EXTINCTION
Over 99% of any species that has lived on this planet has become extinct. This figure includes all dinosaurs, the disappearance of which still remains one of the great mysteries.
Most extinctions are not caused by major catastrophes but by small changes in climate or habitat. For example, when flowering plants first appeared, taking the place of conifers, a knock-on effect was that many conifer-eating dinosaurs were wiped out. But the fall of one species will always give rise to another, in this case those that ate liked flowering plants. How then could all the dinosaurs disappear at once?
One theory for their extinction is that a huge meteorite hit the earth causing a massive dust cloud to be thrown up. The explanation is that this dust cloud (lasting years perhaps) blocked out the sun causing a sudden change in plant life and temperature. The force of this meteorite is believed to be more than all the present world's nuclear weapons put together. Whilst the earth does have many meteorite craters on its surface, there are none big enough to truly support this theory. Some believe that the crater could have been covered up and still lies beneath the earth's surface waiting to be discovered.
