Many theories have been put forward for the extinction of the dinosaurs, but most of them can be dismissed.

人们提出了许多关于恐龙灭绝的理论，但大多数都是不成立的。

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Changes in climate before that period caused severe fluctuation in sea level, resulting in the extinction of the dinosaurs.

在此之前，气候的变化导致了海平面的剧烈波动，恐龙因此灭绝。

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Some scientists hypothesize that the extinction of the dinosaurs resulted from the effects of an asteroid collision with Earth.

一些科学家假定，小行星撞击地球导致了恐龙的灭绝。

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Some think that the ten-kilometre meteorite that created it threw so much dust into the atmosphere that it blotted out the sun and led to the extinction of the dinosaurs.

ECONOMIST: The ultimate environmental catastrophe

One of the theories put forward to explain the extinction of the dinosaurs 65 million years ago is that they were wiped out by the catastrophic impact of a large asteroid.

BBC: Asteroid impact centre site selected

And it is hoped that there will be numerous things to find from these discoveries, including further clues as to what caused the untimely extinction of the dinosaurs 65 million years ago - the most prominent theory being that it was the result of an asteroid hitting the Earth on what is now the coast of Mexico.

BBC: NEWS | Science/Nature | Golden age of dino finds forecast