Search NOVA Teachers

Back to Teachers Home

Megabeasts' Sudden Death

Program Overview


NOVA explores how scientists are working to solve the mystery of what might have killed off ancient land animals nearly 13,000 years ago.

The program:

  • notes that Greenland's glaciers contain ancient microscopic dust particles that provide environmental records dating back thousands of years.

  • announces one scientist's quest to find ice from the time of the ancient land mammals' extinction and analyze its chemistry to gain insight into what killed off the creatures.

  • travels to southern Arizona, former home to at least 35 species of now-extinct land mammals, including the saber-toothed cat, the giant sloth, and several kinds of mammoths and mastodons.

  • follows scientists as they travel to the black mat, a visible layer of Arizona riverbed that reveals the extinction boundary.

  • notes that Arizona was also home to the Clovis people—the first documented humans to inhabit North America—who apparently disappeared along with the animals.

  • suggests two theories to explain the extinction: the human overkill theory, which proposes that primitive humans may have caused the extinction through overhunting, and the theory of a sudden and drastic climate change.

  • reports on traces of iridium found in the black mat—while rare on Earth, iridium is prevalent in cosmic material, suggesting that an asteroid or comet may have contributed to the extinction.

  • details the discovery of several types of nanoscale diamonds in the black mat, including a hexagonal diamond that is thought to form solely through an enormous high-pressure blast.

  • features scientists who refute the comet impact theory.

  • travels with scientists to Greenland, where they find nanoscale diamonds—including hexagonal diamonds—deposited in the narrow layer of ice from the time the great land animals went extinct, supporting the theory that a comet may have played a role in the extinction.

Taping Rights: Can be used up to one year after program is recorded off the air.

Teacher's Guide
Megabeasts' Sudden Death
WATCH A PREVIEW BUY THE VIDEO WATCH THE VIDEO ONLINE PROGRAM OVERVIEW VIEWING IDEAS RELATED NOVA RESOURCES INTERACTIVE FOR STUDENTS