Page 149 - Science Course 3 (Book 2)

Event What Happened

6. Sea level continues to
rise.

7. Sea levels rise and recede
along North America’s
eastern coastline.

8. The North American
continent slowly and
steadily moves westward.

9. A collision of plates
occurs along the western
coast of North America.

Mo11-L6: Key Concept Check
Direction: On the line before each statement, write T if the statement is true or F if the statement is
false.

1. The Mesozoic era began 65.5 mya.

2. Three periods form the Mesozoic era, including the Triassic, the Jurassic, and the
Cretaceous.
3. The rising of sea levels made the evolution of new organisms dif cult.

4. Organisms during the Mesozoic era adapted to cool environments.
5. Flowering plants appeared toward the end of the Cretaceous period.

6. The dominant reptiles on Earth were crocodiles.
7. Scientists have discovered more than 300 species of dinosaurs.
8. One difference between dinosaurs and present-day reptiles is the dinosaur’s

unique hip structure.
9. Scientists who study dinosaurs think they are more closely related to mammals

than to present-day reptiles.
10. The dinosaur Archaeopteryx had wings and fur.
11. Plesiosaurs were marine reptiles that had small heads and long necks.

12. One pterosaur, the Quetzalcoatlus, had neck length of nearly 12 m.
13. A mass extinction occurred about 65.5 mya.
14. Scientists hypothesize that the Cretaceous extinction event occurred following

the impact of a large meteorite.
15. Large amounts of dust in the oceans cause plants to die.

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