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Bone Diggers

Viewing Ideas

Before Watching

1. Use a map to locate where scientists found the Thylacoleo skeletons. Using a world map, have students first locate Australia and then the Nullarbor Plain (the section of southern land between the town of Norseman in Western Australia and Ceduna in South Australia). Have students use the map scale to calculate the area of the region (about 200,000 square kilometers). Is there a U.S. state of comparable size? (Nebraska and South Dakota are both about the same size.) Discuss the possible difficulties of locating a single, relatively small cave entrance in such large, featureless area. Have students determine the latitude and longitude of the area and predict what the climate may be. (This area is a vast, flat limestone plain that has a desert climate with the mean maximum temperature reaching 28° C and the mean minimum temperature reaching 5° C.)

2. Review the definitions of mammal and marsupial. Ask the class to define the terms mammal and marsupial. (Mammals are warm blooded, milk-producing animals, usually covered in fur, that give live birth to young. Marsupials are a kind of mammal.) What is the major difference between the two? (Although marsupials give live birth, their gestation period is much shorter than other mammals. Mammals with full gestation periods prior to live birth nourish the developing embryo using the mother's blood supply; because marsupials have a different kind of placenta, their young are born very early in an abdominal pouch and nursed until they are developed enough to separate from their mother.) Ask students to think of some examples of marsupials. (Common examples include kangaroos, koalas, wombats, bandicoots, opossums, and Tasmanian devils.) Make a list of students' responses on the board. After the list is completed, organize students into groups and have each group pick an animal to research. Ask students find out whether the example they have picked is an Australian species, and whether it is native to Australia or was introduced to the continent. After all groups have presented, ask students whether they notice anything about the distribution patterns of the animals. Can students infer why these species might be found in the same geographic region?

3. Describe how scientists used the information from the Thylacoleo remains to obtain a better understanding of the animal. Scientists are using the Thylacoleo skeleton to determine such things as what the animal looked like, how it moved, and what it ate. Copy the following table for the students. Explain that the table lists different parts of the Thylacoleo's body. As they watch the program, they should fill in the table, showing what information each body part revealed to scientists that helped them understand Thylacoleo or its life.

   Body Part	Information Revealed	Conclusions Reached
   Total size of skeleton
   Complete tail bones
   Jaw bones
   Type of teeth
   Nasal bone
   Brain cavity in skull
   Foot/hand bones and claws
   Limb bones
   Muscle markings on limbs

After Watching

1. After watching the video, have students discuss their findings. Which part or parts of the body proved to be most helpful in getting a better understanding of Thylacoleo and why? What can a skeleton reveal about an animal? (Some information a skeleton can reveal includes overall size and structure and function of its various body parts. Additional inferences can be made about how the animal may have lived and hunted by comparing it to its modern-day counterparts.) What cannot be learned from skeletal remains? (Scientists cannot gain information about the animal's coloration, soft tissue anatomy, or physiology.)

2. Discuss the importance of the Nullarbor Plain discovery. Although other Thylacoleo remains have been found, several features of the Nullarbor Plain discovery made it unique, including the discovery of a complete, intact skeleton; the age of the remains; and the quality of the remains. Have students discuss why these qualities made the discovery so important. (Until scientists were able to view the complete skeleton, there were many large gaps in our knowledge of Thylacoleo. A complete, carefully preserved skeleton allowed scientists to get a more comprehensive picture of both what Thylacoleo looked liked and how it lived. In addition, the age of the remains helps scientists better identify the period of time in which the animal lived.)

3. Compare and contrast extinct Australian megafauna with their modern-day relatives. Millions of years ago, megafauna, or very large animals, roamed the continent of Australia. While these species are now extinct, some have modern-day relatives, which are much smaller in size. Divide the class into small groups. Assign each group one of the following extinct species: Procoptodon (giant kangaroo), Phascolonus (giant wombat), Megalania (giant goanna), and Dromornis stirtoni (Stirton's Thunder Bird) and the respective modern species, gray kangaroo, common wombat, monitor lizard, and ostrich. Have students research their animals and compare and contrast their sizes, features, and possible habitats. Have students share their results with the rest of the class.

4. Evaluate the scientific decision-making process. The caves at Nullarbor turned out to be a graveyard for scores of extinct Australian animals, including a number of previously unknown species. Yet because of the remote location of the caves and the difficulty and expense of transporting the remains from the caves back to the museum, the scientists had to select just a small portion of the remains to take back to the museum. By leaving behind many other fossils, they ran the risk of losing irreplaceable data to thieves and scavengers. Have students write a paragraph describing what factors would help them choose what to take and what to leave behind in such a situation. Have students create a three-column chart to accompany the paragraph, listing items in the cave they would take, the advantages and disadvantages of taking those items, and what their reasons are for choosing them over items they would not take. Or, have students write a persuasive letter to a government agency stating why it is important to provide additional funding to further research the cave's contents.

Web Sites

NOVA—Bone Diggers
www.pbs.org/nova/bonediggers
Provides information on why Australia is home to so many marsupials, considers what killed off Australia's megafauna, details the anatomy of Thylacoleo, and profiles some of the vanished beasts from down under.

Fossil Sites of Australia
www.amonline.net.au/fossil_sites/index.htm
Examines some of the key fossil sites in Australia (but does not include the recent finds at Nullarbor Plain).

Thylacoleo: Australia's Marsupial Lion
www.naturalworlds.org/thylacoleo/index.htm
Presents a natural history of the Thylacoleo, including descriptions of the animal, fossil images, timelines, and links to suggested readings.

Western Australian Museum: Thylacoleo
www.museum.wa.gov.au/exhibitions/online/thylacoleo/intro.asp
Chronicles the Western Australian Museum discovery of the remains in the Nullarbor Plain.

Wonambi Fossil Centre: A Virtual Tour
www.parks.sa.gov.au/naracoorte/wonambi/index.htm
Provides viewers a virtual tour of a walk-through diorama of the Naracoorte Caves with life-sized models of extinct animals in their ancient habitats.

Books

Beyond the Dinosaurs: Sky Dragons, Sea Monsters, Mega-Mammals, and Other Prehistoric Beasts
by Howard Zimmerman. New York: Athenenum, 2001.
Includes information on megafauna and prehistoric marsupials. Includes details about the animals' size, eating habits, looks, and when and where it lived.

National Geographic Prehistoric Mammals
by Alan Turner. National Geographic Children's Books, 2004.
Presents illustrated explanations of prehistoric mammals.

Viewing Ideas Author

Margy Kuntz has written and edited educational materials for 20 years. She has authored numerous educational supplements, basal text materials, and trade books on science, math, and computers.