guide to see if they are able to answer any of them at this time in
Part A. Statements 1–3 are addressed in this first segment.

The second segment, which ends at 11:24, focuses on how this one
species diverged into the 13 species that exist today. Statements 4 and 5
are addressed in this segment.

The third and final segment focuses on how species remain as separate
species. Statements 6 and 7 are addressed in this segment.

b. (literacy) Instruct students to complete Student Sheet 7.1.

152 ELRS689 Students should first complete the Viewing Guide individually.
153 NGLS4A1 Afterwards, they should compare their responses with those of their
154 NGLS4A2
155 NGLS3B2 EVOLUTION  99

ACTIVITY 7  ORIGINS OF SPECIES

partner and/or group. Encourage pairs or groups to work towards a
consensus. Direct students to “Developing Communication Skills” in
Appendix E in their Student Books. This page offers suggested questions
to ask of their peers when discussing the statements in the Viewing Guide.

BUILD UNDERSTANDING

4. The class discusses the answers to Student Sheet 7.1.

a. Facilitate a class discussion about the statements on the Viewing Guide.

See “Teacher Discussion Starters” in Teacher Resources II, “Diverse
Learners” for guidance on how to facilitate whole-class or group
discussion.

See Sample Student Response to Student Sheet 7.1 at the end of this
activity.

b. Come to a class consensus on the statements.

You may wish to record the consensus responses on chart paper or on a
projected version of the Viewing Guide.

After the discussion, students should understand the following:156157158159

• There is variation among birds in a population, and this variation is
passed from parents to offspring.

• In some environments, natural selection favors one beak shape; in
others, a different shape is favored.

• This change, or evolution, can happen over a very short period of time.

• When it happens over a long period of time and the changes involve
mating behaviors, the populations may become separate species.

• The mating behavior maintains the separation.

5. Students answer the Analysis.

a. (exp assessment) Direct students to Analysis item 1.160161

Consider using Student Literacy Sheet 4a, “Constructing Explanations,”
if your students need structured support in writing explanations. 162

b. Direct students to Analysis item 2, and elicit their responses.

156 NGLS3B2 This item addresses the assumption that natural laws operate today as
157 NGLS4C1 in the past, and by extension, will continue to operate in the future.You
158 NGCCCE2 may want to ask students, “In the future, will there be more finch species?
159 NGLS4B1 fewer species? different species?
160 NGSPCE2
161 ELWH682
162 SELTWF1

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ORIGINS OF SPECIES ACTIVITY 7

If any student suggests that there will be exactly the same 13 species, ask
them what would need to happen in order for that to be the case. Only
if the environment stayed constant for the next millions years would the
same 13 species still exist. Ask them if they think this is likely. Given that
the environment in the Galapagos changes from year to year, this is highly
unlikely.

c. Direct students to Analysis item 3 about evolutionary trees.

This question introduces students to an evolutionary tree, which will
be further explained in the next activity. Allow groups to discuss this
question for some time. Circulate throughout the room to identify groups
to share their responses with the entire class. Because students will revisit
this concept in the next activity, it is not essential that students have a
complete understanding yet.

Encourage students to continue using the questions on the “Developing
Communication Skills” page in Student Book Appendix E during the
whole-class discussion.

d. Discuss Analysis item 4 about the nature of science as a class.163

This question highlights the nature of science as a human endeavor.
Scientists possess certain personal and professional qualities that they
use or rely on when engaging in scientific research. The Grants exemplify
many of these qualities.

SAMPLE RESPONSES TO ANALYSIS

1. (exp assessment) Explain how environmental factors, genetic variation, and
natural selection resulted in the evolution of the 13 Galapagos finch species
1o6b41s6e51r6v61e6d716t8o16d91a7y0,17w1 hen originally there was just one finch species on the islands.

SAMPLE LEVEL-4 RESPONSE

Dry or wet environments led to changes in what sorts of foods were more common.
For example, dry weather that led to large seeds favored birds with larger and stronger
beaks.Wetter weather made the large seeds less common and favored the smaller
beaks. Different islands had different environments, and the birds on those islands
evolved to have different beak shapes. For example, on the island with a lot of cacti,
a longer beak shape evolved, which allowed the birds on that island to probe cactus
flowers. Some of the mating behaviors also evolved.When two populations from
different environments came into contact after a long period of time, the mating

behaviors prevented them from breeding together.They were then considered different
species.This happened several times until there were 13 species on the islands.

163 NGCCCO1 EVOLUTION  101
164 NGLS4A1
165 NGLS3B2
166 NGLS4C1
167 NGCCCE2
168 NGSPCE2
169 SEASEX1
170 ELWH682
171 NGCCPA1

ACTIVITY 7  ORIGINS OF SPECIES

2. Do you predict that the same 13 finch species that exist today in the
Galapagos Islands will exist in 1 million years? Explain. 172

I predict that there will be some different species in a million years, and there may be
more or fewer species.The environment in the Galapagos Islands is always changing,
which results in evolution happening all the time. If the environment changes, the
species are also likely to change.

mainland small ground
medium ground
large ground
cactus
large cactus
sharp-beaked ground
small tree
large tree
medium tree
mangrove
woodpecker
vegetarian
warbler

3. How does the figure above represent the evolution of the 13 species? 173

LabAids SEPUP IAPS Evolution 3e

SFitguudree:nEtvor3eespTEo7n_s1es may vary and might not be as complete as the sample that
fMolylroiawdPs.roSRteugd9e.n5/t1s1might at this point understand some or all of the following:
branching indicates separation of species, the tree shows descent from ances-
tors, and/or more recently branched species are more closely related. Accept
their answers for now, as they will have a chance to build understanding of
these ideas. One sample response is shown here:

This shows the original finch species from the mainland at the bottom.This finch
got to the Galapagos Islands around 3 million years ago. Over time, as the finches
spread to all the islands with different food sources, different beak types were favored.
Eventually, the whole population had a different beak size and it became a new
species. Each time this happened is shown by the branches splitting.The species at
the top show the 13 species that exist today and what food they eat.What they eat
depends on their beak size and shape.

172 NGLS4A2
173 NGCCPA2

102 EVOLUTION

ORIGINS OF SPECIES ACTIVITY 7

4. What qualities do you think Peter and Rosemary Grant have that led to their
becoming successful scientists? 174

The Grants are hardworking and persistent, working on the same population of
finches for over 40 years.They are observant and precise in collecting and keeping
data.They use reason and logic to construct explanations about the past and current
evolution of Galapagos finches.

EXTENSION 1

For students who are interested in the process of speciation, encourage them to
view the video Evolution in Action in Salamanders on the SEPUP Third Edition
Evolution website at www.sepuplhs.org/middle/third-edition.

EXTENSION 2

For students who are interested in exploring the actual data collected by Peter and
Rosemary Grant on the medium ground finch, encourage them to visit the SEPUP
Third Edition Evolution website at www.sepuplhs.org/middle/third-edition and go to the
link for Grant Data. These data are in a 1-page spreadsheet and include various
measurements on birds that survived the drought in 1977 and those that didn’t.
Students can confirm the result that finches that survived had larger beaks than
those that didn’t. They can also look for patterns in other variables, like weight,
wing length, and tarsus (leg) length.

REVISIT THE GUIDING QUESTION

How do new species evolve?

New species evolve when changes in the environment lead to different traits
being favored by natural selection. Eventually the whole population is made up
of individuals with that new trait. When this happens for a long time and enough
changes occur that breeding between two populations are rare, they are considered
to be different species.

ACTIVITY RESOURCES

KEY VOCABULARY
evolution
natural selection
species
speciation

174 NGCCCO1

EVOLUTION  103

ACTIVITY 7  ORIGINS OF SPECIES

BACKGROUND INFORMATION

SPECIATION

Darwin’s ideas about natural selection were based to a large extent on observations
made during his famous round-the-world voyage on the H.M.S. Beagle. Twenty
years after his voyage, when at last he completed and published On the Origin
of Species, he was able to refer to copious evidence gathered on his journey. His
argument began with an analogy between breeding, or artificial selection, and
natural selection. But since plant and animal breeding takes so long, Darwin did
not see the production of unambiguous cases of new derived species. He had to
refer to indirect evidence from embryology, morphology, the fossil record, and the
geographical distribution of living species.
Darwin’s conclusions relied heavily on careful observations of live organisms
during his journey and collected specimens of finches that he took back to
England. Both DNA comparisons and observations by contemporary scientists of
subtle but ongoing population changes have confirmed Darwin’s hypothesis: the
multiple finch species arose from one ancestral species. The Galapagos Islands are
close enough to one another to allow for occasional migrations yet isolated enough
to facilitate divergence in response to local conditions (e.g., availability of food
sources like insects and seeds). The divergence, or branching, of one species into
two distinct species is now called speciation. When one species branches into many
species, the process is called evolutionary radiation or adaptive radiation.

104 EVOLUTION

©2017 The Regents of the University of California Name______________________________________________________________ Date____________

STUDENT SHEET 7.1

VIEWING GUIDE: GALAPAGOS FINCH EVOLUTION
Instructions: Scan the statements on this guide before watching the video. Afterwards, place
a check mark in the space next to the statements with which you agree in both sections. Be
prepared to explain your choices.
Part A: What did they say?

_______ 1. There are millions of species on Earth today.

_______ 2. The Galapagos Islands are all very similar to one another.

_______ 3. Many species of finch arrived in the Galapagos Islands from the mainland.

_______ 4. During the drought in 1977, the medium ground finches with the smallest beaks
had the most trouble.

_______ 5. The environment rarely changes in the Galapagos Islands.

_______ 6. Species are defined as populations whose members don’t interbreed.

_______ 7. Males respond only to song, not to appearance, of other birds.

Name______________________________________________________________ Date____________

STUDENT SHEET 7.1

VIEWING GUIDE: GALAPAGOS FINCH EVOLUTION
Instructions: Scan the statements on this guide before watching the video. Afterwards, place
a check mark in the space next to the statements with which you agree in both sections. Be
prepared to explain your choices.
Part B: What did they mean?

_______ 8. Speciation, or the evolution of new species, in Galapagos finches results because
natural selection favors different beak types on different islands.

_______ 9. Birds with a beak type poorly shaped for the current environment are able to
adapt by changing their beak types.

_______ 10. Medium ground finches with relatively large beaks tend to have offspring with
relatively large beaks.

_______ 11. While evolution of Galapagos finches happened in the past, it is no longer
happening today.

_______ 12. When species come into contact with closely related species, they interbreed and
become one species again.

©2017 The Regents of the University of California

©2017 The Regents of the University of California Name_______S__a_m___p_l_e__s_t_u_d__e_n__t_r_e__s_p_o__n_s_e___________________________ Date____________

STUDENT SHEET 7.1

VIEWING GUIDE: GALAPAGOS FINCH EVOLUTION

Instructions: Scan the statements on this guide before watching the video. Afterwards, place
a check mark in the space next to the statements with which you agree in both sections. Be
prepared to explain your choices.

Part A: What did they say?

___X____ 1. There are millions of species on Earth today.
Our planet has millions of species, including over 300,000 beetle species, 17,000 butterfly

species, and several thousand species of fish, birds, and mammals.

_______ 2. The Galapagos Islands are all very similar to one another.
The islands are very different from one another. They differ in size, topography, and height.

_______ 3. Many species of finch arrived in the Galapagos Islands from the mainland.
Only one species arrived from the mainland. Based on DNA evidence, all of the finches are

more related to one another than any one is to a species on the mainland.

___X____ 4. During the drought in 1977, the medium ground finches with the smallest beaks
had the most trouble.

Small and medium seeds disappeared during the drought, and only birds with large beaks
could crack open the large, hard seeds.

_______ 5. The environment rarely changes in the Galapagos Islands.
In 1977, there was a drought, and in 1982, there was 10 times as much rain as normal. The

plants changed depending on how dry or wet it was.

___X____ 6. S pecies are defined as populations whose members don’t interbreed.
The narrator gave this exact definition.

_______ 7. Males respond only to song, not to appearance, of other birds.
Males respond to both song and appearance. Males courted only females of the same

species, not females of another species.

©2017 The Regents of the University of California Name_______S__a_m___p_l_e__s_t_u_d__e_n__t_r_e__s_p_o__n_s_e___________________________ Date____________

STUDENT SHEET 7.1

VIEWING GUIDE: GALAPAGOS FINCH EVOLUTION

Instructions: Scan the statements on this guide before watching the video. Afterwards, place
a check mark in the space next to the statements with which you agree in both sections. Be
prepared to explain your choices.

Part B: What did they mean?

____X___ 8. Speciation, or the evolution of new species, in Galapagos finches results because
natural selection favors different beak types on different islands.

Beak size affects which foods a bird is able to eat. Different islands have different plants.
Only birds with the beak size and shape that allows them to eat the food on that islands
will be able to survive.

_______ 9. Birds with a beak type poorly shaped for the current environment are able to
adapt by changing their beak types.

The birds beaks don’t change, but birds with a more suitable beak type will be able to
produce more offspring, so in the next generation, there will be more birds with that
beak type.

____X___ 10. Medium ground finches with relatively large beaks tend to have offspring with
relatively large beaks.

Beak size is inherited, so birds with larger beaks have offspring with larger beaks. Birds
with smaller beaks have offspring with smaller beaks.

_______ 11. While evolution of Galapagos finches happened in the past, it is no longer
happening today.

Evolution happens continually depending on the environment, which can change from
year to year.

_______ 12. When species come into contact with closely related species, they interbreed and
become one species again.

When species diverge, they develop unique appearances and songs that are used in
mating. When they come back together, these traits prevent the species from interacting.
They remain separate species.

8 History and Diversity of Life

reading
1–2 class sessions

ACTIVITY OVERVIEW

NGSS CONNECTIONS

Students obtain information through text and graphics about the history and
diversity of life. They learn how life forms have evolved over time, with all
organisms sharing a common ancestor. They build on their understanding of
speciation and evolutionary trees as a way to represent evolutionary relationships,
and they are introduced to the process of extinction.

NGSS CORRELATIONS

Performance Expectations

Working towards MS-LS4-1: Analyze and interpret data for patterns in the fossil
record that document the existence, diversity, extinction, and change of life forms
throughout the history of life on Earth under the assumption that natural laws
operate today as in the past.

Working towards MS-LS4-2: Apply scientific ideas to construct an explanation for
the anatomical similarities and differences among modern organisms and between
modern and fossil organisms to infer evolutionary relationships.

Disciplinary Core Ideas

MS-LS4.A Evidence of Common Ancestry and Diversity:

The collection of fossils and their placement in chronological order (e.g., through
the location of the sedimentary layers in which they are found or through radio-
active dating) is known as the fossil record. It documents the existence, diversity,
extinction, and change of many life forms throughout the history of life on Earth.

Anatomical similarities and differences between various organisms living today
and between them and organisms in the fossil record, enable the reconstruction of
evolutionary history and the inference of lines of evolutionary descent.

EVOLUTION  109

ACTIVITY 8  HISTORY AND DIVERSITY OF LIFE

Science and Engineering Practices
Constructing Explanations and Designing Solutions: Apply scientific ideas to construct
an explanation for real-world phenomena, examples, or events.
Obtaining, Evaluating, and Communicating Information: Integrate qualitative
scientific and technical information in written text with that contained in media
and visual displays to clarify claims and findings.

Crosscutting Concepts
Patterns:
Patterns can be used to identify cause and effect relationships.
Graphs, charts, and images can be used to identify patterns in data.

Common Core State Standards—ELA/Literacy
RST.6-8.7: Integrate quantitative or technical information expressed in words in
a text with a version of that information expressed visually (e.g., in a flowchart,
diagram, model, graph, or table).
WHST.6-8.2: Write informative/explanatory texts to examine and convey ideas,
concepts, and information through the selection, organization, and analysis of
relevant content.

WHAT STUDENTS DO
Students read text and examine graphs and charts to obtain information about
both a brief history of life on Earth and a glimpse at the diversity of life on Earth
today, as well as in the past. Stop to Think questions guide them through the
Reading to develop an understanding of the dynamic nature of life on Earth.

MATERIALS AND ADVANCE PREPARATION

■■ For the teacher

1 Visual Aid 8.1, “Write a Caption for This Evolutionary Tree”
1 Scoring Guide: communicating concepts and ideas (com) (optional)

■■ For each student

1 Student Sheet 8.1, “Vertebrate Evolutionary Tree”

110 EVOLUTION

HISTORY AND DIVERSITY OF LIFE ACTIVITY 8

TEACHING SUMMARY

GET STARTED

1. Students are introduced to the diversity and history of life on Earth.
a. Ask students to summarize what they learned about the history and
diversity of Galapagos finches.
b. Ask them if they think that this same process has happened for all species.

DO THE ACTIVITY

2. Students read about evolutionary trees, diversity of life, extinction, and history
of life.
a. (literacy) Enhance student sensemaking by using the Stop To Think
strategy as they read the text.
b. Let students know that they will need to combine information from the
text with information in the figures to answer some of the questions.

BUILD UNDERSTANDING

3. Students answer Analysis items 1–3.
a. Direct students to Analysis items 1–3 to discuss in their groups and then
to answer in their science notebooks.
b. Have a brief class discussion about these items.

4. (com quick check) Students write a response to Analysis item 4.
a. Direct groups to Analysis item 4.
b. Project the communicating concepts and ideas (com) Scoring Guide.
c. Have students first write their own caption, and then have groups develop
one caption based on the individual responses.
d. Have groups record their captions on the board or chart paper, and have
students read the captions of other groups.

TEACHING STEPS

GET STARTED
1. Students are introduced to the diversity and history of life on Earth.

a. Ask students to summarize what they learned about the history and
diversity of Galapagos finches.
Students should be able to recall that Galapagos finches evolved from
one mainland finch species that arrived around 3 mya to 13 species
throughout the islands.

EVOLUTION  111

ACTIVITY 8  HISTORY AND DIVERSITY OF LIFE

b. Ask them if they think that this same process has happened for all species.

Accept all responses at this point, as this activity will expand upon this
question.

DO THE ACTIVITY

2. Students read about evolutionary trees, diversity of life, extinction, and history
of life.175176177178

a. (literacy) Enhance student sensemaking by using the Stop To Think
strategy as they read the text. 179180

You may choose one of the following strategies for the reading: have
students read the text with their partner or group, have one or more
students read passages out loud, or read the text out loud yourself.

The Stop to Think questions are designed for you and the students to
monitor comprehension as they proceed through the Reading, and serve
a different function than the Analysis found at the end of the activity.You
might have students jot some notes in their science notebooks in response
to the questions, discuss them in their pairs or groups, and/or discuss as
a class. For more information on this strategy, see the Literacy section of
Teacher Resources II, “Diverse Learners.”

b. Let students know that they will need to combine information from the
text with information in the figures to answer some of the questions.

Stop to Think 1 requires students to use Student Sheet 8.1, “Vertebrate
Evolutionary Tree.” Stop to Think 2 requires them to make mathematical
estimations.You may wish to model how to answer this question by saying,
“I see that there are around 1 million species of insects, and looking at
the rest of the slices in the pie, it looks like there are around another half
million species. That means there are around 1.5 million species.” It is
not important that students add up the numbers to determine the precise
sum.

Circulate throughout the room as students are answering the questions
to ensure that they are making connections between the text and the
graphics.

175 NGLS4A1
176 NGLS4A2
177 NGCCPA2
178 NGCCPA1
179 SELTST1
180 ELRS687

112 EVOLUTION

HISTORY AND DIVERSITY OF LIFE ACTIVITY 8

STOP TO THINK SAMPLE STUDENT RESPONSES

STOP TO THINK 1

a. Using Student Sheet 8.1, “Vertebrate Evolutionary Tree,” find the place in
the diagram, also shown below, that represents the point in time when birds
and crocodiles diverged, or split apart. When did this happen? Add the time in
millions of years ago (mya) to the diagram.

See figure below.
b. Find the place in the diagram that represents the point in time when mammals

diverged from birds/crocodiles. When did this happen? Add the time in millions
of years ago (mya) to the diagram.
See figure below.

fish amphibians mammals crocodiles birds

150 mya

200 mya

270 mya

530 mya

common ancestor

LabAids SEPUP IAPS Evolution 3e
Figure: Evo3e TE 8_1
MyriadPro Reg 9.5/11

STOP TO THINK 2

a. Use the key to calculate how many total known species there are.
When I add the rounded numbers in the pie chart, I get around 1.5 million species.
b. Calculate the approximate percentage of insects.

A round 60%. I got this by estimating 900,000 insects out of 1,500,000 species.That’s
the same as 9/15 or 3/5, and 3/5 is 60%.

EVOLUTION  113

ACTIVITY 8  HISTORY AND DIVERSITY OF LIFE

c. The figure in the previous section shows the evolutionary tree for vertebrates.
Which “slice” in the figure below would be home to this tree?
That’s the piece labeled “Chordates” with 43,000 species.

STOP TO THINK 3

What are some reasons why a species might go extinct?

Maybe the environment changed and the species didn’t have traits that helped it survive
in the new environment. Maybe new types of species evolved and the species couldn’t com-
pete with them. Maybe a meteor hit Earth.

STOP TO THINK 4

a. Which life forms no longer exist today?
Trilobites and dinosaurs went extinct.
b. When did flowering plants first evolve?
Flowering plants evolved around 70 mya.
c. When did the first humans, Homo sapiens, evolve?

The first humans evolved around 200,000 years ago.

BUILD UNDERSTANDING

3. Students answer Analysis items 1–3. 181182

a. Direct students to Analysis items 1–3 to discuss in their groups and then
to answer in their science notebooks.

Encourage groups to discuss the items and develop a consensus answer
that students can enter into their science notebooks.

b. Have a brief class discussion about these items.

These items are intended for students to understand the “big picture”
of the history and the tremendous diversity of life on Earth over a vast

181 NGSPCE6
182 ELWH682

114 EVOLUTION

HISTORY AND DIVERSITY OF LIFE ACTIVITY 8

period of time. It is not important that students walk away with details
about years or names of organisms.

4. (com quick check) Students write a response to Analysis item 4.183184

a. Direct groups to Analysis item 4.

Explain that this item requires students to communicate their
understanding of the evolutionary processes of speciation and extinction
by writing a caption to a diagram. This question introduces the practice
of communicating concepts through a Quick Check. A Quick Check is a
formative assessment to provide you with feedback that you can use in the
subsequent lessons on evidence for evolution from fossils.

b. Project the communicating concepts and ideas (com) Scoring Guide.

Explain that students will not be assessed using this Scoring Guide in this
activity, but they will in a later activity.

Point out how it has the same levels as previous guides but different
descriptions for each level. Review the levels as needed. For more
information, see Teacher Resources III, “Assessment.”

c. Have students first write their own caption, and then have groups develop
one caption based on the individual responses.

Encourage students to carefully consider all of the group members’
captions before deciding on the best or creating a new one using input
from the individual captions.

d. Have groups record their captions on the board or chart paper, and have
students read the captions of other groups.

Have a discussion about which caption or captions best communicate the
meaning of the diagram using Visual Aid 8.1, “Write a Caption for This
Evolutionary Tree.” If time permits, consider coming to a consensus on
the best caption or developing one caption that the class can agree on.

SAMPLE RESPONSES TO ANALYSIS

1. Why do scientists who study evolution think of 20 million years as a short
time? 185

Earth is over 4 billion years old, which is 4,000 million years.Twenty million years is
a short period of time when you think of 4,000 million years.

183 SEASCM1
184 NGSPOE1
185 ELWH682

EVOLUTION  115

ACTIVITY 8  HISTORY AND DIVERSITY OF LIFE

2. What does the statement “extinction and speciation are both parts of
evolution” mean?

Speciation is the evolution of new species. At the same time as some new species
evolve, some other species may go extinct.When species go extinct either because they
were poorly adapted to the changing environment or by chance, this may leave oppor-
tunities for new species that can survive in the new environments to evolve. So the
appearances and disappearances of species are both parts of the process of evolution
that led to the species observed on Earth today.

3. How did there get to be such a great variety of life? 186

Whenever the environment changes, a new species may evolve to fit into that new
environment. Because the environment is always changing, there are always new
species evolving.When this happens over millions of years, we can get millions of
species evolving.

4. (com quick check) Write a detailed caption for the diagram shown below. 187188

lizards and crocodiles most all meat-eating birds
snakes plant-eating and very large

dinosaurs dinosaurs

common ancestor

SLAaMbPALidEsLSEEVPEUL-P4IRAEPSSPEOvNoSluEtion 3e
Figure: Evo3e TE 8_2

TMhyisriaddiPargorRaemg 9sh.5o/1w1s the relationships between a group of organisms descended from
a common ancestor.The more recently two groups separated, the more closely they
are related.The diagram shows that birds are closely related to dinosaurs, especially
those that ate meat and the large plant-eating dinosaurs. Both birds and these kind of
dinosaurs descended from a common ancestor that was also an ancestor to crocodiles
and most plant-eating dinosaurs. All of these organisms share a more distant common
ancestor with lizards and snakes.

186 NGSPCE6
187 NGSPOE1
188 SEASCM1

116 EVOLUTION

HISTORY AND DIVERSITY OF LIFE ACTIVITY 8

REVISIT THE GUIDING QUESTION
How are the diverse species living today related to each other and to the species
that once lived on Earth?
All species are related because they descended from a single common ancestor
from billions of years ago, but species can be grouped according to how closely
they are related, which depends on how recently they shared the common
ancestor.

ACTIVITY RESOURCES

KEY VOCABULARY
ancestor
ancestral species
evolution
extinction
natural selection
speciation
species
REFERENCES
Grimaldi, D., & Engel, M. S. (1993). Evolution of the insects. New York, NY: W. W.
Norton and Company.

EVOLUTION  117

Name______________________________________________________________ Date____________

STUDENT SHEET 8.1

VERTEBRATE EVOLUTIONARY TREE

fish amphibians mammals crocodiles birds

common ancestor

LabAids SEPUP IAPS Evolution 3e
Figure: Evo3e TE 8_3 Student Sheet
MyriadPro Reg 9.5/11

©2017 The Regents of the University of California

VISUAL AID 8.1

WRITE A CAPTION FOR THIS EVOLUTIONARY TREE

lizards and crocodiles most all meat-eating birds
snakes plant-eating and very large

dinosaurs dinosaurs

©2017 The Regents of the University of California common ancestor

LabAids SEPUP IAPS Evolution 3e
Figure: Evo3e TE 8_4 VisualAid
MyriadPro Reg 9.5/11



9 Fossil Evidence

l a b o r at o r y
2 class sessions

ACTIVITY OVERVIEW

NGSS CONNECTIONS

Students examine actual fossils of four species representing a diversity of life
forms that existed at different points in the past. Then they examine simulated
stratigraphic data to detect patterns in the fossil record. They analyze and interpret
these patterns to place the four species in chronological order and, thus, determine
their relative ages.

NGSS CORRELATIONS

Performance Expectations

Working towards MS-LS4-2: Apply scientific ideas to construct an explanation for
the anatomical similarities and differences among modern organisms and between
modern and fossil organisms to infer evolutionary relationships.

Working towards MS-LS4-1: Analyze and interpret data for patterns in the fossil
record that document the existence, diversity, extinction, and change of life forms
throughout the history of life on Earth under the assumption that natural laws
operate today as in the past.

Disciplinary Core Ideas

MS-LS4.A Evidence of Common Ancestry and Diversity:

The collection of fossils and their placement in chronological order (e.g., through
the location of the sedimentary layers in which they are found or through radio-
active dating) is known as the fossil record. It documents the existence, diversity,
extinction, and change of many life forms throughout the history of life on Earth.

Anatomical similarities and differences between various organisms living today
and between them and organisms in the fossil record, enable the reconstruction of
evolutionary history and the inference of lines of evolutionary descent.

MS-ESS1.C The History of Planet Earth: The geologic time scale interpreted from
rock strata provides a way to organize Earth’s history. Analyses of rock strata and
the fossil record provide only relative dates, not an absolute scale.

EVOLUTION  121

ACTIVITY 9  FOSSIL EVIDENCE

Science and Engineering Practices

Analyzing and Interpreting Data: Analyze and interpret data to determine
similarities and differences in findings.

Constructing Explanations and Designing Solutions: Apply scientific ideas to construct
an explanation for real-world phenomena, examples, or events.

Connections to Nature of Science: Scientific Knowledge Is Based on Empirical Evidence:
Science knowledge is based upon logical and conceptual connections between
evidence and explanations.

Crosscutting Concepts

Patterns: Graphs, charts, and images can be used to identify patterns in data.

Cause and Effect: Phenomena may have more than one cause, and some cause and
effect relationships in systems can only be described using probability.

Connections to Nature of Science: Scientific Knowledge Assumes an Order and
Consistency in Natural Systems: Science assumes that objects and events in
natural systems occur in consistent patterns that are understandable through
measurement and observation.

Common Core State Standards—ELA/Literacy

RST.6-8.3: Follow precisely a multistep procedure when carrying out experiments,
taking measurements, or performing technical tasks.

WHAT STUDENTS DO

Students examine and describe four types of fossils from various localities
and geologic time periods. Students then examine four simulated drill cores,
representing a fictional series of rock layers found in different parts of the world.
The fossils in the drill cores are the same four fossils they examined. Based on
the fossils contained within the layers, students are asked to determine how the
layers in each locality correlate to the layers from the other localities. They are then
challenged to use this fossil evidence to construct a timeline showing the relative
timespans of each species represented by the actual fossils.

MATERIALS AND ADVANCE PREPARATION

■■ For the teacher

1 Scoring Guide: analyzing and interpreting data (aid)
1 Visual Aid 9.1, “Fossil Identification Key”
1 Visual Aid 9.2, “Stratigraphic Column”

122 EVOLUTION

FOSSIL EVIDENCE ACTIVITY 9

1 Visual Aid 9.3, “Correlation of Rock Layers”
1 Visual Aid 9.4, “Timeline for Fossils”

■■ For each group of four students

1 set of 4 fossils (Alethopteris serii, Ammonite, Elrathi kingi, and Knightia)
1 set of 4 simulated drill cores
* 1 pair of scissors
1 metric ruler
colored pencils

■■ For each pair of students

1 hand lens

■■ For each student

1 Student Sheet 9.1, “Stratigraphic Columns from Drill Cores”
1 Scoring Guide: analyzing and interpreting data (aid) (optional)

*not included in kit

TEACHING SUMMARY

GET STARTED

1. Students are introduced to the study of fossils by paleontologists.
a. Ask students, “How do scientists know that fish evolved 530 mya or that
species like the saber-toothed cat have gone extinct?”
b. Ask students, “What is a fossil?”

DO THE ACTIVITY

2. In Part A, students examine real fossils of four different species.
a. Project Visual Aid 9.1, “Fossil Identification Key,” and let students know
that they will examine real fossils of these species.
b. Distribute a container with one of each of the four fossils to each group,
and instruct students to follow Procedure Steps 1–5.
c. As a class, discuss what observations and inferences students made about
each fossil.
d. Ask the class what other kind of information they would like to know
about the fossils.
e. Direct students to Procedure Step 6, and have students read about how
scientists find fossils.

EVOLUTION  123

ACTIVITY 9  FOSSIL EVIDENCE

f. Project Visual Aid 9.2, “Stratigraphic Column,” to reinforce the law of
superposition.

3. In Part B, students examine simulated drill cores containing fossils of the four
species they just examined.
a. Hold up one of the drill cores.
b. Explain that students will draw stratigraphic columns based on evidence
from each drill core using Student Sheet 9.1, “Stratigraphic Columns
from Drill Cores.”
c. Direct students to follow Procedure Steps 7–12.
d. Ensure that each student draws a correlation chart in their science
notebook.

BUILD UNDERSTANDING

4. The class interprets the evidence from the stratigraphic column correlation.
a. Project Visual Aid 9.3, “Correlation of Rock Layers.”
Point out the matches among both the fossil types and the rock types.
A question mark indicates a match that is less certain. Explain that two
occurrences of the same rock layer, whether they are found hundreds
of miles apart or just a few feet away from each other, often have fossil
compositions and other features that are not identical.
b. Ask students what additional evidence would have helped them make
their correlations or given them more confidence in their correlations.
Students are likely to mention that they would have liked to have known
a precise age for at least one rock layer within each drill core. Others may
wish that they had a better sense of how complete their information was
about the fossils found in each layer.
c. Provide additional data about the ages of the rocks in the drill cores by
projecting Visual Aid 9.4, “Timeline for Fossils.”
Say to students, “Geologists—scientists who study rocks and soil to learn
about the history of Earth—have a way to estimate the age of rocks. They
use a technique called radiometric dating. They took samples of the rocks in
the drill cores we examined and were able to estimate the age of the rocks.
Using this data, we can construct a timeline for the fossils we examined.”
Ask, “How old is the oldest fossil?” Students should be able to read the
scale to determine that the trilobite may be as old as 520 million years.

124 EVOLUTION

FOSSIL EVIDENCE ACTIVITY 9

d. (aid assessment) Direct students to Analysis item 2.

Explain that students will be assessed with the aid Scoring Guide.
Students will need their correlation chart to answer this item. Score all
three parts of the answer together to give a single score.

TEACHING STEPS

GET STARTED

1. Students are introduced to the study of fossils by paleontologists.189190191

a. Ask students, “How do scientists know that fish evolved 530 mya or that
species like the saber-toothed cat have gone extinct?”

Students may mention that scientists study fossils or DNA. Accept any
reasonable response at this point. If students don’t specifically mention
fossils, ask them if fossils would be helpful to scientists.

b. Ask students, “What is a fossil?”

Help students develop an operational definition of a fossil as anything that
provides evidence of a pre-existing species. Keep this discussion short, as
the activity provides experience with fossils.

DO THE ACTIVITY

2. In Part A, students examine real fossils of four different species.192

a. Project Visual Aid 9.1, “Fossil Identification Key,” and let students know
that they will examine real fossils of these species.

The four fossils that students will examine are Elrathi kingi, Alethopteris
serii, an Ammonite species, and a Knightia species. More information about
these fossils is found in the Background Information section. Refrain from
sharing too much information about these fossils with the students at this
point.

b. Distribute a container with one of each of the four fossils to each group,
and instruct students to follow Procedure Steps 1–5.

Each student should spend a couple of minutes examining each fossil,
making observations, and taking notes in their science notebook. Allow
enough time for each student to examine each of the four fossils.

c. As a class, discuss what observations and inferences students made about
each fossil.193194195

189 NGLS4A1
190 NGLS4A2
191 NGES1C1
192 NGSPAD1
193 NGSPCE6
194 NGSPNS1
195 NGCCNS3

EVOLUTION  125

ACTIVITY 9  FOSSIL EVIDENCE

Observations are made directly by the senses and provide direct evidence
for the observer. Inferences, on the other hand, involve interpretations of
those observations and, thus, provide indirect evidence. For example, for
Alesthopteris serii, one observation is that there are lobe-like structures
projecting out on both sides from a central axis. An inference would be
that Alesthopteris serii is a plant because it resembles how a fern looks today.

d. Ask the class what other kind of information they would like to know
about the fossils.

Students may say some of the following: where the fossils were found,
what kind of rock they’re in, and what else was found near the fossils.
Accept all responses at this point.

e. Direct students to Procedure Step 6, and have students read about how
scientists find fossils.

You may have them read individually or with their partner or group. Or
you may choose to have a student read the text out loud or to read the
text out loud yourself.

f. Project Visual Aid 9.2, “Stratigraphic Column,” to reinforce the law of
superposition.196

Consider inviting one or two students to explain the law of superposition
using the Visual Aid.

3. In Part B, students examine simulated drill cores containing fossils of the four
species they just examined.

a. Hold up one of the drill cores.

Briefly point out that each core contains a similar, but not identical,
sequence of alternating layers of simulated shale (pinkish, with solid
shading) and sandstone (beige, with speckled shading). Each layer
contains one or more different fossils within them.

b. Explain that students will draw stratigraphic columns based on evidence
from each drill core using Student Sheet 9.1, “Stratigraphic Columns
from Drill Cores.”

Consider sketching an imaginary column on the board or chart paper,
reinforcing the point that the bottom layer is the oldest and the top layer
is the youngest.

c. Direct students to follow Procedure Steps 7–12.197

196 NGCCCE2
197 ELRS683

126 EVOLUTION

FOSSIL EVIDENCE ACTIVITY 9

Procedure Step 11 asks students to make a chart showing the correlations
from core to core. This will be a difficult task for many students. Many
students try to match only one layer at a time, which provides very many
possibilities to consider. As you circulate, focus their attention on trying to
match the fossils and rock types of two or three consecutive layers from core
to core. Make it clear that not all layers in one core will match with any of
those in another core, and that equivalent layers do not have to be identical.

If a group is having trouble getting started, suggest they first decide which
two cores are most similar overall, and try to figure out how the layers of
these two cores correlate. If necessary, help them correlate the layers of
drill cores 1 and 2 (see Visual Aid 9.3, “Correlation of Rock Layers,” for
the entire correlation.) Once they have successfully correlated the layers
for two of the cores, it should be easier to figure out how to correlate the
layers of all four cores.

d. Ensure that each student draws a correlation chart in their science
notebook.

The students will need this chart to answer the Analysis.

BUILD UNDERSTANDING

4. The class interprets the evidence from the stratigraphic column correlation. 198199

a. Project Visual Aid 9.3, “Correlation of Rock Layers.”

Point out the matches among both the fossil types and the rock types.
A question mark indicates a match that is less certain. Explain that two
occurrences of the same rock layer, whether they are found hundreds
of miles apart or just a few feet away from each other, often have fossil
compositions and other features that are not identical.

b. Ask students what additional evidence would have helped them make
their correlations or given them more confidence in their correlations.

Students are likely to mention that they would have liked to have known
a precise age for at least one rock layer within each drill core. Others may
wish that they had a better sense of how complete their information was
about the fossils found in each layer.

c. Provide additional data about the ages of the rocks in the drill cores by
projecting Visual Aid 9.4, “Timeline for Fossils.”

Say to students, “Geologists—scientists who study rocks and soil to learn
about the history of Earth—have a way to estimate the age of rocks.

198 NGSPAD1
199 NGCCPA2

EVOLUTION  127

ACTIVITY 9  FOSSIL EVIDENCE

They use a technique called radiometric dating. They took samples of the
rocks in the drill cores we examined and were able to estimate the age of
the rocks. Using this data, we can construct a timeline for the fossils we
examined.”

Ask, “How old is the oldest fossil?” Students should be able to read the
scale to determine that the trilobite may be as old as 520 million years.

d. (aid assessment) Direct students to Analysis item 2.200201202

Explain that students will be assessed with the aid Scoring Guide.
Students will need their correlation chart to answer this item. Score all
three parts of the answer together to give a single score.

SAMPLE RESPONSES TO ANALYSIS

1. Imagine that scientists have discovered two new fossils. Describe two ways that
scientists can figure out the ages of the fossils and whether the two organisms
existed at the same time. 203

Scientists can look at which layers of rock the fossils were found in. Because of the law
of superposition, they will know that the fossil in the lower layer is older than the fossil
in the upper layer.They can also use radiometric dating to determine the age of the
rock, which will let them know the approximate age of the fossils.

2. (aid assessment) Based on evidence from all four drill cores, answer the
following questions: 204205206207208209

200 SEASAD1 SAMPLE LEVEL-4 RESPONSES
201 NGLS4A1
202 NGLS4A2 a. Which, if any, of the organisms represented by the fossils may be from
203 NGSPCE6 species that are now extinct? Explain.
204 NGSPCE6
205 NGCCPA2 Because Layer 1 in both Core 3 and Core 4 are the youngest layers, and neither
206 SEASAD1 contains ammonites or trilobites, these two species may be extinct.
207 NGSPAD1
208 NGLS4A1 b. Which of the fossils that you examined in Part A is or are from a group of
209 NGLS4A2 organisms that may have gone extinct, and how long ago did that happen?

Elrath kingi, a trilobite, and the ammonite species are from groups of organisms
that went extinct.The trilobite went extinct around 250 million years ago and
the ammonite went extinct around 65 million years ago. Neither of these was
found in the top layer, which probably means they went extinct.

128 EVOLUTION

FOSSIL EVIDENCE ACTIVITY 9

c. Which fossil species could have lived at the same time? Explain.
From the evidence in these cores, it appears that trilobites and ammonites,
ammonites and ferns, and ferns and fish (but not necessarily ammonites and
fish) could have lived at the same time.These determinations are based on the
observation that these pairs of fossils are found in the same layers, so it must be
inferred from this that the pairs of species might have lived at the very same times.

REVISIT THE GUIDING QUESTION
What kind of evidence do fossils provide about evolution?
Fossils can let us know what kinds of life used to exist on Earth, and which life
forms went extinct and when. We can figure out when new life forms evolved and
which types of organisms were living at the same time.

ACTIVITY RESOURCES

KEY VOCABULARY
fossil
law of superposition
paleontologist
stratigraphic column

BACKGROUND INFORMATION

FOSSILS: DIRECT EVIDENCE OF EVOLUTION

Long before Charles Darwin and Gregor Mendel, scientists speculated on
the origins of life on Earth and the relationships among the various life forms.
Fossils—remains of organisms preserved in rocks—are the primary source of
evidence that scientists first used to develop their theories, and they remain a vital
source of information to today’s researchers. Fossil specimens have been found in
rocks of all ages, except for the very oldest rocks known. Every species alive today
has ancestral relatives, some of which have been preserved as fossils.
The process of fossilization favors the preservation of organisms with hard
body parts, such as shells or bones. Conditions that promote fossilization—a
gentle environment with fine sediment—are characteristic of certain aquatic
ecosystems. Conversely, the relatively harsh environmental conditions on land
make fossilization much less likely there (the extreme case is a lava flow, which

EVOLUTION  129

ACTIVITY 9  FOSSIL EVIDENCE

produces new rock layers but usually incinerates specimens before they can
fossilize). Therefore, aquatic organisms, especially those with hard shells or internal
skeletons, are disproportionately represented in the fossil record.
Most fossils provide a great deal of evidence concerning the size, shape, and
preservable features of an organism, yet they do not reveal nearly as much
information about soft structures. Although modern imaging technologies, such
as CT scans, are now providing us with more information about internal features,
these features as well as behavioral characteristics must often be inferred using
comparisons with related living species and with other evidence and fossils found
in the same location. The types of rock in which the fossils are found also provide
important information, since different environments produce different rocks (e.g.,
beaches produce sandstone, oceans and lakes produce shale, volcanoes produce
basalt lava). Information about habitat allows scientists to infer more about an
organism, such as the function of certain anatomical features.

RECONSTRUCTION OF GEOLOGIC TIME

No one location has a complete set of all the rock layers that exist on Earth.
To reconstruct the geologic history of Earth, geologists and paleontologists—
geologists specializing in the study of fossils—have to record, compare, and
correlate information from all over the world. Our reconstructions of geologic
history are by no means perfect or complete. There are huge gaps in the rock and
fossil evidence available for study due to the incredibly long span of geologic time,
the ever changing nature of Earth’s surface, the wide range in the probability of
fossilization for different organisms, the difficulties involved in recovering fossils,
and the inaccessibility of much of Earth’s surface. Nonetheless, the combined
work of thousands of geologists from around the world has provided us with strong
evidence of when and where many of the known fossil species lived. Stratigraphic
relationships and the law of superposition allow paleontologists to construct
relative timelines; in addition, for certain types of rocks, geochemists can derive
absolute dates of origin through the use of radiometric dating technologies.

REFERENCES
Gould, S. J. (Ed.) (1993). The book of life. New York, NY: W. W. Norton and
Company.

130 EVOLUTION

Name______________________________________________________________ Date____________

STUDENT SHEET 9.1

STRATIGRAPHIC COLUMNS FROM DRILL CORES

Core #4

Core #3

Core #2

©2017 The Regents of the University of California Core #1

VISUAL AID 9.1 Knightia

FOSSIL IDENTIFICATION KEY

Alethopteris serii

Ammonite Elrathi kingi

©2017 The Regents of the University of California LabAids SEPUP IAPS Evolution 3e
Figure: Evo3e TE 9_2 VisualAid
MyriadPro Reg 9.5/11

VISUAL AID 9.2 stratographic
column
STRATIGRAPHIC COLUMN

limestone
shale
sandstone

©2017 The Regents of the University of California LabAids SEPUP IAPS Evolution 3e
Figure: Evo3e TE 9_3 VisualAid
MyriadPro Reg 9.5/11

VISUAL AID 9.3

CORRELATION OF ROCK LAYERS

Core #1 Core #2 Core #3 Core #4

=? =? =? Layer 1: =? Layer 1:
(sandstone) (sandstone)

sh sh
fern

Layyeerr11:: =? =? =? Layer 2: =? Layer 2:
(shallee)) (shale) (shale)
ammonite
ferrnn fern
ammonite

Layer 2: Layer 3: Layer 3:
(sandstone) (sandstone) (sandstone)
fern = = = fern = fern

ammonite ammonite ammonite

Layer 3: Layer 1: Layer 4: Layer 4:
(shale) (shale) (shale)
ammonite = ammonite = (shale) = ammonite
trilobite ammonite trilobite
Layer 4: trilobite trilobite
(sandstone)
ammonite Layer 2: Layer 5:
Layer 5: = (sandstone) = (sandstone)
(shale)
trilobite ammonite ammonite

Layer 3: Layer 6:
= (shale) = (shale)
trilobite trilobite
©2017 The Regents of the University of California
Layer 4:
(sandstone)

trilobite

Layer 5:
(shale)
trilobite

VISUAL AID 9.4

TIMELINE FOR FOSSILS

66 mya fish
251 mya ?

fern
ammonite
?

trilobite

©2017 The Regents of the University of California 541 mya



10 Fossilized Footprints
i n v e s t i g at i o n
1-2 class sessions

ACTIVITY OVERVIEW

NGSS CONNECTIONS

Students look for patterns in a set of fossilized footprints, a kind of trace fossil.
They analyze the patterns to draw inferences about the organisms that left these
traces, including the behavior and size of the organisms. They argue for the most
plausible explanation for these patterns.

NGSS CORRELATIONS

Performance Expectations

Working towards MS-LS4-1: Analyze and interpret data for patterns in the fossil
record that document the existence, diversity, extinction, and change of life forms
throughout the history of life on Earth under the assumption that natural laws
operate today as in the past.

Working towards MS-LS4-2: Apply scientific ideas to construct an explanation for
the anatomical similarities and differences among modern organisms and between
modern and fossil organisms to infer evolutionary relationships.

Disciplinary Core Ideas

MS-LS4.A Evidence of Common Ancestry and Diversity:

The collection of fossils and their placement in chronological order (e.g., through
the location of the sedimentary layers in which they are found or through radio-
active dating) is known as the fossil record. It documents the existence, diversity,
extinction, and change of many life forms throughout the history of life on Earth.

Anatomical similarities and differences between various organisms living today
and between them and organisms in the fossil record, enable the reconstruction of
evolutionary history and the inference of lines of evolutionary descent.

Science and Engineering Practices

Analyzing and Interpreting Data: Analyze displays of data to identify linear and
nonlinear relationships.

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ACTIVITY 10  FOSSILIZED FOOTPRINTS

Engaging in Argument from Evidence: Use an oral and written argument supported
by evidence to support or refute an explanation or a model for a phenomenon.
Connections to Nature of Science: Scientific Knowledge Is Based on Empirical Evidence:
Science knowledge is based upon logical and conceptual connections between
evidence and explanations.

Crosscutting Concepts
Patterns:
Patterns can be used to identify cause and effect relationships.
Graphs, charts, and images can be used to identify patterns in data.
Cause and Effect: Phenomena may have more than one cause, and some cause and
effect relationships in systems can only be described using probability.
Connections to Nature of Science: Scientific Knowledge Assumes an Order and
Consistency in Natural Systems: Science assumes that objects and events in
natural systems occur in consistent patterns that are understandable through
measurement and observation.

Common Core State Standards—ELA/Literacy
RST.6-8.3: Follow precisely a multistep procedure when carrying out experiments,
taking measurements, or performing technical tasks.

WHAT STUDENTS DO
Students interpret fossilized footprint evidence that is presented to them in stages.
Through this process, they develop their skills at distinguishing observations from
inferences, and at modifying hypotheses in light of new evidence. They also learn
about other kinds of evidence that can be gathered from fossils, such as behavior.

MATERIALS AND ADVANCE PREPARATION

■■ For the teacher

1 Scoring Guide: engaging in argument from evidence (arg)

■■ For each group of four students

1 set of 3 Fossil Footprint Cards
1 metric ruler

■■ For each student

1 Scoring Guide: engaging in argument from evidence (arg) (optional)
1 Literacy Student Sheet 4b, “Writing Frame—Engaging in Argument”

(optional)

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FOSSILIZED FOOTPRINTS ACTIVITY 10

TEACHING SUMMARY

GET STARTED

1. Students learn about trace fossils.
a. Have students read the introduction about trace fossils.
b. Discuss the difference between an observation and an inference.

DO THE ACTIVITY

2. In Part A, students examine a series of cards with depictions of fossilized
footprints.
a. Explain to students that they will need to create a data table in their
science notebooks to record observations and inferences about three
Fossil Footprint Cards.
b. Ask student to again consider the difference between observations and
inferences.
c. Hand out Fossil Footprint Card 1 to each group of four students, and
instruct them to record observations and inferences in their data table.
d. Hand out Fossil Footprint Card 2 to each group, and again allow time for
discussion and for students to record their observations and inferences.
e. Hand out Fossil Footprint Card 3, and allow time for small-group
discussion.

3. (arg assessment) In Part B, students consider additional evidence about the
footprints to construct an argument to explain the pattern.
a. Formally introduce the practice of engaging in argument from evidence.
b. Direct students to Procedure Steps 10 and 11, and instruct them to revise
or refine their arguments to explain the pattern of the footprints in light of
this new evidence.

BUILD UNDERSTANDING

4. Students discuss how studying fossils helps scientists understand evolution.
a. Direct students to Analysis items 1–3.
Decide which Analysis items you will have students respond to in their
science notebooks and which ones you will have students discuss in their
groups and/or as a class.

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ACTIVITY 10  FOSSILIZED FOOTPRINTS

b. Discuss Analysis item 4 as a class.

Consider using Teacher Discussion Starters if your students need support
in generating and/or sustaining a class discussion.

Let students know that in the next two activities, they will continue to use
data on fossils to explore evolutionary relationships.

TEACHING STEPS

GET STARTED

1. Students learn about trace fossils.

a. Have students read the introduction about trace fossils.210211

This brief introduction lets students know that fossil evidence of past
life is sometimes just a “trace” of that organism, not the remains of the
organism itself. In this activity, students will explore footprints.

b. Discuss the difference between an observation and an inference.212

Students were introduced to this difference in the previous activity. If
necessary, clarify that whereas an observation is an objective description
of one or more pieces of evidence, an inference is a conclusion drawn
from that evidence. It can be hard to distinguish between the two because
we are so accustomed to jumping to conclusions, even when we don’t
realize we are doing so.

Because students are familiar with dinosaurs and their fossils (and
because dinosaurs are mentioned in the introduction to the activity),
they may assume from the beginning that they are looking at dinosaur
footprints.You may wish to point out the inference involved in their
assumption.

DO THE ACTIVITY

2. In Part A, students examine a series of cards with depictions of fossilized
footprints.213214215

a. Explain to students that they will need to create a data table in their
science notebooks to record observations and inferences about three
Fossil Footprint Cards.

For students who are struggling, remind them that the data table should
have three rows for the three cards, with one column for observations and
one column for inferences.

210 NGLS4A1
211 NGLS4A2
212 NGSPAD1
213 ELRS683
214 NGCCPA2
215 NGCCPA1

140 EVOLUTION

FOSSILIZED FOOTPRINTS ACTIVITY 10

b. Ask student to again consider the difference between observations and
inferences.

Ask students whether the statement “These are sets of footprints” is
an observation or an inference. It depends on how strictly you define
observation, but note that the assertion that the shapes are footprints is
based upon both their individual shapes and the apparent walking pattern.

c. Hand out Fossil Footprint Card 1 to each group of four students, and
instruct them to record observations and inferences in their data table.

Point out to students that they will be using the practice of engaging in
argument from evidence. Explain that arguing is an essential practice of
scientists, but arguing in science is different from arguing with a friend.
Arguments in science help scientists develop better explanations for
scientific phenomena. Remind students that they do not need to come to
agreement with their group members, but they are expected to explain
why they disagree and to listen to one another carefully. Remind students
of “Developing Communication Skills” in Appendix D in their Students
Books for suggested ways of communicating with their peers. Allow at
least 5 minutes for students to discuss their ideas in groups.

If desired, hold a brief full-class discussion; alternatively, circulate while
the groups work and hold smaller discussions. Regardless, use questions
to prompt students to examine their assumptions and reasoning, as well as
the evidence before them. For example:

• “Were the tracks left at the same time?” If students ask whether the
scientists know that the two sets of footprints are the same age, you can
answer that the fossils were found at the same stratigraphic level, or
depth in the rocks. Because what appears to be a moment in geologic
time can actually last for many days, or even years, we cannot be certain
whether the prints were left at precisely the same time (though their
appearance suggests this was the case).

• “What can you conclude about the sizes of the animals that left these
tracks? How?” Students are likely to argue that the larger tracks were
left by a larger animal. This inference is based upon the observation
that the larger tracks are both longer and wider.

• “What additional information would be helpful in interpreting the foot-
print evidence?” For example, the depths of the prints are not given: if
the smaller prints were much deeper, they might actually have been left
by a heavier creature. (See Procedure Part B for an exploration of the
types of inferences that can be drawn from footprint depth.)

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ACTIVITY 10  FOSSILIZED FOOTPRINTS

• “What must the ground have been like at the time these footprints were
left for them to have become preserved?” The ground must have been
soft, and soon afterwards a layer of sediment or ash must have been
deposited rapidly enough to cover and protect the tracks yet gently
enough not to erase them.

d. Hand out Fossil Footprint Card 2 to each group, and again allow time for
discussion and for students to record their observations and inferences.

Remind students not to alter what they wrote regarding Card 1 but to
record their new ideas under Fossil Footprint Card 2. By doing so, they
are refining their argument to be more closely aligned to the evidence.
Discussion is likely to be a lot livelier at this point.

Possible questions to guide and focus the discussion follow:

• “Do the new footprints come from a time before or after the first set of
footprints? How do you know?” Stating that the prints on Card 2 were
made after those on Card 1 is an inference, but our evidence about
living animals says that toes face forward and that animals rarely walk
backward for such long stretches.

• “Why do the larger footprints become more widely spaced well before
the smaller footprints do?” The spacing could indicate either a down-
ward slope where the animal was walking or that the larger animal
began to run before the smaller animal did.

• “What feature of the footprints is missing?” Depth. For instance, if the
larger animal began to run where the prints are more widely spaced,
the footprints should get deeper; if there was a downward slope, or if
the larger animal had been slowly negotiating small boulders, the prints
might not be much deeper than before.

• “Why do the prints approach each other gradually and then inter-
mingle?” Perhaps an obstruction was between the animals, preventing
visual contact until the last moment; perhaps the larger animal was
sneaking up on the smaller animal; or perhaps the prints were made at
different times and the two animals never actually interacted.

e. Hand out Fossil Footprint Card 3, and allow time for small-group
discussion. 216

If desired, after a few minutes, have groups pair up and debate because
groups may have arrived at different favored hypotheses. These are likely
to include the following:

216 NGCCCE2

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FOSSILIZED FOOTPRINTS ACTIVITY 10

• A mother or father sneaked up on a baby, picked it up, and carried
it off.

• A larger animal ambushed a smaller one and a struggle ensued, causing
one of these three things to occur: the larger animal killed the smaller
one and left the carcass behind, the larger animal carried off the smaller
animal, or the smaller animal flew away to escape.

• A larger animal sniffed the ground where a smaller one had died after
staggering around and then walked off, or dined upon the carcass, or
picked up the carcass and walked off.

More objective students might notice how difficult it is to distinguish
between, for example, the picked-up-baby model and the fight-and-
carried-off model. Analysis item 3 will explore how further evidence
regarding the depth of these same footprints might add to the richness of
the discussion while still leaving the answer unresolved.

Point out to students that no argument is ever truly proven; evidence
can either refute an argument or support the argument. For example, if
further fossil evidence revealed that the smaller footprints on the Fossil
Footprint Cards were made by a dinosaur that lacked wings, the argument
that the smaller dinosaur flew away would be refuted. If the larger
footprints were found to have been made by a member of a carnivorous
predator species, those arguments involving capture and consumption
would be supported, though not proven.

3. (arg assessment) In Part B, students consider additional evidence about the
footprints to construct an argument to explain the pattern.217218219220221

a. Formally introduce the practice of engaging in argument from evidence.

Remind students that arguing is an essential practice of scientists, but
arguing in science is different from arguing with a friend. Arguments
in science help scientist develop better explanations for scientific
phenomena. Scientists develop preliminary explanations, or hypotheses,
that explain the evidence, and then they develop arguments for why one
explanation is better than another.

Explain that Procedure Steps 10 and 11 in this activity are the first use
of the engaging in argument from evidence (arg) Scoring Guide.
Optionally project or distribute the Scoring Guide, and point out how
it has the same levels as previous guides but different descriptions for
each level. Review the levels as needed. For more information, see

217 NGCCNS3
218 NGSPNS1
219 NGSPEA2
220 NGSPAD1
221 SEASAR1

EVOLUTION  143