Extinction of the Dinosaurs

According to paragraph 1, which of the following is true of the Late Cretaceous climate?

• Summers were very warm and winters were very cold.

• Shallow seas on the continents caused frequent temperature changes.

• The climate was very similar to today’s climate.

• The climate did not change dramatically from season to season.

Which of the following reasons is suggested in paragraph 2 for the extinction of the dinosaurs?

• Changes in the lengths of the days and nights during the Late Cretaceous period

• Droughts caused by the movement of seaways back into the oceans

• The change from mild to severe climates during the Late Cretaceous period

• An extreme decrease in the average yearly temperature over 10,000 years

Why does the author mention the survival of “snakes, lizards, turtles, and crocodiles” in paragraph 3?

• To argue that dinosaurs may have become extinct because they were not cold-blooded animals

• To question the adequacy of the hypothesis that climatic change related to sea levels caused the extinction of the dinosaurs

• To present examples of animals that could maintain a livable body temperature more easily than dinosaurs

• To support a hypothesis that these animals were not as sensitive to climate changes in the Cretaceous period as they are today

The word “cope” in the passage is closest in meaning to

• adapt

• move

• continue

• compete

According to paragraph 3, which of the following is true of changes in climate before the Cretaceous period and the effect of these changes on dinosaurs?

• Climate changes associated with the movement of seaways before the Cretaceous period did not cause dinosaurs to become extinct.

• Changes in climate before the Cretaceous period caused severe fluctuation in sea level, resulting in the extinction of the dinosaurs.

• Frequent changes in climate before the Cretaceous period made dinosaurs better able to maintain a livable body temperature.

• Before the Cretaceous period there were few changes in climate, and dinosaurs flourished.

The word “fluctuations” in the passage is closest in meaning to

• extremes

• retreats

• periods

• variations

Which of the sentences below best expresses the essential information in the highlighted sentence in paragraph 4? _{Incorrect choices change the meaning in important ways or leave out essential information.}

• The fossil record suggests that there was an abrupt extinction of many plants and animals at the end of the Mesozoic era.

• Few fossils of the Mesozoic era have survived in the rocks that mark the end of the Cretaceous.

• Fossils from the Cretaceous period of the Mesozoic up to the beginning of the Cenozoic era have been removed from the layers of rock that surrounded them.

• Plants and animals from the Mesozoic era were unable to survive in the Cenozoic era.

In paragraph 4, all the following questions are answered EXCEPT:

• Why is there a layer of clay between the rocks of the Cretaceous and Cenozoic?

• Why were scientists interested in determining how long it took to deposit the layer of clay at the end of the Cretaceous?

• What was the effect of the surprising observation scientists made?

• Why did scientists want more information about the dinosaur extinctions at the end of the Cretaceous?

The word “bombard” in the passage is closest in meaning to

• approach

• strike

• pass

• circle

Paragraph 5 implies that a special explanation of the Ir in the boundary clay is needed because

• the Ir in microscopic meteorites reaching Earth during the Cretaceous period would have been incorporated into Earth’s core

• the Ir in the boundary clay was deposited much more than a million years ago

• the concentration of Ir in the boundary clay is higher than in microscopic meteorites

• the amount of Ir in the boundary clay is too great to have come from microscopic meteorites during the time the boundary clay was deposited