How did Megalodon sharks go extinct?
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Moment of Om comes to you from ABM Studios. I'm Chum McSharkerson, the Tiger Shark. Um... I'm working on some homework for Shark School. Check it out. We're supposed to pick a famous shark species that we admire and dress up like them. I obviously picked Megalodon, a.k.a. the most epic shark that ever lived.

These prehistoric sharks lived a long time ago, and they weren't just big. They were really, really big. They could grow almost 60 feet long, which is longer than a school bus. Plus, they had huge teeth, about as long as a dollar bill. So, Megalodon went extinct more than 3 million years ago, but I've always wondered why.

My human buddy Sienna was asking about this too. Let's ask someone who knows a lot about ancient sharks.

Unfortunately, or fortunately, however you look at it, megalodon is definitely extinct. My name is Callie Moore. I manage the fossil collection at the University of Montana in Missoula. So megalodon was one of the largest predatory sharks that has ever lived. It may have been upwards of 50 feet long. So that's like the width of a basketball court.

How do we know that Megalodon is definitely extinct? Well, we've got really good fossil records from the time that Megalodon lived in between 23 and about 3.5 million years ago. And we find these very complete outcrops of rock that show Megalodon teeth up to a certain point. And then after that certain point, you don't find anymore.

And if Megalodon was still alive today, they lose teeth just like modern sharks do. So they're constantly replacing their teeth and they're falling out and they're falling into the bottom of the ocean that turns into the rock that we look in for fossils someday.

And so when we see that there's no more of these fossil teeth and then there's no more giant non-fossilized teeth out there, it gives us a pretty good idea that megalodons aren't around anymore. The difference between the teeth would probably be in color and how well they are preserved. So a lot of megalodon teeth can be very colorful. The fossilized ones, obviously, they can be almost black, grays, browns, tans, reds.

Basically, any color that you can have in rock, you can have in a megalodon tooth. But modern shark teeth, fresh shark teeth are white. They're pearly whites.

There was a lot of things happening around the time of its extinction about three and a half million years ago. There was some climate change happening. It was a global cooling event. The sea levels were falling because ice was sucking up water and dropping sea levels. We know that megalodons kind of like the warmer areas.

You can find Megalodon teeth almost globally, but they'd never lived into the Arctic, the far north or the far south. So we think they liked warmer weather. And if things are cooling down and your sea levels are dropping, you are restricting their range because the cold weather is coming farther south or going farther north.

You also had some ocean circulation change. So today we have Central America and that's where Panama is and some other Central American countries. That hasn't always been there. And about three and a half million years ago, it was uplifted and completely cut that ocean circulation off.

So if you were a megalodon and you needed to pass through the Panamanian seaway to get to your breeding grounds, let's say, and now all of a sudden there's a continent and you can't get there anymore. We know from modern salmon, when you block these fish off from their breeding grounds, it can have devastating effects on their population numbers. And this is also changing the availability of their prey. We think that

Megalodon, while they were gigantic, they actually liked small prey. They really, really liked to eat little tiny whales. And we do see a decline in little tiny whales around this time too. So you have climate change, you've got the ocean circulation change, you've got prey availability changing, and then you also have

Um, uh,

Scientists think a few different things might have caused Megalodon to go extinct. About three and a half million years ago, the Earth's climate started getting cooler. Megalodon liked warmer waters, so when the oceans got colder, it was bad news for these prehistoric sharks.

Some of the Earth's continents were also shifting around back then, which might have cut off Megalodons from the places they wanted to find mates and have babies. And if that wasn't enough, they were also competing for food with great white sharks. It was a pretty rough time for our giant pal, the Megalodon.

Okay, add a few dabs of glue here and a couple of sequins there, and I think that should do it. My school project is done! I've made the perfect Megalodon costume. One problem though. How am I supposed to get this 60-foot long prehistoric shark costume through the door?

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This costume definitely needs more sequins. That's scientifically accurate, right?