Fossils and Evidence of Past Life — Answer Key
Part A: Multiple Choice
Circle the best answer for each question.
1. In Grade 3 science, which modern animal is most similar in body plan to an ancient trilobite?
A) Horseshoe crab
B) House cat
C) Bald eagle
D) Oak tree
Horseshoe crabs share a segmented, armored body plan with extinct trilobites.
2. In Grade 3 science, fossils show modern birds are most closely related to which ancient group?
A) Jellyfish
B) Small meat-eating dinosaurs
C) Giant plant-eating dinosaurs
D) Sharks
Feathered fossils link modern birds to small theropod dinosaurs that walked on two legs.
3. In Grade 3 science, shark teeth from millions of years ago look very similar to today's teeth, which shows sharks have ___.
A) changed completely
B) never existed
C) changed very little
D) become plants
Shark teeth are almost the same shape over time, meaning shark bodies changed very little.
4. In Grade 3 science, a mammoth is considered an ancient ___ of today's elephant.
A) enemy
B) ancestor
C) robot
D) predator
Mammoths share a family tree with elephants, making them ancient ancestors of today's elephants.
Part B: Fill in the Blank
Write the correct answer on each line.
1. In Grade 3 science, the horseshoe crab is often called a living fossil because it barely changed.
Horseshoe crabs look almost identical to their fossil ancestors, earning the name 'living fossil.'
2. In Grade 3 science, an earlier species that a modern animal descends from is called an ancestor.
An ancestor is an earlier species or relative from which modern animals are descended.
3. In Grade 3 science, feathered dinosaur fossils support the idea that birds evolved from dinosaurs.
Feathered dinosaur fossils show a clear link, suggesting modern birds evolved from dinosaurs.
4. In Grade 3 science, comparing fossils of different ages helps scientists see how animals have evolved.
Tracking fossils across time shows how species evolved, developing new traits over generations.
5. In Grade 3 science, a shark tooth fossil is a hard clue because teeth are made of tough enamel.
Enamel is the hardest body material, so it survives long enough to fossilize into stone.