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What caused the first mass extinction on Earth? – Aayush, 10, New Jersey

December 12, 2024 melissamayer

Dear Aayush,

It’s sad when living things go extinct. That means they’re gone forever. I think about extinct unicorns all. the. time.

My friend Jodi Rosso told me that a mass extinction is when a huge number of species die out all at once. She teaches earth science at Washington State University.

“There are periods when a whole lot of animals and plants die off in a short time,” Rosso said. “When we say a short time, we mean less than 2 million years. From a human perspective, that's forever. But in geologic time, that's short.”

Groups of living things are always expanding or shrinking their numbers. Scientists think there are as many as 10 million species on Earth right now. Between 100 and 10,000 of them go extinct every year.

A mass extinction is when big percentage of all species die off.

Did man live with dinosaurs together? – Daniel, 9, Republic of Korea

August 15, 2024 melissamayer

Dear Daniel,

When I think about dinosaurs, I usually picture the big ones. I think of triceratops with its pointy horns or apatosaurus with its long, long neck.

I asked my friend John Blong if those dinos ever lived with people. He’s an environmental archeologist at Washington State University. He studies early humans.

He told me that people and dinosaurs never lived at the same time. Well, mostly.

Dinosaurs went extinct 66 million years ago when a giant asteroid crashed to Earth. It threw up tons of dust and soot. It made Earth super cold and dark. It stayed that way for a long time. The world became a very hard place to live. Eventually, 75% of all living things died, including all the big dinosaurs.

People didn’t live on Earth at that time. The only mammals that lived back then were tiny. They looked like shrews or moles. It would take millions of years before mammals adapted enough to become primates. Scientists think the first humans showed up about 300,000 years ago. That was long after the dinosaurs died out.

But some dinosaurs survived the asteroid.

How did one comet kill all the dinosaurs? If crocodiles, snakes and birds came from dinosaurs, did it actually kill all of them? — Mya, 11.4, Virginia

October 12, 2023 melissamayer

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.

Did dinosaurs eat humans? – Brileigh, 10, North Carolina

March 2, 2023 melissamayer

Dear Brileigh,

If you looked inside a T. rex mouth, you’d see some 12-inch teeth. That’s longer than my tail!

I asked my friend Aaron Blackwell if dinosaurs used those big chompers on humans. He’s an anthropologist who studies human biology at Washington State University. He told me dinosaurs and humans didn’t live at the same time.

“Dinosaurs died out 65 million years ago—before there were even primates,” Blackwell said. “So, they could never have eaten a human or even a monkey.”