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高三阅读理解题For 150 million years during the age of the

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For 150 million years during the age of the dinosaurs, a group of dolphin-like reptiles called ichthyosaurs ruled the ocean – until everything started to go wrong.

After multiplying into about 100 known species, ichthyosaurs began to disappear from the oceans around the middle of the Cretaceous period, a time of turbulent changes in the environment. The aquatic reptiles went extinct 28 million years before the rest of their dinosaur cohort.

Scientists have been unable to find a singular cataclysmic event, such as a volcanic eruption or meteorite strike, that could explain ichthyosaurs’ abrupt disappearance from the fossil record.

Now researchers have new explanation for the lizard fish’s demise: They had lost their ability to adapt to a swiftly changing climate.

The aquatic lizards thrived throughout the early years of the dinosaurs in the Permian, Triassic and Jurassic periods. Then came the Cretaceous.

That was a turbulent time to live on Earth. The poles were nearly ice-free, causing sea levels to reach great heights. Temperatures were among the hottest the planet has seen in the last 250 million years.

Scientists have blamed the demise of the ichthyosaurs on their inability to keep up with other predators or the loss of key prey species. But a new study by Valentin Fischer, a paleontologist who studies ichthyosaurs at the University of Liege in Belgium, and his colleagues says neither of these explanations could account for the scale and speed of the die-off.

Writing in the journal Nature Communications, Fischer and his colleagues argue that the unstable climate contributed to the disappearance of ichthyosaurs during a 5-million to 6-million-year window in the Cretaceous known as the Cenomanian stage.

While the rising temperatures and higher seas wouldn’t have had a direct effect on the ichthyosaurs, they could have played an indirect role in their decline, Fischer said. The changing climate could have made their food more scarce, or disrupted migratory routes and birthing places, among other consequences.

Despite their variety of body shapes and survival strategies, ichthyosaurs were unable to keep up with all of these changes, the study authors wrote.

They reached this conclusion by comparing the geological record of the Cretaceous to a newly reconstructed history of ichthyosaur evolution based on museum specimens and a review of information in previously published studies.

What became clear was the ichthyosaurs’ extinction coincided with global climate shifts and the animals’ slower rate of evolution, which left them unable to adapt as their environment changed, the study found.

“They were probably very well adapted to their niches, and their environments were probably pretty stable,” Fischer said. “That could have lowered the pressure of natural selection and thus lowered their rates of evolution.”

Think of the Cenomanian stage as a transition period.

61. The underlined word “That” in Paragraph 6 refers to the period of ________.

A. Permian B. Triassic C. Jurassic D. Cretaceous

62. Fischers and his colleagues came to their conclusion by ________.

A. making comparisons B. conducting experiments

C. analyzing samples D. observing weather changes

63. Which of the following sentences can be used to conclude the last but one paragraph?

A. No pains, no gains. B. No man is wise at all times.

C. A bad beginning makes a bad ending. D. Born in misery and die of happiness.

64. What might be the best title for the passage?

A. A new research focused on the history of ichthyosaur evolution

B. A swift climate change followed the disappearance of Ichthyosaurs

C. Climate change taught ancient ichthyosaurs a lesson: Adapt or die

D. Ichthyosaurs ruled the ocean for 150 million years before disappearing


答案 61-64 DADC


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