 For those of you, for those of you who weren't here when I told you, unfortunately, Steve wasn't to be able to be here in person. As you can see, he's ready and waiting online. I hope you can hear as okay. Steve. Yes, I can. Can you hear me. So I'll just, first of all, say that Steve is a paleontologist. He's Professor at the University of Edinburgh. He works on the evolution of dinosaurs and the ball of the dinosaurs and the rise of the mammals, which is what he's going to talk to us about. Steve is an internationally renowned figure in this area and we're very fortunate to be able to capture him for this evening. The lecture format will be as usual, there will be the opportunity for questions afterwards. Steve has written a number of books, very popular books about the dinosaurs and the mammals, if you want to follow up on that afterwards. I'll just hand over to Steve. Steve, if you can share your screen and if you share sound and video, we're going to be using that as well and over to you. Great. Thank you. Can you all hear me. Okay. Thumbs up there. Okay, great. Okay, so you should be seeing my screen here. So thank you. So thank you very much. First of all, for the invitation. I really appreciate it. You know, society as prestigious as yours to get an invite was a great honor and I am very sorry I can't be there in person today. It just turned out to be, we planned this so many months ago when I didn't know my teaching schedule and this has just turned out to be a crazy week. I'm doing three field trips this week for our students and four lectures and I have a young son at home and a family and I needed to, there's no way to get in between the teaching today in Glasgow with also with family time. So I do apologize for that, but I promise I will come in person as I've said in a few years time when I'll have my next book out which will be about birds, the evolution of birds. And the other promise I'll make is that any, if any of you have books and wanted to get a book signed or anything, you're always welcome to drop by and see me at the University of Edinburgh. Just send me an email. My email is pretty easy to find and I will make time to say hi and meet you in person and sign your book, but hopefully I'll see you all in a few years for a lecture in person. Okay, so I'm going to talk to you today about dinosaurs and a little bit about mammals, about how our ancestors took over from the dinosaurs. I'm a paleontologist. I'm one of those fortunate people that gets to dig up dinosaur bones and other fossils for my job. I grew up a long way away from Scotland in the middle part of America, not too far from Chicago. But I've been here for over a decade now teaching at the University of Edinburgh, and I have fallen in love with Scotland. I'm a dual citizen now, have a Scottish family, a little Scottish boy. And so, you know, I'm here for the long haul and really enjoy working here, teaching here at a great university like Edinburgh and digging up fossils here in Scotland, including some dinosaurs, which I will tell you a little bit about in a bit. Now, one of the things I do in addition to my academic job of teaching and research and lab management is I love to write about science and communicate science to the public as broadly as I can. So over the last few years, I've written a few books, one on dinosaurs and then a follow up on mammals. And these are really pop science books that tell these broad stories of evolution and try to make them accessible to people from all walks of life. And what I'm going to do today is more or less tell the story that I tell in my dinosaur book and then a little bit of the story in the mammal book. And really, these stories are stories of evolution. It's one big story, frankly, of the last 250 million years or so. And if we go back in time to about 250 million years ago, the earth looked like this. Very different. All the land was gathered together into the single super continent of Pangea, which stretched from the North Pole to the South Pole covered by harsh deserts across much of that land. This was a hard place to live. Arid, dry, monsoons battered the coasts. It was a challenging place. But as always, there were plenty of plants and animals that were adapted to that world and the animals that ruled this world on Pangea in what's called the Permian period of Earth history were actually relatives and ancestors of mammals. They were distant cousins and ancestors of ours. They were the top predators, the top plant eaters on this giant landmass. But then something happened. Something dramatic happened about 250 million years ago as the Permian period ended. And what happened was that enormous volcanoes started to erupt in what is now Russia. And of course, right? It's always Russia 250 million years ago today. It's always Russia. And then it was these huge volcanoes that basically fishers in the earth, Grand Canyon size holes in the earth that opened up and spewed out tsunamis of lava for hundreds of thousands of years. And it was catastrophic. Not just the lava itself, but that is the lava burnt up through the earth's crust. It released a lot of carbon dioxide, a lot of methane, these nasty greenhouse gases that poison the atmosphere led to runaway global warming caused a terrible extinction, probably the closest life has ever come to totally dying out ever since the first life evolved about 4 billion years ago. And this extinction killed about 95% of all species, absolutely devastating. But some things did manage to survive. And when I was a student, particularly, I was really interested in this extinction, what lived, what died, how the earth was reshaped afterwards. So I found myself spending a lot of time in Poland looking for fossils. And maybe Poland doesn't strike you as fitting that stereotype you might see on TV on the Discovery Channel or National Geographic of paleontologists, guys that look like Indiana Jones going out into the desert, brushing sand off of the bones. That does happen. But really, we can find fossils anywhere where there's rocks of the right age and the right type. The sorts of rocks that were formed from mud and from sand and the places, rivers, lakes, ponds, swamps, the kind of places dinosaurs and other animals lived. And in Poland, there is a series of rocks layer by layer of clay rock that's actually mined to make bricks in these big quarries. And those layers of rocks span that extinction. And those layers of rocks are full of fossils. So you can read those layers like the pages in the book to see what lived, what died and what came afterwards. And my friend in Poland, Gregor, she grew up in this part of central Poland surrounded by these fossils. He started collecting them as a teenager. I started to work with him. And we found some fossils, some humble little fossils in rocks just about one million years. Rocks that formed just about one million years after those terrible volcanoes. And these fossils, these were not fancy skeletons, not big scary jaws and teeth and the kind of fossils that you might go to a museum and gawk over. These are much smaller fossils, much more humble fossils. And they're actually the traces that these animals left behind their hand prints and footprints. And that's what you see here, a footprint and a hand print. And they're very small, just a few centimeters long, just about the size of a cat's paw print. And we can do the Cinderella thing and look for skeletons that fit the footprints and the hand prints. And that tells us that it was an animal like this that made these tracks. And this animal about the size of a cat, kind of an awkward looking creature, long, gangly arms and legs. Clearly this is an active dynamic, fast-running animal. And this is, believe it or not, a type of reptile. And it's a reptile that we call a dinosauromorph. And that's just a fancy name for the closest relatives of dinosaurs, the ancestral stock that dinosaurs came from. So the dinosaur story, their origins go back to the recovery from this great extinction. When these little reptiles evolved from a few ancestors that made it through that volcanic hellfire. And from there, about 250 million years ago, these dinosauromorphs and then the true dinosaurs that evolved from them, they continued to adapt and change. But for the next 50 million years, throughout what's called the Triassic period of Earth history, the next 50 million years, the dinosaurs were not very special. They were not the dominant animals on the super continent of Pangea. They were character actors, bit characters, B-list characters, whatever you want to say, background characters, in a drama that was really about other types of animals. And we found fossils of these other animals in abundance in Portugal, where we've done digs down in the Algarve. And in these red rocks, about 20 miles inland from those beaches where so many tourists like to go, we found a graveyard, fossil graveyard from the Triassic period, from the time dinosaurs were starting to evolve. But it's not full of dinosaurs. It's full of hundreds of skeletons of these creatures, amphibians, basically salamanders, but giant salamanders the size of cars. If you can imagine something so grotesque as a salamander the size of a car, and then imagine a flock of them, thousands of them probably living together in the rivers, in the lakes, in the Triassic period. If you were one of those small little early dinosaurs, you would have stayed away from the shoreline, because these things would have been greeting you there. But it was no safer, no better on dry land, because back in the Triassic period, it was the age of crocodiles. And today, crocodiles, alligators, they're part of our world. They're plenty scary. You don't want to meet one. You always see these stories go viral in the news of somebody, usually some guy in Florida doing something stupid, getting too close to a gator, and something bad happened. So you don't want to mess with them. But to be honest, they're not big parts of our world. They really only live in the tropics and the subtropics. They don't live here. It's far too cold. It's only about 25 species of them. But back in the Triassic period, there were hundreds and hundreds of different species of crocodiles and their close relatives. And these included things that were nearly the size of buses. Ones that were covered in armor and spikes all over their bodies. Ones that were top predators that had heads that looked like the heads of a mini T-Rex. Some had sails on their backs. Some replaced all of their teeth with beaks, if you can imagine. Something as weird as a crocodile with a beak. And some even ran only on their hind legs. The Triassic was the flourishing of the crocodiles. They were more diverse, more successful than the dinosaurs of the time. So the Triassic world was one where dinosaurs were living. Dinosaurs were evolving. Dinosaurs were spreading around, but most of those dinosaurs were just the size of cats, dogs up to the size of people. The very biggest ones got to be about the size of a giraffe. And that's what dinosaurs were like for the first several tens of millions of years of their evolution. Nothing very special. Just one group of many animals evolving on the super continent as the world recovered from that terrible extinction. But then something happened that changed everything. It changed the story. It set life on a new course. And it gave dinosaurs their opportunity. And what happened was about 200 million years ago, the super continent began to break apart. And of course it did. That's why we have separate continents today. And that's why South America looks like it fits into Africa like a puzzle piece, because they were once conjoined land and they broke apart. Now the dividing line of that breakup today is the Atlantic Ocean. But before water rushed in to fill the gaps between the separating continents, first the Earth-Bled Lava. And once again it was a time of massive volcanic eruptions, not quite as bad as those 50 million years earlier. But these eruptions were still bad enough to cause more global warming and another big extinction. And this extinction nearly wiped out the crocodiles and their cousins. It spared only a few species, a few survivors, the ancestors of today's crocs. It wiped out a lot of the amphibians and a lot of the other animals. But for some reason, dinosaurs were the great survivors of that extinction. And we don't know why. I wish I could sit here and tell you why. I wish there was an easy explanation. Maybe they had higher metabolism, maybe they ran faster, maybe they were smarter. We don't know. We know the what. What happened is that that extinction wiped out the competitors of dinosaurs and spared the dinosaurs, but we don't know the why. And it's really one of the biggest mysteries that remains about dinosaurs. And there's plenty of mysteries that remain about dinosaurs. And I do think this is one that somebody in the younger generation of paleontologists will figure out. But until then, we don't really know why this happened. We just know that it did happen. And as those volcanoes die down, the Triassic period turned into the next interval of geological time, which is the Jurassic period. And there's a reason that the book and the film are called Jurassic Park. If it was Triassic Park, it'd be a film about giant crocodiles and super salamanders. I mean, it'd be a great film, but it probably wouldn't make billions of dollars at the box office because it wouldn't be about big dinosaurs. It was only in the Jurassic period that dinosaurs really started to assume control, to assume dominance, to grow to enormous sizes, to spread fully around the world, different species living on these different land masses that were breaking up as the supercontinent split apart. And this is when enormous dinosaurs with long necks and the meat eaters that got up to the size of buses and dinosaurs with horns and spikes and frills and duckbills and domeheads and plates on their backs and all of those wonderful, sublime things we think of when we think of dinosaurs. It's in the Jurassic when these dinosaurs are evolving. So this sort of scene, this iconic picture of the world of dinosaurs, it took like 50 million years of dinosaur evolution to get there and the good fortune of surviving that extinction. Now, we are learning more about dinosaurs than ever before. There's probably about 2,000 species of dinosaurs that have been found now and people are finding more than ever before. Somewhere around the world, somebody's finding a totally new one, a totally new species of dinosaur once a week on average, which is just, to me, just remarkable. About 50 new species of dinosaurs turn up every year. It's because there's more people looking than ever before, a lot of young people looking and not just people in Britain or America or Canada or Western Europe that are studying paleontology and looking for fossils. It's really the large growing countries like China, Brazil, Argentina, Mongolia, South Africa, where so many young people are going out looking for dinosaurs and people are finding dinosaurs really all over the world now. Remember, anywhere with rocks of the right age, so formed during the time of dinosaurs and the right types, formed in environments where dinosaurs lived, you might find dinosaur fossils. And to prove that, we're finding them even right here in Scotland. And this is a pretty new thing because the very first dinosaur fossil found in Scotland was found only in the 1980s, around the time I was born. And that was a single footprint of a dinosaur that had fallen off a cliff here on the Isle of Skye. What I think is one of the most beautiful places in the world with this enchanting landscape that's become a backdrop for so many Hollywood films just because it's so gorgeous. And for those of you that have been to Skye, you've probably gawked at this landscape. But maybe what you might not have realized and what most people wouldn't realize is that a lot of this beautiful landscape, especially in the northern part of the island, north of Port Tree, is actually sculpted out of Jurassic age rocks. The rocks that were formed on beaches in lagoons and rivers and lakes about 170 million years ago as dinosaurs were diversifying. And so the fossils we find here help tell the story of how dinosaurs took over the world in the Jurassic. Now we go to Skye quite often and we bring our students to Skye. It's a great place to teach our students fieldwork and geological and paleontological exploration skills. And there's no exaggeration to say that our students always find the best fossils. And I wish I could say I found the best fossils all the time. Because fossil hunting, it is kind of a competitive little game. We always want to find the best stuff, but all the time the students deliver. The best example of that, this is Amelia Penney here in the middle. Amelia's actually just been hired as a lecturer now in Edinburgh, which we're very happy about. But when Amelia was a student here, we brought her out in the field. She was walking along the beach. She saw something interesting sticking out of the rock in the tidal zone. It turned out to be the head of a pterodactyl, a pterosaur. One of those giant reptiles that flew over the heads of dinosaurs, but not dinosaurs. They're not dinosaurs. They're cousins of dinosaurs. So I won't say any more about it. It's up just to say last year we named it as a new species. And we called it Yarkskianoc. That's a Gaelic term that roughly means winged reptile from Skye. So we don't only find dinosaurs on Skye. We find a lot of fossils. This is Moji, who came from Nigeria to study with us. She actually studied, she did a master's on the fossil, fishes of Skye. And so here she is cutting some small little fish bones out of the rock. The rock is very hard, concrete level hardness, because it's been baked by volcanoes over time. So that means that we can't use hammers and chisels like we might at most dig sites. Instead we have to cut the bones out. And if it's little fish bones, fish teeth, you can use an angle grinder like this. If it's dinosaur bones, you need bigger tools. And this is Doogie Ross, our dear friend who built and runs the Staffin Museum on Skye, north of Port Tree, the museum that houses a lot of Skye's fossils. Doogie is a builder by trade and a crofter who built the museum when he was actually a teenager. And he has a lot of diamond tipsaws. He knows how to use them. And here he is cutting a dinosaur bone out of a big boulder on the beach. Now I can speak forever about Skye. We love Skye so much. We've found so many cool things there. But I want to tell you just one story that should illustrate why the dinosaurs are important and how they fit into the global story of dinosaur evolution. And this is a discovery we made a few years back at the northern tip of the island, a place called Dantola, which is on the main a-road north of Port Tree, kind of as you're looping around the top of the island. As I'm taking this photo, I'm standing in the shadow of the ruins of a 14th century castle. And you might notice that the sky is beautifully blue, hardly any clouds. And so you may wonder, why am I not taking advantage of this very narrow window of good weather on Skye to look for fossils? Well, the problem at this time is it's high tide. The waves are lapping up against the beach. But when the tide goes down, this beach turns into a rock platform that juts out about 100 meters into those very, very cold waters. And a geologist friend of ours found a tiny little jaw bone there, and that got our attention. There's fossils here at this site. There's bones. Maybe the jaw is part of a skull. Maybe we can find the host skull. Maybe we can find the skeleton. We got very excited. We went there. We spent nearly a whole day on our hands and knees scrutinizing the rock. We didn't find anything. And that's the reality of collecting fossils. Really, we don't just go out and find a new species of dinosaur every day that we look. It is hard to find fossils. It's like prospecting for gold or diamonds. You have to be patient. You have to have luck. And this was just shaping up to be a very bad day. So we called it a day. We started walking back to our cars. It was going to be dinner time soon. And as we were doing so, we started to look at these tide pools. And these are normal tide pools, algae, seaweed, limpets, barnacles, hermit crabs, all the normal stuff from the Scottish seashore lived in these things. But we started to notice that there were actually a lot of these tide pools. There were over a hundred of them, and they were all roughly the same size and shape. They were holes that were about the size of car tires. And we noticed that some of them had a pattern to them, a zigzagging left, right, left, right sequence. Some of them we could see from the side and we can see they were impressed into the rock. So something in the Jurassic was impressing down into the sand before it hardened into sandstone rock. It wasn't just random tidal erosion causing these things. Some of these holes were filled in with a harder rock that stood out and actually brought out some features. These weren't just indiscriminate holes. They actually had bits sticking up on one end, one, two, three, four at the top end of that photo. And some of them were paired together, a big horseshoe shaped one with the smaller crescent shaped one in front. And they were big, big, again, each one about the size of a car tire. Some of them a bit smaller, those little crescent ones a bit smaller, but most of them about the size of car tires. So after a few minutes it dawned on us that actually this was a very good day. We had found fossils, just not the fossil bones and skeletons that we were hoping for. Instead we found trace fossils, the marks that animals left behind, footprints and hand prints, but so much bigger than those Polish ones because we're now in the Jurassic period, dinosaurs are getting bigger. And these definitely are dinosaur footprints and hand prints. And there's only one type of dinosaur, really only one type of animal that's ever lived on land in the entire history of the Earth. That was so big that every time it's hand or foot touched the ground, it left a hole the size of a car tire. And that's the sauropod dinosaurs, the long neck ones with the big bellies and the sturdy limbs that look like Greek columns. The ones Brontosaurus teplodocus, those famous giant dinosaurs. The ones living on the Isle of Skye 170 million years ago were some of the biggest animals that had ever lived in the history of the Earth up to that point. They were the size of about three elephants put together. Now later on in the Cretaceous period, the time after the Jurassic, some of these long neck sauropod dinosaurs got even bigger and became heavier than Boeing 737 airplanes. The record for heaviness and size and weight of any animal that's ever lived on land. Only eclipsed by some peculiar mammals that live in the water well. Now, the more we go to Skye, the more trackways we find. And it's not only the giant long neck dinosaurs. We have ones of meat eating dinosaurs. We have ones of stegosaurs, the dinosaurs with plates on their backs. We have ones of duck bill dinosaurs. So there's an entire ecosystem of dinosaurs living in the Jurassic of Skye. PhD student Paige has been exploring a lot of these sites and she is a whiz. She actually has an engineering background in addition to a geology background. And so she's been using drones, but also some of her own photographic rigs to make a really high resolution maps of these sites. And those help tell us how many footprints and handprints we have, which ones are associated into trackways, how fast those dinosaurs were moving, and what environments they were living in. And we can tell that a lot of these dinosaurs were making their tracks either along the beaches or actually while waiting in shallow water in ancient lagoons. And so their world would have looked something like this. This is artwork that was made by a good friend and colleague of ours, John Hode. He's an artist who's based in Perth and he specializes in reconstructing these ancient scenes. And here he envisions the aftermath of a storm. The winds have died down. The dinosaurs are going out into the shallow water looking for food. And those big long neck dinosaurs are on the hunt for anything they can eat to power their giant bodies and their metabolism. But in the foreground, something else lurks, a different type of dinosaur just about the size of a human that only walked on his hind legs that had sharp teeth and claws. And these dinosaurs, these theropod dinosaurs, these were the ancestors of T-Rex. These were the very first Tyrannosaur dinosaurs. They lived 100 million years before the great T-Rex. They were only the size of humans. In fact, some of them are only the size of dogs. And if you just look at one of these things, it doesn't look a whole lot like T-Rex, but like dinosaurs themselves starting from the humble cat-sized reptiles, Tyrannosaurs also started small. From small things, great things would come. And so over time, Tyrannosaurs got much, much, much bigger, culminating in T-Rex, literally the size of a double-decker bus. So how did that happen? Well, there are some new fossils from of all places. Uzbekistan in Central Asia, an enormous country, but one that's a bit off the beaten track, maybe not a place you think of when you think of dinosaurs. Me neither, until I started working with some colleagues there. And a few years ago, we described a new type of Tyrannosaur. We called it Timmerlangia, named after the great warlord of Central Asia. And this is an intermediate Tyrannosaur. It's kind of halfway in between, both an age and size. So it's about the size of a horse. So it's in between those first dog or human-sized Tyrannosaurs and the ones the size of a bus. It also comes from the middle part of the Cretaceous period. So it's intermediate between those first Tyrannosaurs that lived about 170 million years ago in T-Rex, which lived about 66 million years ago. So this intermediate species is really important. And what you see here on the screen is a photo of the back of its head, the skull. And that hole is where the spinal cord goes into the brain cavity. Now, we can take that skull and put it in a CAT scanner and use the X-rays of the CAT scanner to see inside, just like a medical doctor would do. And we can use software to build 3D digital models of the spaces inside the head, the cavity where the brain was, the sinuses, the ear, the nerves, the blood vessels. And therefore, we can build a model of what the brain and the ear of this Tyrannosaur look like. What's in blue there is the back end of its brain. That thing that looks like a pretzel in pink is the inner ear. What's important here is we can measure the size of that brain, compare it to the size of the body of this animal. And long story short, this Tyrannosaur had a very big brain for a horse-sized reptile. Also, that ear, that bit sticking down from the pretzel, that's the cochlea. That's the bit of the ear that hears sound. And we know from modern-day animals that the longer the cochlea, the greater range of sounds you can hear. So the key thing here is that these Tyrannosaurs, while they were still relatively small, just the size of horses, they were evolving bigger brains, greater intelligence, keener senses. And later on, their descendants, the big Tyrannosaurs, would inherit those things from these ancestors. Now, it seems like these good senses and intelligence were important because in the Cretaceous period, there was a smaller extinction. We don't know much about it. There's not a lot of fossils, but it seems to have been caused by climate and environmental changes. Maybe a bit of global warming, maybe changes in sea level, hard to say for sure, but we know that a lot of the incumbent large meat-eating dinosaurs died. But the small Tyrannosaurs, no bigger than a horse, made it through. Maybe because they were smaller, maybe because they had evolved these bigger brains and keener senses. For whatever reason, they made it through, and then this job at the top of the food chain was open, and then Tyrannosaurs filled that job. And as they did so, they grew enormously in size and stature. Again, T-Rex the size of a bus, its head the size of a bathtub, 50 teeth in there, each one the size of a banana, but a sharp banana with serrations like a knife. T-Rex literally crushed the bones of its prey. We have shattered bones of triceratops found right next to T-Rex's with bite marks that perfectly match the size of T-Rex teeth. But what really made T-Rex special is not just that it was big, it had brawn, yes, but it also had brains because it inherited those larger brains and keener senses from its ancestors. And that's what made T-Rex the ultimate predator, brawn and brains. Now, while Tyrannosaurs were getting bigger over time, another closely related group of meat-eating dinosaurs was doing the opposite. They were getting smaller, and these were the raptor dinosaurs. What you see here is what the real Velociraptor would have looked like. Don't believe what you see in the movies. The Jurassic Park Velociraptor is far too big, and it looks like an overgrown lizard. It's green, it's covered in scales. The real Velociraptor was the size of a miniature poodle, and it had feathers all over its body, and it even had wings on its arms. And this is not some mad hallucination of this artist, my good friend Todd Marshall, one of the great paleo artists who's illustrated my books. Todd has a great imagination, but this is based on reality. It's based on real fossils. We know from real fossils that dinosaurs had feathers and some even had wings. And these fossils, one of the great misfortunes, one of the great instances of bad timing, the first ones were discovered in China in 1996, three years after Jurassic Park came out. So Steven Spielberg didn't know that dinosaurs had feathers, but we now do know. And these fossils are found in far northeastern China, a place called Liaoning Province, which shares a long border with North Korea, really tucked away a land of factories and rolling hills and farms. And it was in the mid-90s that some of the farmers, when they were out working their land, started to find some very peculiar things in the rocks. Skeletons of dinosaurs, exquisitely preserved, and not just the bones, but the soft bits, too, with feathers all over the bodies. These dinosaurs, and in fact, the entire ecosystems they lived in, had the great misfortune of being buried by volcanic eruptions, kind of like Pompeii. And like at Pompeii, where the village was buried and people, sadly, were interred showing about their everyday lives, cooking breakfast, walking their dog, whatever they were doing. These dinosaurs were caught unaware, captured at moments in their everyday life, and they couldn't decay. They were caught in stone. These are freeze frames. That's why the preservation is so good. That's why it took so long to find fossils of dinosaurs with feathers, because it takes almost a miracle of preservation to get them. But the more farmers looked, the more they found. And we now have over 1,000 fossils of dinosaurs covered in feathers. And these fossils tell us a few things. First of all, they were the final piece of evidence to clinch something that scientists had debated since the time of Darwin, and that is this idea that birds evolved from dinosaurs. There's a lot of other evidence for that, but the feathers were really that final nail in the coffin. Feathers are so unique. Only birds have feathers today. They're so highly complex. The fact that dinosaurs had them, too, in combination with all this other evidence from the skeletons of dinosaurs, features they share with birds, that sealed the deal. Today's birds evolved from dinosaurs. But more than just proving that point, these fossil dinosaurs with feathers from China tell us how birds and how flight evolved from dinosaurs. And the first thing they tell us is that feathers were normal for dinosaurs. All different kinds of dinosaurs from these Chinese volcano rock deposits had feathers. Meat eaters, plant eaters, little ones, like this Tyrannosaur here. These are some of the tailbones down here of this Tyrannosaur. But there's even a bigger Tyrannosaur there that weighed about a ton that was about 30 feet long. Its body was covered in feathers, too. Feathers were a normal thing for dinosaurs, just like hair is normal for mammals. But the types of feathers that were normal for dinosaurs are these feathers. Above those tailbones, there's these things that look like scratches in the rock. Those are feathers, but they're simple feathers. They look like little strands of hair. And that's what most dinosaurs had. So no way could these dinosaurs fly with those feathers any more than we can fly with our hair. And that means that feathers must have evolved for some reason other than flying. And in fact, we think feathers probably first evolved in this simple form for the same reason mammals evolved hair. And that is to keep the bodies warm, to regulate the body temperature as these animals were developing higher metabolisms, eventually fully warm-blooded metabolisms. So most dinosaurs had these simple feathers. Most dinosaurs would have looked fluffy, probably, especially the smaller dinosaurs. But one group of dinosaurs did something different. They elaborated those feathers. And these were the raptor dinosaurs. And as their bodies were getting smaller and smaller over time, they packed those feathers ever more densely around their bodies. And they started to line up some of those feathers on their arms. And those feathers got longer and they started to branch out. They turned from things that looked like little hairs into brushes. And they lined up along the arm, overlapping each other. And they flattened out into the classic quill pen shape. And some dinosaurs evolved full on wings, as you can see here. Now this really looks like the wing of a bird. The types of feathers, the way they attach to the forearm and the hand, the way they overlap each other. This is a dead ringer for the wing of a modern day bird. But this is not a bird. It is a raptor dinosaur. One that I had the great privilege of being invited to help study by my dear friend Jun Chong Lu, who was one of China's great dinosaur hunters. A new species that we call Genuan Long, one of the most beautiful fossils I've ever seen, discovered by a farmer and brought to a museum in China. And then we were called in to help study it. Gorgeous fossil feathers all over the body, wings on each arm. Now if we saw this thing alive, it would have looked roughly something like this. Now it was a big animal. It was about the size of a Saint Bernard or a small donkey, something of kind of that range. Covered in feathers, wings on its arm. I think if you saw it alive, you would just consider it a bird. A weird bird? Yeah, a weird bird. It has sharp teeth and big claws on its feet. A weird bird. But it really isn't any weirder than an ostrich or an emu or a turkey. No, it's not. But we don't call it a bird because by convention, birds are those species that can flap their wings and fly through the air. Or ones like ostriches that have lost the ability to fly but descended from flying ancestors. That's the convention. So this thing's not a bird by definition. It is too big. Its wings are too small that if it flapped those wings, it couldn't have done anything in the air. And in fact, the first wings show up in dinosaurs that are about the size of horses. Those wings are about the size of a laptop screen. Way too small to do anything involved in flying. So instead we think that wings too evolved for other reasons. And we think it's most likely that they evolved for display as advertising billboards sticking out of the arms of these dinosaurs to attract mates and intimidate rivals. Which of course, many birds do with their feathers today. Think of a peacock. It's not flying with all of those gaudy feathers. No. But you can imagine evolution over time. Remember, the raptors are getting smaller and smaller. So you can imagine some species are getting smaller. Maybe they're elaborating their feathers, making bigger display billboards. And at some point, a threshold would have been crossed. The body size would have been small enough. Those advertising billboards big enough that if that dinosaur started moving its arms around just by the laws of physics, those billboards were going to start providing a little bit of lift, a little bit of thrust. And these dinosaurs could start flapping about moving around in the air. And at that point, flight was born. And it wasn't preordained. Evolution doesn't work that way. Evolution doesn't plan ahead. It only works in the moment to adapt organisms to their immediate environment and their immediate needs. So feathers, wings, these things evolved for other reasons. When they first evolved, the dinosaurs that evolved them would have had no idea their ancestors would co-opt them, repurpose them into things that could be used to fly. The same way that whoever invented the propeller, whoever invented the wheel, they would have never known that the Wright brothers would put those things together and make a flying machine. And that's really how evolution works as well. Now, I know it's a weird thing to think about birds evolving from dinosaurs. And not just that, the fact that birds are dinosaurs. They are dinosaurs. In the same way a T-Rex or a Brontosaurus is a dinosaur. They evolved from other dinosaurs. They are part of the dinosaur family tree. They are dinosaurs. Now, it's weird to think of it that way. But we should think of birds the same way we think of bats. What are bats? Bats are mammals. Of course, they're mammals. Nobody would argue. They have hair. They feed their babies milk. They have molar teeth. They have all the things that mammals have. They evolved from other mammals. They're part of the mammal family tree. But they just so happen to be a weird mammal that got small, evolved wings, and developed the ability to fly. And a bird is just a weird type of dinosaur that got small, evolved wings, and developed the ability to fly. The difference, of course, being that birds are the only dinosaurs that have made it through the gauntlet of extinction. So you can imagine some alternative world where bats are the only living mammal. And that's really where we're at. Which means there are dinosaurs still among us. Only one peculiar type of dinosaur, birds. But there are about 14,000 species of birds today. That's more than double the number of mammal species. So in some ways, the age of dinosaurs continues. And some birds are majestic and beautiful. And we spend our time going bird watching and looking at these animals with awe. Others, not so much. And my goodness, we see a lot of these in Edinburgh. I'm sure you see a lot of them in Glasgow. And if you've ever encountered one of these goals, trying to steal your chips, steal your ice cream, I think in that moment, the nastiness, the feistiness, the cunning, you can sense the inner velociraptor in a seagull. And that's not really just a metaphor or a turn of phrase. It's actually real. Velociraptor was one of the very closest relatives of birds. So dinosaurs live on in the form of birds. But all the other dinosaurs died out 66 million years ago at the end of the Cretaceous period. By that time, the land had continued to move around. The continents were looking more similar to their present day position. But one Wednesday evening, 66 million years ago, let's say, the world would have looked like this. There were dinosaurs living on every continent. There were big ones and small ones, meat eaters and plant eaters. They were still firmly in control of their world. And then everything changed. This six mile wide rock was hurtling through the heavens more than 10 times faster than a speeding bullet. There was a piece of space junk, an asteroid. It could have gone anywhere. But it just so happened to make a beeline for the earth. And it smashed into the earth with the force of over one billion nuclear bombs put together. Unimaginable energy. And it punched a hole in the earth's crust more than 100 miles wide. And you can still see some of that crater in Mexico today where it gets. It unleashed chaos. Earthquakes, volcanoes, wildfires, dust blocking out the sun. For many years, the earth went dark and cold. It was a global nuclear winter. Plants couldn't photosynthesize. They died. Plant eating dinosaurs and other animals had no food. They died. The meat eaters had no food. They died. No systems collapsed like houses of cards. And there was a mass extinction. The most recent mass extinction in earth history, 75% of all species died because of this asteroid. Now dinosaurs were there. T-Rex, Triceratops, these duckbill dinosaurs, they were all literally there the day the asteroid hit. And none of them, other than birds, as far as we know, survived for much longer. They seem to have been so well adapted to their own world, to the norms of their own world that they couldn't change and adapt in this sudden moment. They were too specialized. They were too big. Their diets were too specific. They were well adapted to their world, but unable to quickly adapt when things changed around them. But the earth recovered. The earth always recovers. And the more I studied dinosaurs, the more I become interested in what happened after the dinosaurs. And so I spent a lot of time in New Mexico. This does look like the sort of place where you would find fossils, the stereotype you see on TV, the desert, the badlands. And this happens to have one of the best records anywhere in the world of the last dinosaurs, the extinction, and then the animals that took over from the dinosaurs. And I've been going there for a long time working with my good friends at the New Mexico Museum of Natural History and Science and Albuquerque, Tom Williamson, a great fossil collector. I've taken many of my students there. This is Sarah, my very first PhD student. And Sarah very quickly became one of the world's experts in those animals that took over from the dinosaurs. And you start to find their fossils all over the place in Cretaceous Age rocks in New Mexico. Those rocks are bursting with dinosaur bones. Literally, there's places where we can't walk without stepping on shattered limb bones and vertebrae of dinosaurs. And then as you walk up through the rocks, the dinosaur bones disappear, the extinction. And then you start to find a lot of new fossils, different fossils, these kind of fossils, fossils of our ancestors, of mammals. They survived the asteroid because they were smaller. They could eat lots of different foods. They could hide easily. They were more adaptable. They were able to grow and reproduce quickly. They were able to change as the world changed around them. And it was mammals that took over from the dinosaurs. And it was one type of mammal in particular that really blossomed. And these were the placental mammals, the ones like us that can give live birth to well-developed babies that spend a lot of time in the womb. And we have fossils of these from New Mexico in abundance. Now, today there's about 6,500 species of mammals. There's still a few monotree, primitive mammals that lay eggs like the platypus. There's a handful of marsupials, koalas, kangaroos that give birth to tiny little babies that they raise in pouches. But about 95% of mammals are like us, like my little boy here, just gone down to bed, are placental mammals. And so is placental bats and whales and elephants and dogs and cats and otters and primates, monkeys, humans, all of these things that eventually blossom from these placentals that started to diversify quickly after the dinosaur extinction. Now, what the placentals were able to do was they were able to grow inside very quickly. Now, for 150 million years, there were mammals living with dinosaurs. Our ancestors were living with the dinosaurs, but living underfoot of the dinosaurs. For 150 million years, no mammal ever got bigger than a badger. Mammals lived in the shadows of dinosaurs, unable to grow to larger sizes because the dinosaurs were incumbent in those ecological niches. But then, within 200,000 years of the asteroid in New Mexico, we have mammals the size of pigs. Within a million years, mammals the size of cows. Their bodies got really big really quick. And in fact, as Ornella, my colleague in recent postdoc has shown by cat scanning a lot of the skulls of these mammals, they got so big so fast that their brains actually didn't keep pace. Their brain size relative to their body size got smaller after the extinction because the bodies ballooned in size so much. And because it's brain size relative to body size that really matters for intelligence, we can say a little bit glibly, but we can say the mammals actually got stupider after the dinosaur extinction. It wasn't their intelligence that was making them adapt to the new world. Body size, getting bigger, filling some of those niches left by T-Rexes and Triceratops, that was paramount. So how did they do it? Well, we have some exciting new evidence that Greg, another colleague of mine in recent postdoc, has led a project that has actually taken very thin microscopic sections of teeth and bones and there's daily lines of growth inside of teeth, including our own teeth. He's also looked at the chemical composition of these teeth and he can tell from changes in the amount of zinc and the amount of barium exactly two important moments in the history of these mammals lives. When they were born and when they weaned, when they stopped drinking their mother's milk and started to eat solid food. And we know for modern day mammals that those two elements changed dramatically at birth and at weaning. And Greg's been able to find these same changes in teeth more than 62 million years old of some of these first placental mammals living after the extinction. And we've been able to tell that some of these first placental mammals raised their babies in their wombs for seven months. Those babies drank milk from their mother for one month and then started eating solid food and then within a year they started making their own babies. And so we think that it was this ability to raise the young in the womb for such a long period of time to give birth to larger, more developed young that was the key to these placental mammals ballooning in body size so quickly after the extinction, once they have their chance, once those pesky dinosaurs were gone. And that culminated really in the world that we have today, a world that in many ways is dominated by mammals. Yes, there are more species of birds, certainly there's more species of insects and all kinds of other things. But if you look at the variety of size and shape and diets and behaviors and ways of moving and environments that placental mammals live in looking at things that range from elephants to bats to whales to humans, the diversity is staggering. And these placental mammals really only got their opportunity once the dinosaurs were wiped away. Now, within just about a few tens of thousands, at most 100,000 years of the asteroid, a lot of small teeth start turning up in the fossil record. A little bit later there's a nice skeleton that matches these teeth from New Mexico and it's called Torahonia. It's a small animal just about the size of a house cat at most, long gangly arms and legs, but long fingers and toes for grabbing onto the branches. This was a primate, one of the very first primates, an ancestor of ours. It only got its opportunity once the dinosaurs died. And to me, although the dinosaurs were surely a sad and very catastrophic thing, out of that death came our opportunity. Our forebears finally had a chance and our own evolution, our own development goes back to that pivotal moment in Earth history when that asteroid out of nowhere randomly, one Wednesday evening struck the earth. So it's all connected dinosaurs and mammals. I hope to have given you a little bit of insight into this story. Thanks a lot for hearing me. I know I went quickly. It's the 45 minutes to do 250 million years of evolution, but I'm very happy to take any questions you have. Of course, I tell the story in greater detail in the books. Once again, my apologies for not being able to be there in person tonight. The book I'm writing now to follow up from dinosaurs and mammals, as I said, it's about birds. It'll be out in a few years. I've promised I'll come and see you guys in person then. And in the meantime, I'm serious. If anybody has a book, anybody wants to stop it and say hi. Come to Edinburgh. Visit our lab. Just come in and get a book sign. Say hi. Please do let me know. Please do reach out. I'm more than happy to do so. So thank you very much for your attention and very curious to hear what questions you might have. Thank you. Questions. Yes, it is. I wonder if dinosaurs became extinct, not counting the birds. Are mammals going the same way? Well, I think very good question. I think, first of all, I would say if dinosaurs did not go extinct, if that asteroid was a near miss, if it just kind of whizzed by rattled the waters of the atmosphere, went salin on by no dinosaur, they've ever known that. I think dinosaurs would have continued to evolve. Dinosaurs had already been around for 150 million years, more than that actually. They already weathered global warming, cooler times, rising seas, falling seas. They've gotten through volcanic eruptions. Dinosaurs had been through a lot. And so I have no reason to think they wouldn't have kept adapting to the world. And it wouldn't be that T-Rex would still be alive, but other dinosaurs, you know, dinosaurs would continue to change and adapt. And that probably would mean that our mammal ancestors just wouldn't have had that opportunity. They might still very well, you know, have been small animals living in the shadows of dinosaurs, not yet getting their chance to break out. Now, of course, the world is changing very quickly around us today, in large part because of us, and mammals now are at their most perilous point, our most perilous point as a family, since our ancestors, our little furry ancestors, stared down that asteroid. And so I don't know what the future holds, but I would say that, you know, if things continue with the rapid pace of climate and environmental change, we could be talking about a large extinction of mammals, and especially of the larger mammals. And in fact, a lot of the really large mammals, the woolly mammoths, the giant sloths, the saber-toothed tigers, have already gone extinct, probably in large part because of us. Okay. So you talk a lot about the early mammals that you found in kind of the area in New Mexico and stuff. Have you found any evidence for that in Scotland in particular at all? That rocks of those age, of that age, like the boundary between the Cretaceous and then the extinction of the time that came after, which is called the Paleocene. There's not really rocks of that age in Scotland. There are, well, there are rocks of that age, but they're volcanic rocks, mostly. And in fact, a lot of the rocks of the Hebrides and parts of the Highlands are from these volcanic eruptions during the Paleocene time as the North Atlantic was opening. We don't really have sedimentary rocks, mud rocks, sand rocks and stuff that preserve fossils of that age. There are ice age mammals from Scotland, so things that lived with, you know, kind of between 10,000 and 2 million years ago. So there are woolly mammoths and things like that. There are also very, very primitive mammals from the Isle of Skye. Things that lived in the Jurassic while those huge dinosaurs were stomping around in those lagoons and Amelia's pterodactyl was flying overhead. There were tiny little mouse-sized mammals that lapped their teeth and occasionally their skeletons on the Isle of Skye. So there are fossil mammals here. They're quite limited, but they're very tantalizing, and surely there's more to be found. Hi. I wonder why size gets selected for dinosaurs and they grow so big. And what then limits that growth? And if it's good for dinosaurs to get so big, why don't mammals get so big? Yeah, good questions. Well, the first thing I'll say is mammals did get bigger than dinosaurs, but they're whales and whales live in the water. So the buoyancy of water can help support their bodies. They don't have to hoist themselves up against gravity, so it's not really a fair competition there. The biggest mammals that have ever lived on land are actually the few types of elephants and a few types of rhinos that got up to maybe between like 17 and 20 tons, which is a lot. That's really heavy. The biggest elephants today are like five tons, something like that. But even a 20 ton mammal is nowhere near the mass of some of these long neck dinosaurs that were 50, 60, 70 tons, the ones that were getting bigger than jet airplane. Now, not all dinosaurs were like that. And really what made dinosaurs special is not that they were big, but as they had such a range of sizes from things that were not even including birds, but just the non bird dinosaurs. Some were the size of pigeons and then they got up to things bigger than jet airplane. So the range of size was intense and extreme and really quite remarkable. Why were they able to get so big? Well, those long neck dinosaurs probably had a few different superpowers that kind of enabled it. I mean, they had the long neck so they could reach high into the trees. They had basically an all you can eat buffet of food that no other dinosaurs could get to. So that is helpful. The other thing is we can tell that they had lungs that were very similar to the lungs of birds, but very different from the lungs of mammals. This is important because the lungs of mammals, including our lungs, are actually not very efficient. We breathe in, we breathe out, breathe in, we breathe out, breathe in oxygen, release carbon dioxide. Our lungs is basically a back, you know, a series of ever smaller bags that inflate and deflate. The lungs of birds are more like a set of straws or a set of pipes or a set of tubes. Air can only go through them in one direction. And bird lungs have these balloons that stick off from them that are called air sacs. And those balloons store some oxygen rich air that doesn't immediately go across the lungs when the bird breathes in. So when the bird breathes out, those air sacs deflate and that air that still has oxygen goes across the lungs. That means that when a bird breathes in, it takes in oxygen. When it breathes out, it's also taking in oxygen from those air sacs. That means birds have a lot more efficient lungs. They take in a lot more oxygen than mammals. Dinosaurs, many dinosaurs, including the long neck dinosaurs, had those lungs. And how do we know it? It's not because we find fossil lungs that would be really hard to preserve, something so delicate. But it's because those air sacs that extend from the lungs make marks on the bones, and they often invade the bones and hollow out the bones. And the marks on these dinosaur bones are identical to those on birds today with these air sacs. So having these more efficient lungs that could take in more oxygen was probably one reason why these dinosaurs could get so much bigger than land mammals. It might not be the whole story, but I think it's an important piece of that story, because there's definitely something to it. Mammals have had a lot of time to evolve, but none of them have ever gotten anywhere near the size of the biggest dinosaur. And whether there was a limit to the size of dinosaurs, probably there was some physical limit, some biomechanical limit beyond which the dinosaur couldn't move anymore. It would be too bulky. Hard to say what that is. It would be an interesting thought experiment for a theoretical biologist to do. Hi. You speak a lot about how wings are developed and flight developed kind of as a side effect of wings getting bigger. And we know that the bones of birds today are lighter to help them support flight. Has there been any work done on the bones of dinosaurs and whether the lightweight skeleton developed alongside bigger wings or whether it was kind of a side effect that developed later on to help support flight once this was developed? Yeah, good question. So that's absolutely true. Birds have very lightweight skeletons. A lot of their bones are hollowed out. And a lot of their bones are hollowed out by the air sacs that extend from the lungs. And so those air sacs not only help bring more oxygen to the bird, but they lighten the skeleton as well, which is really important for flight. Now we know that a lot of dinosaurs have those air sacs. A lot of dinosaurs had fairly hollow bones. So the bone hollowing actually goes down very deep in dinosaur evolution. But birds probably did hollow out more of their skeleton as they were evolving flight. It's just really hard to tell because although we have good fossils of these dinosaurs covered in feathers, they're crushed a little bit by that volcanic ash essentially. And so it's hard to get really good three-dimensional views of those bones to see how hollow they were and how the hollowness changed kind of species by species across the family tree. What we do know, though, is that that bone hollowness did start before flight definitely as those bird-like lungs evolved. My suspicion is that the bird skeleton became extra hollow as they were evolving flight and refining flight. But I don't quite know how to test that. I don't think anybody has. And I think it comes down to the quality of the fossils that we have available. How does the transition from cold bloodedness to warm bloodedness play into the transition across those two mass extinctions? Oh, it's too late at night to try to unpack that. No, that's a great question. And there's been so much debate. I mean, I could go on forever about metabolism and what we know and what we don't know. Ultimately, it's very hard to tell if a fossil species was warm-blooded or not. Because warm-blooded animals like us and like birds, we have a constant body temperature, whether it's January, whether it's August, whether we're in Glasgow or we're back in Chicago where I'm from, wherever. Whether it's morning or night, whether we're in the sun or the shade, our body temperature is basically constant. And it's also a high body temperature. And we maintain that internally. Those are the key, you know, the different components of being fully warm-blooded. Now, of course, in nature, there's lots of shades of gray. It's not that you're either cold-blooded or warm-blooded. There's lots of intermediate things. To really tell if a fossil species was warm-blooded in the same way we are or a bird is, you really need to stick a thermometer in it and see how its body temperature changed from the morning to the night when it went in the shade versus the sun. It's really hard to do. What we know for sure, two things. First of all, we know that both mammals and dinosaurs in the form of birds did evolve proper full-on warm-bloodedness because birds and mammals today are warm-bloodedness. So there was some evolutionary transition to warm-bloodedness from cold-blooded ancestors. The other thing that we know is that regardless of exactly how dinosaurs maintained their body temperature, they were active, energetic, dynamic animals. They were more like birds in the way they moved and behaved and grew than they were like reptiles, like lizards or crocodiles. I think that is what we can be confident in. I do think probably some dinosaurs like velociraptors and those dinosaurs had pretty elevated metabolites. Were they fully warm-blooded the same way a bird is today? I don't know. Even some of the very first birds, the ones that still had teeth and claws, there's some evidence that maybe their metabolism was not as elevated as modern-day birds. But that's kind of proxy evidence. It's based on looking at growth lines in the bones, kind of like the tree rings in a tree trunk and building growth curves and, you know, seeing how fast they grew over the course of their life and comparing that to modern animals. So there's a lot of extrapolation, a lot of proxies when it comes to this, even harder, therefore, to see, to test how metabolism may have affected survival across extinction. But it is very possible in my mind that part of the reason dinosaurs survived that entriassic extinction when the crocs were so decimated could have been something metabolic, something about their metabolism or their growth rate. Hard to test it, but I have a suspicion that was probably part of the story. Hello. Has your studies into the life of prehistory and the mass extinctions that happened and the climate change that happened at different times at all, like, informed or affected your view of the current mass extinction and climate change that we're going under? And what effect has it had? Yes, absolutely. I mean, when it comes down to it, this is really why we study fossils. I mean, yes, a lot of us become paleontologists because when we were younger, we went to museums underneath the T-Rex. We were awed by these animals. So there is something very cool just about discovering dinosaurs and learning about these amazing creatures from prehistory. And that in itself is important. But the main reason really why we, those of us that become scientists and study these things, do it is because whether it's dinosaurs, woolly mammoths, trilobites, whatever, fossils are clues from the past and they are real organisms, real plants and animals, parts of ecosystems that dealt with all kinds of climate and environmental change. And the fossil record does tell us what happens when real plants and animals and ecosystems are faced with asteroids, volcanoes, global warming, global cooling, whatever the case may be. And what the fossils certainly tell us is that, the things that are happening to the Earth today have all happened before. There have been other times of global warming, other times of rising sea levels, other times when the ocean is becoming more acidic, more anoxic. This is not happening for the first time. The cause is different. We are causing this today. But these things have happened in the past. And the Earth has always gotten through it one way or another. So I don't really fear for the Earth itself. But what the fossil record is also telling us is that even the biggest extinctions in Earth history, like the one at the end of the Permian, 95% of species died during an episode of global warming. Temperatures probably went up by about 8 degrees Celsius. That took a few tens of thousands of years, most likely. What we're doing now is on the scale of decades at most a century or two. The pace of current climate change is dramatic and drastically faster than anything in Earth history. That gives me pause. And again, it doesn't really give me pause for the Earth. The Earth isn't going to become a barren wasteland. Things will survive. Some plants and animals are resilient. They always are. But it does mean that there probably might be a lot of extinctions. There'll be a lot of upheaval. There'll be a lot of changes in environments. There'll be a lot of dislocation. And for us humans, the world that we grew up in will change. You know, we evolved in a relatively calm interglacial period. You know, in the Ice Age when climates were better, basically, this interglacial time. That's the world we're used to. That's the geography we're used to. Our cities perched on shorelines. Many of our major cities, you know, shorelines change. They will change. So the world, the climate, the temperature, the geography that we are used to that our species grew up in, that our species adapted to, that our civilization started, and that will change. So we will have to adapt. And if there's one lesson, overall lesson of Earth history is that things do adapt, but some things don't when there's a big extinction or a big burst of climate or environmental change. So that will really be the choice for us how we adapt. Of course we should do whatever we can to mitigate the worst effects of this to keep the temperature rise to a minimum. The more we can keep it in check, surely the better it will be. Maybe I could ask you a last question. Steve, just following on from that one. Yeah. If you were to hazard a guess about what kind of animal is waiting there to take over from the mammals. And we'll never know, of course, if you were right, because you'll be there. Well, which kind of animal do you think has the potential to survive and flourish after we've destroyed much of the Earth? Keith Richards, obviously, is number one on my list. You see these guys that just released a new album. So some humans are resilient no matter what. But no, I mean, I say it half jokingly. I think, you know, it would be species that are able to adapt. Things that are able to deal with the darkness, with the filth, with the underground that can deal with toxins, with pollution, with environments that change around them. And if you look at the world today, I mean, I think you just want to look at the types of animals that can live in extreme conditions. And that can prosper in conditions that other animals don't. And, you know, it is maybe a bit cliched, but we're, you know, talking about things like subway rats and pigeons and cockroaches, these kind of things that just seem to love the grime and the filth and the carnage around them. So whether, you know, those species are surround, I don't know, but it's basically those kind of things. There's things that are small, things that can reproduce really quick, things that could hide away easily, that can kind of disappear into the cracks and the crevices, things that can eat lots of different foods. Those are the types of things that generally are more adaptable when the world changes quickly. And as we've seen in the past, at least, when there have been instances of global warming, oftentimes larger species are more susceptible to extinction. And it makes sense because larger species, they need more food. It takes more time for them to grow from a baby into an adult. They usually have larger ranges that they live in, larger home ranges. And so those things, you know, become liabilities when temperatures go up. So I, although I don't love to try to predict the future, I'm much more comfortable looking back into the past as a paleontologist. We can take what we know from the past and help us inform about what maybe could happen in the future. So I am confident that life will continue to evolve no matter what goes on with the climate and the environments and humanity over the next decades and centuries. But it's probably going to be those adaptable, resilient types of creatures that can handle a lot of stuff thrown their way that will have the best chance of getting through whatever happens. Well, we can probably be glad that we won't be there when there are going to be cockroaches the size of buses. There you go. I love it. So, Steve, I'd just like to thank you on behalf of all of us for a fascinating opening up lots of things to think about, about the past and the future. But thank you for making it so exciting and so clear. So thank you. Well, thank you. And I'm sorry you had to just see me on the screen. And I couldn't be there standing in front of you, but I really appreciate it. It's great for me to see the audience here, to see all of you guys. A packed lecture hall. I love it. We don't always get this when we teach the undergrads. So thank you for turning out tonight. And again, I look forward to meeting many of you in person, hopefully in a few years. And please do seriously if you do have a book or something. And you want me to scribble in it. Look me up online. I'm easy to find. Stop by my office. So thanks a lot everybody. And until next time. Bye.