The Ancients - Dinosaurs: The Last Days

Episode Date: March 5, 2023

Around 66 million years ago, an asteroid the size of Mount Everest slammed into our planet, triggering the mass extinction of the dinosaurs and countless other species unable to adapt to the sudden environmental catastrophe that followed. What exactly happened on that fateful day, and what about the thousands of years after? Why did the most prominent creatures on the planet, the huge dinosaurs we know and love, die instantly, and how did other creatures like birds and crocodiles survive through to today?In this episode, Tristan is joined by author Riley Black to take a deep dive into the disaster’s immediate effects, including the massive shockwaves, earthquakes, tsunamis and years of darkness that would trigger the extinction of three-quarters of all plant and animal species on our planet. Welcome to the single worst day in the history of life on Earth.Riley's new book The Last Days of the DInosaurs is available here.For more Ancients content, subscribe to our Ancients newsletter here. If you'd like to learn even more, we have hundreds of history documentaries, ad free podcasts and audiobooks at History Hit - enter promo code ANCIENTS for a free trial, plus 50% off your first three months' subscription.

Hi, I'm Tristan Hughes, and if you would like the Ancient ad-free, get early access and bonus episodes, sign up to History Hit. With a History Hit subscription, you can also watch hundreds of hours of original documentaries, including my recent documentary all about Petra and the Nabataeans, and enjoy a new release every week. Sign up now by visiting historyhit.com slash subscribe. It's the Ancients on History Hit. I'm Tristan Hughes, your host. And in today's episode, well, get this, we're talking about the worst single day in the history of life on earth the extinction of the dinosaurs that occurred some 66 million years ago when an asteroid some seven miles across slammed into the earth

causing the extinction of more than half of the known species in the world, including, of course, most famously, the dinosaurs. So what do we know about this paleontological Armageddon? What do we know about this day, the days that followed, the months, the years that followed, how the Earth began to recover from this absolute catastrophe. Well, to explain all about these last days of the dinosaurs and the creation of the world we know today, I was delighted to interview the highly renowned science writer Riley Black. Riley has written a number of books all about dinosaurs, about paleontology, and one of

her most recent books is all about this topic, about the mass extinction, about the asteroid and what followed, what happens next. It was a great pleasure to interview Riley all about this, no doubt it's going to be a very, very popular topic and I really do hope you enjoy. So without further ado, to talk all about this mass extinction event, the fall of the dinosaurs, this great asteroid, the worst day in the history of life on Earth, here's Riley. Riley, it is wonderful to have you on the podcast today. Oh, it's so lovely to be on. Thank you. You're more than welcome. And we've done a few dinosaur episodes in the past with the likes of Steve Brassati and Henry G. So it's wonderful now to have you on as well. And to talk about this, the final days of the dinosaurs and what happened next, because Riley,

I mean, correct me if I'm wrong, but is it fair to say that the meteorite, it takes all the headlines, but what happens after the impact itself in those days, weeks, months, years, thousands of years following that and the recovery of Earth? Is this fair to say that that part of the story is sometimes a little overlooked? Oh, I'd say it's a lot overlooked, really. I've been so concerned with where our favourite dinosaurs went for so long. I feel like sometimes we even forget that this was a mass extinction. This was the world's fifth mass extinction. So, 75%, even just the animals we know about, disappeared literally overnight. And yes, the asteroid, it's this huge thing. It inspired two

blockbuster movies, like in the 1990s, Deep Impact and Armageddon came out the same summer, because people were so fascinated by this idea. that how life recovered, how it came back, how we got into the age of mammals, as we call it now, often gets overlooked. And I think it's a historical thing. You can go back 100 years ago before we knew anything about the asteroid impact and read paleontology textbooks. And paleontologists were going like, we don't know why dinosaurs were around for so long. They're big and they're ugly and they're weird.

Mammals should have taken over a long time ago. We don't understand any of this. Maybe they just got too big. I don't know. So it was this mystery for so long. And then we have this like fantastic kind of solution to it. But you're entirely right that the recovery from that, what happened in the next hours, days, weeks, months,

million years after, we usually take that as a given. Like, of course, life would come back. And that's not really the case. you know, hours, days, weeks, months, million years after. We usually take that as a given, like, of course life would come back, and that's not really the case. I mean, absolutely not. And one thing I'd love to focus on first, because we were just chatting about it before we started recording, is in this field of paleontology which you focus on, Riley, it sounds as if more and more evidence, more and more research is coming to the fore almost every week. Oh, entirely. So on average, even just like new dinosaur species, like the rate at which we're finding them, and this is just dinosaurs, this is nothing of fossil plants or insects or things that lived in the oceans or any of that, just our favorite dinosaurs.

There's a new species named about every two weeks. And then on top of that, there's all the environmental reconstructions and what were they eating and what did they look like and all this information. This field keeps me incredibly busy. I did not intend to be a full-time paleontology writer. It just kind of became that way because there is so much to talk about. I feel inundated sometimes by the amount of new research coming in because it really is, it's not just a lost world. Like it's one place in time. We're talking about hundreds of millions of years of evolution all around the planet. And anytime you find any one particular thing, it connects to something else. And it's a group of hundreds of experts around the world basically arguing over the same puzzle and what goes where. And

sometimes we very much agree and sometimes we very much don't agree. But you can see why like both through just rate of discovery and the way that science works. Yes, this is an incredibly vibrant field. I mean, Riley, okay, you've written this lovely narrative book about the end of the dinosaurs and what happened next. And so, as background, set the scene 66 million years ago before the meteorite crashes into Earth. What does the world look like? So the world at the time, if we were to have like the big picture view, it's a little bit warmer than it is now. There's not as much global ice at the poles. You have the remnants of this ancient seaway that used to split North America in half. So most of our famous dinosaurs, most of what we

know about from this time period comes from areas in Montana and North and South Dakota, a little bit in Wyoming and Utah, all these basically pockets where the seaway was receding. So we're talking about a global event, but most of what we know comes from Western North America so far. And at the time you have your community of like some of our most favorite dinosaurs. There's Tyrannosaurus rex, there's Triceratops, Edmontosaurus, you know, from things that are about the size of a sparrow all the way up through like these nine-ton monsters, basically, you know, they're filling the environment. There's been a lot of discussion, debate over the years of, you know, were dinosaurs fading away? Was their diversity going down? There's not really a sign of like anything going wrong. It's just a

perfectly average day at the end of the Cretaceous, going on much the same way as it had for millions of years prior. To give you an idea, T-Rex was around for about 2 million years, from about 68 to 66 million years ago. So, if not for that asteroid, if that asteroid had missed, everything would have continued going on as it had. This was a world that was full of dinosaurs, a diversity of little mammals scurrying around. There were birds, not just birds with beaks, but birds with teeth. Pterosaurs were in the air. Out in the seas, you had things like plesiosaurs and mosasaurs swimming around. Those coiled-shelled ammonites, they're so fun to

collect, were out in the seas. So, it was like what we think of sometimes in ecology as like a climax community in that there are multiple interconnected tiers. So, you have apex predators and predators in the middle and herbivores of all shapes and sizes. So, this is really a well-formed and established community of organisms. And then basically, snap of your fingers, that all changed. It all changes indeed. I mean, one more quick question before we delve into that. I noted in your book the name of one particular place, Hell Creek. I mean, what is this? This seems to be an important location for this time in pre-pre-pre-history. Right. So, if you travel through Montana, especially the eastern part of the state, you know, these little roadside towns like Ekalaka that you'll pass through, and you look around you and you see this rolling landscape. And that is what we call the Hell

Creek Formation. So, it's this unit of rock that spans about 2 million years. And if you want to find some of these dinosaurs, if you're going to go looking for a Tyrannosaurus or Triceratops, this is where you go for it. And it's incredibly fossil rich. People have sometimes done fossil surveys just like picking up every single thing they could find like in a mile radius and saying, This is where you go for it. And it's incredibly fossil rich. People have sometimes done fossil surveys, just like picking up every single thing they could find like in a mile radius and saying, okay, what does like the population of the animals look like? So it's incredibly fossiliferous. It sold us an incredible amount.

I've been lucky enough to go out and do some field work out there. And I love these particular places called microsites because microsites, you get like a census of who is around. So you don't get big bones, but you get a lot of teeth. You got scales from fish. You have bits of mammal jaw, things like that kind of helps paint this picture. So yeah, so much of what we know about what happened before the impact and after comes from this area because we have the before and after snapshots. It's not just about the Hill Creek formation where our favorite dinosaurs are. There's an overlying geological formation

that basically you can track, okay, we've got dinosaurs here, we can find the boundary layer where the impact occurred, and then we can see life for the million years or so after that. And that is incredibly useful in figuring out who survived, who went extinct, what has shifted around. But we really start in the book, The story starts in what we now know as the Hell Creek Formation. Right. Well, to get that, therefore, narrative, let's go into the story proper. Riley, you're going to tell us the story now. We've got to start with the Armageddon, the catastrophe itself. What do we know, therefore, about the asteroid? Right. So this is the neat thing about the asteroid. We have the crater. It's in the

Yucatan Peninsula. It's called the Chisholub Crater. It was found in the mid-20th century, I think in the 1960s, by an oil geologist. They didn't quite know what they had found just yet. It took quite a while to start putting all these pieces together. the planet. It was about seven miles across. It's more or less, it's been likened to Mount Everest. So if you can imagine Mount Everest slamming into the planet at tens of thousands of kilometers per hour as the earth is turning, as the earth is spinning, the amount of kinetic energy that was released for this. And there's a whole backstory to that too, which I love. We often forget, like this asteroid wasn't just like hanging out in our solar system and decided to pay us a visit. This is something that it seems to be what we call a carbonaceous chondrite. So it's a kind of asteroid that's kind of like debris. It's leftovers from the formation of our solar system that might've been hanging out in this kind of

debris cloud called the Oort cloud that's around our solar system and gradually kind of got pulled in by the gravitational pull of the sun and Jupiter. And this was happening during the time that dinosaurs are first evolving and diversifying. So, in a sense, like their conclusion was already sealed when they originated. And this is basically happening. It's just physics playing this out and it's coming towards them until one day, 66 million years ago from our present time, this chunk of rock hits the planet in basically modern-day Central America. And the effects are just immediately devastating. In the area there, I mean, whatever was living there would pretty much be vaporized by the amount of energy and heat created by this impact.

You had tsunamis that went out from the impact site that were as tall as skyscrapers. They had so much energy to them that they hit the coastline and then rebounded back. So when we look at the crater today, it looks like a mess because it's actually been covered over by the sediment moved by all those tsunamis. And one of the worst parts about all this, you have all these small effects, you have tsunamis, you have seismic reaches you know the whole creek ecosystem within about 15 minutes to an hour or so after impact but the worst part of all this you have so much debris that's basically pulverized by this impact all these little bits of rock and glass and quartz and other things like that get thrown up into our

atmosphere and it starts to spread around the planet and as these things come down if you've ever seen a science fiction film with like space shuttle reentering Earth's atmosphere and starts to heat up from all the friction from hitting the air, that's what's happening on a small scale to all these little things. So, any one particular thing, it doesn't really matter. It's almost microscopic how small these things are. But there's so much mass, there's so much material that they're all doing this, that the friction creates what we call an infrared pulse. So basically it heats the air to about what you would use to broil a chicken in your home oven. Like basically the max setting for your home oven is what the

air was like. And this is within the first day. This is within the first 24 hours. So unless you are adapted to, unless you live in the water, unless you can burrow underground, unless you have some kind of shelter from this heat, there's no way to get away from it. And it's so hot that like dry tree material, plant material out in the forest at the time would have spontaneously caught fire. caught fire. So you don't just have the heat, you have the forest fires are sitting here. It's really apocalyptic. It truly is. And that's even before we get into all the after effects in the following years of the impact winter. So you have this incredible heat pulse. It's like nothing in the world has ever been through before. That dies down. Life has already taken a major hit. Where the asteroid struck used to be an ancient reef made of limestone, basically. So, these are compressed fossils that were made millions of years before the impact. They're already fossils in the time of the dinosaurs. It's so full of sulfur-based compounds, those get aerosolized. And we know from some of our own human activities

that these sulfur-based compounds, when you put them into the atmosphere, they're really good at reflecting sunlight back. And after you have this heat pulse, after you have the fires, that dies down. You start to have this incredibly quick global cooling. You have an impact winter that drops temperatures around the planet. Photosynthesis has almost stopped. We know this from some fossils in the ocean, where if you're a photosynthesizing algae, which is one of the most important creatures on the planet, they provide so much for oxygen and everything else. They disappear. You only have things that are basically able to scavenge, to make do on whatever little morsels they can find.

And that goes for about three years. So you have this perfectly idyllic, for a dinosaur, Cretaceous day, an asteroid impact within 24 hours. It's so hellish that most creatures that went extinct probably went extinct in this interval. And then even if you survived that, you had to deal with years of basic scraping by and whatever you could possibly find. And that's this extra extinction filter. So this really was, there's not a mass extinction like it. All the previous four that we know about were caused by things like volcanic activity or changes in oxygen levels. They took tens of

thousands of years to transpire. This we're really talking about, like the blink of an eye, that all of this happened, the world changed. It's fascinating, as you say, 24 hours, one day. And Riley, so do we think, therefore, that the whole world was gripped, basically became an oven in those 24 hours? Or was it more centered around where the asteroid actually hit? So far as we're able to tell, the models suggest that this was global. This wasn't just localized somewhere, but all this debris basically got scattered so high into our atmosphere and spread so far that they're coming down all over the planet. And we've been able to verify this. If you go to New Zealand, if you go to Italy, if you go to China, if you go to all

these different places around the world, you find impact debris. You find little spherules of glass and little bits of rock and what we call shocked quartz. So quartz that's been hit so hard, it's actually kind of cracked on the inside. So that was one of the ways that this event was first identified. It was geologists looking at saying, okay, we have this like impact layer. We want to try and figure out how quickly it formed. And they started to realize this isn't just in this one locality, this is global. So even though like the direct effects of the impact were very local, the after effects, sort of how quickly this asteroid was moving, the angle at which it hit, the rock that it hit. All of these things played into it.

And that's what really gets me about this whole thing, is that it didn't have to be this way. We have impact craters that are, in fact, larger. There's one in Siberia called the Papagai Crater that was made around 50 million years or so ago that is not tied to any kind of mass extinction whatsoever. So, you know, we would treat it as obvious, you know, big rock strikes planet, there's going to be a mass extinction. Most of the time, that's not true. Most of the time, life on Earth is outside of like the local area that that impact would have affected has gone on pretty much unimpeded. This is the one time, this is the one worst case scenario where everything that could have possibly went wrong, went wrong. It's absolutely extraordinary, Riley.

And before we go on to the longer aftereffects, you mentioned impact winter. But from what you were saying there, dinosaurs, the acme creature on land before then, it seems like if they were on land, not underwater or any of those places, that are they the creatures most affected by this immediate effect of the asteroid strike? So we think of our non-avian dinosaur friends. I say non-avian because dinosaurs are still alive in the form of birds. They're the ones that survive. I'm not sure we'll talk about that. At the time, non-avian dinosaurs, they were sort of the most, I want to say the most prominent creatures in the landscape. We often talk about dominance, but that doesn't really mean

anything. That's just something that we use to make them sound impressive. But the fact is that they existed in sizes from absolutely tiny to gigantically huge, and all these different roles and niches and everything else, they were important creatures. They're sort of like the equivalent of what mammals are today. And of course, this basically wipes them out entirely, because with the exception of maybe a few species that were able to find refuge in burrows that they were small enough or they'd made themselves and they eventually still went extinct, there wasn't anywhere for them to go. If you are a Tyrannosaurus rex, let's say you're not even the biggest, let's say you're like 30 feet long and something like six tons,

still a big animal, you're not going to dig something deep enough, fast enough to escape this. They didn't have any pre-existing adaptations to help them through. And that's really what made the difference for this. You can't plan for an event like this. It's really the luck of the draw in terms of what you do. But I want to be clear that the dinosaurs were literally decimated. We lost them beyond the beaked birds. But there are also mass extinctions of mammals, birds, and lizards, and snakes. Amphibians do really well. And we're really only starting to understand why that is. That's always been a big mystery.

And even in the oceans, you had almost total ecosystem collapse as a result of this. So we lost the ammonites and the mosasaurs and the other marine reptiles. And even these clams that were like the size of a toilet seat called rudas disappear. And nobody talks about them. I always like that. Yeah, we could have had giant clams if not for this impact. So dinosaurs, I think, were most affected in terms of like most shaken up by this. They were cut back incredibly severely. Whereas for most other groups, they went through mass extinctions was kind of a reshuffling. So like for mammals, marsupial mammals used to be much more prominent around the world, especially in the Northern Hemisphere.

They became much less prominent afterwards and gave our placental mammal relatives and ancestors a shot to proliferate through those spaces. So yeah, I think that's part of the reason that we focus on the dinosaurs so much is that they were around for so long. They survived the continents shifting around, changes in global climate change, all these things. They lived through Earth's fantastic changes for 150 million years. And then in a day, they're basically gone. That demands an answer. We want to know why, like as much as we might feel directly for mammals or other things.

It's to look at these animals that we kind of, like you said, look at as the acme of these paragons of success, and then it vanishes suddenly. And this impact, this mass extinction, is really showing us why, how that happens. Riley, I'm in absolutely two minds at the moment, whether to continue the story, but I've got one question that my brain is just dying for me to ask now, which is, you've mentioned burrowing already, and these catastrophic 24 hours right at the start. So how can a few inches, centimetres of soil save so many of these smaller mammal-like animals in this first day compared to those that don't have anywhere to burrow into? Right. So the secret really is the soil, or if you're an ancient

turtle or crocodile or something like that, even just a few inches or a few centimeters of water can make a huge difference. And as far as soil goes, that's because soil is great at acting as a buffer against heat. And we know this from modern forest fires. There are some forest fires that get so intense that it kind of recreates some of these conditions from 66 million years ago. And we know that the moisture that's held in the soil, sort of what soil is made of, not just sort of particles of like rocks and things have been ground up, all the organisms and things in there. It's really good at taking up heat and acting as a buffer. So really, I think it was about 10 centimeters. It's really all it

took to buffer the effects of the equivalent of this heat pulse. So you didn't have to go down very far. So if you are a burrowing mammal, you don't have to go far down. But there are also other organisms, like we know there are ancient turtles and crocodiles and even some dinosaurs burrowed. And these animals didn't always just make a burrow and live there their whole lives. They'd make them season after season and move place to place.

So even there were abandoned burrowsrows or what we know from organisms today that sometimes different species share the same burrow. And this was definitely like an any port in the storm kind of moment during this heat pulse. So if you were able to get underground that quickly, or at least had this sort of refuge, you wouldn't really be able to tell very much of what was going on on the surface above you it acts that well as a buffer so that i guess is the one actionable piece of advice if you ever say okay you know we're gonna have an impact tomorrow break out the shovel and start digging in the backyard because really that's the best thing you could probably do love that how to survive armageddon yeah yes norm dinosaur style over on the Warfare podcast by History Hit,

we bring you brand new military histories from around the world. Each week, twice a week, we release new episodes with world-leading historians, expert policy makers, and the veterans who served. From the greatest tanks of the Second World War. And so what are you actually trying to get out of your tank? You're trying to get manoeuvrability, and you're trying to get a really big gun. Your Tiger and your Panther are there to dominate the battlefield, primarily on the Eastern Front

and in the North Africa and all that sort of stuff. But by the time they're actually coming in in decent numbers, that moment has already passed. Through to new histories that help us understand current conflicts. Any invader, any attacker, any adversary will exploit gaps within society. It was true then, it's true today. But the Finns signaled that they were united. And I think that's what the Ukrainians should signal today too. Subscribe to Warfare from History Hit wherever you get your podcasts and join us on the front lines of military history. Riley okay let's continue with the story then so we've got past this first day so the first few days temperature decreases if I'm correct and you've mentioned a word already the impact winter

so what is this the impact winter is this event that's specifically tied to the kind of rock that the asteroid struck. And this for a long time is thought to be the main killing mechanism. We didn't know about the heat pulse until relatively recently during the 1980s when this hypothesis was first coming forward and there was a lot of debate about it. And this was sort of the end of the Cold War. And it was very much into worries about nuclear winter. So if you think about sort of like fears over nuclear winter, it's kind of like that, but naturally caused. So what happened was you had all these sulfur-based compounds that went out into the atmosphere

that are reflecting sunlight back, like enough to send enough sunlight back that photosynthesis on our planet was reduced by about 20% or so. That doesn't sound like, you know, it's surely significant, but it doesn't sound like it would be lethal. But the thing is, all of our ecosystems are basically based on photosynthesis. So if you don't have plants to eat, then you're not really going to have very many insects. You're not going to have the things that eat those insects. It's really getting by on what we can.

And it seems to dovetail with some other evidence that we've found, or at least other hypotheses, about why certain creatures survived. Another died out. Just to give an example of this, birds are living dinosaurs. But we know during the Cretaceous, the day before the asteroid struck, we had bird-like raptors. So basically, things like Velociraptor covered in feathers, and they had teeth and claws. We also had toothed birds that ate little lizards and insects and things like that. And we had beach birds that specialize in vegetation and seeds and that sort of thing. So during this impact winter, we don't really have plant material and you don't really have very much prey to go hunt. The carnivorous species disappear. The toothed birds and the raptor-like dinosaurs, they go extinct. But beaked birds make

it through because they had already adapted to shift to basically these underground storage organs, you know, seeds, nuts, things like that. They're in the seed bank that are preserved in the soil. So they can get enough of those things to make it through. So even though this is, you know, it might seem like not all that long, it's three years compared to some of these other mass extinction events that took tens of thousands of years to play out. That is still an excruciating long time if you're an organism trying to like

make your way through to continue to survive and reproduce and all these things that life does. When we look in the oceans, the oceans were so close to basically being thrown back 500 million years. By that, I mean going back to almost a state where only singled-cell organisms lived there. We can tell this because there are these little things called coccoliths. They're basically algae. They're these little clumps of algae that kind of make these circular structures.

And before the mass extinction, you have ones that photosynthesize, and you also have ones that are able to eat organic matter. They're called myxotrophs. So they can photosynthesize, but if they can't photosynthesize for some reason, they can find other food. After the extinction, you only find the mix of troughs. The photosynthetic ones entirely disappear for a time. So if those algae basically hadn't evolved this, not carnivorous isn't the right word, but these algae that are able to feed on other organic matter hadn't existed, then the oceans would have been entirely 100% collapsed and would

have been worse even than it was. So we came that close to having basically the reset button pressed on the planet. So it was three years of really scraping by however life possibly could. We're still learning about what happened in that interval. It's hard to be that precise when we're looking this far back in time, but that picture is starting to come into view. And it seems a lot more dire than we thought. There'd be a lot of cartoons I remember seeing as a kid of dinosaurs wandering around this darkened and kind of ashen landscape.

And that's the sort of caricature image. The reality of it was like this was a time of great struggle. Really, if you're able to make it through that first day, then you had three years of really hanging on however you could. I mean, it's interesting that you mentioned just three years. So is it almost as if you get through those three years, is that almost a moment when it, I guess, could you say a recovery starts or does it take much longer? Yeah, that's a great question though. Like what does recovery look like? We talk about this recovery. We'd like to think, you know, 66 million years later that life has recovered, and yet we don't have anything like a 20-ton million years after impact. You start to see the beginnings of recovery after the impact winter dies away, but it still takes time. animals and organisms and plants that do well in disturbed environments.

So, for example, at 100,000 years, more or less, after impact, you see fern pollen appear in great amounts all over the world. If you look at the rocks, like basically just above the impact layer, and this has been referred to as the fern spike. And ferns, we know this from places like where volcanoes are up today, they do very well in places that have recently been shaken up in some way, or that ground has been disturbed. And the way that they reproduce, even though it's very dependent on water and moisture, they do really well in those. So that was kind of the beginning of sort of life beginning to really reseed and build up these forests so that by a million years after, you have forests growing

in ways that they never did before. It's different than it was. But you can start to say, okay, life seems to be not just even settling in, but evolving in different ways. Mammals, for example, by that time were getting big so quickly. So, you'd have a mammal that was the size of a German shepherd, but with the brain the size of its Cretaceous ancestors. So the body size just explodes during this interval, but brain size and these other sort of traits and adaptations haven't caught up just yet. But we can look at that and say, okay, this is the beginning of life really starting to proliferate and fill these ecosystems and do something different than before. Riley, for me as an average Joe Bloggs, it still absolutely blows my mind that

species such as mammals, amphibians, crocs, they were able to survive that incredibly catastrophic, tumultuous period, which, as you mentioned, was 100,000 years or more, and then are able to start thriving in this new world where the dinosaurs and those huge reptiles in the sea are no longer there. It's strange, right? It's strange thinking about this world that's so full of possibility, really. One of the things I love learning about and writing this, and I really wanted to drive home, was the interconnections between all this. We often focus on a singular animal or icon and what is it doing? We try and understand the whole ecosystem through its adaptations and its perspectives. And really, it's all these interconnections.

So, we think about forests, for example. That is a really critical part of the story because when animals like Triceratops and Edmontosaurus were around, they're not just eating plants. They're trampling things down depending on where they walk. They are spreading seeds in their dung as they go about their business. They are basically shaping the landscape. These are what we call mega herbivores today, the equivalents of elephants and giraffes and things like that, that not only have their place in the ecosystem, but they change it and they make it open. Even though the plants were very, very different, if you imagine almost any documentary you've seen on Eastern Africa and the grasslands and stuff there, how it's kind of these stands of trees and big spaces in between them, that's kind of what a dinosaur-created forest would somewhat look like. But then after the impact, you don't have these big animals eating so much and pushing trees over and trampling the ground down. So forests grow denser.

trees over and trampling the ground down. So forests grow denser. And when you have that, when you have this dense canopy kind of environment, you have a lot more sort of ecosystem space per square kilometer. So you have organisms that are going to burrow into the soil and then those that live on the surface and those that live on the trunk of the tree and at different levels in the canopy. So for any given space, you have a lot more different habitats. And that's what really underwrites this evolutionary explosion that we see, you know, about a million years or so after the impact. It's that there's more room to do something different, to evolve in a new way. You're having a hard time, you know, getting the food you require on the surface of the ground. Maybe you start climbing trees if you're able to do that. And like, I don't mean to make this sound like Lamarckian, like these creatures are deciding to do it or something somehow. But through all this competition for this incredibly rich space, all these organisms

are kind of nudged into doing new things that they didn't do before. And it really allows this, you know, mammals and birds and all these other creatures to come forward. One of the things I love about crocs, for example, is they look like they're ancient. They haven't been doing anything new. But what we understand from some newer research is that they evolve incredibly quickly. They just keep doing the same thing. It's like when you have your favorite takeaway place and you order the same thing each time

almost. Crocs are doing that in an evolutionary sense, where instead of doing something different or becoming dinosaur-like, they're just doing the semi-aquatic ambush predator thing over and over again. So even the organisms that make it through, they're not just doing it because they're stalwart in their niche or their adaptations, they're still responding to all this change and often evolving very quickly to meet these new conditions. I've got to ask this, how do we know all of this? Yes. It really comes together from a lot of different lines of information. And this really, in the past five years, we have learned so

much more than possible. The book that I wrote, I probably wouldn't have been able to write it with as much detail if I tried to do so maybe even five years ago. So one of the most critical places where a lot of this information comes from, there's a spot outside Denver, Colorado called Corral Bluff. And it's a great place because you not only have fossils of the animals, they come in these concretions. It's kind of neat. If you imagine kind of like a geode or almost like a boulder, you have to crack them open and prep away this really hard rock to see them. But you have mammals and turtles and crocs and things like that, but also plants. And also it's really well constrained in time. So we're able to get good dates from it. To get a good date in paleontology is phenomenal because

then you can finally say that this was happening at this time and we're not doing the more, give or take, a million years or five million years, which is a long span of time. So at Corral Bluffs, we're able to see how life is responding about 100,000 years after impact, about a million years after impact, in the same place, basically in the same geographic spot where all these changes are unfolding. And it's discoveries like that, this was something that someone had actually found long ago, and paleontologists only recently went back to have another look. So it's things like that, the continued research and modeling of what would happen as we get a better understanding of impacts through history and what happens and the speeds and forces, and better constrain what this asteroid was doing and how it struck the planet. All these little pieces come together. And that's what really the book is. The reference list is really a synthesis of all these little bits and pieces that are just starting to come together, that we finally have these sort of computing power and discoveries

and the curiosity to look at this in a different way. It used to be that we took the extinction of the non-avian dinosaurs as a given. Why wouldn't they? They're big, weird lizard things. the non-avian dinosaurs as a given. Why wouldn't they? They're big, weird lizard things. Once we realized that this was something exceptional, then we could start to ask these questions and sort of refine what we thought. And it's really been relatively new. The impact hypothesis came out in 1980. I was born in 1983. So this really has only been in my lifetime that we even knew that this happened, much less getting the clarity that we do now. So I am really curious to see, you know, 40 years from now, if I'm lucky to be around to see it, like how our understanding will have changed. So that's something I tried to be

transparent about in the book. This is all sort of the best information that we have right now. I'm probably wrong about some of it, and I'm going to be happy to find out what actually happened when we get to that point. It must be very, very exciting for the future indeed, therefore. I mean, I'd love to go into one particular case study now. You mentioned it earlier. I could ask more about mammals, I could ask more about crocodiles, but I want to ask about amphibians. Why do amphibians survive the impact so well and then go on to thrive? Yeah, this is something that we haven't really been able to get our heads around. It doesn't seem to make sense. You have these ectothermic organisms. They get their temperature

regulation. They regulate their body temperature based upon the environment they're in, and they go through incredible heat and then incredible cold. How does this make sense? Acid rain was thought to play a role in this because a lot of those sulfur-based compounds, they also create acid rain that probably has something to do with why fossils are so difficult to find from this interval that a lot of them were kind of eaten away by the acid rain that eventually came back out of the atmosphere. But in terms of amphibians specifically, there was just a paper that came out about body size, how if you're very, very small and you're an amphibian or you're very, very large, you're much more affected by environmental changes. Things like, for example, if you're very, very small and you're an amphibian or you're very, very large, you're much more affected by environmental changes.

Things like, for example, if you're a very, very small frog, a slight change in the temperature of your environment can make it very much more difficult to regulate your body heat, to do things like reproduce and eat and all that sort of stuff that a frog would normally do. Same thing if you're really, really big. It can be very difficult to lose excess heat or to warm up if things get too cold. Whereas if you're kind of in the middle, those amphibians seem to do a little bit better. But that's just really describing a pattern. That's not really telling us precisely why. It's more just like these seem to do a bit

better. And it's possible that for the acid rain component of this, like number one, that it wasn't as much of an amphibian killer as we previously believed. And also, there are a lot of ponds and water sources that had limestone, basically, as their foundation. And if you have that, the acidity of the rain would react with the calcium carbonate in that limestone. And basically, the rock acted as a buffer. It reduced the acidity, so those water sources didn't become as hostile to amphibians as we previously believed. But that's really the main outline. That's something that like it really has only been in the past year or so that this is starting to come into focus. I think one of the, that question of why do these things like bony fish and crocs and amphibians do so well when our big charismatic

favorite creatures don't do very well and there's probably there might be something we don't know just to end on on you know that question on this particular point i remember seeing a presentation number of years ago just looking at like each of the species that makes it through. How long are they around, just in evolutionary terms? What is the turnover for it? So a dinosaur species on land, most organisms on land are really only around for a million years, two million years before they either evolve into something else or they go entirely extinct. Organisms in freshwater environments, you can go back 10 million years before the impact and find the same species of crocodile and turtle and fish and things like that. So there's something about those environments

that they're stable enough or the conditions are stable enough or organisms have evolved in such a way that there's always a kind of place for them, that they have a longer staying power through all these shifts. They're kind of adapted to deal with environmental turbulence in the way that organisms on land are almost constantly changing to try and keep up with all these little shifts. And that might have something to do with this pattern that we see. Well, it must be very exciting for paleontologists in the future and budding paleontologists and people like yourself, Riley, looking to learn more and more about this incredible past while very, very, very distant past. I mean, to wrap it all up now, it is so extraordinary to talk about this topic

because we do, as hinted at at the start, we always focus on the catastrophe. 75% roughly of life is wiped out with the meteorite, but it's the recovery and the resilience of the Earth, which is equally, if not more astonishing, isn't it? and the resilience of the Earth, which is equally, if not more astonishing, isn't it? Oh, absolutely. I mean, the fact that since life originated on Earth, so far as I know, barring any early extinctions that we wouldn't know about, but basically if we go back to the last common ancestor of all life on Earth, over three and a half billion years ago, life has never disappeared since then. It has always made it through. It's been battered, it's been cut back, it's had to deal with extreme circumstances,

but it has always made it through somehow. And I found a lot of personal meaning in that. I talk about this a bit in the conclusion, where during the time I was writing this book, I was going through a lot of personal changes and some big shakeups in my own life. And I took a lot of solace in the idea that after going through what felt like a very personal kind of asteroid impact in a way in the life that I had, being more or less swept away and starting something new, especially through transition, it was focusing on that story of resilience. That life can grow in a different way, but it's not lesser. It's not something that has to compete with what existed before. It's amazing that it can exist and grow in a different way.

And I love that on the geological timescale, this is really that story. We are here because of this. And I love the fact that our ancestors were there. And I don't just mean that in a general sense. This animal might not be a direct ancestor of ours, but the first primates were around the same time as T. rex. So when that asteroid struck, our primate forebears, who had just evolved, really, that were these new things on the planet, made it through that, whereas our favorite dinosaurs didn't. And if things had been just a little different, the primate story, our story, would have been snuffed out before it even started.

And yet we're here. And I think that's fantastic. And I think rather than the loss, especially through all the various stresses and things like our world has been through recently, a story of resilience like this is a really important one to tell. Well, Riley, that's a lovely comment to finish the podcast episode on. Last but certainly not least, your book on this topic, it is called, Riley? The Last Days of the Dinosaurs. Well, fantastic. Riley, it just goes for me to say absolute pleasure and thank you so much for taking the time to come on the podcast today. This has been wonderful, Tristan. Thank you.

Well, there you go. There was Riley Black taking us back some 66 million years to the worst day in the story of life on earth the extinction of the dinosaurs the asteroid collision with the earth and how the planet recovered in the wake of this massive catastrophe i hope you enjoyed the episode today the last things for me you know what i'm going to say well if you're enjoying the ancients and you want to help us out you can do something very easy very simple just leave us a lovely rating on apple podcast and spotify wherever you get your podcast from it greatly helps us as we continue to share these amazing stories with our distant past with you and with as many people as possible have you got any thoughts on the ancients podcast

what you love about it but also ways you think that we can improve, we can be better in the future. Please do also drop us a comment too. I love reading the comments, hearing your thoughts, whether it's good praise, but also constructive criticism too. I welcome both because in both cases, it helps us improve the podcast in the days, the weeks and the months ahead. It lets us do our job even better. But that's enough rambling on from me and I'll see you in the next episode.