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Updated: 2004-10-29 10:27
Day from hell may have killed off dinosaurs

地獄開啟之日 恐龍滅絕之時(shí)

Day from hell may have killed off dinosaurs

Challenging conventional theory, new scientific research suggests the dinosaurs may have been scorched into extinction by an asteroid collision 65 million years ago that unleashed 10 billion times more power than the Hiroshima nuclear bomb. (Reuters)

One minute you're a big T-Rex, the next you're toast.

Challenging conventional theory, new scientific research suggests the dinosaurs may have been scorched into extinction by an asteroid collision 65 million years ago that unleashed 10 billion times more power than the Hiroshima nuclear bomb.

Earth's temperatures soared, the sky turned red and trees all over the planet burst into flames, said atmospheric physicist Brian Toon of the University of Colorado.

Among the few survivors would have been animals living in water or burrowed in the ground like turtles, small mammals and crocodiles.

"Essentially, if you were exposed you were broiled alive. That is probably what happened to the dinosaurs. They were big creatures that didn't have anywhere to hide," said Toon.

Scholarly debate over how the dinosaurs died is fierce and the theory put forward by Toon and others adds one more twist to the greatest forensic mystery of all time.

Despite opposition from some scientists, the idea that the dinosaurs were killed by an asteroid that slammed into Mexico's Yucatan peninsula has won general acceptance since it was first mooted in the early 1990s.

Under that argument, academics say the giant reptiles mostly froze or starved to death when a huge cloud of particles kicked up by the meteorite blocked the world's sunlight for months.

But Toon, the co-author of a study published in the Geological Society of America Bulletin in May, reckons the dinosaurs' end was even more dramatic.

Creatures living near ground zero would have been vaporized immediately while those in the Caribbean area and southern United States would have drowned in 330-feet-high tsunamis when the asteroid impacted near today's Gulf of Mexico shoreline at a speed of 33,750 mph.

Then, a column of red-hot steam and dust soared thousands of miles into space and most of it fell back toward Earth within a few hours, turning the heavens into hell.

"The entire sky would be radiating at you. It would be like standing next to a giant fire; you'd be burned very severely," Toon said, whose research is based on mathematical and computer models.

Land dinosaurs all around the world perished from the intense heat of several hundred degrees Fahrenheit, said Toon.

He agrees with other scientists that the dust cloud later cooled and blocked out the sun, but says the land dinosaurs were already history by that time.

(Agencies)

頭一分鐘你還是一頭霸王龍,下一分鐘就變成了烤面包片。

一項(xiàng)挑戰(zhàn)傳統(tǒng)理論的新研究成果表明,恐龍可能是在6500萬年前的一次小行星撞擊地球中因高溫?zé)贫鴾缃^的。那次碰撞釋放出的能量比廣島原子彈爆炸的一百億倍還多。

美國科羅拉多州立大學(xué)的大氣物理學(xué)家布賴恩·圖恩這樣描述當(dāng)時(shí)的情景:地表溫度迅速升高,天空變?yōu)槌嗉t色,地球上所有的樹木都熊熊燃燒。

只有水生生物和在地下掘穴而居的動物成為極少的幸存者,比如海龜、小型哺乳動物和鱷魚等。

圖恩說:“事實(shí)上,如果你暴露在外面,你會被活活烤焦,恐龍當(dāng)時(shí)可能就是這樣,它們是體形龐大的生物,根本無處可藏。”

關(guān)于恐龍如何滅絕的學(xué)術(shù)討論很激烈,圖恩等人提出的理論給這個(gè)一直以來爭議最大的謎團(tuán)又增添了一分曲折。

很早就有科學(xué)家認(rèn)為恐龍是因?yàn)槭艿叫⌒行亲矒裟鞲缬瓤ㄌ拱雿u的影響而滅絕的,盡管這一觀點(diǎn)遭到了一些科學(xué)家的反對,但自從20世紀(jì)90年代初首次提出以來,就贏得了廣泛的贊同。

根據(jù)這種觀點(diǎn),學(xué)者們認(rèn)為當(dāng)隕星揚(yáng)起的巨大粒子云擋住了陽光,陽光長達(dá)數(shù)月無法照射到地球上時(shí),這種大型爬行動物大部分被凍死或餓死。

但是圖恩推測恐龍的結(jié)局可能更富有戲劇性。今年五月,圖恩與人合作在《美國地質(zhì)學(xué)會通報(bào)》上發(fā)表了一篇有關(guān)方面的研究論文。

當(dāng)小行星以每小時(shí)33,750 英里的速度撞擊今天的墨西哥灣海岸線附近時(shí),生活在爆炸中心周圍的生物可能會立刻蒸發(fā),而生活在加勒比海地區(qū)和美國南部的生物則可能會淹沒在330英尺高的海嘯中。

隨后,一部分紅熱的蒸汽和灰塵柱上升幾千英里后進(jìn)入太空,絕大部分物質(zhì)在幾個(gè)小時(shí)內(nèi)落回到地球上,將天堂變?yōu)榈鬲z。

圖恩說:“整個(gè)天空都在向你輻射熱量,就像站在一個(gè)巨大的火爐旁一樣。你會被嚴(yán)重?zé)齻?。”他的研究是建立在?shù)學(xué)和計(jì)算機(jī)模型基礎(chǔ)上的。

圖恩表示,全球范圍內(nèi)的陸生恐龍都死于高達(dá)幾百華氏度的高溫。

他同意其他科學(xué)家的觀點(diǎn):隨后塵埃云團(tuán)變冷,阻擋了陽光。但是他認(rèn)為那個(gè)時(shí)候陸生恐龍已經(jīng)成為歷史了。

(中國日報(bào)網(wǎng)站譯)

 
Vocabulary:

scorch: to become scorched or singed (烤焦,被烤焦或變枯萎)

unleash: release or vent(釋放)

forensic: of, relating to, or used in debate or argument; rhetorical (辯論的)

reptile: any of various cold-blooded, usually egg-laying vertebrates of the class Reptilia, such as a snake, lizard, crocodile, turtle, or dinosaur, having an external covering of scales or horny plates and breathing by means of lungs (爬行動物)

tsunami: very large ocean wave caused by an underwater earthquake or volcanic eruption (海嘯,由海底地震或火山噴發(fā)而造成的巨大海浪)

 
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