Fossils and Evidence of Past Life — Answer Key
Part A: Fill in the Blank
Write the missing word or number on each line.
1. An animal that no longer lives anywhere on Earth is said to be extinct.
Grade 3 science defines extinct as no longer living anywhere on Earth.
2. If a sea creature fossil is found on a mountain, that area was once under water.
Grade 3 students infer the area was once ocean because sea creatures need water.
3. Large, hairy elephants called mammoths lived long ago and are now extinct.
Grade 3 science names mammoths as extinct relatives of modern elephants.
4. Big reptiles known as dinosaurs are extinct but are well known from fossils.
Grade 3 science uses dinosaur fossils as common examples of extinct organisms.
5. Fossils of ferns in icy places tell us the climate was once warmer there.
Grade 3 science uses plant fossils as evidence of past climate.
6. A hardened copy of a shell made of minerals is called a cast.
Grade 3 science defines a cast as a mineral-filled copy of a mold.
7. The hollow shape left in rock by a shell is called a mold.
Grade 3 science defines a mold as the empty shape left when remains dissolve.
8. Fossils form best when organisms are quickly buried in sediment .
Grade 3 science says sediment covers and protects remains so they can fossilize.
9. Scientists compare fossils to modern animals to learn what extinct ones were like.
Grade 3 science compares fossils with modern animals to understand extinct species.
Part B: Matching
Match each item on the left to the correct answer on the right.
1. Match each item to its correct answer.
Extinct
→ No longer living anywhere on Earth
A scientist who studies fossils
Trace fossil
→ Footprint left in mud long ago
Footprint left in mud long ago
Body fossil
→ Bone preserved in rock
Bone preserved in rock
Paleontologist
→ A scientist who studies fossils
No longer living anywhere on Earth
Grade 3 vocabulary: extinct means gone, trace fossils show activity, body fossils are real parts, and paleontologists study fossils.