Article

TeamDAF/Shutterstock.com (soccer ball); skynesher/Getty Images (concussion)

The Day the Dinosaurs Died

Millions of years ago, the mighty dinosaurs were wiped out. But just what happened on that deadly day? 

Gary Hanna

Boom! Suddenly, the sky was on fire. Boiling-hot beads of glass rained down, blanketing and burning the ground. Dinosaurs fled in every direction, running for their lives. It was more than 66 million years ago, and a fiery space rock called an asteroid had just slammed into modern-day Mexico.

“Your eyeballs would have melted, your eardrums would have been destroyed,” says paleontologist David Burnham. 

The asteroid set off volcanic eruptions and earthquakes all over the world. While some species survived, 75 percent died—including dinosaurs. But how did dinos in areas thousands of miles away from the asteroid strike die? Without witnesses, that has remained a mystery for millions of years. Now scientists, including Burnham, have uncovered an area in North Dakota filled with fossils. They say it provides a terrifying snapshot of the day the dinosaurs died. 

Killer From Space

Andrea Danti/Alamy Stock Photo

For decades, experts debated what did the dinosaurs in. Some said it was a freezing ice age. Others argued that it was hot lava from volcanoes. Some had goofier guesses—like aliens kidnapping the dinosaurs! 

Evidence discovered in 1977 strongly suggests that the asteroid killed the dinosaurs. Scientists found a rare metal in Earth’s crust. It dates back to when the dinosaurs became extinct. The metal, called iridium, is rare in Earth rocks. But it’s common in asteroids.

In 1990, a giant crater, or hole, was also found deep underwater near the Yucatán Peninsula in Mexico. It showed the location of the asteroid strike. But no fossils were ever found to link the dinosaurs to the asteroid. 

“Everybody’s always said, ‘Your theory sounds really good, but where are the bodies?’” explains Burnham. “Well, we just found them.” 

A Deadly Day

The fossils were discovered in North Dakota in 2013. The area is nearly 3,000 miles away from where the asteroid struck. The fossils include the remains of fish, plants, and even a horned dino called a Triceratops.

Burnham and his team believe the site was preserved within hours of the asteroid strike. After studying the area, the team determined that it was once a riverbank near the shore of a shallow sea. 

Gary Hanna

When the asteroid slammed down, waves from the sea sloshed violently. They quickly grew into a terrifying 300-foot wall of water, rocks, and sand that buried creatures alive. 

The scientists found traces of iridium in the fossils. Burnham says this helps prove the asteroid theory once and for all.

Burnham and the team have spent the past few years studying the fossils. They released the first details from their once-in-a-lifetime find earlier this year. 

“It’s a huge milestone,” says Burnham. “It’s going to be in the textbooks.”

  1. Describe the effects of the asteroid that hit Earth.
  2. What is iridium? Why is it mentioned in the article?
  3. How is the sidebar “How Fossils Form” related to the article?

Close-Reading Questions

Click the Google Quiz button below to share these Close-Reading Questions with your class.

Download .PDF
Back to top
videos (1)
Skills Sheets (2)
Skills Sheets (2)