Why did the dinosaurs die out?

The dinosaurs probably died out because of a combination of natural disasters: global warming over millions of years, followed by a series of colossal volcanic eruptions that released vast quantities of poisonous gas, at almost the same time as a massive asteroid smashed into the earth.

The dinosaurs ruled the planet for over 160 million years, but 65 million years ago, something terrible happened that wiped out every species of dinosaur (except for the ancestors of birds). So what was this terrible event? The common explanation these days is that an asteroid or meteorite killed the dinosaurs (an asteroid is bigger than a meteorite, and a meteorite is a meteoroid that has entered a planet’s atmosphere), and there is a lot of evidence that an asteroid around 6 miles across slammed into Mexico about 65 million years ago. The crater it left is hidden under rocks and water, beneath an area called Chicxulub, and the event is known as the Chicxulub impact.

The Chicxulub impact blasted a crater more than 100 miles wide, setting off earthquakes around the planet. The explosion took out most of North America almost instantly with a flash of intense heat and a destructive shock wave, battering the rest of the planet with super-powered hurricanes, or hypercanes, five times more powerful than the biggest hurricanes we get today. A huge wall of water known as a tsunami raced outward from the impact site, reaching up to more than 300 yards high and sweeping nearly 200 miles inland. But all this was only the beginning.

The location of the Chicxulub impact

Vast amounts of melted rock were thrown into the sky and rained down all over the planet, setting fire to everything. Up to a quarter of all life on land was burned to ash. The dust and smoke shut out all sunlight, probably for several years, so that the earth froze in the darkness as temperatures fell by up to 59°F. Plants could not photosynthesize, and poisonous gas made the oceans toxic. The ozone layer was damaged, so that when the smoke finally cleared, the earth’s surface was bathed in deadly ultraviolet light.

As if this were not bad enough, life on Earth was probably already suffering as the result of a series of volcanic eruptions in an area of what is now India called the Deccan Traps. These were not like ordinary volcanic eruptions; they were much, much worse. About 123,000 cubic miles of molten rock poured out of a titanic gash in the earth’s surface. When it cooled, it left a layer of solid rock over 1.24 miles thick in places, covering an area of about 193,000 square miles.

The final blow

The heat, ash, and poisonous gas released by the Deccan Traps eruptions helped push the dinosaurs close to extinction. The Chicxulub impact, contrary to popular belief, was probably the thing that finished them off.

Humanity could easily go the way of the dinosaurs. There are several places on Earth, such as Yellowstone National Park and the area around Naples in Italy, where eruptions on the scale of what occurred in the Deccan Traps could happen at any moment. Also, there are millions of asteroids that cross the earth’s orbit, and some of them could be 6 miles wide or bigger. Over a long time scale, your chances of dying because of an asteroid impact are roughly equivalent to your chances of dying in an airplane crash.