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  3. Conventional wisdom has long held that mammals stayed minions of years on earth. As long as dinosaurs roamed the lands, our dist

Conventional wisdom has long held that mammals stayed minions of years on earth. As long as dinosaurs roamed the lands, our dist

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问题     Conventional wisdom has long held that mammals stayed minions of years on earth. As long as dinosaurs roamed the lands, our distant ancestors never got to be much more than chicken-hearted creatures that sneaked out at night to grab bits of plants when the terrible lizards were asleep. Only when they were wiped out did mammals begin to earn a little evolutionary respect.
   But that picture changed dramatically with the announcement in Nature of two impressive fossils. One, of a brand-new species named R. giganticus, broke apart the notion that most dinosaurage mammals were never larger than squirrels. The animal had the dimensions of a midsize dog-by far the biggest dinosaur-age mammal ever found. And the second, a new specimen of a previously discovered species called R. robustus, refuted the notion that it was always the mammals that got eaten. Inside the skeleton where the animal’s stomach would have been are the fossilized remains of a baby dinosaur. "This discovery was the chance of a lifetime," says Jin Meng, scientist and coauthor of the paper.
   Indeed, Meng didn’t expect to find things like this at all. The smaller skeleton was discovered about two years ago by villagers in China’s Liaoning province, site of some of the richest fossil beds in the world. They brought it to the attention of scientists, who took it to an institute for examination. "We didn’t see the stomach contents at first," says Meng.
   After they did, however, it didn’t take them long to realize they had struck scientific gold. On closer examination, the scientists determined that the remains were those of a juvenile dinosaur. Some of the arm and leg bones were still attached to each other, suggesting that R. robustus didn’t chew its food thoroughly but wolfed it down in large chunks.
    Taken together, the finds overturn the already eroded idea that early mammals were tiny and timid. Now paleontologists can stop cooking up theories to explain why mammals were so little-that they had to be small to avoid being found, for example, or they couldn’t grow larger because dinosaurs already occupied those ecological spaces.
   But it’s now clear that mammals did fill some of the spaces reserved for larger animals. "It’s quite possible," says paleontologist Anne Well, "that they competed with dinosaurs for the same prey. " And because they ate dinosaurs, they may even have had an influence on dinosaur evolution. What sort of influence? "We don’t know," she says. "That’s how it is with the best finds. They leave you with more questions than answers. "
Mammals in the dinosaur age used to be described as
选项 A、fierce and dangerous.
B、shrewd and swift.
C、doglike and sneaky.
D、small and cowardly.
答案D
解析 恐龙时代的哺乳动物曾经被描述为什么?根据第一段第二句“As long as dinosaurs roamed the lands，our distantancestors never got to be much more than chicken-hearted creaturesthat sneaked out at night to grab bits of plants when the terrible liz-ards wgre asleep”可知，传统观点认为我们远古的祖先只会等到可怕的恐龙在夜晚入睡的时候，才胆小如鼠地从藏身之地偷偷出来采集植物充饥。根据第二段第一句“One，of a brand-newspecies named R．giganticus，broke apart the notion that most di-nosaur-age mammals were never larger than squirrels．”可知，全新的物种R giganticus化石的发现，推翻了大多数恐龙时期的哺乳动物都不比松鼠大的观点。由此可知，恐龙时代的哺乳动物曾被描述为瘦小而懦弱，故选D。
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