Dinosaurs WERE wiped out by an asteroid crashing into Earth
By David Derbyshire
Last updated at 9:08 AM on 05th March 2010
Some believe they were killed off by massive volcanoes, others that they were a victim of prehistoric climate change.
Now a major study claims to have conclusive proof that dinosaurs were wiped out within weeks of an asteroid the size of the Isle of Wight slamming into the Earth.
Researchers say the impact sent a vast flume of dust into the atmosphere 65 million years ago, unleashed a torrent of powerful earthquakes and triggered forest fires across North America, blocking out the sun and wiping out half of all species.
Collision: Dinosaurs were wiped out after an asteroid the size of the Isle of Wight hit the Earth 65 million years ago (artist's impression)碰撞：在一如懷特島大小的小行星，六千五百萬年前撞擊地球後，恐龍滅絕（藝術家的印象）
Proof: A graphic reveals a gravity map of the Chicxulub crater where the massive asteroid hit. Boreholes have revealed the presence of 'shocked' quartz and other impact evidence證明：一張圖形揭示希克蘇魯伯隕石坑的地心吸力圖，在那裡大型的小行星撞擊過。鑽孔已揭示出'震動'石英和其它影響證據的存在
The panel of 41 international experts - including British researchers from Cambridge, Imperial College and the University of London - looked at 20 years of research to settle the long-running debate about what killed the dinosaurs.
The mass extinction event also wiped out the bird-like pterosaurs and the large marine reptiles - clearing the way for mammals to become the dominant species on Earth.
Scientists have long argued about whether the dinosaurs were killed by a space collision or by volcanic activity in India, where a series of 'super volcanoes' erupted for more than a million years, cooling the atmosphere and triggering torrential acid ran.
Dr Joanna Morgan, co-author of the review at Imperial College London, said: 'We now have great confidence that an asteroid was the cause of the extinction.
'This triggered large-scale fires, earthquakes measuring more than 10 on the Richter scale and continental landslides, which created tsunamis.
'However, the final nail in the coffin for the dinosaurs happened when blasted material was ejected at high velocity into the atmosphere.
'This shrouded the planet in darkness and caused a global winter, killing off many species that couldn't adapt to this hellish environment.'
The paper, published in Science, pieces together powerful evidence collecting since the 1990s.
Impact zone: The location of the giant crater, in Chicxulub, Mexico影響區域：巨型火山口的位置，在墨西哥希克蘇魯伯
The collision triggered large-scale fires, earthquakes and continental landslides撞擊引發大規模的火災、地震和大陸性滑坡
The 'smoking gun' is the 65-million-year-old layer of iridium that is found in rocks all over the world.
The metal is extremely rare in the Earth's crust, but is common in asteroids and almost certainly came from a collision with a massive asteroid.
Geologists have also found large amounts of 'shocked quartz' dated to the same time.
The mineral is created during meteorite collisions or nuclear explosions.
The fossil record shows that immediately after the asteroid impact, there was a dramatic fall in the number of animals species.
In the previous 500,000 years, however, there are no signs of species dying out - despite the large number of active 'super volcanoes'.
Scientists say that is more proof that an asteroid - and not volcanoes - killed off the dinosaurs.
Power: The impact of the asteroid unleashed a torrent of powerful earthquakes and triggered forest fires, wiping out half of all species力量：小行星宣洩一強烈地震的洪流和引發森林火災的影響，消滅所有物種的一半
Researchers have also found a 65-million-year-old 125-mile-wide crater - caused by the impact with a nine-mile-wide asteroid - at Chicxulub, Mexico.
The asteroid is thought to have hit the Earth with the force of one billion Hiroshima-sized atomic bombs - and would have blasted material at high speed into the atmosphere where it would have blocked out the sun.
Computer models also suggest that the gases spewed out by the Indian volcanoes would have been short-lived - and unable to trigger a mass extinction, the researchers say.
Dr Gareth Collins, of Imperial College London, said: 'The asteroid was about the size of the Isle of Wight and hit Earth 20 times faster than a speeding bullet.
'The explosion of hot rock and gas would have looked like a huge ball of fire on the horizon, grilling any living creature in the immediate vicinity that couldn't find shelter.
'Ironically, while this hellish day signalled the end of the 160-million-year reign of the dinosaurs, it turned out to be a great day for mammals, who had lived in the shadow of the dinosaurs prior to this event.
'The extinction was a pivotal moment in Earth's history, which ultimately paved the way for humans to become the dominant species on Earth.'
http://www.dailymail.co.uk/sciencetech/article-1255484/Why-WAS-asteroid-smashing-Earth-wiped-dinosaurs.html
科學家確認導致恐龍滅絕的原因
更新時間 2010年 3月 4日, 格林尼治標準時間20:48
恐龍絕跡原因一直是科學界的一個爭議科學家說，現在他們可以明確支持小行星撞擊地球導致恐龍絕跡的理論。
長期以來科學界對導致恐龍和地球上一大半動物物種滅絕的原因一直有爭議。
一些科學家認為是小行星撞擊地球導致恐龍消亡，另一些科學家認為是火山爆發的原因。
但是一項被稱為最全面的研究發現的資料，為小行星撞擊論提供了證據。
這項新發現刊登在最新一期的《科學雜誌》上。
由41名專家組成的一個國際科研小組所作的研究結果發現，6千5百萬年前一顆小行星在墨西哥海岸撞擊地球。
撞擊引起了地震和火焰風暴，還把幾十或幾百億噸的物質拋入大氣層，遮擋住太陽的光線。
這一科學小組由此得出結論，現在終於可以把恐龍滅絕的原因歸咎於小行星對地球的撞擊了。
科學家還說，這一導致恐龍滅絕的撞擊還為包括人類在內的許多新的物種創造了進化的環境和條件。
但是記者們說，關於導致恐龍消亡的爭議，估計還會持續下去。
http://www.bbc.co.uk/zhongwen/trad/world/2010/03/100304_dinosaur.shtml
研究認定隕石撞擊造成恐龍滅絕
(法新社)2010年3月5日 星期五 09:20
（法新社華盛頓 4日電） 科學家今天指出，因巨大隕石撞擊地球，釋放出相當於10億顆原子彈的能量，造成恐龍滅絕，並盼此說法能平息長久以來對6500萬年前物種大規模滅絕原因的爭議。
一個由國際專家所組成的小組檢閱了20年來所蒐集與白堊紀-第三紀（Cretaceous-Tertiary，KT）物種滅絕相關的證據，。這場大滅絕消滅地球上超過一半的生物，包括恐龍在內。
該小組的科學家認為大滅絕起因於墜落在現今墨西哥（Mexico）契克蘇魯（Chicxulub）一個約15公里（9英里）寬的巨大隕石。這起隕石墜落事件也為哺乳類動物成為地球主要物種鋪路。
刊登在「科學」雜誌（Science）上的這項研究指出：「撞擊地球的這顆隕石，據信釋放出比廣島原子彈還強10億倍的能量。」研究員表示，這樣的撞擊將地球物質以高速炸進大氣層，引發一連串事件，造成全球進入冬季，數日內毀滅地球上多數生物。
這個由41名科學家組成的小組，盼研究成果最終能平息造成白堊紀-第三紀大滅絕的爭論。（譯者：中央社蕭倩芸）
http://hk.news.yahoo.com/article/100305/8/gv0o.html
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http://www5.uwants.com/viewthread.php?tid=9506579&extra=page%3D1
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