Why did the dinosaurs die?
(Lansing State Journal, April 19, 1995)
A number of explanations have been suggested to explain their disappearance including food shortage or dramatic change in climate.
However, the most accepted hypothesis is that a large asteroid, probably several miles in diameter, struck the Earth hitting so hard that it actually vaporized tons of rock, soil and other things in its path. The dust and debris that was stirred blocked out much of the sunlight for possibly months or years. This, of course, killed off a lot of plants. Without plants, plant eating dinosaurs began to die off. Without plant- eating dinosaurs, meat eating dinosaurs didn't have much to eat, so they died off.
This hypothesis is supported by the fact that fossil records show that many plants died off at the same time the dinosaurs did.
Another piece of evidence in support of the hypothesis is that the element iridium, which is very rare on Earth but more common in asteroids, has been found in higher than normal amounts in rock sediments that were formed during the same period the dinosaurs became extinct.