Paige Desorbo (1:26)

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Dr. Samantha Yuin (1:30)

Hi, Sam here. Before we get into it, can I just say that ratings and reviews on Apple Podcasts or Spotify make a real difference for the show. So if you like the podcast rate and review us and tell your friends. Thanks for listening. The Spinosaurus marabellis is a newly discovered dinosaur that's creating quite the buzz. So in this episode, I'll talk with Dr. Paul Serino, who trekked deep into the Sahara desert to dig up this new dinosaur. We'll share the story behind this find and what it means for our understanding of dinosaurs. Before that, we'll take a look at what scientists are calling humanity's last exam. It's me versus the machine, and I'm actually a little bit nervous about that. One last we'll explore a fascinating study that reveals how our brain's wiring can unlock new potential in endurance sports. This is Curiosity Weekly and I'm Dr. Amien, as artificial intelligence advances, what does that mean for us? We've seen certain scenarios play out in movies like iRobot, the Mitchells versus the Machines, and one of my favorites, the Matrix. I know these are fiction, but here in the real world, AI systems are achieving impressive results on a bunch of different human standardized tests and assessments. So that prompts the question, oh, little pun there. Are they really approaching true human understanding, general intelligence and independence? To explore this, researchers took some bold steps. They designed a test that goes beyond simple facts. It focuses on depth, context and specialized expertise. You know, the qualities that give human knowledge its unique flavor. They called this test Humanity's last exam. And it aims to challenge AI in ways traditional assessments can't. So the challenge is set, human versus machine. And the real question is, can AI rise to the occasion? Can I? Nearly a thousand researchers from over 50 countries came together to create Humanities last Exam. That name might sound a bit apocalyptic, but it's not meant to inspire doom and gloom. The test itself is intended to be a reminder of just how much we still rely on human intelligence when it comes to high level expertise. The test consists of 2,500 questions intentionally designed to stump the most advanced AIs on the market. The questions spanned dozens of subjects. Math, physics, biology, medicine, humanities, linguistics, computer science and engineering, to name a few. Coming up with these questions was a massive task. They had to be closed ended, meaning that the answers had to be highly specific and ambiguous. They also had to be non searchable so that the AI couldn't just scrub the Internet for the answer. And they required graduate level expertise on highly specific topics. 14% of the questions required the AI to simultaneously understand an image and text. Nearly a quarter were multiple choice questions and the remainder were short response questions. To make sure that the finalized questions were as unsolvable as possible, the research team would do quick checks with AI at the first phase of the review. Any question the AI could answer easily didn't make it to the final exam. The next two review rounds were with human experts. Now, the authors decided not to publish the majority of questions to ensure the test can be usable in the future. But they did give us some sample questions. So let's try one out. This is one I haven't seen until now. My producers are going to reveal it to me right now. This is the first time I'm seeing it. Here it is. Hummingbirds with apodiformes uniquely have a bilaterally paired oval bone, a sesamoid embedded in the caudilateral portion of the Expanded cruciate epineurosis of insertion of M depressor cauda. How many paired tendons are supported by the sesamoid bone? Answer with a number. Okay, if I were trying to figure this out. Sesamoid 6. I don't know. I'm just gonna guess 5. How about this? At least 2. I feel pretty confident about that. Did you get it? Yeah, clearly me neither. And turns out the majority of AI also have trouble with it. The highest scoring large language model, Gemini 3.1 Pro, was only able to achieve 50% accuracy on the exam overall, with most AI hovering around 5% accuracy. The researchers involved are passionate about creating a strong reference point in assessing AI capabilities so that we can have more informed discussions and policies around how to use the technology moving forward. There are risks in allowing AI to flourish unchecked. And I'm not just talking about robots taking over the world. But risks include that AI could perpetuate or even amplify existing biases. Or AI tech, especially in surveillance and data collection, can infringe on our privacy. Or even the develop of AI and autonomous weapons. That also creates huge ethical concerns, not to mention the convincing but false misinformation. So in Human versus Machine, human still wins. For now. Phew. And all it took was the top experts, a specialized test, and the power of teamwork. Something only people can understand. Take that.

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you've heard of a T. Rex, a Triceratops, a Pterodactyl, but have you heard of a Spinosaurus? As the name hints, the Spinosaurus has unique sail like features on their back. And I have some exciting news for dinosaur lovers everywhere. Researchers unearthed a brand new Spinosaurus species, Spinosaurus mirabilis. And it wasn't an easy feat. The researchers described their journey in a February 2026 article in the journal Science. They found it after trekking for days deep into the Sahara desert. And leading the charge was Dr. Paul Serino, a paleontologist from the University of Chicago who's been exploring the secrets of our prehistoric past for over 30 years. He's with me to talk about this amazing discovery and what it means for the future of our understanding of dinosaurs and the planet. Welcome to the show. Paul.

Dr. Paul Serino (9:55)

Great to be here.

Dr. Samantha Yuin (9:56)

First, can you tell us more about the new species you discovered and recently published about? Specifically what distinguishes it from other species within the same family?

Dr. Paul Serino (10:06)

Yeah, it's always, it's always nice to find a species that you can recognize from 30ft because it's got the scimitar shaped crest on the top of its head, the tallest crest on the top of any theropod dinosaur head that we've ever found. It actually extends upwards more than the skull exists downwards from it. This is also a very Peculiar animal that is become iconic now as sort of like the T. Rex of the southern continents, but very rare in the fossil records. And so it gives us a chance to really double down on what this dinosaur was doing for a living. Now we've got it inland, you know, in a waterway, sitting next to some new sauropod dinosaurs and fish and some other things. And so we, we feel it confirms our suspicions, looking at the other one, that these are not deep sea marine mosasaur like animals. These are landlubbers. When they did like the shoreline though, they liked to wade in and go after fish and rivers and on the coastlines. But they were really a land adapted animal, as water adapted as any dinosaur has ever gotten, but still basically keeping its feet on the ground.

Dr. Samantha Yuin (11:21)

I read that it likely ate fish and was very colorful. But how do we know that? And what clues did you find in the fossil that hint at some of its behaviors?

Dr. Paul Serino (11:31)

So the fish eating, we're on more stable ground. What it looked like, we have to take a little bit more liberal paintbrush too. But for what it, what it's eating. We ended up discovering something really remarkable about the way the teeth interact. They, they go in between each other, the lower jaw teeth. Instead of being inside the skull, tucked inside like Tyrannosaurus rex and all other dinosaurs, the teeth actually go in between the upper teeth to project outward, creating a vise for catching slippery fish. This is not the first time evolution has created this kind of a dentition. We call it an interdigitating dentition. In fact, it's been invented by other fish eaters. Crocodiles, pterosaurs, ichthyosaurs, plesiosaurs, anything that really is in the business of catching fish has evolved this kind of dentition. Because if you try to catch a fish with your hands, you know what I'm talking about, they have a slime on the outside of their body that makes them particularly hard to snare. And this is a dentition that is meant to pierce the fish and hold it tight. Now a lot of people say, well you know, you're 40ft, you need to be 40ft to catch fish. We know bears catch salmon and so on, but there were larger fish in the riverways and the sea margins during the Cretaceous. There was coelacanths with now our deep sea fish. These are quite large fish, they're 4 or 5ft long. They were in the riverways. There were lungfish that got that big. There were sawfish that are sharks that are adapted for fresh water. They were in the Riverways. And there was also a fish that we're going to describe and we're going to call Superfish. We got the skull of it right next to the Spinosaur. The skull is almost 2ft long. So this was another 10 foot fish. There's an aquarium fish that's a descendant that you can get. It's called the dinosaur fish. It looks very strange, it looks eel. Like this was huge version of it. That was around when Spinosaurus was around. So it's plenty to eat, but you'd have to be pretty large to handle a fish that size. Five, six feet long, several hundred pounds. And so that's what this fish was. This animal was, was really preying upon.

Dr. Samantha Yuin (13:46)

And can you set the time period for this, by the way? Like, how long ago did Spinosaurus mirabilis live?

Dr. Paul Serino (13:51)

So this is the dawn of the late Cretaceous. This was about 95 million years ago. So about 20, 25 million years before T. Rex. They never would have met in time and they never would have met in space. They were on different continents. And nothing like the Spinosaurus has ever been found in North America. This is what really impressed the Jurassic park folks. They said, what is this? And there was nothing like a Tyrannosaur down in Africa.

Dr. Samantha Yuin (14:18)

Thinking of all these timelines and given that this is the first new Spinosaurid species found in over a century, what implications does that have for our understanding of, of dinosaur and evolution? Has it taught us anything new?

Dr. Paul Serino (14:32)

Yeah, I mean, I think the most immediate thing is that behavior is really hard to get out of a fossil. You find the bones, you're lucky if you can get the pose right. You start talking about movement or what it's eating or its particular habitat, it's almost always lost to time. But with this animal being so peculiar and so well modeled, we know the skeleton quite well and the teeth being so diagnostic, I think we can say it was the hell heron now and not a marine animal found in the riverways inland. So that's the first big evolutionary thing. At no point in the history of all of vertebrate life that we know of for the last half billion years, 500 million years, has any marine animal like a whale, like a porpoise, like a mosasaur or a plesiosaur or an ichthyosaur ever lived up the rivers that was even half the size of Spinosaurus. So we have a hell Heron on our hands. Something that, you know, and the broadest picture of evolution, if you wanted to ask me, is that we look at herons today. And that is our best analog. There's nothing like this. Could something like this evolve today? It could be successful today, especially on the, on the coastlines where you have big tides, just like a heron. But we don't. You know, evolution doesn't. It has a chance to evolve something, and Sometimes it takes 50 million years to get to the point of an animal like Spinosaurus. And it doesn't guarantee that if it goes extinct, it's going to evolve again. And so this is part of evolution. We think about this with regard to our own species. Would humans arrive again if we drive ourselves extinct? Would they arrive on some other planet? This is the biggest picture of evolution that Spinosaurus sort of causes us to reflect on. Why has something like this not evolved when clearly it was dominant for 5, 10 million years like no other animal on Africa?

Dr. Samantha Yuin (16:32)

Now, I want to shift gears to understand more of the process and what it's like being a paleontologist making these discoveries. So can you take us back to 2019? Your team's in the Sahara. Can you describe the initial moment when you all realized you discovered a new species? What was that like?

Dr. Paul Serino (16:50)

It starts with a reverie. I was looking at a French monograph written by a truly intrepid explorer that was doing his dissertation work in the 1950s. I mean, if you think going into the desert, at least I have a GPS and I know where I am when I get stuck forever, or I have a drone and I can actually see some of the world around me. This guy did it without any of that. And he went out and mapped. And in one of his pages in that 1966 monograph, he ultimately published it in 1966, very modest Frenchman says, I found the saber taped tooth. And it was at a remote site. And it was a little dot on one of his maps, a Keraceras. And I always dreamed about going back. Could I ever get back to this? Maybe it was swallowed by sand. Maybe that was the only thing that was there. But I. No one had been back. It's been 70 years. And so I finally had my chance in 2019. And. And you know what often happens, and you have to be prepared for this, is that you take his map, you make a GPS coordinate based on that map, and you go there. You eventually get there. It takes you years. You eventually get there, and what do you see? Absolutely nothing. We saw nothing. And when I say nothing, I mean nothing. It was flat, 360, a little bit of sand, but there was nothing. And you're like, okay, I'm going to take this on the chin. I'm not giving up yet. His map. We don't know that we're actually in his spot. So we. We drive several kilometers, you know, to the north. We get out the drone, we get out of binoculars. We're all on the tops of our trucks. And then we see this little thing on the horizon, a little blip of rock, and we decide to head towards it. And then we find, as we drive up, car, car. Dinosaurs, teeth lying on the surface. And then the old well, we. We had found it. And so that may have been the end of the story because we exhausted the site. It was a small site, and we looked all around and there was nothing. We headed back to our camp, which is. When I say headed back, I mean, it takes a day and a half, two days to get back to our oasis. And in walks this particular individual, Abdul Nassar. And he says through his language, through French to me, I can show you where some big bones are. We followed Abdul Nassar for a day and a half. We were beginning to get panicky. And he drives up, gets off his bike here, and we come up to the biggest bones I've ever seen in my life. I mean, it was a thigh bone, longer than me. It was six feet. It was a leg of a dinosaur, and there were others. And it was like a graveyard. And the sun was going down. So, you know, we set out our cots and slept as best we could. The next morning, we had half an hour before we had to head back. We had no more time. We went scurrying around, Dan and I, we picked up two jaw pieces, couple of jaw pieces, and a bone we didn't recognize, which turned out to be the crust, and we brought it back. Then the pandemic hit, and it held us up for two years from going back. So that was 2019. It wasn't until 2022 that we had the chance to return. I had been building a team for two years. I called them from everywhere. Spain, Italy, Canada, Niger, the United States. We headed down. We were 20 strong. We had 64 armed guards. There were Tuareg guys. And we were headed back now at the very end of our expedition. And we couldn't even get the truck in. It's so remote. It's hard to believe we did not to this. At this point, we did not know what we would find. We didn't know we'd find more of the dinosaur. I'd like to emphasize that because there's several points in this story where I said we don't Know the chances that we're not going to find more, but you still go there, you're driven. That's what discovery is about. We arrive, I'm arranging the tents. My colleague Dan runs up, excited, one hour after we got there and says, you won't believe this, but the snout is going in the ground and everyone gathers around. And then more came to light, and then a crest came to light, and we understood what we had found in the first expedition. And because we're in the digital era, he was able to grab these bones in three dimensions with 200 photographs and then put them into his computer, powered by a solar cell. And we're sitting there in the middle of the Sahara, just out of our minds what we had discovered, because we could see it. We could see this incredible spinosaur with a crest that swooped up from its skull. We knew this was landmark not only for the new species of Spinosaurus, but what it meant for unraveling its biology. And it was just an amazing moment that none of us will ever forget.

Dr. Samantha Yuin (21:29)

So it sounds like you had this initial site you were going for, and then you had a local expert, this Tuareg individual that you mentioned, who, who had some insight based on their experience and knowledge of the area. And so I'm wondering how that type of international collaboration factors in to this type of research.

Dr. Paul Serino (21:49)

I would say a couple things about that, but two most important things. First of all, this particular individual, Abdul Nassar, we are friends. Every once in a while, I get a WhatsApp call from the middle of Sahara, and they're out there looking for more things for us. They are thrilled, they are absolutely thrilled that they actually are responsible for a story about their country, about their backyard that went around the world and is now famous. And so it was found because I get in and I get to know local people. I love doing that, actually, and I love this country and I love that culture and their people. It's a beautiful culture. And I, you know, it was one of the greatest things when they called me their brother. I've been there for 30 years. The. The second part of this is you naturally ask yourself, and I've asked myself this early on, as a professional paleontologist, what isn't it for anybody or any place that I go and I make my discoveries and have my fun, find my things, make my papers and a name and what isn't it for them? And it was pretty clear to me, excavating into this culture, that there was something very much that they wanted. What did they want? Well, they might want a, well here or a school there. We've done that. But they really want a museum. They want a museum not only for the dinosaurs, but for their culture. If you can imagine this, you can imagine the expanses of the Sahara and nomads like the one that I've, that have traditions, clothing, music, written language that is fragile, quite frankly, in today's world. And there's no museum for any of this, not just their dinosaurs. So at the crossroads of the desert, Agadez. Yes, in the capital, we're going to make a museum and they set aside land for that. But we're going to make a museum in Agadez and we're looking at the spot and we've designed it and you can see it online. It's actually won architectural awards for zero energy museums. We started a group with Nigerians as well, an international group called Niger Heritage. It translates very well into their common language, French. Niger's heritage, Niger's patrimony. It's not only the dinosaurs, but it's also the cultures of the north that have no museum, but have, have every reason and right to have one. So there's the Ying and the Yang. They let me and help me to understand an environment that is as beautiful as it is daunting. It will shake you to your core sometimes thinking that you're not going to get out. And then the Yang, which is. I'm hoping that this work doubles back to Niger in the way of national museums. A whole generation of scholars that we're beginning to train right now, museologists, paleontologists, archeologists, and a new beginning and future for that country. So that drives me. My life's goal work is to try to describe some of this lost world that I found, which is the only continent which you could find. Dozens and dozens of behemoths that haven't been named Africa. And Niger has that story. I've also found human, ancient humans older than the Egyptians in The green Sahara, 100 skeletons and graves of those and, you know, be able to put that back in museums that have some kind of future. If you don't have the scholars, the museums, the storerooms, the knowledge and the understanding of the importance of these finds, they will eventually be destroyed. So if I didn't have enough impetus out of goodwill, then I certainly do because I see a feel of responsibility for this dinosaur. You know, it's now well known and it's beautiful and there's only a few specimens of it. We got to preserve this, this for the rest of Time.

Dr. Samantha Yuin (26:03)

Destroyed by who? I haven't. Just curious.

Dr. Paul Serino (26:05)

So, destroyed by who? So these fossils are fragile. So when I brought the first fossils back.

Dr. Samantha Yuin (26:10)

By time.

Dr. Paul Serino (26:10)

Yeah, when I bought the first fossils back, there's no place to really store them. They're in their original crates. Eventually, knowledge is lost. And you don't know whether we take it for granted that if you have a fossil like that, it's going to be in a collection, a storm in a museum with knowledgeable. Okay. We have to build that around these specimens because they don't have that big collection. They don't have that legacy. But that doesn't mean they can't have it. And it's very clear now the country wants it, and they're going to drive to get it.

Dr. Samantha Yuin (26:41)

Last quick question. Can you tell us about some of the technology used for this work? For example, the CT scanners that helped render the models of the skull?

Dr. Paul Serino (26:50)

Yeah. This is, you know, a display of modern technology from beginning to end. So finding it, we actively use drones. They don't crash anymore, and they're really great. We actually will go out and look what's ahead, especially in the desert where it's extremely difficult to move. Sometimes you can go over that dune with a drone and see what's on the other side. We use gps. When we get to an actual site, we're using photogrammetry to record the site, even stages of the excavation. We can reconstruct things in the field. When we're really excited, begin to write the papers. We use tools that are saving our hands. So instead of the chisel and hammer and you're hitting your hands all the time now. Lithium battery pack. Charging little tiny jackhammers to big jackhammers. Everything in between allows us to carve dinosaurs out with a speed and dexterity that we never had 15, 20 years ago. You just got to power those batteries. So then you need solar packs, then you need generators, but they make generators smaller now, et cetera, et cetera. The equipment is really change to make this more efficient. And so those are some of the things when we get back into the lab again, a suite of things. We're in the era of nanotechnology. So we're interested down to the molecular level of these fossils. What can they tell us about the diet of Spinosaurus by looking at the molecules in the enamel of their teeth. But it's for bigger structures, too. We take everything and cat scan it. If it's big, we put it on the bed where a human would be in the hospital. If it's small, we put it in a higher powered scanner. Sometimes we go to industrial scanners for big skulls. So everything we want to see inside, but as you can know, we want to see the outside in digital form. Then we can mount them digitally. I can give the digital skeleton and have I was the first to do it to a printer and print a skeleton. I've given it to Hollywood to put the skin on. And as you can see, we're getting good at that ourselves. We put the skin on this animal to give you an idea of what it looked like in the lead up to the COVID of Science. That was fun.

Dr. Samantha Yuin (28:56)

Very cool. Thank you so much, Paul. Thanks for being on our show.

Dr. Paul Serino (28:59)

Great to be here.

Dr. Samantha Yuin (29:00)

Dr. Paul Serino is a paleontologist at the University of Chicago whose team discovered Spinosaurus mirapilis. Okay, I have to tell you, I was just looking on ebay where I go for all kinds of things I love.

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Let's say you're running every day to build your endurance. Or perhaps you've been swimming less and now you can finish 300 meters, no problem. There are lots of changes in our body as we improve with practice. We're building muscle, our cardiovascular fitness gets more efficient. But until now, we didn't realize something else may also be changing in our brains. A study published in the journal Neuron found that in mice, repeated exercise sessions actually rewire the brain, and that rewiring turns out to be essential for building endurance. Now, when I first started reading about this, I thought, sure, it must be some motivational thing, right? After all, grit is key. But this isn't about the psychology of performance or even other classic roles for the brain in exercise, like coordinating movements. This study showed how the brain acts as a gatekeeper for the physiological changes behind endurance gains. Or, as one headline put it, no brain, no gain. The research team, led by neuroscientist Nicholas Betley at the University of Pennsylvania, focused on the ventromedial hypothalamus. It's a part of the brain known for helping regulate the body's metabolism, monitoring things like hunger and blood sugar. There's a group of neurons there called SF1 neurons, and when they removed a key gene in those neurons from mice, they found that the mice couldn't build endurance. So this research team put mice on a treadmill and watched these neurons more closely. They used fiber optics to monitor calcium signaling in the mice as they ran. That's a good proxy for neurons firing. And what they saw was that the SF1 neurons fired during the run. But surprisingly, a subset of the neurons only switched on after the run ended. With each training session, the signal became stronger. In mice that trained consistently for three weeks, those SF1 neurons had physically changed. They were easier to activate than before, and the number of excitatory synapses had had doubled. With training, the brain apparently rewires itself, but this could just be correlation, not causation, right? Perhaps the changes are just a side effect of building endurance. To test causality, they used a technique called optogenetics. It's a really cool technique that lets scientists turn specific neurons on or off just by shining a light. Thanks to a genetic edit, when the team turned off the SF1 neurons right after exercise, the mice stopped improving. They performed just like untrained mice, never building the stamina that training should give them. This suggests that post run activity in SF1 neurons is required to build endurance. The reverse was true too. Cranking up activity in these neurons after a workout gave the mice an endurance boost. They could run farther and faster than mice who otherwise had the exact same training program. The authors suggest that the post run firing may be how the brain encodes the physiological changes that actually build endurance, engaging energy stores and triggering muscle remodeling. This was done in mice, and whether the same mechanism plays out in humans is still an open question. But it's a reminder that our brains are usually doing a lot more behind the scenes than we give them credit for. When we put in work, our brains do too. For Warner Bros. Discovery, Curiosity Weekly is produced by the team at Wheelhouse. The senior producer and editorial correspondent is Teresa Carey. Our producer is Chiara Noni. Our audio engineer is Nick Karisimi. And head of Production for Wheelhouse DNA is Cassie Berman. And I'm Dr. Samantha Yuin. Thanks for listening.

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Paige Desorbo (35:52)

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