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科学美国人60秒:研究发现侏罗纪迷惑龙甩尾或已能突破音障

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It seems the first resident of Earth to break the sound barrier wasn't Chuck Yeager, after all.
He was about a hundred million years ,too late.
Apatosaurus was a cousin of Brontosaurus,but even bigger,with a 40-foot-tail more than three feet thick at the butt end but no wider than your pinky at the tip.
That dainty end made the tail too fragile for clubbing attackers.
So what was it for?Maybe this:
The idea that Apatosaurus might have used its tail like a bullwhip—to scare off predators, communicate or even show off for potential mates—gained traction about 20 years ago.
That's when paleontologist Philip Currie of the University of Alberta teamed with Nathan Myhrvold to create a computer simulation that showed the whip-cracking tail was plausible.
Myhrvold is the founder and CEO of Intellectual Ventures
an invention firm in the Seattle suburbs—where I'm executive editor.
This week at a meeting of the Society for Vertebrate Paleontology, Myhrvold, Currie and Dhileep Sivam, also of Intellectual Ventures, unveiled a quarter-scale physical model of an Apatosaurus tail made from aluminum vertebrae and steel tendons.
Give the big end of the model a strong push and pull, and it does this:
Our analysis of high-speed video of the tail in action found that the tip moves at more than 800 miles an hour—fast enough to break the sound barrier and create a small sonic boom.
A full-size apatosaur whipping its tail in this way could probably have produced a sound loud enough to shatter human eardrums.
Which must have really gotten their attention back in the late Jurassic.

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重点单词   查看全部解释    
intellectual [.intil'ektʃuəl]

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n. 知识份子,凭理智做事者
adj. 智力的

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invention [in'venʃən]

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n. 发明,发明物,虚构,虚构物

 
analysis [ə'næləsis]

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n. 分析,解析

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barrier ['bæriə]

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n. 界线,屏障,栅栏,障碍物

 
fragile ['frædʒail]

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adj. 易碎的,脆的,精细的

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transaction [træn'zækʃən]

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n. 交易,处理,办理,事务
(复)trans

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paleontologist [,pæliɔn'tɔlədʒist]

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n. 古生物学者 =palaeontologist

 
communicate [kə'mju:nikeit]

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v. 交流,传达,沟通

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executive [ig'zekjutiv]

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adj. 行政的,决策的,经营的,[计算机]执行指令

 
boom [bu:m]

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n. 繁荣,低沉声,帆杠,水栅
vi. 急速增

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