7-Extinctions: Dinosaurs, a Big Rock, and…Climate Change?

When you hear the word “extinction,” chances are you probably think of the extinction of the dinosaurs and a big rock. But did you know that there were other factors at play that lead to that extinction including volcanos and sea-level rise? We talked with David Mascato and Will Harris of the Common Descent podcast about dinosaurs (of course), K-Pg misconceptions, and what an asteroid-included change in climate then can teach us about climate change now.

This episode was produced by Shane M Hanlon and mixed by Collin Warren. Artwork by Irene Crisologo.


Shane Hanlon:              00:00                Hi, Vicky.

Vicky Thompson:           00:01                Hi, Shane.

Shane Hanlon:              00:03                Welcome to Third Pod.

Vicky Thompson:           00:05                Oh, thank you. I’m so, so excited to be here.

Shane Hanlon:              00:08                Yeah. For those of you who are just joining us, you should go back a few. At least. My former co-host, Nanci, has left us, but we still love Nanci.

Vicky Thompson:           00:17                Love Nanci.

Shane Hanlon:              00:19                Very excited to have Vicky Thompson with us. Vicky’s one of my colleagues at AGU and she’s going to be my new co-host moving forward. We’re going to have a great time.

Vicky Thompson:           00:32                It’s going to be so fun.

Shane Hanlon:              00:33                Yeah. To start off this great time, because no pressure, I have a question for you.

Vicky Thompson:           00:39                Okay. Shoot.

Shane Hanlon:              00:40                If an asteroid was hurling towards the planet-

Vicky Thompson:           00:43                Oh my gosh.

Shane Hanlon:              00:47                … and you could do one last thing… no limitations… you could do one last thing, what would that thing be?

Vicky Thompson:           00:54                This is a hard question.

Shane Hanlon:              00:55                It is a hard question.

Vicky Thompson:           00:59                So, classic me. I have multiple answers, but I have one that I think is the fun answer. I think, actually, I just want to have the most perfect barbecue in your backyard with all of your friends. You know that kind of day?

Shane Hanlon:              01:15                Yeah.

Vicky Thompson:           01:15                That’s what I want. Where it’s just good food, friends, beer-

Shane Hanlon:              01:21                That’s very nice.

Vicky Thompson:           01:22                … silly stuff. But I think what would actually… I’d probably just lay down on the floor and cry and that would be my last hurrah on Earth.

Shane Hanlon:              01:34                I write most of these questions, but it’s funny. I don’t actually think about my own answers for them.

Vicky Thompson:           01:37                On the spot.

Shane Hanlon:              01:40                Probably in line with your latter. Yeah. I’d probably grab my partner and my dog and just lay and-

Vicky Thompson:           01:49                Weep.

Shane Hanlon:              01:50                … cuddle and sob. I’d like to say it was something different, but probably not.

Vicky Thompson:           01:55                Well, really, what is the last thing that you do going to change? Anything.

Shane Hanlon:              01:58                Exactly.

Vicky Thompson:           02:01                There’s no hope.

Shane Hanlon:              02:01                It’s an emotional time.

Vicky Thompson:           02:02                Yeah. Just lean into it.

Shane Hanlon:              02:10                Science is fascinating. But don’t just take my word for it. Join us as we hear stories from scientists for everyone. I’m Shane Hanlon.

Vicky Thompson:           02:19                And I’m Vicky Thompson.

Shane Hanlon:              02:21                And this is Third Pod From the Sun.

Shane Hanlon:              02:24                Well, so y’all might have guessed that we are talking about either the movie Don’t Look Up, if you’ve seen it, or in our case, the extinction of the dinosaurs.

Vicky Thompson:           02:38                This isn’t fair. This is not a good way for me to start my Third Pod tenure. Just doom and gloom.

Shane Hanlon:              02:46                Everyone, welcome Vicky to the podcast. We’re going to talk about mass death.

Vicky Thompson:           02:53                Yes. Awesome. Thank you.

Shane Hanlon:              02:56                Well, okay. So, you’re right. That is unfair. But here we are, so pushing forward.

Vicky Thompson:           03:01                It’s real.

Shane Hanlon:              03:02                So there were five… There’s classically accepted that there were five big extinction events. And the one that wiped out the dinosaurs is… I’m not even say perhaps. It’s the most known one. Though, interestingly, not the biggest one. But since it’s the one that everybody know about and talks about, I figured this would be a great… great is doing a lot of work here… good way to start our extinction series.

Vicky Thompson:           03:31                Yeah. It’s definitely the most obvious way to start it, for sure. I think that that places us all on the same page, but also, it’s dark.

Shane Hanlon:              03:42                It is dark, but we’re going to-

Vicky Thompson:           03:44                Extinction is dark.

Shane Hanlon:              03:45                Extinction is dark, but we’re going to make it as… The good thing is all the ones we’re talking about have already happened and we’re going to make it as fun and entertaining as possible. One thing folks will learn with not just extinctions, but a lot of things, is that I personally… I love to speculate wildly.

Vicky Thompson:           04:06                Oh, me too.

Shane Hanlon:              04:06                I don’t make any assertions of fact. I am a science communicator. But if I don’t know something, I like to guess about it and then find out what the truth is. That’s kind of what I did with this extinction event. I think I know some things about it, but I then took the opportunity to chat with a couple of folks who knew much more than I did.

David Moscato:             04:32                I’m David Moscato.

Will Harris:                   04:33                And I’m Will Harris.

David Moscato:             04:34                And we are both paleontologists. We both got our master’s in paleontology at East Tennessee State University together ish several years ago. We’ve both done research in paleontology. Mostly on reptiles and mostly on more recent stuff than dinosaurs and things like that. We are the hosts of The Common Descent Podcast, a podcast about paleontology, evolution, and life history, and we are both affiliated with the Gray Fossil Site and Museum here in East Tennessee.

Shane Hanlon:              05:08                So we are here today to talk about the K-Pg extinction. And so as kind of a primer or a background for folks who might not be familiar with that terminology, can we just get a CliffNotes version of when we say K-Pg extinction? What are we talking about out?

David Moscato:             05:29                Right. So the K stands for the Cretaceous period in sort of a circuitous way and Pg stands for the Paleogene period, which are the two periods on opposite ends of this geologic boundary at about 66 million years old, which marks the end of the Mesozoic era. The end of what we commonly call the age of dinosaurs. It is a boundary where, in the fossil record, we see the end of the record of most dinosaurs at the time…. pterosaurs, mosasaurs, ammonites… lots of different groups of animals, also plants, marking a major extinction event that separates the Mesozoic era from our modern Cenozoic era.

Shane Hanlon:              06:19                That was the most recent major extinction if we are not talking about the Anthropocene, correct?

David Moscato:             06:26                Yes.

Will Harris:                   06:27                Yeah.

David Moscato:             06:28                So, geologists commonly talk about the big five, which are extinction events at the end of important time periods. The Ordovician, the Devonian, the Permian, the Triassic, and the Cretaceous being the most recent what we refer to as a mass extinction, meaning of course that lots and lots and lots of things went extinct in a very short period of time.

Will Harris:                   06:48                And typically on a global scale.

Shane Hanlon:              06:51                That was going to be something I asked. There have been isolated extinctions of not just one species, but there have been isolated groups, whether that’s on a continent or whatever. That’s not what we’re talking about. It’s literally across the globe or at least what our records have found across the globe.

Will Harris:                   07:08                Yes.

Shane Hanlon:              07:09                You mentioned that… We were talking about 66 million years ago. This is the end… quote, unquote… the end of the dinosaurs. If we’re talking in millions of years, how long is this period within that? Is it one million years? Are we talking a hundred years? How long was the actual extinction event or at least what we know of it?

David Moscato:             07:31                That’s a great question. The shortest answer is it’s hard to say. Geologically short. A mass extinction is complicated. A species doesn’t go extinct overnight and especially hundreds and thousands and thousands of species don’t go extinct overnight. Generally speaking, this extinction probably lasted a number of thousands, maybe tens of thousands of years, during which time ecosystems around the world were so interrupted and so disturbed that lots of different groups of organisms couldn’t survive.

Shane Hanlon:              08:08                Tens of thousands is much shorter than millions of years, but still, within our human timeframes, is quite long.

David Moscato:             08:17                In the geologic record, thousands or tens of thousands of years can be a blip.

Will Harris:                   08:22                It can be very hard to actually detect time on that small scale. For our lifespan, you might not notice it happening, were you alive during it, because you wouldn’t live long enough to experience it, but geologically, it just goes by just a blink.

Shane Hanlon:              08:40                Just to give us some scale, you mentioned that 66 million years ago was the end of this era of dinosaurs. What is commonly accepted as the beginning?

David Moscato:             08:52                So the Mesozoic era starts at the end of the Permian… with the Permian mass extinction, which was even bigger and even worse. That was 250 million years ago. The earliest dinosaur fossils, the earliest true dinosaurs, show up around 230 million years or so. Dinosaurs really rise to prominence, like really become major players on the global stage, closer to 200 million years ago or so. So the Mesozoic starts 250 million years ago, which is almost five times older than the end of the Mesozoic at 66. The age of dinosaurs, if we want to call it that, doesn’t really have an official beginning. But if we say it’s starts when dinosaurs really become a big deal, then it was probably 200 million years ago or so that that started.

Shane Hanlon:              09:50                I love this idea of dinosaurs, quote, unquote, becoming a big deal. I just can’t imagine a time when dinosaurs were around where they weren’t a big deal.

Vicky Thompson:           10:00                No, absolutely. I mean, I feel like kids are obsessed with them the second that they learn about them and then forever. So they are big deal.

Shane Hanlon:              10:09                Yeah. It’s weird to think about, geologically, there were points in time when they were around and just weren’t the dominating force out there.

Vicky Thompson:           10:18                Oh.

Shane Hanlon:              10:19                Yeah. Kind of in the beginning of their… like when they popped up, it took a while for them to kind of… I don’t know. Not get with it, but really take over to become the it thing.

Vicky Thompson:           10:31                Get their following going.

Shane Hanlon:              10:32                Get their following going. Get those social media followers.

Vicky Thompson:           10:35                Get the clicks.

Shane Hanlon:              10:38                And so I like… I already kind of pleaded ignorance. I like that I was learning things during this interview and learning that whether or not… or frankly, when or not dinosaurs were the, quote, unquote, it thing. I also realized that I might not know what the literal definition of a dinosaur is.

David Moscato:             11:01                First of all, yes, dinosaurs is a term that we… It’s like mammals or insects. It is a specific group of life that is defined by particular features. Some people think dinosaur and they think any ancient animal that we’ve seen in a movie.

Will Harris:                   11:15                Especially if it’s scaly.

David Moscato:             11:16                Yes, exactly. Pterosaurs, which are the flying reptiles of the Mesozoic. Mosasaurs and plesiosaurs and ichthyosaurs sores, which were aquatic. Mosasaur famously featured in the newest Jurassic World movies, so now very famous.

Shane Hanlon:              11:29                That’s the giant one that jumped out of the water and ate the… Was it a crane?

Will Harris:                   11:37                The shark.

David Moscato:             11:37                It eats the shark and it also attacks a helicopter.

Shane Hanlon:              11:43                That’s what I’m thinking of.

David Moscato:             11:43                Yep.

Shane Hanlon:              11:45                All right.

David Moscato:             11:47                So those are things that are not technically dinosaurs. They don’t fit under that group of related evolutionary lineages.

Will Harris:                   11:56                They’re ancient reptiles, but of different groups. Some related to dinosaurs, some close cousins, but not actually in the group we would call dinosauria.

David Moscato:             12:05                That also includes crocs and alligators.

Will Harris:                   12:07                Yeah. Those are cousins… They’re on a branch off to the side, but not actually dinosaurs.

David Moscato:             12:14                And then the point about what went extinct is actually really interesting, I think, because we call it the extinction of the dinosaurs, but on the one hand, lots of things went extinct that weren’t dinosaurs. We lost the last of the pterosaurs, mosasaurs, all those aquatic reptile groups didn’t make it through to the end of the Cretaceous. Ammonites, the spiral shelled cephalopods, cousins of octopus and squid, for example, did not survive this extinction. Lots of ancient mammals went extinct. Lots of ancient reptiles, ancient amphibians, ancient plants. Basically every major group of life was impacted to some degree by this extinction event.

David Moscato:             13:02                The other reason why it’s kind of funny that we think of it as the extinction of the dinosaurs is, first, that not all the dinosaurs went extinct. A small group of birds survived the extinction to give rise to our modern birds and they do fit under the umbrella of the dinosaur evolutionary tree. And at the other end of things, most dinosaurs were already extinct when this happened. So if you think about… Dinosaurs were around for 160 million years or so before this. So your stegosaurs, your brachiosaurs, your allosaurs. A lot of these big deal groups showed up, spent tens of millions of years being successful and a big deal-

Will Harris:                   13:44                And awesome.

David Moscato:             13:45                And awesome. And then went extinct. Long before the end of the Mesozoic actually happened.

Will Harris:                   13:50                It’s often portrayed that every type of dinosaur we know died off at the end of the Cretaceous, but many had had their time and gone away before those Cretaceous dinosaurs ever showed up.

Shane Hanlon:              14:02                So it’s depicted as essentially the opposite of Noah’s ark. Instead of every animal coming onto the boat, it’s every animal going extinct at the same time.

David Moscato:             14:12                Well, if you think back to Fantasia, it was all the dinosaurs are all together and then they all die in the same event. But in reality, Stegosaurus and Tyrannosaurus never would’ve met each other. Stegosaurs were long extinct before the early things we’d recognize as Tyrannosaur cousins even showed up on the scene.

Will Harris:                   14:34                That’s why you have all those memes of saying that it’s more accurate to show T-Rex on a unicycle than interacting with Stegosaurus because there’s less time between those two.

Shane Hanlon:              14:49                I’ve seen so many of these memes of the this is closer to this. I literally just looked up one that said Cleopatra lived closer in time to the building of the first Pizza Hut than to the building of the pyramids. I mean, that’s wild, right?

Vicky Thompson:           15:05                That’s totally wild and it doesn’t fit in the order of things that I have made in my mind. That doesn’t fit at all. That’s wild. But regardless of Cleopatra’s first day working at Pizza Hut, what I was wondering is how some things made it through the event and some didn’t.

Will Harris:                   15:29                That’s always a really important question for extinctions.

David Moscato:             15:31                This has been discussed quite a bit. Oftentimes, we talk about it, like, well the dinosaurs all died, but then mammals happily made their way across the extinction boundary and birds all survived.

Will Harris:                   15:44                Just skipped on through the fields of death.

David Moscato:             15:45                Right. But of course that’s not true. Most birds seem to have gone extinct.

Will Harris:                   15:52                We almost lost birds.

David Moscato:             15:53                We almost lost birds. And lots of mammals went extinct. There are some patterns that we observe in this and other general mass extinctions and extinctions in general, where certain things survive and others don’t. One of the most obvious patterns is that, the bigger a species is and the more resources it needs, the more likely it is to go extinct when things get tough.

Will Harris:                   16:18                Those organisms do not tend to respond to change as quickly and need more specific needs requirements met to survive.

David Moscato:             16:27                More space, more food. We see this today. Most of the animals in the world today, the famous endangered species that are in trouble because of habitat loss or pollution, those effects really hit big animals hard. If you think of a species alive today that’s bigger than a human being, odds are it’s endangered because being big just means you have a really hard time adapting to ecological disturbance.

David Moscato:             16:57                So during the K-Pg, we see the… I’ve often seen it cited that nothing bigger than a house cat survived the extinction.

Shane Hanlon:              17:03                Oh, geez.

David Moscato:             17:05                Generalists tend to do better than specialists. So if a species could only eat one particular kind of plant or could only live in one particular kind of habitat, those tended to go extinct more often than things that were less picky.

Will Harris:                   17:22                I think of it like picky eaters versus non picky eaters on vacation. That you’re going to have a harder time while you’re traveling around in new places and strange foods if you’re a picky eater, but if you’ll just eat anything, then you’re fine.

Vicky Thompson:           17:41                Wait, wait, wait. How did we get talking about dietary preferences?

Shane Hanlon:              17:46                So at the time… Granted, this was a late after work interview. But at the time, I thought it was on topic.

Vicky Thompson:           17:54                You know what would be on topic? If you actually talked about what caused the extinction event, so let’s get [inaudible 00:18:02]

Shane Hanlon:              18:03                Yeah, it’s funny. We did it. It took us a while, but we did get around to that.

David Moscato:             18:08                Shortest answer? Big rock.

Will Harris:                   18:10                Big rock.

David Moscato:             18:11                We have definitive evidence of a major asteroid impact that happened right at the boundary. Right at the end of the Cretaceous. In fact, in many places in the world, that boundary in the geologic record right at 66 million years, you can actually see the boundary between the Cretaceous and the Paleogene because there is this layer that is full of… when look very closely and do chemical tests on it, full of meteorite stuff. It’s full of meteorite dust and it’s full of elements like iridium that show up in high amounts in asteroids and in the dust that asteroids put off. Also includes a lot of what are called tektites, which are basically little formerly molten droplets of debris that came raining down all over the world.

Will Harris:                   19:10                It’s like those little welding beads you get from metal coming off.

David Moscato:             19:15                There was a massive crater. Buried underground. We can detect it by scanning the ground in the Yucatan Peninsula in Mexico, which is where the asteroid appears to have hit, which fits because the biggest evidences of impact destruction tend to be more severe closer to the Yucatan.

Shane Hanlon:              19:35                Okay. They hit in Mexico and longitudinally our part of the world, but these effects were felt the all around the world, right? I mean, if you’d literally go 180 around the world, they’re experiencing the effects of this strike. So what caused that? Because it wasn’t the strike itself. There had to be some other secondary effects or consequences.

Will Harris:                   20:01                That’s definitely one of the biggest miscategorizations of the asteroid impact is that it hit and it was like a missile strike and just killed everything.

David Moscato:             20:11                We often talk about it that way. We say an asteroid killed the dinosaurs and it sounds like it landed on all their heads and they all keeled over. But a mass extinction is caused by ecological disturbance. The ecosystem around the world had the rug pulled out from under it. I often think about the impacts, so to speak, of the asteroid as three different time scales. You had immediate effects. So like hours and days afterwards, you would’ve had massive shock waves. Massive earthquakes, which would’ve caused landslides. We have evidence in the geological record of tsunamis washing up on shorelines around the world. And then you would’ve had, within the first few hours at least, raining debris spread for thousands of kilometers in all directions. Just the falling chunks of rock and formerly vaporized and re-solidified bits of rock. These would’ve been very hot, so they also would’ve caused a heat burst in the atmosphere, which probably would’ve set off wildfires and been extremely dangerous for anything on the surface. And then of course, anything in this crater space is gone.

Will Harris:                   21:26                It’s just not a thing anymore.

David Moscato:             21:27                It’s vapor. So the first day or so is going to be directly devastatingly damaging. And then in the years and decades after that, you would’ve dealt with the fact that most of the dust kicked up by the asteroid impact is sticking around in the atmosphere. It’s hanging around up there in the sky and it is predicted by models of asteroid impact and also by some geologic evidence that we have that that dust in the air would have blocked sunlight, which would have not only led to short term cooling… so global climate would’ve dropped for a while… but also that’s really bad for plants. No sun means hard time for plants, which means hard time for herbivores and so on down the chain.

Will Harris:                   22:20                Even if it wasn’t a perpetual night, a notable dip in sunlight percentage has huge effects. It takes a lot less of a decrease in solar radiation reaching Earth to affect the plant productivity and temperatures than people might think. You don’t have to actually put the shutters on and make it hard to see. A little bit of blocking dust would actually have a huge effect.

David Moscato:             22:46                And that opaque dust, that dark dust in the air, would have lasted and had this impact for years and years and years. Eventually, that would’ve cleared and you would’ve been left with the fact that, even after the dark dust cleared, that impact especially hitting carbonate rocks on the surface of the Earth would have pumped a ton of carbon dioxide into the atmosphere. And as we are very familiar with today, when you ratchet up carbon dioxide in the atmosphere, you lead to increased temperatures. After this short term cooling, there would’ve been a longer term warming effect as that carbon dioxide was lingering in the atmosphere. For probably hundreds to thousands of years after the impact, global climate was still out of whack, now in the other direction, and ecosystems around the world would’ve been struggling in the aftermath of all those earlier effects as well. So there would’ve been this devastating early consequences, these relatively short term struggles, and then these long term lingering effects. Once the dust settled, so to speak, lots of ecosystems and lots of species just didn’t make it through.

Will Harris:                   24:13                Really, what just happened is the levels of chaos were increased exponentially and ecosystems do not maintain well in chaotic situations. As things were just constantly shifting and constantly changing, you’re going to lose players as they just can’t keep up or they get pushed out by others trying to survive. It winds up killing off a lot just because things aren’t as they were or that species needed it to be.

David Moscato:             24:44                And that has a cascading effect. If one species of plant goes extinct, then the things that ate that plant are now going to have trouble. And if one predator goes extinct, then it’s prey is going to expand and that might impact other species. Every time a species disappears or diminishes or goes extinct, that’s going to have ripples across the ecosystem. So this was just rippling back and forth for probably millennia before recovery started up again.

Shane Hanlon:              25:17                Do we have a sense of… Like you said, it dipped relatively… The temperatures dipped for the short term and then increased dramatically over the long term. What was average temperatures back then? Were you talking about temperatures now? Or is it very different than these climates in which dinosaurs existed? What was it like?

David Moscato:             25:36                That’s a good question. I don’t know numbers off the top of my head. During the late Cretaceous, it was a warmer world than it is today. Basically, anywhere you were in the world, it would’ve been warmer. There were polar forests during the Cretaceous. So even the poles were warm enough to support forest ecosystems. They wouldn’t have been tropical forests.

Will Harris:                   25:58                But still fairly lush.

David Moscato:             26:01                So it was a much warmer world than it is today. And then the dip and then rise again following the extinction event probably would’ve seen at least a few degrees change in either direction.

Will Harris:                   26:16                And that, once again, is one of those where that’s not as dramatic as people might have had in mind after we got hit by a giant rock from space.

David Moscato:             26:22                It wasn’t 20 degrees.

Will Harris:                   26:24                Yeah. It wasn’t turning the oven from mid to high.

David Moscato:             26:27                Well, for a little bit.

Will Harris:                   26:28                Yeah, right? Yeah. For that second.

David Moscato:             26:30                For a couple of days, it turned the oven to broil.

Will Harris:                   26:34                But a two degree in Fahrenheit or Celsius, whichever one you’re using… A few degrees constant change is huge. That’s a lot of energy that is globally… that the temperature is experiencing. So it doesn’t actually take that much of a shift for ecosystems to be shocked by it.

Shane Hanlon:              26:54                Yeah. I feel like that is a good from a communication perspective, bad for human life perspective comparison to what folks are looking at now with climate change when we talk about a few degrees. It’s like, oh, it’s a few degrees. That’s not bad. It’s like, it killed the dinosaurs.

David Moscato:             27:12                It’s also worth considering that the peak of the ice age about 20000 years ago, the last glacial maximum was… I think it’s about four degrees colder than today. And Boston was covered in an ice sheet as thick as Antarctica.

Shane Hanlon:              27:27                Oh, that’s wild.

David Moscato:             27:29                So it doesn’t take a lot to create pretty major differences.

Will Harris:                   27:33                When you scale it up to a planetary temperature shift of that much, that’s a lot of energy that you’re losing or gaining.

Shane Hanlon:              27:53                Kind of puts present day climate change into perspective, huh?

Vicky Thompson:           27:58                Yeah. I’m really disappointed and worried about this, but I think… Yeah. I mean, it is doom and gloom. There’s nothing… We’re doomed.

Shane Hanlon:              28:08                You’re going through some feels right now.

Vicky Thompson:           28:10                I’m really having feelings. I don’t even know. There’s no words. I’m just half sentences here.

Shane Hanlon:              28:13                Well, on the upside of this or the potential upside of this, the dinosaurs didn’t really have the capacity to do anything about it, where we do. So let’s not be too gloom and doom about it.

Vicky Thompson:           28:25                No, that’s true. Oh yeah. Yeah, yeah. Just gloomy.

Shane Hanlon:              28:29                Gloomy, yes. And real. We’ll be real about it.

Vicky Thompson:           28:31                Oh, absolutely.

Shane Hanlon:              28:33                So in addition to the big rock that caused all this havoc at the time…. That’s the big thing, no pun intended, that was going on at the time. But it turns out there actually might have been other things going on as well.

David Moscato:             28:46                So there were definitely other things. This didn’t occur in an absence of general change on earth.

Will Harris:                   28:52                Yeah. It wasn’t that things were just hunky-dory, completely normal.

David Moscato:             28:56                One that often gets talked about is sea level change. This was a time period of dramatic shifting of sea levels, which meant rearranging of ecosystems especially near the coast.

Will Harris:                   29:09                Currents were shifting when that happens.

David Moscato:             29:12                Some researchers have suggested that that period of transition for some ecosystems may have left them a little more vulnerable than they otherwise would’ve been to a major disturbance. But the big one after asteroid that often gets brought up is volcanic activity. And this is actually… It’s very funny because oftentimes you’ll see artwork or movies depicting the age of dinosaurs and there’s always a volcano in the background.

Will Harris:                   29:41                Just puffing away.

David Moscato:             29:43                I think when we talk about volcanic activity associated with the extinction of the dinosaurs, I think that’s probably what comes to mind for people is like Mount Saint Helens or Krakatoa sort of smoking in the background, but that’s not the kind of volcanic activity that has been linked to this extinction event. We are talking about a type of volcanic activity that leaves behind what geologists call a large igneous province, which basically means an area of thousands of square kilometers, sometimes millions of square kilometers of igneous rock laid down by consistent volcanic eruptions over thousands, sometimes hundreds of thousands, of years.

David Moscato:             30:28                So when this asteroid hit, it hit during a time period where volcanic activity in India, which left behind a geologic formation we call the Deccan Traps, had been going on for many, many thousands of years and continued, it seems, for thousands of years after this. All that volcanic activity would’ve been pumping out volcanic gases potentially impacting the atmosphere. Potentially impacting environments for a long ways in all directions. There’s been a lot of discussion with the volcano and an asteroid and sometimes it even comes down to… You’ll see news reports that treat it as sort of like volcano versus asteroid. Which one really did it?

Will Harris:                   31:14                Who’s the true murderer?

David Moscato:             31:16                Which one’s the smoking gun? And the reality is it’s very difficult to tease apart how important was one effect versus the other because we can’t… We don’t have another Earth to experimentally test. What if we hit it with an asteroid, but without the volcanoes? Although we can model those things digitally. Generally speaking, as far as research today, most experts seem to agree that the asteroid impact was almost certainly the thing that was the event that really tipped things over the edge, but there’s been a lot of back and forth in research on just how important that volcanic activity was in perhaps weakening or exacerbating the struggle that ecosystems were going through at the time.

Will Harris:                   32:06                It’s a situation where, had we been hit by the asteroid without that volcanic activity, maybe there would’ve still been an extinction event but it wouldn’t have been as dire or the effects would’ve been notably different. That’s where the debate is did that have an effect on the side effects of the asteroid or would the asteroid have done what it did regardless?

Vicky Thompson:           32:38                It sounds we’re just talking about many different, very bad, terrible things.

Shane Hanlon:              32:44                You’re no bad… What is it? No good, very bad millennia essentially?

Vicky Thompson:           32:51                Yeah. Yeah.

Shane Hanlon:              32:53                So yes. In this case, definitely. And frankly, in all cases. All scenarios. Regardless of whether it was all these things put together, whether it was probably just going to be one of these scenarios, dinosaurs were going to get the short end of the stick.

Will Harris:                   33:07                I’d say another one of the big ones though that I see get thrown around with this is that this is somehow an indicator of the flaws in dinosaurs. That this is a definitive of like, well, look, the dinosaurs didn’t make it.

David Moscato:             33:22                Clearly, they were unfit to survive.

Will Harris:                   33:24                Exactly. They had their chance and they blew it. Yeah, it’s often portrayed that this is somehow an indicator that dinosaurs were faulty. The truth is that all the groups that you think of as surviving also still took major hits. Like crocs come up. What we think of as crocodiles today hadn’t actually evolved. The species we see today weren’t around and the group had just barely come around. So it’s not actually the crocs we have today were hanging around with dinosaurs and then just survived through. There were still tons of species that went extinct. There was a huge variety that we no longer have. And so it’s not that the things that made it just made it through because they were superior. They happened to survive for a number of reasons as did a bunch of dinosaurs in the form of birds.

David Moscato:             34:27                Yeah. Many of the things that survived the extinction event probably did because they had certain adaptations that allowed them to survive. They were more generalists. They were smaller. They lived far inland where they avoided tsunamis or whatever. And that is just as much adaptation to ecological disturbance as it is luck. A lot of the survivorship across this extinction boundary probably came down to luck. Dinosaurs like T-Rex and Triceratops and Ankylosaurus were extremely successful groups of animals. And oftentimes for millions of years. Their groups were successful for tens of millions of years. The dinosaurs, in some respects, were actually doing better during the late Cretaceous than any time before during the Mesozoic era. It’s not like this happened and all the dinosaurs were just waiting for that last straw. Many groups were doing about as good as they had ever done and this was an unlucky event for those organisms.

Will Harris:                   35:30                It sometimes gets portrayed that dinosaurs went stale. That they had had hit a plateau and this asteroid was what shook things up for things for mammals to take over. And that is so far from what all the evidence shows. That dinosaurs had not slowed down. They were not hitting the end of what dinosaurs could do. Unfortunately, space threw a rock at them and a lot of them did not make it.

Shane Hanlon:              36:00                It’s easy for us to say on our relatively short timeline here on Earth that they were weak and just couldn’t cut it when they were around for literally millions of years compared to the thousands of years that go back to our ancestors. Like we’ve been around for very different scales. I was going to say. Easy to throw stones at glass houses. A little bit too on the too on the nose there.

Will Harris:                   36:24                Too soon.

David Moscato:             36:24                Throw stones at greenhouses.

Shane Hanlon:              36:33                I love this image of dinosaurs being washed up and living in the past.

Vicky Thompson:           36:39                Yeah. I’m picturing Jerry O’Connell as Trip McNeely in Can’t Hardly Wait. Do you remember this movie?

Shane Hanlon:              36:46                I do remember this movie.

Vicky Thompson:           36:48                So I’m specifically like imagining the scene where he’s like sitting on this bench at a high school party just being sad because none of the high school girls like him anymore even though he’s like 25.

Shane Hanlon:              37:02                No, that’s a… I was going to say. Folks, Google it, but that is actually a fantastic summary. That’s that’s all the imagery you need. Yeah. Dinosaurs were not… They were not perpetuating the stereotype by any means. It would’ve been bad news no matter how, quote, unquote, tough they were. It was everyone’s time except for a select few and that’s why we have what we have today, I guess.

Vicky Thompson:           37:29                Thanks, Trip McNeely.

Shane Hanlon:              37:33                All right. Well, that’s all from Third Pod From the Sun.

Vicky Thompson:           37:36                Thanks so much to Shane for bringing us this story and to David and Will for sharing the work with us.

Shane Hanlon:              37:42                This episode was produced by me with audio engineering from Colin Warren.

Vicky Thompson:           37:47                We’d love to hear your thoughts on the podcast. Please rate and review us. You can find new episodes on your favorite podcasting app or at thirdpodfromthesun.com.

Shane Hanlon:              37:56                Thanks all and we’ll see you next week.

Vicky Thompson:           38:04                I keep looking at your musical notes on the wall. Did you choose those?

Shane Hanlon:              38:10                Mm-hmm (affirmative). Yeah.

Vicky Thompson:           38:13                It’s really on theme. Is the rest of your house like thematic in any way?

Shane Hanlon:              38:19                Actually, yeah. Our house is very national park-y because that’s our jam.

Vicky Thompson:           38:25                So no sad cows.

Shane Hanlon:              38:27                No sad cows. I’m trying to think if I ever… I’m sure I did something like that. Like I had that version. Oh, actually, I do have something like that.

Vicky Thompson:           38:35                You have a sad cow? Why do you have that?

Shane Hanlon:              38:37                Because it’s silly. Look at that.

Vicky Thompson:           38:39                It is silly.

Shane Hanlon:              38:40                It’s a frog with glasses. So we actually only have one bathroom in his house. It’s actually one of the reasons why we got it for the price we did. There’s just two of us. But in our old house, the one we rented, we had two bathrooms so we had like his and hers bathrooms and my bathroom was-

Vicky Thompson:           38:55                Frog themed?

Shane Hanlon:              38:55                It was herp themed. So it was… My shower curtain was a giant… was literally a salamander the whole way across the curtain. That thing was hanging up in there. I have little different knickknacks of frogs and salamanders and stuff from indigenous tribes that are really cool that actually still are around somewhere. But yeah. So that’s what that was.

Vicky Thompson:           39:13                That’s nice. I like that.

Shane Hanlon:              39:15                Yeah. We’re cute.

Vicky Thompson:           39:17                I’m learning so much.

Shane Hanlon:              39:18                You’re going to learn more.

Vicky Thompson:           39:20                I love it.


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