How did ferns survive the dinosaur extinction?

MAYA: You're listening to Brains On, where we're serious about being curious.

PRESENTER: Brains On is supported in part by a grant from the National Science Foundation.

MO GREEN: What's a fern like you doing on a plane like this?

JAMES FROND: Needed to uproot myself for a bit, darling.

MO GREEN: I know the feeling. I'm Green, Mo Green.

JAMES FROND: Enchanté, Ms. Green. The name is Frond, James Frond. International fern of mystery.

MO GREEN: [CHUCKLES]. Your soil is looking a little dry. Would you care for a drink, Mr. Frond?

JAMES FROND: Of water. Shaken, not stirred.

MO GREEN: Coming right up.

JAMES FROND: You know, I'm actually on my way to Brains On HQ. Have you heard of it?

MO GREEN: Brains On HQ, you say? I don't think so. But I have a funny feeling you won't be getting there, Mr. Frond.

JAMES FROND: Did you just pull for a nominally large scissors out of your tight-fitting green trousers, Ms. Green?

MO GREEN: I did, Mr. Frond because it's time to give your fern fronds a little trim.

JAMES FROND: I don't think so.

MO GREEN: How are you going to escape? Ferns don't have feet. You're not going anywhere, Double O Stemming.

JAMES FROND: Yes, but you forgot one thing. You are about to step on that large green button on the floor.

MO GREEN: I just stepped on a large green button on the floor.

JAMES FROND: Which just opened this handy little trap door next to me. Time to activate my emergency parachute and let these fronds fly.

MO GREEN: I'll get you next time, Mr. Frond. Just you wait.

[MUSIC PLAYING]

MOLLY BLOOM: You're listening to Brains On from APM Studios. I'm Molly Bloom. And my co-host today is Maya from Tuscaloosa, Alabama. Hi, Maya.

MAYA: Hi, Molly.

MOLLY BLOOM: And today, we're talking ferns.

MAYA: Ferns are a kind of plant.

MOLLY BLOOM: They don't have flowers, but they do have what are called fronds. So Maya, how would you describe what a fern looks like?

MAYA: Small, spiky plants with long leaves.

MOLLY BLOOM: Yeah. When I think about it, I think it's like if a feather was a plant. And ferns are super cool because they're found all over the world and in all kinds of climates. So Maya, you live in Alabama. Do you have any ferns near you?

MAYA: I have a few ferns. Most of them are like planted, not really wild.

MOLLY BLOOM: I know you're something of a gardener yourself. Can you tell me your favorite part about gardening?

MAYA: Playing in the water.

MOLLY BLOOM: Are you using a hose, a can? How do you water your plants?

MAYA: Sometimes we use cans. But for the first time-- like when we plant them, we use hoses.

MOLLY BLOOM: Awesome. And what kind of plants do you have in your garden?

MAYA: We have a hibiscus tree, two of them, some flowers.

MOLLY BLOOM: And do you grow any vegetables or anything for eating?

MAYA: Maybe this year, we will.

MOLLY BLOOM: Cool. OK. Let's say there's other kids out there who are interested in helping garden, what advice would you give them?

MAYA: Make sure you water them almost every day. Even when it's hot, maybe water them like two times a day to make sure it gets more water.

MOLLY BLOOM: Good advice. And what's your favorite thing about hanging out with plants?

MAYA: Watching them grow. It's very calming, like being outside in nature.

MOLLY BLOOM: Those are all really good reasons. Well, this whole episode is inspired by this excellent question sent to us by Gideon from New City.

GIDEON: How did ferns survive the dinosaur extinction? And are they the same ferns that we see now?

MAYA: That is an excellent question.

MOLLY BLOOM: You may have heard that ferns have been around since before the dinosaurs and that's true.

MAYA: But dinosaurs are extinct, and ferns aren't.

MOLLY BLOOM: So we're going to tackle Gideon's excellent questions by looking at the second part, first.

MAYA: Are the ferns we see today, the same as the ones the dinos lived with?

WESTON TESTO: The answer is yes and no.

MOLLY BLOOM: That's a fern friend with an excellent name, Weston Testo.

MAYA: That is an excellent name.

MOLLY BLOOM: He studies plants at the University of Vermont and he's also the director of the Pringle Herbarium.

MAYA: It's a museum dedicated to plants.

MOLLY BLOOM: OK. So Weston, what do you mean when you say the answer is yes and no?

WESTON TESTO: So ferns have been around for a very, very long time. There's evidence that ferns have been around probably at least 360 million years.

MAYA: That means they were around even before the dinosaurs.

WESTON TESTO: But most of the species that we have around today are much younger. So they seem to have evolved much more recently than the age of the dinosaurs. But there are some species of ferns out there that we think have been basically unchanged since the time of the dinosaurs, which I think is really exciting.

MOLLY BLOOM: OK. I get the yes and the no, now. Yes, there are some species that were here when the dinos were. But not all ferns we see today have been around that long.

MAYA: One of the oldest fern species still around today is a cinnamon fern. You can see them all over North and Central America.

MOLLY BLOOM: They have brown, shaggy, cinnamon-colored stalks that grow up from the middle of the fronds.

MAYA: If you see one of these, we recommend pretending you're a dinosaur, at least for a little while.

MOLLY BLOOM: Here's my dino impression, [GROWLS]. What's yours, Maya?

MAYA: [ROAR]

MOLLY BLOOM: Oh, yeah. Yours is much more fierce than mine. Excellent. And in addition to being old, ferns are everywhere. They love humidity like in tropical places. They also do great in forests here in North America.

MAYA: But you can also find them in lots of other places too.

WESTON TESTO: There are many, many ferns that grow in deserts, which I think is really surprising to a lot of folks. But thinking within the United States, for example, one of the states that has the highest richness of ferns would be New Mexico.

MOLLY BLOOM: And the same species of ferns can be found in parts of the world that are really far away from each other.

MAYA: You see the same species of ferns in far off places, like Europe and Asia.

MOLLY BLOOM: This isn't because humans have planted them all over the world, like say tomatoes or potatoes.

MAYA: Yeah. Ferns have become world travelers all on their own.

MOLLY BLOOM: And it's all thanks to the special way they grow and make more ferns.

MAYA: Lots of plants need pollinators to help them make more plants. Like a bee needs to take pollen from one flower to another before the plant can make seeds.

MOLLY BLOOM: But ferns don't need any help from pollinators. That's because they make something called spores.

MAYA: Spores are like teeny, tiny seeds the size of a piece of dust that ferns release into the wind.

WESTON TESTO: And those blow around in the wind. And if they land in the right kind of habitat, they'll produce a new fern there. And because of that, ferns are really good at getting around the world. One of the most interesting experiments I've ever heard of is researchers put double-sided tape on little microscope slides and hung them off airplane wings. And flew those airplanes way, way up in the air. And they picked up lots of spores. If you're ever in an airplane going a really long distance, you can imagine that there are ferns spores blowing around way up in the air around you.

MOLLY BLOOM: Spores are International travelers.

MAYA: That is so cool.

JAMES FROND: And that surprises you when I exist? James Frond, International fern of mystery?

MAYA: Excuse me, how did you get in here?

JAMES FROND: James Frond has his ways and they are top secret.

MOLLY BLOOM: OK, then. Moving on.

JAMES FROND: OK, fine. I'll tell you. How would you react if I told you there was a network of top secret fern agents underground?

MAYA: Probably like this, gasp!

MOLLY BLOOM: And I'd probably go, whoa, whoa, whoa, whoa, what?

JAMES FROND: Well, there is a network of top secret fern agents underground.

MAYA: Gasp!

MOLLY BLOOM: Whoa, whoa, whoa, whoa, what?

JAMES FROND: Since you were honest about your reactions, I feel comfortable telling you more.

MOLLY BLOOM: Yes.

MAYA: Molly, be cool.

MOLLY BLOOM: All right. Go on, if you want. Whatever.

JAMES FROND: We, ferns have what are called rhizomes. They're underground stems. And that's where our leaves come from. And many of us have intricate, creeping networks of these rhizomes that can stay alive even if all of our leaves are gone.

MOLLY BLOOM: So even if you got munched on by an animal or your leaves got burned in a forest fire, you could easily grow back from those underground stems?

JAMES FROND: You're right on the money, Honey.

MAYA: OK. That is some super secret spy stuff right there.

JAMES FROND: We ferns are unstoppable. We've survived not one, not two, but three mass extinction events.

MOLLY BLOOM: Whoa. Those are times millions of years ago when most species on the planet went extinct, and only a few survived. One of those was the mass extinction event that wiped out the dinosaurs.

JAMES FROND: Got to say, we ferns don't miss the dinos. They never watched where they were going. And they had such big feet.

MAYA: It's pretty cool that ferns have outlived so many other species.

JAMES FROND: I have yet to meet a foe I couldn't vanquish.

MAYA: And by vanquish, do you mean outlive by staying very still and using your evolutionary advantages to survive?

JAMES FROND: I'll never tell. That's for me to know and you to "ferned" out. And with that, I must be off.

MOLLY BLOOM: That was thrilling. But you know what might be even more thrilling, it's time for the--

[SHUSH]

PRESENTER: --Mystery Sound.

MOLLY BLOOM: Here it is.

[CHOP]

Maya, what do you think?

MAYA: I believe it's like chopping something hard like celery, or like a keyboard.

MOLLY BLOOM: Both excellent guesses. Both very different. What made you think it might be chopping celery?

MAYA: Because I heard like the knife hitting a wooden cutting board or a cutting board.

MOLLY BLOOM: Yeah. That's a really good guess. And what parts of it made you think it might be a keyboard?

MAYA: At first, I thought I heard like clicking on a keyboard.

MOLLY BLOOM: Mmm. OK. Very interesting. Well, we'll hear it again, give you another chance to guess and hear the answer at the end of the show. We're working on an episode about cavities. Those tiny holes we sometimes get in our teeth. Nobody likes getting cavities, but luckily brushing your teeth helps keep them from forming. So we want to hear from you. If you could design the toothbrush of the future, what would it be like? Maya, what would your toothbrush of the future be able to do?

MAYA: Mine will have tiny bristles and shoot out water. Like anything you put in the capsule, like mouth freshener or mouthwash and put it in those tiny holes that you get to clean them out.

MOLLY BLOOM: Oh nice. So it's like everything in one convenient package that you would need.

MAYA: Mmh.

MOLLY BLOOM: I love it. Are you a fan of brushing your teeth?

MAYA: Yes.

MOLLY BLOOM: Excellent. I love to hear it. What is your preferred flavor of toothpaste?

MAYA: Probably watermelon.

MOLLY BLOOM: Oh, excellent. Excellent choice. Well listeners, record yourself describing your super snazzy toothbrush of the future and send it to us at brainson.org/contact. And while you're there, you can send us mystery sounds, drawings, and questions--

MAYA: --like this one.

LISTENER: My question is, how does concrete get hardened?

MOLLY BLOOM: Again, that's brainson.org/contact.

MAYA: And keep listening.

[MUSIC PLAYING]

(SINGING) Brains On.

MAYA: You're listening to Brains On. I'm Maya.

MOLLY BLOOM: And I'm Molly.

MAYA: OK. So we just found out that some of the ferns on Earth today were actually around when the dinosaurs were.

MOLLY BLOOM: And that ferns can spread super far, thanks to their teeny, tiny spores. Plus, they can live in all sorts of places.

MAYA: But we still need to answer this part of Gideon's question.

GIDEON: How did ferns survive the dinosaur extinction?

SANDEN TOTTEN: Oh, such a great question, and one that scientists are actually trying to answer right now.

MAYA: Hey, it's Sanden Totten.

SANDEN TOTTEN: Everyone's favorite Brains On producer.

MOLLY BLOOM: I so admire your confidence.

SANDEN TOTTEN: I do too. Anyway, I'm so excited to share this new play I've been working on about this very topic. But first, let me wheel in my cart of highly trained polypodiopsida thespians.

MOLLY BLOOM: Your what?

SANDEN TOTTEN: Polypodiopsida means fern. And thespians are actors. You know, ferns who act. Molly, Maya, meet the world's most talented/only all fern theater troupe. We've got Fern Drescher, Sporelando Bloom, Jane Fronda, and Keanu Leaves. Say hi, everyone.

MAYA: I don't hear anything.

SANDEN TOTTEN: Oh, that's because they're already in character. They're very method.

MAYA: In character as?

SANDEN TOTTEN: As ferns.

MAYA: Sanden, they are ferns.

SANDEN TOTTEN: Yes, they truly are any role they step into. Oh, you should have seen their production of Wicked. Jane Fronda literally turned herself green for the role of the witch, Elphaba. Oh, it looked so real. Anyway, my fern friends are going to re-enact key moments of the dinosaur extinction in a play called, As the World Ferns. A new play written, produced, directed, choreographed, scored, financed, reviewed, and widely praised by me, Sanden Totten. First, you'll need some background. So let me tell you about a trip I took to meet our play's scientific advisor and fellow fern aficionado, Regan Dunn.

REGAN DUNN: Ferns are very cool for a lot of reasons.

SANDEN TOTTEN: Regan studies super old plants at the La Brea Tar Pits museum in Los Angeles.

REGAN DUNN: They've lived through a lot of different events in history, and they're still here today.

SANDEN TOTTEN: I met at her lab to learn about how ferns survived the big extinction that happened 66 million years ago.

MAYA: That's one that wiped out most of the dinosaurs.

SANDEN TOTTEN: Right? It's a dramatic tale. Perfect for a play that will no doubt sweep the Tony's this year. We can't go back in time to see what happened. But Regan says, there are lots of ferny clues about what happened, buried deep underground.

MAYA: Ferny clues?

SANDEN TOTTEN: Yeah. Stuff like ancient fern leaves and fern spores. You know, those teeny, tiny specks that ferns use to make more ferns. Regan and her team, they dig up these clues, put them on thin sheets of glass called slides, and look at them under a microscope. She showed me some of these slides using a very big microscope at her lab.

REGAN DUNN: Here is a bunch of microscope slides that have been processed and they're stacked up here. There's 100 slides here from one of our sites.

SANDEN TOTTEN: Yeah. It's this little tray full of all these tiny sheets of glass. Each one is pretty thin. And it has this almost like, it looks like a little cloud of red specks on it. What are the red specks?

REGAN DUNN: So those red specks are the spores.

SANDEN TOTTEN: Spores from ancient ferns. Each slide gives us a picture of what Earth was like at a given moment in history. Regan first showed me one from just before the big extinction during a time called, the Cretaceous. The slide was full of these fern spores, as well as pieces of lots of other plants.

REGAN DUNN: All right. So 66 million years ago in the Cretaceous, life was great. It was really warm. There was high carbon dioxide. And there were a lot of plants growing everywhere that the dinosaurs were chomping on.

SANDEN TOTTEN: It was a great time to be alive for plants. But then all that changed.

[DRAMATIC MUSIC]

A giant asteroid came hurtling to Earth from space. It smashed into the Yucatan Peninsula near Mexico. [EXPLOSION]

That sent massive tsunamis flooding the coasts. Whoosh, whoosh. It sparked wildfires that ravaged the land. It kicked up dust that blocked out the sun, making things super chilly and dark. Very quickly, around 75% of all life went extinct.

[GASPING]

Poof. I'm dead. But what happened to our heroes? Spotlight on the ferns. Oh, that was brilliant, y'all. I could see the fear on your fern faces, especially you, Keanu Leaves. Bravo. Make sure you channel that exact same energy for previews.

MAYA: Wow. 75% of all life? That's huge.

MOLLY BLOOM: Yeah. And it wasn't just dinosaurs. It also wiped out giant marine reptiles like the ichthyosaurus, and huge shelled creatures called ammonites.

SANDEN TOTTEN: 70% of all plant life too. It was grim. Next, Regan showed me a slide with the microscope that had stuff on it from just after the meteorite impact. Unlike the last slide, this one had hardly any signs of plant life on it, except for one.

REGAN DUNN: What we see if we look really closely at samples-- teeny, tiny little samples are the spores of ferns. So ferns were growing in these ecosystems prior to the event. But after the event, that's pretty much what you see. They really dominated the landscape.

SANDEN TOTTEN: Picture this. The curtain rises on a new day. The bones of giant dinos are strewn across the stage. There are charred husks of trees. It's silent. Still. But then, the light shine on one plant that's still standing. Our protagonists, the ferns. Yes. Yes. Great frond works, Sporelando Bloom. Fern Drescher, give me more resilient courage. Oh, yes. That's perfect. Perfect.

MAYA: You know, I'm really buying these performances from the ferns.

SANDEN TOTTEN: I'm telling you, they're going to be stars. So for hundreds of years after the asteroid hit, ferns were the main plant growing on Earth. It was a ferntopia, if you will. But another cool thing about ferns is they're really good at making healthy soil. So these ferns, they ruled the world. But they were kind, and benevolent, and generous rulers. Over time, they made rich, fertile soil that helped other plants come back and new ones evolve. Those plants fed bugs. Small mammals ate those bugs, and bigger mammals ate the smaller ones. And soon a whole new world was born.

MOLLY BLOOM: Wow. All thanks to ferns?

SANDEN TOTTEN: Well, not totally. But they played a huge role in helping the world recover. We humans, might not be here today, if it weren't for ferns.

MAYA: I never thought of it like that.

MOLLY BLOOM: So how did they do it? How did they survive when so many other plants and animals didn't?

SANDEN TOTTEN: Oh, great question. We don't totally know all the pieces, but we do know that ferns have a lot of great traits that make them born survivors. You already mentioned some of them, but I'll let recap.

REGAN DUNN: Ferns are great survivors because they can grow in very low light environments, one. Secondly, they have rhizomes or these stems that grow underground that can sprout and grow new plants when they've been disturbed by a fire, or like a lawn mower, or something like that, or a dinosaur chomping away at them. Third, they reproduce by tiny, little spores. And so a tiny spore that is just like a quarter of the width of your hair.

One single stranded hair is all it needs to produce a whole fern plant. And so all a spore needs is a little wet spot on the ground. The spore can land there and then generate a plant in a very short time period.

SANDEN TOTTEN: Even with all these superpowers of survival, we know things were really bad after the meteor hit Earth. There were fires, dark skies, cold weather. Regan and her team wanted to know more about how ferns survived all that. So they decided to recreate the extinction.

MOLLY BLOOM: How do you do that?

MAYA: Yeah. That sounds dangerous.

SANDEN TOTTEN: You do it on a very small scale. They took a greenhouse and stuffed it with plants similar to the kinds of plants you would find in the Cretaceous period.

REGAN DUNN: There are seven different species of plants, including redwoods, and Dawn redwoods, and several types of ferns, and even palm trees because palm trees were also growing at that time.

SANDEN TOTTEN: They also made the air and temperature in that greenhouse a lot like what it was back in the days of the dinosaurs.

REGAN DUNN: And so we let those plants just grow in this really nice environment. Everything was happy. It was warm. And then we decided to simulate the impact.

SANDEN TOTTEN: To do that, they painted the walls. So very little light could get in. They lowered the temperature inside the greenhouse until it was super chilly.

REGAN DUNN: And some plants even were treated with acid. We painted it on with paint brushes because that's one of the things that happened after the impact was that acid rain rained out. And that has pretty detrimental effects on leaves.

MOLLY BLOOM: Whoa. Painting with acid? This is an extreme experiment.

MAYA: Totally.

SANDEN TOTTEN: I know, right? Then they monitored the plants for six months to see how they did.

REGAN DUNN: Well, it was pretty surprising. Every plant did their own thing. So some plants had no problems. Redwoods, they don't care. They just continued to grow. Other plants that lose their leaves, they lost their leaves immediately and stayed sort of dormant like a maple tree when it loses its leaves in winter. And then a lot of the plants died.

SANDEN TOTTEN: Regan and her team are still studying what happened in that greenhouse. They're hoping to learn things about how the ferns used water during this harsh period, how they responded to not having much light, and more. She says unlocking the secrets of how ferns survive is important because right now, our climate is changing. Greenhouse gases are warming up the planet, and that's going to affect a lot of plants. Ferns might just teach us how to help those other plants survive too.

MAYA: That's really cool. Ferns really do so much for the world.

MOLLY BLOOM: Yeah. So how does your play end?

SANDEN TOTTEN: Well, it ends with a glimpse into the future. It's the year 2100. The stage is bathed in a rusty red light. The landscape is bare, rocky, alien. We're on Mars. Humans have just set up a colony and they need a plant that can grow in extreme conditions. One that can help make rich soil for other plants to follow. We see a platform rise from center stage. It's lifting up, up, up. It's the ferns. Human astronauts stand around them, saluting the ferns for their bravery.

That's your cue, guys. Look heroic. Oh, perfect. The music swells and end scene. The curtain falls, the crowd goes wild. Yay, ferns are amazing! We love you! We love you! This is the best play ever! Let's give it all the awards! I agree! Ooh Yeah!

MOLLY BLOOM: You know what, I'll totally go see this play. It does sound amazing.

MAYA: Yeah. We'll come opening night.

SANDEN TOTTEN: Oh, I'm pretty sure it'll be sold out. But maybe I can get you on a standby list or something. Now, I better get my ferns to their dressing room to rest. As you can imagine, a performance like that really takes it out of them.

MOLLY BLOOM: Of course.

MAYA: Thanks Sanden. Bravo ferns.

[MUSIC PLAYING]

Ferns are ancient plants that were around during the time of the dinosaurs, and they're still thriving today.

MOLLY BLOOM: They have underground networks of stems called rhizomes that allow them to grow back even if their tops are trampled or burned.

MAYA: And they spread by sitting little things called spores into the air. Those spores can ride the wind far and wide before landing on some wet soil and growing into a whole new fern.

MOLLY BLOOM: Scientists are still trying to understand how ferns survived the last great extinction. What they learn could show us how to help other plants survive as our climate changes. That's it for this episode of Brains On.

MAYA: This episode was written by Molly Bloom and Sanden Totten. It was produced by Rosie DuPont, Anna Goldfield, Aron Woldeslassie, Anna Weggel and Marc Sanchez.

MOLLY BLOOM: We had editing help from Shahla Farzan, sound design by Rachel Breeze. And we had engineering help from Derek Ramirez, Nick Golden, George [? Edmundson ?] and [? Elyssa ?] Beckwith. Beth Perlman is our executive producer. The executives in charge of APM Studios are Chandra Kavati, Alex Schaffert and Joanne Griffith. Special thanks to my dad, Stewie Bloom.

MAYA: Brains On is a non-profit public radio program.

MOLLY BLOOM: There are lots of ways to support the show. Head to brainson.org.

MAYA: While you're there, you can send us mystery sounds, drawings, and questions.

MOLLY BLOOM: And you can subscribe to our Smarty Pass. It gives you a special ticket to Brains On universe bonus content, plus ad-free episodes. OK. Maya, are you ready to listen to that mystery sound again?

MAYA: Yes.

MOLLY BLOOM: OK. Here it is.

[CHOP]

MAYA: Think cutting celery or something hard.

MOLLY BLOOM: This is an excellent, excellent guess.

MAYA: I feel like it's a vegetable though.

MOLLY BLOOM: OK. Celery or some vegetable being cut. I love it. Should we hear if you're right?

MAYA: Yes.

MOW GREEN: OK, here's the answer.

SUMAYA: My name is Sumaya. I'm 11 years old. I live in Berkeley, California. That was the sound of me chopping celery.

MOLLY BLOOM: Stop. Maya, incredible ears. How do you feel?

MAYA: Awesome.

MOLLY BLOOM: That's so good. Oh my gosh, I think this must be because you spend so much time with plants, that you really understood what it sounds like when celery is being chopped.

MAYA: Or my mom cuts a lot of celery.

MOLLY BLOOM: Or that too. Nice work. Amazing Now, it's time for the Brains Honor Roll. These are the kids who keep the show going with their questions, ideas, mystery sounds, drawings and high fives.

[LISTING HONOR ROLL]

We'll be back next week with an episode all about cavities, and why we get them.

MAYA: Thanks for listening.