Content Benchmark L.12.D.3
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Students know the fossil record gives evidence for natural selection and its evolutionary consequences. E/S

When teaching all of the L.12.D benchmarks, it is imperative to help students understand the process of science. Most objections and misconceptions about evolution are directly related to the misunderstanding of how science works. When students understand the nature of science, they will understand how scientists have studied the process of evolution. As questions arise about a “supernatural” creation of Earth and the Universe, students who understand the nature of science will understand why supernatural forces cannot be studied as part of scientific processes.

The study of fossils is called paleontology. The study of rocks and land formations is called geology. By combining paleontology and geology, much can be learned about the history of Earth and the history of life on Earth. Fossils are the remains of once living organisms. Most fossils are remains of the hard parts of organisms that are no longer alive (extinct species). The most common types of fossils form when shells, bones, or other parts of organisms are rapidly covered with layers of sediment. As additional sediment is deposited, the organism’s remains become compacted by the additional weight of the new sediment. Water in the soil seeps into the original bones and other solid remains, gradually replacing the original components of the once-living organism with minerals found in the water. Fossil formation occurs over a long periods of time, as the minerals in the organism are gradually dissolved and replaced to form a rock-like material, as spaces in the original organism are filled in with minerals.

To learn more about how different kinds of fossils form, see http://www.discoveringfossils.co.uk/Whatisafossil.htm

Fossils are found in sedimentary rocks. Sedimentary rock forms in layers. In most cases, the lowest layer is the oldest. Successive layers of sedimentary rock contain different groups of fossils. The different types of fossils in the different layers provide evidence that changes have occurred in living things through time. For additional information on the fossil record and how it contributes to our understanding of evolution, see “Evolution and the Fossil Record” found at http://www.agiweb.org/news/evolution.pdf

For additional information concerning strata, fossils,
and geologic structure see benchmark E.12.C.1

Geologists today are able to establish the relative age of the various layers of the earth’s crust based on their position and the fossils they contain. Both relative and absolute age of various rock layers can be determined using evidence provided in that layer, and the layers found immediately above and below. Fossils and geological formations can be used to provide relative ages of rock layers. For example, if the same type of fossil is found at two locations that are a great distance apart, the fossil provides evidence that the rock layers are probably of a similar age. Figure 1 (below) shows Index Fossils that are used to help establish the relative age of various rock formations.

Figure 1. Diagram of Index Fossils by Geologic Age. For more information as to how fossils are used to determine relative ages of rock layers see http://pubs.usgs.gov/gip/geotime/fossils.html

Using radioactive isotope half-life knowledge, absolute age of rocks can be determined (Figure 2)

Figure 2. Diagram of the relative amount of a radio isotope left in a sample after 3 half-lives. From: http://anthro.palomar.edu/time/time_5.htm

The relative concentration of a radio isotope to its daughter products can be used to help determine the absolute age of the strata, or fossil in question.

For further explanation of radiometric, or absolute dating, see the following sites: http://lilt.ics.hawaii.edu/belvedere/materials/Mass-Extinctions/Raddate.htm, http://www.agiweb.org/news/evolution/datingfossilrecord.html or
http://pubs.usgs.gov/gip/fossils/numeric.html

It is estimated that our earth is approximately 4.5 billion years old. The first life (prokaryotes) probably appeared about 3500 million years ago (3.5 billion years ago). When the age of the rock layers are known, any fossils found in those layers can be considered the same age as the rock. Thus if a fossil is found in a rock layer that is known to be 100 million years old, then it is known that the fossilized organism lived (and died) about 100 million years ago.

Different types of fossils are found in different aged layers of rock. Therefore, the fossil record supports evolutionary theory by providing evidence that organisms that have lived in the past did change over time. If we examine fossils found in various layers of rock, and look at progressively older layers, we can see that there is a layer below which no human fossils are naturally found. As we progress backward in time, we will eventually see a layer below which no fossils of birds, no mammals, no reptiles, no fish, and eventually, no animal of any kind is found. This is evidence that the kinds of plants and animals, and other organisms have changed over time and is called the Law of Fossil Succession (Figure 3 and 4).

Figure 3 Stratigraphic ranges and origins of some major groups of animals and plants (from, http://pubs.usgs.gov/gip/fossils/succession.html).

To learn more about the Law of Fossil Succession, go to
http://pubs.usgs.gov/gip/fossils/succession.html).

Figure 4. This diagram from the American Geological Institute illustrates
how different fossils have been found in different aged layers of the earth.
The illustration is from http://www.agiweb.org/news/evolution/evolthrutime.html

Natural selection is considered a mechanism of evolution. Charles Darwin gathered evidence on many different organisms during voyages in the 1800’s. Careful study and characterization of his data led Darwin to his theory of evolution through natural selection. His theory was based on four premises:

1. Variations exist among individuals within the same species.
2. All organisms produce more offspring that are able to survive.
3. Competition for space, food, other survival needs leads to the elimination of some
organisms of each population.
4. The organisms that have variations which enable them to survive within their
environment and through competition, are the ones most likely to survive and reproduce, thereby passing their characteristics on to their offspring (survival of the fittest, or natural selection).

For more information on Darwin’s theory, go to http://www.agiweb.org/news/evolution/darwinstheory.html

Fossils provide evidence that divergent and convergent evolution has occurred. Divergent evolution is when two or more related species become more and more dissimilar to each other. The species involved had a common ancestor, but due to natural selection and adaptations to different environments, the species became increasingly different from each other.

Convergent evolution occurs when two or more unrelated species develop similar characteristics as they adapt to similar environments.

Figure 5. Illustrates convergent evolution of some large vertebrate animals. The shark, ichthyosaur, and porpoise evolved separately, but have similar characteristics which enable them to live in the water and to be efficient predators (from: http://bio-ditrl.sunsite.ualberta.ca/detail/?P_MNO=1800).

To learn more about divergent and convergent evolution see
http://bioweb.cs.earlham.edu/9-12/evolution/HTML/converge.html

To learn more about the link between paleontology, geology and evolution, see: http://www.agiweb.org/news/evolution/paleo_geo_evol.html The information contained within this web site can be viewed as is, printed as a booklet, or ordered from the Website.

There are gaps in the branches of the fossil records of life. Gaps exist in the fossil record, partly because plants, microorganisms, and soft shelled organisms (majority of marine animals), are not likely to fossilize. Even hard bodied organisms do not frequently fossilize. In addition, changes in the land (erosion, metamorphosis, geological events) can destroy fossils if they were present. However the fossil record does provide significant evidence of evolution and of the history of life on earth.

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Performance Benchmark L.12.D.3

Students know the fossil record gives evidence for natural selection and its evolutionary consequences. E/S

Common Misconceptions associated with this benchmark

1. Students incorrectly believe that individuals adapt to their environment.

Students incorrectly believe that adaptations occur in individuals in response to changes in their environment or the needs of the individual, rather than adaptation occurring on the species level and being changes in a population that accumulate over time. Students think that adaptations and hence, natural selection occurs as an organism changes due to some need, or changes in the environmental conditions, and that this change is then passed to their offspring.

Students have difficulty understanding basic concepts of evolution such as natural selection. They don’t conceptualize that mutations often occur randomly and that some of these random changes are selected for because they help in the survival and reproduction of the organism. Rather, students often believe that new variations occur due to some need, use of a function, or environmental condition, and that once an organism has acquired a characteristic, the change will be passed on to the offspring. This misconception was held by Lamarck in the 1800’s, who concluded that parents can pass acquired characteristics on to their offspring.

To read more about Lamarck, see: http://www.pbs.org/wgbh/evolution/library/02/3/l_023_01.html

2. Students incorrectly believe evolution through natural selection occurs through variations and changes in DNA that occur naturally and randomly.

If a particular mutation is found in an organism which enables the organism to better survive in its environment, the organism is more likely to live, and to reproduce (survival of the fittest). Because the change that occurred was in the DNA of the organism, that DNA, and therefore the trait, can be passed on to the offspring. Over time, when a significant number of changes have occurred, a new species may develop. Mechanisms of evolutionary change include:

mutation—changes in the DNA of an organism
migration—a group of organisms from a particular species may migrate to a new, geographically isolated area and begin interbreeding among themselves but not with the parent population.
genetic drift—normal variations that occur in the genes of organisms, related to mutations.
natural selection—the organisms most likely to live and reproduce will be the ones that pass on their traits.

More information about evolution through natural selection can be found at: http://www.pbs.org/wgbh/evolution/library/11/2/e_s_4.html

3. Students incorrectly believe that fossil evidence does NOT support evolution because there are too many “missing links” or missing transitional fossils.

A transitional fossil is one that links a more modern organism with a more primitive organism. A transitional fossil would have characteristics in common with both the primitive organism and the more modern organism. Transitional fossils are often called “missing links.” According to evolutionary theory, however, all organisms are in transition and therefore a specific “missing links” may not actually exist as organisms evolve. In addition there are many organisms that have existed in the past for which no fossils will ever be found, so there will always be gaps in the fossil record. This is because conditions required for fossilization to occur are not always present when on organism dies. Many examples of transitional fossils do exist, providing evidence that species do transition. Several examples are listed below, with links for additional information.

Reptiles to birds:
http://www.agiweb.org/news/evolution/examplesofevolution.html
http://www.talkorigins.org/faqs/faq-transitional/part1b.html#bird
http://www.fossilmuseum.net/paleo/paleonews/Archaeopteryx.htm

Terrestrial mammals to whales:
http://www.agiweb.org/news/evolution/examplesofevolution.html
http://news.bbc.co.uk/1/hi/sci/tech/1553008.stm
http://www.talkorigins.org/features/whales/

Horse evolution
http://chem.tufts.edu/science/evolution/HorseEvolution.htm
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1159167

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Performance Benchmark L.12.D.3

Students know the fossil record gives evidence for natural selection and its evolutionary consequences. E/S

Sample Test Questions

1. Why is a mammoth more likely to fossilize than a caterpillar?
a. hard parts such as bones and teeth fossilize easier than soft parts.
b. mammoths lived a long time ago and caterpillars live today.
c. large organisms tend to fossilize easier than small organisms.
d. caterpillars have too short of a life span for fossilization to occur.

2. Some organisms never become fossils because
a. they live in water environments where no fossils form.
b. they are destroyed after death so nothing remains to be fossilized.
c. a hard shells prevent fossilization from occurring.
d. there are no minerals in the soil where the organism dies.

3. The process of natural selection over time has resulted in the extinction of some species, and the success of others. Why has natural selection NOT caused the existence of a single best overall adapted species?
a. A single organism would not survive well in all the different environments.
b. This would result in many harmful mutations and even the best adapted species would then become extinct.
c. Acquired traits would begin to be selected for and natural selection would not continue.
d. Not enough time has passed yet for the ultimate overall adapted species to develop.

4. Which of the following is one reason that fossils from all organisms where ever alive will NEVER be found?
a. organisms moved from one place to another, so the location of some fossils will never be found.
b. some parts of the world have never had sedimentary rock, and therefore fossils could not form
c. some animals consume fossils and therefore, there are none left to be found.
d. many organisms that have lived had no hard solid structures that survived long enough to be fossilized.

5. Several fossils were uncovered in different layers of rock in a desert area. The following diagram indicates the fossils found and the layers they were found in.

(image from: http://www.tea.state.tx.us/student.assessment/resources
/online/2003/grade10/science/p113no3.gif)

Based on the fossils found, this area was most likely once a
a. forest that was replaced by a lake
b. lake that was replaced by a forest
c. an ocean that was replaced by a forest
d. a lake that was replaced by a desert.

6.

FIG. 1

Use Fig. 1 to help answer the following question. Carbon dating of a fossil was completed and was found to contain approximately 25% of its original Carbon 14. This indicates that the fossilized organism probably died about

a. 40, 000 years ago
b. 32,000 years ago
c. 12,000 years ago
d. 5,000 years ago

Students know the fossil record gives evidence for natural selection and its evolutionary consequences. E/S

1. (a)
2. (b)
3. (a)
4. (d)
5. (a)
6. (c)

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Performance Benchmark L.12.D.3

Students know the fossil record gives evidence for natural selection and its evolutionary consequences. E/S

Intervention Strategies and Resources
The following list of intervention strategies and resources will facilitate student understanding of this benchmark.

1. The Evolution & the Nature of Science Institutes (ENSI)
ENSI has produced a Website with a multitude of Evolution lessons. The lessons relate to the nature of modern science and evolution. They are appropriate for high school students and most can be modified to meet the needs of a diverse level of students. The lessons can be accessed via http://www.indiana.edu/~ensiweb/evol.fs.html

Within this Website, the following activities specifically address fossils and dating layers of rock.
Date a Rock http://www.indiana.edu/~ensiweb/lessons/date.les.html
Who’s on First, a relative dating activity http://www.ucmp.berkeley.edu/fosrec/BarBar.html
History of Earth Timeline http://www.indiana.edu/~ensiweb/timeline.html

2. Activities linking geology, paleontology and evolutionary biology
The following Website developed by the American Geological Institute, is an excellent source of information linking geology, paleontology and evolutionary biology. Several specific pages were indicated in the background information for this standard, but it is well worth the teacher’s time to read thorough all of the pages of this website. http://www.agiweb.org/news/evolution/index.html

3. Evolution and the fossil record
To help students understand the development of the geologic time scale, to introduce students to the major time periods in earth’s history, and to introduce the role fossils play in helping to understand earth’s history, use: http://www.sciencenetlinks.com/Lessons.cfm?DocID=44

This site uses a USGS booklet (Internet accessible), and has additional extension activities.

4. Organism by geologic period
The University of California Museum of Paleontology provides a tour of geologic time. Students can click on a specific period of time and learn about the organisms that were alive during that time.

Go to: http://www.ucmp.berkeley.edu/exhibits/geologictime.php

5. Evolution activities
Many excellent evolution education modules for many grade levels can be found at http://www.ucmp.berkeley.edu/education/explotime.html. Following are specific fossil related activities:

a. The UCMP module, “Life has a History”, sponsored by the NSF, takes the students through a lesson on fossils and biological time. Access this activity at http://www.ucmp.berkeley.edu/education/explorations/tours/intro/index.html . Students have to answer questions and visit detailed information before moving on to the next stage of the module. Very good basic information is presented on how current observations and the fossil record provide evidence for natural selection. There are two levels, Level one is for K-4 and Level 2 is for grades 5-12. However, Level one might be helpful for ELL students and students with low reading abilities. The teacher’s Guide has handouts and assessments to accompany the activity.

b. Getting into the Fossil Record helps students learn how fossils form
http://www.ucmp.berkeley.edu/education/explorations/tours/fossil/index.html

c. Students can visit any geological time period and learn about the rocks, environment, and life that existed during the time period. http://www.ucmp.berkeley.edu/help/timeform.html

6. Fossil Record Adaptation activities
Another set of lessons from the University of California Museum of Paleontology, this series of activities can help students evaluate the importance of fossils to our knowledge of past life, identify conditions necessary for fossilization, understand how organisms are adapted to their environments, and understand the relationships of modern and ancient communities with their environments. http://www.ucmp.berkeley.edu/fosrec/Breithaupt2.html

7. Human Evolution Activities
For an activity on human evolution, Building Bodies is an online interactive lesson that demonstrates how bipedalism in humans developed as a series of adaptations over time. http://www.becominghuman.org/building_bodies

8. Additional Evolution information
For additional information on what is recommended in evolution education, see: Evolution on the Front Line: An Abbreviated Guide for Teaching Evolution from Project 2061 at AAAS at: http://www.project2061.org/publications/2061Connections
/2006/media/Evo_Handout_Teachers.pdf

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