Evolution: Evidence of Change via Fossil Evidence
Standards:
 8e: Students know how to analyze fossil evidence with regard to biological diversity, episodic
speciation, and mass extinction.
 IE-1d: Students will formulate explanations by using logic and evidence.
 IE-1g: Students will recognize the usefulness and limitations of models and theories as scientific
representations of reality.
Objectives:
 What can fossils tell us regarding evolution, extinction and animal behavior?
 Can fossil evidence be interpreted in more than one plausible way?
 Do fossils have to be actual physical remnants of organisms?
Duration:
40 minutes, depending on pre- and post-lab discussion. “Optional Extension” below can take an extra class
period if done.
Teacher Notes:
This lab is designed to get students thinking that fossils aren’t exclusively bones dug up; they can also be mere
evidence of organisms’ existence in a particular place and time. It’s also a great idea to have obtained from
fossils and passed them around by now while discussing. My favorite fossil to pass around is a coprolite. I don’t
tell anyone what it is until it’s gone around the entire classroom and then back to me. I make a big deal about
polishing it off and getting their “student germs” off of it before I explain what it is. Good times.
Optional Extension For Teachers:
There are two optional activities. One depends on time allotted and the other depends on both time and budget.
1. Time: Find out if there is a relationship between the depth of a footprint and the mass of a living thing.
Have different people step in soft clay or soil. Measure the depth of the footprint and determine the
relationship between the mass of the person and the depth of the footprint. Organize your information in
a chart, then interpret an “unknown” footprint. This can easily be done outside the classroom in some
moist dirt for free! Alternately, you can get some dirt from elsewhere in the school and spread it out
beside your room.
2. Time/Budget: Make a cast of leaves, twigs, footprints or bones (chicken bones are always good) using
plaster of Paris or clay. Relate this process to fossil formation. Note: Plaster of Paris can cost more per
40 lb bag; I’ve discovered that cement costs less and does a similar job.
Pre-Lab Discussion:
A fossil is any evidence of life in the prehistoric past. Fossils can be actual remains of animals, impressions,
carbon residues or tracks left by a living organism. By using fossil records, scientists are able to piece together
the story that fossils tell about the history of earth.
In this investigation, you will use some present day knowledge and common sense to interpret fossil evidence.
Problem:
How can fossils relate the history of an era?
Materials:
Writing materials only.
Evolution: Evidence of Change via Fossil Evidence
Procedure: Part A:
1. Observe the diagram of the fossil footprints in Figure 1.
2. Use Figure 1 to answer questions 1-6 in Observations.
3. Using the answers to these questions and some common sense, interpret the events that may have
occurred in Figure 1. Note: Your interpretation should be consistent with the diagram.
Part B:
1. Observe the diagram of the fossil footprints in Figure 2.
2. Use Figure 2 to answer questions 7-9 in Observations.
Evolution: Evidence of Change via Fossil Evidence
3. Using the answers to these questions and some common sense, interpret the events that may have
occurred in Figure 2. Note: Your interpretation should be consistent with the diagram.
Observations: Part A: Use Figure 1 to answer questions 1-6 on separate sheet of paper. Thanks!
1. How can you tell in which direction the animals were walking? By examining the position of the claws.
2. How do footprints differ when an animal walks from when it runs? Footprints are closer together when
an animal walks and farther apart when it runs.
3. Did any of the animals change speed? Yes. When the animal in the upper left possibly smelled the
large animal and fled; when the large animal left the attack area.
4. How many different types of animals are represented? Two or possibly three (students may suggest
only two because two sets of footprints are similar).
5. How did the animals interact with each other? One ran away; one attacked another.
6. How would footprints be formed and preserved? Students may suggest that animals made footprints in
soft soil or mud that hardened and lithified.
Part B: Use Figure 2 to answer questions 7-9.
7. Did any of the animals change speed? The animal on the far left moved faster, possibly when it smelled
or saw the middle animal.
8. How many different types of animals are represented? Three.
9. How did the animals interact with one another? The animal on the far left fled; the animals on the left
and in the middle attacked each other.
Analysis and Conclusions: Part A: Use Figure 1 to answer questions 1-4.
1. In what kind of environment did this all take place? In soft soil or mud.
2. If all the footprints were made within minutes of one another, which way was the wind blowing?
Explain your answer. Probably from south to north. One interpretation might be that the animal in the
upper left corner smelled the larger one and fled. The large animal smelled the smaller one on the
bottom right and attacked it.
3. What might the lines between the footprints of two of the organisms represent? The animal possibly has
a tail or is dragging an animal it has captured.
4. Write a paragraph interpreting the events in Figure 1. Support your interpretations with evidence from
the diagram. Answers will vary. Accept any idea, even unusual ones that are supported by the fossil
evidence in the diagram.
Part B: Use Figure 2 to answer questions 5-7.
5. Is it possible that the animals that made the footprints represented in the diagram never actually met
each other at the same time? Explain your answer. Yes. Possibly a smaller animal left footprints while
looking for food. A larger animal arrived later. It smelled the smaller animal’s scent and came to
investigate. Finding nothing, it flew away.
6. What might depth of a footprint tell an interpreter? The depth of a footprint might indicate the mass or
foot structure of the animal.
7. Write a paragraph interpreting the events in Figure 2. Support your interpretations with evidence from
the diagram. Answers will vary. Accept any ideas, even unusual ones, that are supported by the fossil
evidence in the diagram.
Critical Thinking/Applications:
1. In what type of rock would you be most likely to find fossils? Explain your answer. Fossils will most
likely be found in sedimentary rock. Most fossilized organisms were buried in sediments after they
died, and these sediments eventually changed to sedimentary rock.
2.
3.
4.
5.
Evolution: Evidence of Change via Fossil Evidence
Would you be likely to find the fossil remains of a jellyfish or a worm? Explain your answer. You would
not be likely to find the fossilized remains of a jellyfish or a worm. Most invertebrate organisms decay
before leaving an imprint, and no hard body parts remain afterward.
The exposed rock layers of the Grand Canyon are rich with fossil specimens. What does the presence of
fossil coral, sponges, shellfish and trilobites indicate about the past climate of the Grand Canyon area?
The presence of sea-dwelling organism fossils indicate that, at one time, the area was under water.
How could paleontologists reconstruct our present day environment 25,000 years from now if all written
history were to be lost or destroyed? Paleontologists would be able to unearth buildings in urban
environments much as we now do with ancient cities. Artifacts might also be found in these diggings.
Prints from living organisms and vehicles might be analyzed. Core samples could be taken to
determine soil and sediment types found in rock layers.
Scientists have found fossils of the same kind of organism on different continents. How might this have
occurred? The continents may have at one time been connected to each other; seeds from a plant may
have moved through the air to another continent; a flying animal may have moved from one
continent to another, etc.