The K-Pg extinction event · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.
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The K-Pg extinction: how the dinosaurs' reign ended

Science · Dinosaurs & Paleontology · ages 9-11
Name ______________________   Date ____________

  1. Which group of dinosaurs died out completely in the K-Pg extinction?

    • Non-avian dinosaurs, which were not birds
    • All dinosaurs, including every kind of bird
    • Only dinosaurs that were smaller than birds

  2. A dinosaur fossil comes from a rock layer dated to about 66 million years ago. How does that time compare with the K-Pg extinction?

    • Many millions of years before the K-Pg extinction
    • At about the time of the K-Pg extinction
    • Many millions of years after the K-Pg extinction

  3. Evidence links a large asteroid impact to the K-Pg extinction.

    Circle one:   True   False

  4. Scientists find a thin rock layer from the time of the K-Pg extinction in many parts of the world. Which metal is unusually abundant in it?

    • Iridium
    • Iron
    • Gold

  5. What is the name of the crater linked to the asteroid that struck Earth 66 million years ago?

    • Cretaceous crater
    • Palaeogene crater
    • Chicxulub crater

  6. Why does the widespread iridium-rich layer support the asteroid impact explanation?

    • Iridium is found only in dinosaur bones and never in Earth's rocks.
    • Iridium is scarce in Earth's crust but richer in many asteroids.
    • Iridium is found only in volcanoes and never in rocks from space.

  7. Which event happened before the impact's dust and soot reduced sunlight around the world?

    • The asteroid struck and made a crater
    • Less sunlight slowed the growth of plants
    • Less plant growth reduced food for animals

  8. Leo says, "All dinosaur species died the moment the asteroid hit." Which correction fits the evidence?

    • Birds also died out, but new birds appeared only after the skies cleared.
    • No birds survived, and all dinosaurs died only where the rock landed.
    • Some birds survived, and loss of sunlight disrupted food supplies.
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Answer key

For grown-ups. Fold this page away before handing over the rest.

The K-Pg extinction: how the dinosaurs' reign ended W1-mt_QHKqckBdAk-s1

  1. Non-avian dinosaurs, which were not birds · All non-avian dinosaurs died out. Non-avian means not birds. Some birds survived.
  2. At about the time of the K-Pg extinction · Both dates are about 66 million years ago, so the fossil comes from around the time of the extinction.
  3. True · Chicxulub crater and rocks from the time of the extinction support the asteroid impact explanation.
  4. Iridium · The layer is rich in iridium. Its age and wide spread help link it to the asteroid impact.
  5. Chicxulub crater · The impact formed Chicxulub crater near what is now Mexico's Yucatan Peninsula.
  6. Iridium is scarce in Earth's crust but richer in many asteroids. · Many asteroids contain more iridium than Earth's crust does. A widespread iridium-rich layer dated to the extinction supports the idea that material arrived from an impact.
  7. The asteroid struck and made a crater · The asteroid impact came first. Dust and soot then reduced sunlight, harming plant growth and food supplies.
  8. Some birds survived, and loss of sunlight disrupted food supplies. · Some birds survived. Reduced sunlight also harmed plant growth and food supplies over time, affecting animals far from the crater.
Worksheet · LightMySky