Reading the Rocks: teacher key

Dinosaurs, grade 9 edition, written for 9th grade. Carbon dating cannot date a dinosaur, so how do scientists tell its age, its growth rate or even its colour? Read about the rocks, the bones and the numbers.

Read the book. Print this page for the key.

Questions and answers

1. About how far back can carbon dating work?
   • 66 million years
   • 50,000 years or so (answer)
   • 1,000 years
2. In bracketing, what do scientists date?
   • The fossil's skin
   • The animal's teeth
   • Volcanic layers above and below the fossil bed (answer)
3. Use the miles on the page. The Chicxulub crater was how many times as wide as the asteroid, at the least?
   • More than 10 times (answer)
   • About the same
   • About twice
4. What did a 2004 study find T. rex gained a day during its growth spurt?
   • About 200 kilograms
   • Almost nothing
   • More than 2 kilograms (answer)
5. What does pigment mean in 'tiny pigment structures'?
   • Hard bone
   • Natural colour (answer)
   • Fossil dung

Words

• bracketing: dating between layers
• igneous: cooled lava
• pigment: natural colour
• marrow: bone center