Weighing the Evidence: teacher key

Dinosaurs, grade 10 edition, written for 10th grade. Scientists weigh a clay layer, volcanoes, rare fossils and a slow decline that the rocks cannot settle. Bones and feathers add more clues.

Read the book. Print this page for the key.

Questions and answers

1. What did the thin clay layer hold a lot of?
   • Calcium
   • Iridium (answer)
   • Soot only
2. About how old were the youngest rocks of the Naashoibito Member?
   • About 6.6 million years
   • About 252 million years
   • About 66.4 million years (answer)
3. How many mass extinctions in Earth's history were bigger than the end-Cretaceous one?
   • None
   • One (answer)
   • Two
4. What did scientists find in MOR 1125?
   • A feather
   • A footprint
   • Medullary bone (answer)
5. What does decline mean in 'a slow decline late in the Cretaceous'?
   • A new kind
   • A slow fall (answer)
   • A sudden jump

Words

• iridium: rare metal
• medullary: inner bone
• decline: slow fall
• specimen: one example