1. Chapter 14 Earth Science
Geologic Time

2. Words to Know – Section 1 Life and Geologic Time
Geologic time scale
Eon
Era
Period
Epoch
Organic evolution
Species
Natural selection
Trilobite
Pangea

3. Division of Earth’s history into time units based largely on the types of life-forms that lived during certain periods.
Geologic time scale

4. Longest subdivision in the geologic time scale that is based on the abundance of certain types of fossils and is subdivided into eras, periods, and epochs.
eon

5. Second-longest division of geologic time; is subdivided into periods and is based on major worldwide changes in types of fossils
era

6. Third-longest division of geologic time; is subdivided into epochs and is characterized by the types of life that existed worldwide.
period

7. Next-smaller division of geologic time after the period; is characterized by differences in life-forms that may vary regionally.
epoch

8. Change of organisms over geologic time
Organic evolution

9. Group of organisms that reproduces only with other members of their own group
species

10. Process by which organisms that are suited to a particular environment are better able to survive and reproduce than organisms that are not
Natural selection

11. Organism with a three-lobed exoskeleton that was abundant on Paleozoic oceans and is considered to be an index fossil
trilobite

12. Large ancient landmass that was composed of all the continents joined together
Pangea

13. Words to Know – Section 2 Early Earth History
Precambian time
Cyanobacteria
Paleozoic Era

14. Longest part of Earth’s history, lasting from 4
Longest part of Earth’s history, lasting from 4.0 billion to about 544 million years ago
Precambrian time

15. Chlorophyll-containing, photosynthetic bateria thought to be one of Earth’s earliest life-forms
cyanobacteria

16. Era of ancient life, which began about 544 million years ago, when organisms developed hard parts, and ended with mass extinctions about 245 million years ago
Paleozoic Era

17. Words to Know – Section 3 Middle and Recent Earth History
Mesozoic Era
Cenozoic Era

18. Middle era of Earth’s history, during which Pangea broke apart, dinosaurs appeared, and reptiles and gymnosperms were the dominant land life-forms
Mesozoic Era

19. Era of recent life that began about 66 million years ago and continues today; includes the first appearance of Homo sapiens about 400,000 years ago
Cenozoic Era