Move over, TikTokers. It's time to shine a spotlight on some of the earliest influencers around: dinosaurs. When these ecosystem engineers were in their heyday, forest canopies were open and seeds were small. But around the time most dinosaurs were wiped out, paleontologists noticed an interesting shift in the fossil record: Seeds got bigger — much bigger. There was a fruit boom. Did the death of these dinosaurs have something to do with it? And who are the modern day equivalent of dinosaur influencers? To find out, host Emily Kwong talks to Chris Doughty, an ecologist at Northern Arizona University.Tell us what other tales of dino past you want us to regale you with by emailing us at [email protected]! Listen to every episode of Short Wave sponsor-free and support our work at NPR by signing up for Short Wave+ at plus.npr.org/shortwave.Learn more about sponsor message choices: podcastchoices.com/adchoicesNPR Privacy Policy
Chapter 1: What did the world look like in the Cretaceous period?
You're listening to Shortwave from NPR. Today, we are going back in time, all the way to the Cretaceous period. Here's what it looked like.
It would have been a very bright forest. It would have been very open. You have a lot of pine trees.
A time that Christopher Doty loves because of this one kind of dinosaur.
Chapter 2: How did sauropods influence ecosystems?
The sauropods are the biggest terrestrial animal that's ever walked the Earth.
Chris uses big data sets to understand ecosystems. He's an associate professor of ecoinformatics at Northern Arizona University. And he told me that sauropods were so big, they acted like ecosystem engineers.
They can knock down trees. They can distribute nutrients. They can move seeds. They do a lot of really important things. And big animals tend to do that differently than small animals.
And the way sauropods move nutrients and seeds around was through their poop.
Yeah, and their bodies.
The decaying corpse of a sauropod.
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Chapter 3: What happened after the dinosaurs went extinct?
That's true. That's not quite as fun to think about. But yeah, it's like the circle of life.
Maybe there was like a Mufasa sauropod who was like, my son, you'll be the grass someday. That's right.
Yeah, those same elements have cycled through your son that were in a sauropod someday.
Those sauropods were herbivores eating plants. And the plant seeds from this time were actually kind of small, like a centimeter across. And that was fine for them because of all this light in the understory.
Chapter 4: Why did seeds get bigger after the extinction?
And so there was no evolutionary reason for seeds to get big. But what happened was after the dinosaurs went extinct, the forest got really dark.
When the asteroid hit, it wiped out as much as 75% of all life on Earth. And suddenly there were no longer these big dinosaurs to knock down the trees. So the trees grew lush and tall, and the understory between the forest floor and the tree canopy got roughly 20% darker.
For a little seed, that's trouble. You know, these little seeds, they need light.
And paleontologists observed something weird in the fossil record around this time. Not long after the asteroid hit, seeds suddenly got bigger. Much bigger. And there was this sudden boom in fruit, the edible plant ovaries we love today. But why? And what did the death of the dinosaurs have to do with it?
Today on the show, how the mass extinction of the dinosaurs may have led to the fruit and vegetable aisle you see today. And how we're living in another time of mass extinction where the dinosaurs are us. I'm Emily Kwong and you're listening to ShoreWave, the science podcast from NPR.
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It is certainly reversible, but we are no longer living in a liberal democracy.
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Chapter 5: How do scientists study the effects of mass extinction?
And so then what we do is we take, you know, all this information going from fossil records to how plants grow, to how seeds grow, to how forest elephants affect forests, and we put it into a model. You can think of it like a computer simulation.
It's like Roller Coaster Tycoon.
Chapter 6: What is the significance of modern megafauna in ecosystems?
I don't know that one, but yes, like, you know, like, you know, SimCity or something.
Yeah, that's the same genre. You're taking all this real world data and you're putting it into a model and you're saying like, what if?
Exactly. Yeah. And then you just allow, you know, millions of years of ecology to happen. And so basically you just kind of input this into our model and then you see what happens.
So yeah, what's the verdict?
The verdict is, yeah, it worked. So, you know, basically what we saw was the darker understory basically created an evolutionary advantage for bigger seeds. And so those bigger seeds then created fruit that would entice bigger animals to eat them. And these bigger animals would distribute the fruits farther.
And the trees that are moved farther away from their mother tree are very happy because you don't have to put up with the same diseases that your mother has. You don't have to be under her shade. And so that's an evolutionary incentive as well. So basically, they're bribing these animals with fruit to move them around.
In the time immediately following the mass extinction of the dinosaurs, did that eventually give rise to the ancestors of primates?
Yes. Our primate ancestors developed because they were good at climbing trees and eating fruit. And so had there not been fruit, you wouldn't have this incentive to climb up in the tree and eat fruit.
So the death of the dinosaurs was our boon?
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