Dear Mya,

It’s hard to imagine that one space rock wiped out the dinosaurs. But it did more than that. It killed 75% of the plants and animals on Earth. Me-OW.

I talked about that with my friend Barry Walker. He teaches geology classes about Earth’s history at Washington State University.

Walker told me that we call a space rock that hits Earth a meteorite. The meteorite that took out the dinosaurs set off changes on Earth. Those changes lasted for thousands of years. That’s how it killed so many things.

“We’re not saying everything got wiped out immediately,” Walker said. “Something happened, and within a geologically short amount of time—maybe 10,000 years or so—the damage was fully wrought.”

A map showing the Yucatan peninsula with a red circle where the Chicxulub crater is
The Chicxulub crater shown with a red circle and black dotted line  Credit: NASA/JPL-Caltech/David Fuchs/Wikimedia Commons

That something was a meteorite called Chicxulub. It crashed into Earth nearly 66 million years ago. It made a giant bowl-shaped hole in the ground called a crater. The crater is about 100 miles wide and around 12 miles deep. It’s near Mexico.

The meteorite killed everything near the crater. It caused fires for hundreds of miles. It set off earthquakes, huge waves called tsunamis and volcano eruptions.

It also sent up a ginormous cloud of dust and soot. That cloud spread over the planet. Today we can see a layer of rock from that time all over the world. It contains a rare element called iridium that came from the meteorite.

All that dust, soot and wildfire smoke in the air blocked out the sun’s light. Earth became dark and cold. Plants need the sun’s light to make food. Without light, lots of plants died. Then plant-eaters and meat-eaters died, too.

Scientists think Earth was dark for about two years. But the changes on Earth lasted much longer.

The animals that survived mostly got lucky. They adapted to the changes and made homes where other animals couldn’t. It was easier for animals who ate detritus—or bits of dead stuff. Or animals who could go without food for a long time. Like snakes and crocodiles. It was harder for big animals who lived on land. Like the big dinosaurs.

But some dinosaurs did survive. They’re still alive today. We call them birds. They belong to a group of dinosaurs called theropods. That’s the same group that once included T. rex and velociraptors.

Scientists think that bird-dinosaurs without teeth were the ones that survived. They used their beaks to pick out tiny seeds in the soil. They were small so they needed less food.

Of course, no humans were around back then. Everything we know about Chicxulub comes from looking at clues. They’re our best guesses.

“Science is a method of asking questions,” Walker said. “All the stuff we’re talking about is based on evidence. But being comfortable with uncertainty is a good thing. It’s an opportunity.”

The exciting thing about your question is that scientists are still answering it.

For now, I guess you could say surviving the meteorite was for the birds.


Dr. Universe