Theory that an Asteroid Killed the Dinosaurs

The age of the dinosaurs ended dramatically and suddenly around 65 million years ago, when a catastrophe killed off the rulers of the Earth and left the way clear for mammals to take control. For years scientists have studied the geological record and the traces left behind to figure out what exactly killed off the great lizards so quickly, and now new discoveries have brought new insights. New evidence found in the geological record indicates that what caused the mass extinction was, in fact, an asteroid colliding into Earth, causing mass destruction and forcing the world into a brief ice age that would have left the dinosaurs totally extinct.

Scientists have long speculated that the dinosaurs went extinct in what is known as the Cretaceous-Tertiary extinction for one of two reasons – either dramatic volcanic activity caused their destruction or an asteroid crashed into Earth and totally destroyed the ecosystem of the planet. Only recently does the evidence seem to firmly support one side or the other. Close study of the strata of Earth's crust shows a layer of rock and earth that contains a highly unusual amount of iridium. Iridium is rare on earth, but is a very common part of asteroids, and so this correlates well with the idea of an asteroid impact. Also present in the layer is an unusual amount of ‘shocked' quartz, which generally only forms due to sharp and dramatic impacts.. Tellingly, while there are a great number of dinosaur fossils below this asteroid-formed layer, the number drops off sharply just above it, indicating that the asteroid impact did indeed lead to the extinction.

When the asteroid hit Earth, most likely in the area of what is now Chicxulub, Mexico, the immediate effect was enormous. Earthquakes with a magnitude higher than 10 rocked the planet, followed, of course, by massive tidal waves. Fires spread across the world due to the heat of the asteroid, charring forests. The most drastic effect, however, was also the most lasting – massive amounts of debris were ejected into the atmosphere by the impact. This lead to the sky being darkened for a considerable period of time, causing a small ice age that would have killed off any of the dinosaurs that had survived the initial crisis period.

While the asteroid impact was obviously a catastrophe for Earth and for the dinosaurs, it is in many ways responsible for our current existence. Without the dinosaurs dominating the food chain, the mammals that had been able to survive the crisis due to their smaller need for food and their better protection against cold took control of the planet. Reptiles were pushed into the background of the ecosystem and mammals were allowed to spread, diversify, and evolve. This, of course, eventually led to the rise of humanity as we know it today. If the asteroid had not collided with Earth, the world today might lack humans altogether and be dominated instead by the descendents of the ancient dinosaurs. This chain of events shows how even what seems like a crisis at first can lead in the end to benefits for the Earth.




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