Name______
Class______Date______
Chapter 8
The History of Life on Earth
Section: Evidence of the Past
_____1. What type of scientists use fossils to reconstruct the history of life before humans existed?
a. fossilogist c. sedimentologists
b. dinosaurologists d. paleontologists
2. What do fossils show us?
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3. What are fossils?
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Directions: Put the three stages of a fossil’s formation in order from first to last. Write the appropriate numbers from 1 to 3 on the lines provided.
____ 4. Over time, the mold fills with sediment, which forms a cast of the organism.
____ 5. The organism gradually decomposes and leaves a hollow impression, or mold, in the sediment.
____ 6. When an organism dies it becomes buried in sediment.
THE AGE OF FOSSILS
7. When scientists look at which layer of rock a fossil is in they are using the ______method of estimating the age of rocks and fossils.
8. When a scientist finds sedimentary rock, where are the oldest layers usually found? Why?
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9. Scientists can determine the age of a fossil more precisely than relative dating using a method called ______.
10. The particles that make up all matter are called ______.
11. As atoms decay what do they release?
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12. The time it takes for half of the unstable atoms in a sample to decay is the sample’s ______.
13. When scientists measure the ratio of unstable atoms to stable atoms in a sample of rock, what are they trying to determine?
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THE GEOLOGIC TIME SCALE
14. Why is the earth’s history divided into very long units of time?
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15. The calendar scientists use to outline the history of life on earth is called the ______time scale.
16. After paleontologists have dated a fossil, how do they use the time scale to help them understand how organisms have changed over time?
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17. Paleontologists have divided the geologic time scale into blocks of time. The largest divisions are known as ______.
18. Why is the Mesozoic era referred to as the Age of Reptiles?
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19. Does the geologic time scale change? Explain why or why not?
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20. When a species dies out completely we say it has become ______.
21. The periods when many species suddenly become extinct is called ______.
22. What are two events scientists think could have caused the extinction of the dinosaurs?
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THE CHANGING EARTH
_____ 23. Fossils provide evidence that Antarctica was once located.
a. at the North Pole. c. at the South Pole.
b. near the equator. d. where it is now.
_____ 24. The continents may once have formed one landmass called Pangaea which means
a. all seas. c. all Earth.
b. puzzle. d. landmass.
_____25. J. Tuzo Wilson’s theory of how huge pieces of Earth’s crust are pushed around be forces within the planet is called
a. continents. c. plate tectonics.
b. crust tectonics d. Pangaea.
_____26. According to the theory of plate tectonics, how many large rigid plates are there?
a. five c. eight
b. two d. seven
27. How do slow changes, such as moving continents, affect organisms differently than rapid changes, such as a meteorite impact, affect organisms?
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28. Why are fossils found in some places very different from the organisms now living in the same area?
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Section: Eras of the Geologic Time Scale
1. What are the four major divisions of geologic history?
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PRECAMBRIAN TIME
____2. About when did the Precambrian time begin?
a. 2.6 billion years ago c. 430 million years ago
b. 4.6 billion years ago d. 4.5 million years ago
3. What are two differences between early Earth and the present Earth?
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4. How do scientists think that life on Earth developed?
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5. The first organisms, called ______, didn’t need oxygen to survive.
6. The first ______began to release oxygen gas into the oceans and air.
7. Organisms composed of many cells may have evolved from ______.
8. Before a(n) ______layer formed to reduce radiation on Earth’s surface, life existed only in the oceans and underground.
THE PALEOZIOC ERA
_____ 9. When did the Paleozoic era begin?
a. 2.6 billion years ago
b. 430 million years ago
c. 542 million years ago
d. 4.5 million years ago
10. What are three kinds of fossils from the Paleozoic era?
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11. Why is this era given the name Paleozoic, which means “ancient life”?
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12. Name three of the plant species that covered Earth in the Paleozoic era.
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Directions: Put the three types of animals in the order of their appearance on Earth. Write the appropriate numbers from 1 to 3 on the lines provided.
_____13. salamander-like animals
_____14. crawling insects
_____15. reptiles and winged insects
16. What happened to as many as 90% of marine species about 251 million years ago?
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THE MESOZOIC ERA
______17. When did the Mesozoic era begin?
a. 2.6 billion years ago
b. 251 million years ago
c. 542 million years ago
d. 430 million years ago
18. What does “Mesozoic” mean?
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19. Reptiles evolved into many different species during this time, so the Mesozoic era is also known as the ______.
20. Name three types of animals that existed during the Mesozoic era.
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21. About how many years ago did dinosaurs and many other plant and animal species become extinct?
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THE CENOZOIC ERA
_____22. The Cenozoic era began about 65 million years ago
a. ended 40 million years ago.
b. continues to the present.
c. ended in 1000 A.D.
d. ended 35 thousand years ago.
____23. The Cenozoic era is sometimes called the
a. Age of Humans.
b. Age of Fossils.
c. Age of Mammals.
d. Age of Insects
_____24. “Cenozoic” means
a. recent life. c. fossil era.
b. flowering plants. d. saber-toothed cats.
25. Name three of the Cenozoic animals.
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26. How have the ice ages affect organisms in the Cenozoic era?
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Section: Humans and Other Primates
_____1. Humans, apes, and monkeys had a common ancestor
a. 3 million years ago. c. 45 million years ago.
b. 4 thousand years ago. d. 1 billion years ago.
PRIMATES
_____2. The ancestors of primates were
a. ape like. c. bird like.
b. mouse like. d. lizard like.
_____3. The first primates appeared
a. at the same time as dinosaurs.
b. before dinosaurs.
c. after the dinosaurs died out.
d. at the same time as humans.
4. The ancestors of ______may have co-existed with dinosaurs, but actual primates did not exist until after the dinosaurs.
5. What type of animal do scientists think is the closest living relative of humans?
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6. Humans are in a family called ______that includes only humans and their humanlike ancestors.
7. The main characteristic that separates hominids from other primates is ______.
HOMINIDS THROUGH TIME
_____8. Fossils are classified as hominids when they
a. look like apes.
b. share characteristics of modern humans.
c. are found in the Cenozoic period.
d. are found in Africa.
_____9. The oldest hominid fossils have been found in
a. Africa. c. Asia.
b. North America. d. Australia.
_____10. One of the earliest hominid fossils found is
a. 3,000 to 4,000 years old.
b. 65 to 55 million years old.
c. 6 to 7 million years old.
d. 100 to 200 million years old.
11. Early hominids that are similar to apes but different in several ways are classified as ______.
12. What are two of the differences between australopithecines and apes?
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13. How were these new people different from australopithecines?
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14. Members of one type of hominid group, ______, could grow as tall as modern humans do.
RECENT HOMINIDS
15. What two types of hominids may have lived in the same areas at the same time as recently as 30,000 years ago?
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16. What happened to the Neanderthals?
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17. The group of hominids called ______created large amounts of art.
18. What indicates these early humans had an organized and complex society?
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19. Why do scientists keep reviewing their hypotheses about hominids and human evolution?
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Chapter 8: The History of Life on Earth