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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燒灼而滅絕的。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的大氣物理學家布賴恩·圖恩這樣描述當時的情景：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：“事實上，如果你暴露在外面，你會被活活烤焦，恐龍當時可能就是這樣，它們是體形龐大的生物，根本無處可藏。”
關于恐龍如何滅絕的學術討論很激烈，圖恩等人提出的理論給這個一直以來爭議最大的謎團又增添了一分曲折。
很早就有科學家認為恐龍是因為受到小行星撞擊墨西哥尤卡坦半島的影響而滅絕的，盡管這一觀點遭到了一些科學家的反對，但自從20世紀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，學者們認為當隕星揚起的巨大粒子云擋住了陽光，陽光長達數(shù)月無法照射到地球上時，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局可能更富有戲劇性。今年五月，圖恩與人合作在《美國地質學會通報》上發(fā)表了一篇有關方面的研究論文。
當小行星以每小時33,750
英里的速度撞擊今天的墨西哥灣海岸線附近時，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入太空，絕大部分物質在幾個小時內落回到地球上，將天堂變?yōu)榈鬲z。
圖恩說：“整個天空都在向你輻射熱量，就像站在一個巨大的火爐旁一樣。你會被嚴重燒傷。”他的研究是建立在數(shù)學和計算機模型基礎上的。
圖恩表示，全球范圍內的陸生恐龍都死于高達幾百華氏度的高溫。
他同意其他科學家的觀點：隨后塵埃云團變冷，阻擋了陽光。但是他認為那個時候陸生恐龍已經成為歷史了。
（中國日報網站譯） |
Updated: 2004-10-29 10:27