首页 > VOA慢速英语 > 科学新闻 > 【科学新闻】恐龙灭绝促成鱼类的崛起 The extinction of dinosaurs contributed to the rise of fish

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【科学新闻】恐龙灭绝促成鱼类的崛起 The extinction of dinosaurs contributed to the rise of fish

来源:慢速英语   时间:2020-01-11 15:43:33

Tens of millions of years ago,an asteroid hit what is now the Yucatan Peninsula of Mexico.The event led to a global mass extinction that has been linked to the end of the dinosaurs.New research shows what that great disaster led to:a modern age of fish.


几千万年前,一颗小行星撞击了现在的墨西哥尤卡坦半岛。这一事件导致了一场全球大灭绝,这与恐龙的灭绝有关。新的研究表明了那场大灾难导致了什么:一个鱼类的现代时代。


Sixty-six million years ago,the ocean was a different place.Sharks and octopus-like creatures were powerful.But,scientist Elizabeth Sibert says there were other important species as well.


六千六百万年前,海洋是另一个地方。鲨鱼和章鱼一样的生物很强大。但是,科学家伊丽莎白·西伯特说还有其他重要的物种。


"There were also many marine reptiles that were swimming around.And of course there were fish.Absolutely there were ray-finned fish around.It's just that they weren't very dominant."


“还有很多海洋爬行动物在游动。当然还有鱼。当然周围有鱼鳍鱼。只是他们不是很有统治力。”

Ms.Sibert is a graduate student at the University of California,San Diego.She and her professor compared micro-fossil fish teeth and shark scales in sediment that dated before and after the mass death.


西伯特女士是加州大学圣地亚哥分校的研究生。她和她的教授比较了大量死亡前后沉积物中的微化石鱼牙和鲨鱼鳞。


"Basically the deeper down you get,the older you get.So we looked at sediments from 75 million years ago to about 45 million years ago,looking every 200,000 years in some cases,looking at every 10,000 years in other cases."


“基本上,你越深,越老。因此,我们观察了7500万年前到4500万年前的沉积物,在某些情况下每20万年查看一次,在其他情况下每10000年查看一次。”


Fossil evidence showed that the ratio of fish to shark changed sharply after the asteroid hit.Elizabeth Sibert explains.


化石证据显示,小行星撞击后,鱼与鲨鱼的比例急剧变化。伊丽莎白·西伯特解释道。


"We see that instead of having about equal number of shark fossils and fish fossils,we see that the fish fossils more than double and that trend continues while the shark fossils stay approximately the same."


“我们看到,鲨鱼化石和鱼类化石的数量不等,我们看到鱼类化石增加了一倍以上,这种趋势在鲨鱼化石保持不变的情况下继续。”


The study suggests that the mass extinction killed many animals at both the top and bottom of the ocean food chain.This permitted animals in the middle of the chain to increase their numbers.Those animals are the ray-finned fish that represent nearly all fish species today.


这项研究表明,大灭绝杀死了海洋食物链顶端和底部的许多动物。这就允许处于链中间的动物增加它们的数量。这些动物是有鳍的鱼,几乎代表了今天所有的鱼类种类。


"And they radiated into all these newly vacated spots,and possibly some new things that wouldn't have existed at all if the extinction hadn't happened."


“它们辐射到所有这些新的空缺点,可能还有一些新的东西,如果灭绝没有发生,它们根本就不会存在。”


Elizabeth Sibert says her next step is to go back to the micro-fossil record.She will try to learn from it how the fish dealt with other stresses in the ocean,like global warming.


伊丽莎白西伯特说她的下一步是回到微化石记录。她将尝试从中学习鱼类如何应对海洋中的其他压力,如全球变暖。


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