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  3. It was previously believed that dinosaurs were cold-blooded creatures, like reptiles. However, a recent discovery has lad resear

It was previously believed that dinosaurs were cold-blooded creatures, like reptiles. However, a recent discovery has lad resear

admin2010-04-12  66
问题     It was previously believed that dinosaurs were cold-blooded creatures, like reptiles. However, a recent discovery has lad researchers to believe they may have been warm- blooded. The fossilized remains of a 66 million-year-old dinosaur’s heart were discovered and examined by x-ray. The basis for the analysis that they were warm- blooded is the number of chambers in the heart as well as the existence of a single aorta (主动脉).
    Most reptiles have three chambers in their hearts, although some do have four. But these that have four chambers, such as the crocodile, have two arteries (动脉) to mix the oxygen-heavy blood with oxygen-lean blood. Reptiles are cold-blooded, meaning that they are dependent on the environment for body heat. Yet the fossilized heart had four chambers in the heart as well as a single aorta. The single aorta means that the oxygen-rich blood was completely separated from the oxygen-poor blood and sent through the aorta to all parts of the body.
    Mammals, on the other hand, me warm-blooded, meaning that they generate their own body heat end are thus mere tolerant of temperature extremes. Birds and mammals, because they are warm blooded, move more swiftly and have greater physical endurance than reptiles.
    Scientists believe that the evidence now points to the idea that all dinosaurs were actually warm- blooded. Ironically, the particular dinosaur in which the discovery was made was a Tescelosaurus, which translates to "marvelous lizard." A lizard, of course, is a reptile.
What is the basis of the researchers’ new theory?
选项 A、They performed mathematical calculations and determined that dinosaurs must have had four chambered hearts.
B、They found a fossil of an entire dinosaur end reviewed the arteries and veins flowing from and to the heart.
C、They found a fossil of a dinosaur’s heart and discovered it had four chambers and one aorta.
D、They viewed a fossil of a dinosaur’s heart and discovered that it had two aortas.
答案C
解析 文章第一段最后一句话直接指出“The basis for the analysis that they were warm-blooded is the number of chambers in the heart as well as the existence of a single aorta(主动脉)．”恐龙是恒温动物这一分析研究结果的基础在于恐龙心室的数量和它们都有一根主动脉。所以C正确。
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