How Did The Dinosaurs Actually Go Extinct?

An artistic representation of the K-Pg extinction event.

Dinosaurs roamed the Earth for about 165 million years. However, in an instant, about 66 million years ago, most of them just disappeared. This is known as the Cretaceous-Paleogene, or K-Pg, extinction—an event that wiped out about 75% of Earth's species. But how did this happen?

The Asteroid Theory

One of the most widely accepted theories states that the extinction of the dinosaurs was caused by a huge asteroid impact. This asteroid, which is estimated to be around ten kilometers wide, struck what is today the Yucatán Peninsula in Mexico. The collision left a scar on Earth by creating a crater called Chicxulub, which is about 150 kilometers in diameter. The energy from this collision was gigantic—the equivalent of billions of atomic bombs detonating all at once. The immediate effect would have destroyed everything in the vicinity. But the real trouble began after the dust settled—or didn't.

After the Impact

The asteroid impact sent big clouds of dust, ash, and rock into the atmosphere. Many scientists think that these clouds blocked sunlight for months or even years. Without sunlight, photosynthesis ceased, and the plants died. Next to die off were the herbivores with no food, followed by the carnivores that preyed on them. Essentially, the food chain collapsed. In addition, the atmosphere was filled with sulfur compounds from vaporized rocks, which drastically dropped global temperatures, resulting in a prolonged "impact winter".

Global Consequences

The sudden change in the climate was very devastating. The drop in temperature due to the clouds of dust, ash, etc. was significant enough to alter the weather patterns of the world. Oceans were affected by these clouds as well because they reduced the water temperature and disrupted marine life by preventing sufficient sunlight from reaching the water. Acid rain, caused by the sulfur compounds, would have also been another blow to life forms. This combination of events created a domino effect, and it eventually led to the extinction of species that couldn't adapt quickly enough.

The Role of Volcanoes

A drawing of what the Deccan Traps may have looked like.

While the asteroid impact is the star of the extinction story, some scientists believe it was not the only actor. Already well underway at the time was intense volcanic activity in what is now India (the so-called Deccan Traps). These volcanoes were spewing out lava over millions of square kilometers, and they released huge amounts of greenhouse gases like carbon dioxide and sulfur dioxide into the atmosphere. This could have been one of the reasons for climate change both before and after the asteroid impact.

Life in the Shadow of the Asteroid

Not all life on Earth became extinct. Small life forms, especially those burrowing or living in water, had a much better chance of survival. Small and adaptable mammals began to fill the vacant spaces left by the dinosaurs. Birds, which are actually avian dinosaurs, also survived this catastrophe, showing that some "dinosaurs" could make it through this disaster.

The Evidence

A lot of evidence has been collected by scientists to support the asteroid theory. The first important piece of evidence is the global presence of a thin layer of clay rich in iridium, a metal rare on the Earth's surface but common in asteroids. In addition, shocked quartz, which forms only under extreme pressure like that of an asteroid impact, was found in this layer. This theory is also supported by the crater itself, which was found by geophysical surveys.

Other Theories

While the asteroid theory is the most accepted and supported, there are other explanations as well. One such explanation is the idea that the Deccan Traps volcanoes themselves could have caused enough climate change to kill off the dinosaurs on their own. A less popular one involves gradual changes in Earth's climate due to shifting continents and ocean currents, but these changes would have been too slow for such a mass extinction.

The Aftermath

Anyway, when the dust settled and the climate started to recover, life on Earth had changed forever. The extinction event opened the way to the rise of mammals, which would later result in human evolution. The different world that had emerged now had new species adapting to fill the emptiness left by the vanished dinosaurs.

Conclusion

The extinction of the dinosaurs is still a subject of study, with new findings possibly changing our understanding. The asteroid impact theory, which has a ton of geological evidence supporting it, gives the most compelling reason for the dinosaur mass extinction. Still, the combination of volcanic activity, climatic changes, and possibly other elements not fully identified, all acted in one of Earth's biggest biological twists. This event does make us remember that Earth is dynamic, and its life constantly evolves and adapts—or disappears.