FOSSILIZATION AND ADAPTATION:
ACTIVITIES IN PALEONTOLOGY
BRENT H. BREITHAUPT
AS THE concepts of time, past life, and fossils are often difficult for children to comprehend and as many of the National Parks and Monuments have important paleontological resources, Fossil Butte National Monument developed a fossil education curriculum guide designed to aid teachers presenting these principles to students in the second and third grades. The following activities are modified from that guide (Leite, M. B. and Breithaupt, B. H., 1994, Teaching Paleontology in the National Parks and Monuments: A curriculum guide for teachers of the second and third grade levels: National Park Service, Fossil Butte National Monument, Kemmerer, WY 103 p.). For more information on this curriculum guide distributed though the National Park Service, please contact Ms. Marsha Fagnant, Fossil Butte National Monument, P.O. Box 592, Kemmerer, WY 83101.
How does a living thing become a fossil? The mysterious processes by which evidence of past life is preserved are explored in these exercises. By thinking about and participating in some simulated sedimentary processes, children will be able to remove much of the mystery behind fossils and fossilization. These exercises introduce the concept that fossils are remains or traces of ancient living things. They will also begin to think about how rare an event fossilization is.
Objective: After completing these exercises students will be able to: evaluate the importance of fossils to our knowledge of past life; identify conditions necessary for fossilization; construct a possible scenario for formation of fossils; understand how organisms are adapted to their environments; and understand the relationships of modern and ancient communities with their environments (i.e., ecology and paleoecology).
ACTIVITY I: FOSSILIZATION
Message: Not all parts of animals become fossilized. It may not be possible to know some details of what an ancient animal or plant was like because many parts of the anatomy may not become fossils.
Materials: Drawings of horse and Stegosaurus skeletons. (Figures 1 and 2)
Discussion: Fossilization is a rare event. The chances of a given individual being preserved in the fossil record are very small. Some organisms, however, have better chances than others because of the composition of their skeletons or where they lived. This also applies to the various parts of organisms. For example, plants and vertebrates (animals with bones) are made up of different parts that can separate after death. The different parts can be transported by currents to different locations and be preserved separately. A fossil toe bone might be found at one place and a fossil rib at another location. We could assume that they are from different animals when, in fact, they came from the same one.
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Much information is lost in the fossilization process. Think, for example, of a vertebrate (such as ourselves). Much of what we consider important about our own biology is in the soft tissues, such as skin, hair, and internal organs. These characteristics would usually be unknown in the fossil state, because most of the time only bones and teeth are preserved (there are exceptional cases where soft parts are preserved). Bones and teeth are not always preserved together. This exercise is designed to get children to think about the quality of information that comes from the fossil record.
3) What do we know about fossilized animals? Pass out the diagram of the fossil Stegosaurus (Figure 2) and interpret it in light of what we do know. Use the list you made in discussing the living animals. What paleontologists know comes from studying the hard anatomy, in this case bones and teeth. Anything else is a guess, although in most cases it is possible to base the guess on sound biological principles.
1) List facts about a living animal. The skeleton of a horse is used here, but there are many other possibilities (e.g., cow, dog, cat, sheep). The list of facts on the horse might include, but not be limited to: large size, fast runner, eats grass, has grinding teeth, has long hair for a mane and tail, whinnies, is intelligent, is sociable with other horses, makes a good pet.
2) What would we know if this animal was extinct ? Refer to the diagram (Figure 1) and point out an important generalization of fossilization: most of the time, only the hard parts (bones and teeth) are preserved as fossils. Go through the list and ask the class what we would know about the horse if horses were extinct and all we had were fossilized bones and teeth of horses. We would know that it was a large animal and could probably make some good guesses about its weight. We would know that it had grinding teeth and therefore could probably guess that it ate some sort of tough vegetation like grass. The hooves would not be preserved, but the shape of the foot bones would be a good indicator that it had hooves. The skeleton would also be useful to tell us that it was a fast runner. But no details of the hair or skin would be known. Everything about social behavior and vocalization would also have to be guesses.
4) Use your imagination. As a summary to this exercise, have the class put muscles and skin on the diagram of Stegosaurus. Remember, skin color and texture are largely the choice of the artists, since fossil bones are of no help, although some skin impressions have been found.
ACTIVITY I / VARIATION I: Specializations
Both the horse and Stegosaurus have some bones that are not shared by the other. That is because each is specialized in some way. The horse is adapted for fast running, and therefore its feet have become specialized for running. They are simpler than those of Stegosaurus, with only one toe bone on each foot. Horses also have very specialized grinding teeth, while the teeth of Stegosaurus are simple slicing structures. Stegosaurus, on the other hand, has some very spectacular specializations in its huge armor plates and tail spikes. Some specializations of Stegosaurus are for defense because it was not a fast runner. What other differences between the horse and can you find? Can you think of a possible adaptation for these bones?
ACTIVITY I / VARIATION II: Imaginary Creatures
Draw a picture of a made-up creature with adaptations for a special way of life. Examples: a fast flier that eats leaves from the tops of trees; a burrowing animal that digs holes so fast no other animal can catch it. Describe how this animal is special and how it accomplishes what it does. Could paleontologists find out about this way of life from the fossil record?
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ACTIVITY II: THE FOSSILIZATION GAME
Message: It is not easy to become a fossil. Many plants and animals never have the chance to be preserved as fossils.
Materials: Fossilization cards (Figure 3).
— You can make several copies of the page of cards (included with this activity) to use in this. If you make your own, the proportion of "fossilization" cards to "destruction" cards should be small, mimicking the small chance of becoming fossilized in the real world.
Discussion: The fossilization game is a fantasy and role-playing exercise that helps children understand fossilization processes.
1) Choose environment. The game begins with the class or smaller group choosing an environment in which there is a depositional setting such as a lake, pond, stream, river in a forest, or sea floor. The students can use their imaginations to describe this setting in as much detail as they desire.
2) Choose roles. Roles that the participants choose for themselves are possible animal or plant inhabitants of the chosen setting. For example, in the aquatic settings, possible roles include not only snails, clams, fish, salamanders, turtles, alligators, and other aquatic animals, but also horses, deer, monkeys, rabbits, and birds that came there to drink.
3) Begin play. When play begins, the children act out their roles, with each one given a turn to make vocalizations or gestures. For example, a child playing a fish could wiggle his/her body with a fishlike motion and make gulping motions with his/her mouth. A child playing a prairie dog might pretend to dig a burrow and make high-pitched barks. They can also interact with each other as they would in their natural environment. For example, the carnivores could chase the herbivores.
4) "Freeze" and decide the fate of the characters. At a time determined by the teacher, action "freezes" and the time for possible fossilization begins. The students draw cards which tell their fate. Possible cards might be: -You are eaten by scavengers; -You rot away before you can be preserved; -You are swallowed by a crocodile; -You are buried by a mudslide and preserved as a fossil.
5) Discuss the meaning of this exercise. When the entire class has drawn cards, discussion can begin. Have each student discuss his or her role as an organism and what happened to this organism after it died. Make a list of these organisms on the blackboard. Which animals became fossils? Which were destroyed? Remember, the only animals and plants future paleontologists will know anything about are the ones that become fossils. You will become aware of the important question of bias in the fossil record when you compare the list of fossils with the complete list of living animals. Is the list of fossils a good representation of the living community? Why not?
6) If time allows, play the game again with the same animals and plants. How are the results similar or different?
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ACTIVITY III: ADAPTATION
Message: Organisms are adapted to specific environments.
Materials: Art supplies
Discussion: The students choose specific organisms and develop a picture story of how that organism is adapted to its environment.
1) Have the students each create a picture story from the point of view of a plant or animal (either modern or ancient).
2) Ask them to describe their environment in drawings: What is the environment like? What other kinds of plants and animals live with you? What are your special adaptations that allow you to survive in this environment? What do you like to eat? Are you a carnivore, herbivore, or omnivore?
3) After the students complete their drawings of their animal or plant at home in their own environment, ask them to do the picture story again in a "foreign" environment. Perhaps they could swap environments with a classmate. Most of these organisms may be unhappy, to say the least.
4) Follow up this exercise with questions, such as: a) What are your chances of survival in this foreign environment? Why do you think so? b) If you cannot live in this new environment what will happen to you? Have the children discuss chances of their survival. How likely is it that an animal would already have adaptations that would allow it to survive in the new climate? What would those adaptations be?
5) Describe a food web. Pretend your favorite food disappears. If your favorite food is not available, what do you eat? How many different kinds of food fit your diet? What other kinds of food do the other animals in your food chain like to eat?
ACTIVITY III / VARIATION I: Past Communities
A variation on this activity is to have the students use their imagination and what they know about communities and fossils to write an interesting story about communities of the past. Students in this version are limited to being animals because they will write about their favorite foods. The story can be a "formula" based on the descriptions below, or can be free-form.
1) Choose the role of an ancient animal. This should be any animal that the students are familiar with.
2) Describe your environment. This requires some knowledge of the ancient ecosystems as reconstructed by a paleontologist or interpreted by a park ranger or guide. Let the students be as creative as they wish. Some students may include imagined details of the environment that were not previously discussed. This is OK as long as they can justify their reasons.
3) Describe your community. In this part, the students should give examples of the other plants and animals that live with them.
4) Describe a food chain. Begin by listing your favorite food. Are you a carnivore or an herbivore? If you are an herbivore, what animal tries to hunt you? How have you kept from being eaten so far?
6) Imagine a big change. What would you do if all your food disappeared because of that change? What could you do? Would you move away? How would the other members of your food web survive? This is an example of an ecological disaster because food chains and food webs would be forced to come apart.
Some of the best examples of adaptation are seen in adaptation to climate. Using pictures of different environments of the world, begin by talking about extreme environments. Show the class pictures of the Arctic or Antarctic and discuss the kinds of adaptations that are necessary to live in such a climate. Next, discuss deserts such as the Sahara, the tropical rain forest of the Amazon Basin, the Great Plains of North America, coasts, salt marshes, mountain streams, or alpine meadows. Each of these environments presents certain challenges to the organisms that live there, yet most of them contain a wealth of plants and animals that survive quite well under extreme conditions. By discussing these organisms in terms of their adaptations, the class will gain an appreciation for their own environment.
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ACTIVITY III / VARIATION II: Discussing Adaptation
This activity can be made into more of a cooperative exercise for the students by having them bring in old magazines from home (National Geographic and other natural history publications are especially useful). Go through the magazines in class looking for pictures that show different environments. Try to get a sampling of different extremes of climate and topography.
Change in environments is another important topic to discuss. It is sometimes easy to take the world's present environments for granted and assume that they have always been that way. But we know that is not true. Environments have changed in the past and they are always in the process of changing in some way. Environmental change is difficult for humans to understand because it often takes place so slowly that direct observation is difficult. Even the rapid changes that are taking place today as a result of human activity are hard to see. The fossil record contains a compressed view of many millions of years during which environments changed just as they do today. Change in the fossil record is therefore relatively easy to see. Some topics that the class might cover with regard to environmental change include changing climates and the results of rapid climatic change. Consider each of the environments discussed when the class talked about adaptation. What would happen if that climate suddenly (in the course of years to decades) became warmer or cooler? Related to this is the food supply. Herbivores rely on vegetation in their environment. Plants are very sensitive to climate. What happens if an herbivore's favorite food disappears? What happens then to the carnivores that depend on that herbivore for their food supply? The discussion expands to include the entire food web.
The relationship of human activities and environmental change/extinction is an important one to understand. So is the importance of maintaining the diversity of life. The class might discuss what their own stake in this crisis is and what they can do to help.
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