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Overview:
Learning about a modern species can help us understand prehistoric species, and vice versa. Scientists are currently investigating the diets and eating habits of modern crocodilians (including crocodiles and alligators) and the prehistoric SuperCroc species ( Sarcosuchus imperator). They hope that these studies will help them to better understand each species' ecosystems and habitats.
This lesson introduces students to SuperCroc and its diet and eating habits. Students will investigate the diet and eating habits of American alligators and Nile crocodiles. They will draw pictures and write paragraphs explaining the similarities and differences they discover and the reasons they think scientists are so interested in what and how these animals eat.
Connections to the Curriculum:
Geography, life sciences
Connections to the National Geography Standards:
Standard 8: "The characteristics and spatial distribution of ecosystems on Earth's surface"
Time:
Four to five hours
Materials Required:
- Computer with Internet access
- Drawing materials
Objectives:
Students will
- read about scientific studies on crocodilian diets on the Web, and discuss what they learn;
- research and answer questions about the American alligator, Nile crocodile, and SuperCroc;
- draw pictures of these species and their habitats;
- write captions describing what their pictures show about the animals' eating habits;
- share their drawings with the class; and
- write paragraphs about the eating habits of SuperCroc and modern crocodilians and why they think scientists study these things.
Geographic Skills:
Asking Geographic Questions
Acquiring Geographic Information
Organizing Geographic Information
Answering Geographic Questions
Analyzing Geographic Information
S u g g e s t e d P r o c e d u r e
Opening:
Ask students if they have ever seen alligators or crocodiles, either in the wild or in the zoo. How big were the animals? What were their habitats like?
Have students look at some pictures of crocodiles and alligators. Can they tell the difference between crocodiles and alligators? Explain that one of the most noticeable differences is that alligators have broader snouts than crocodiles. By looking at the pictures, can students figure out how crocodiles and alligators breathe, move from place to place, or the types of food they most likely eat?
Have students look at the crocodilian distribution map. Discuss the locations of today's crocodiles and alligators. Students should notice that these species live primarily in tropical and subtropical regions.
Development:
Have students look at this geologic timeline and read the caption. Help them understand what this timeline shows: that the crocodiles and alligators of today shared the common ancestor Archosaur with the dinosaurs. While the dinosaurs became extinct 65 million years ago, crocodilians continued into the present time. One crocodilian species, Sarcosuchus imperator (SuperCroc), lived about 110 million years ago but did not survive into the present.
Explain that scientists are currently studying modern crocodilians and SuperCroc to learn more about all types of modern and prehistoric crocodilians. One thing they are very interested in is what these species eat (or ate) and how they capture (or captured) their prey. Discuss the reasons this information might be interesting to scientists (e.g., to learn about other parts of the ecosystem or to devise ways to prevent modern crocodiles or alligators from attacking humans).
Ask students to imagine that they want to study the diets of modern crocodiles and alligators and of SuperCroc. How do they think they (or scientists) could go about doing this type of study? What might they look for? What methods might they use?
Have students go to the following Web pages to see what scientists are learning about crocodilian diets. Discuss as a class the methods scientists are using (e.g., studying SuperCroc's teeth) and what they are finding.
Divide the class into groups, and assign each group one of the three crocodilians you have discussed: SuperCroc, the American alligator, or the Nile crocodile. Have groups use these Web sites to research their species' diets and methods of capturing prey. Have them answer the questions below as they go through the sites.
American Alligator:
Nile Crocodile:
SuperCroc:
Combination of Species:
Questions to answer:
- What does your species eat?
- How does it capture its prey?
- Why do you think scientists are interested in studying this species' diet and methods of capturing prey?
Closing:
Discuss students' answers as a class. What have they learned about crocodilians' feeding behavior? Are there differences between what and how alligators and crocodiles eat? How does this compare to SuperCroc?
Suggested Student Assessment:
Have each group draw two pictures of its assigned species: one showing the species in its natural habitat and the other showing a close-up of the species' body.
Ask them to draw arrows from each of their pictures to captions that describe the animals' diets and methods of obtaining food. Have groups share their drawings and captions with the class.
Have students conclude by writing paragraphs answering these questions: What are the major similarities and differences between the diets and eating habits of SuperCroc and modern crocodiles or alligators? Why do you think scientists are interested in studying these species' diets and eating habits?
Extending the Lesson:
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