Tyrannosaurus Rex
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Monday.com for whatever you run. Go to Monday.com to learn more. 67 million years ago, West North America, the apex predator prowls the land searching for its next meal. At its full size, it's the height of a double-decker bus and weighs more than seven tons.

Its long line of razor-sharp teeth, each the size of a banana, could easily pierce flesh and crush its prey. It's the ancients on History Hit. I'm Tristan Hughes, your host, and in today's episode we are talking all about the most famous meat-eating dinosaur of them all, the king of the tyrant lizards, we know it better as Tyrannosaurus Rex.

Now to talk through what experts know and don't yet know about this great carnivore, from their anatomy to their poo, to whether T-Rexes had feathers and what exactly the deal is with their tiny little arms, I was delighted to welcome back to the podcast one of my favourite paleontologists, Dr Steve Brassati, who dialled in from the University of Edinburgh.

A media sensation, Hollywood film advisor and best-selling author, not to mention lecturer, Steve has been on the podcast twice before to talk about the rise of the dinosaurs and then the rise of mammals. Definitely check out those episodes once you've listened to this interview.

Now when we recorded this episode there was impromptu building work going on just outside Steve's office. So Steve, the hero that he is, he set up in the faculty's lab just for us so that we could go ahead with this interview as planned. And boy was it worth it. Sit back and relax as Steve explains all things T-Rex, King of the Dinosaurs.

Steve, it is such a pleasure to have you back on the podcast. Always a pleasure, Tristan, to talk dinosaurs with you. And I'm excited today to talk about my favorite dinosaur of all, and that is T-Rex. And I must say, I'm really grateful for your time because we don't have much of it. You are an incredibly busy paleontologist and you are dialing in from your paleontology lab in Edinburgh. So we're incredibly grateful. And I'm really grateful for your time.

But to talk about your favorite dinosaur, correct me if I'm wrong, but the T-Rex always seems like the biggest, baddest, meanest dinosaur of them all, Steve. It is. And that's why I love T-Rex so much. And I know it is a bit of a cliche. And sometimes when I say T-Rex is my favorite dinosaur, other paleontologists will kind of smirk at me and say, come on, you know?

Don't go with the big one. It should be Micropachycephalosaurus or some kind of obscure dinosaur, right? That's what a paleontologist should pick. But for me, T-Rex is my favorite dinosaur because it's such a feat of evolution. To me, it's remarkable that an animal like T-Rex actually lived on this earth. It evolved. It's a feat of evolution. It was one of the biggest meat eaters that ever lived on land in the history of the earth. I mean, it literally was the size of a bus. It had a head the size of a bathtub. It had

50 railroad spike teeth that it used to literally crush the bones of its prey. I mean, we find the shattered bones of triceratops and duck-billed dinosaurs with bite marks that match the teeth of T. rex.

It was a mega predator of the highest order. And it wasn't just a brawny animal. It was a brainy animal, too. It was quite smart. It had great vision. It had a great sense of hearing, a great sense of smell. It was a super predator in a well-rounded way. And I simply think it's a fantastic, fascinating animal.

Steve, you're not the only one. So many people, because it's so often reproduced, whether it be at Jurassic Park or other media, as the postcard dinosaur, the postcard carnivore. But I'm guessing also that has led to quite a few myths developing about Tyrannosaurus rex too. Absolutely. It's a dinosaur that...

that pretty much everybody knows. I think you could take a photo of a T-Rex skeleton in a museum or a piece of artwork showing a T-Rex or a still from Jurassic Park or Jurassic World. You could walk around out on the streets of Edinburgh here or wherever and show those to people. They'll know. They'll know immediately. That's T-Rex. That's the icon. That's the king of the dinosaurs.

And because it is so famous and so well-known and because it's been known for a long time and because it is the star of so many films and books and museum exhibits and so on, that means that misconceptions have popped up. And to me, that's really interesting from a history of science perspective, let's say. This is a dinosaur, and in looking at this dinosaur and how humans have discovered this dinosaur and pondered this dinosaur and studied this dinosaur and used it

new tools and techniques and technologies to study the fossils. In looking at all of that, we get a sense for paleontology as a science and how paleontology has changed as a discipline over time. Now, you mentioned studying T. rex. So do paleontologists like yourself, people who are working on these bones, do you have a large amount of fossils of T. rex surviving? We do, compared to other dinosaurs.

So what I mean by that is let's take a step back and just let me tell you a bit about T-Rex and when and where it lived and how we know about it from fossils. So T-Rex was one of the very last surviving dinosaurs. It was there the day the asteroid hit and wiped out all the dinosaurs except for birds.

T. rex lived in the very, very latest Cretaceous period, about 67 to 66 million years ago. It lived, as far as we know, only in western North America. Back then, much of North America was split in two, really, west versus east by a big seaway. At times, that seaway stretched all the way from the Arctic down to the Gulf of Mexico, and it completely bisected the continent. At other times, the seas retreated a little bit.

But basically there were two different continents back then in what is today North America. And T-Rex lived on the western part of that continent at the time that the Rocky Mountains were starting to rise up. At the time where there were vast rivers flowing off of those young mountains into the seaway, there were forests, there were floodplains.

big mudflats along those rivers. There were no grasslands, no prairies, nothing like that had evolved yet, but it was in that world along the rivers and the lakes and the swamps in the shadow of those rising mountains that T. rex lived. And T. rex was the biggest predator in its ecosystem. It was about 13 meters or 40 feet long as an adult.

weighed about seven or eight tons as an adult. That is roughly the size of a double-decker bus. Ah, so a double-decker, not just a single-decker. Not just a single-decker, a double-decker bus. So next time you're in London or wherever where there's double-decker buses, we have them here in Edinburgh, when you get on that bus, just think for a moment that there was a lusting monster that once lived 66 million years ago the size of this bus. And T. rex would have hunted things like triceratops and duck-billed dinosaurs, many of the plant-eating dinosaurs of

of the time. And the bones of those animals were fossilized when the animals died and they fell into the lakes or to the rivers or into the swamps. When they were buried by sand or mud, they could get petrified over time into fossils. And so we find those fossils of T. rex today in places like Montana, North and South Dakota, Saskatchewan, up across the Canadian border. It's roughly that part of the world where there's rocks of that age, of the very end of the Cretaceous, formed.

in the shadows of the Rocky Mountains and those rivers and lakes. These rocks are called the Hell Creek Formation. It's a great name, I think, for the rocks that preserve T-Rex bones. You find T-Rex, where do you find it? You find it in hell. And that's named, by the way, after a tributary, a little tributary of the Missouri River, one of the big rivers in that part of the country. So we have over the last 120 years, basically,

since the very first T. rex bones were found in the very early 1900s, scientists and commercial collectors and ranchers and just other people out on the land have found a few dozen good skeletons of T. rex. And some of those are really complete. Almost all the bones are there. And there's some famous ones that have nicknames like Sue and Stan. Yes, Sue, isn't it? That's a very famous skeleton of the T. rex. Yes. And Sue was displayed at

The Field Museum of Natural History in Chicago. That was my local museum, basically, growing up. Oh, lucky man. In the late 90s, the Field Museum partnered with McDonald's and Disney to buy that fossil at auction. It was the first big major auction of a dinosaur fossil. And they cleaned it up for a few years. They put it on display in the year 2000.

When I was just finishing my second year of high school, about an hour and a half drive out of the city of Chicago, out in farm country, and I was enamored with Sue. I begged my parents to take me to the official museum opening. And every few months after Sue was put on display, I would just plead with my parents, let's drive to Chicago. Let's drive to Chicago. Let's see Sue.

And seeing that fossil when I was 16 years old, standing underneath its skeleton, looking at all the bones, reveling in the sheer size and the power and the ferocity of the animal, thinking about how old it is, thinking about how different, how weird it is compared to any animals alive today. That

really was one of those things that triggered my fascination with paleontology. If that T. rex was not on display locally, I don't know if I would have become a paleontologist. And Sue is really emblematic of T. rex. It's one of the better known skeletons. There are others. We have skeletons of adult T. rexes. We have skeletons of teenage T. rexes. We have a pretty good growth series showing how they

They changed as they went from little babies into bus-sized adults. We can tell from looking at growth rings inside of their bones that they would have only lived to be about 30 years old. So I would have been long dead by now if I was a T-Rex. And, you know, it took them at least a decade, probably a bit more, to become mature, to start making their own babies. So they grew quite a bit, but they grew relatively fast.

to reach such huge sizes. And those are the kind of things that we can glean from the actual fossils that we have. And frankly, we're quite lucky with T. rex. Most dinosaurs are known from only one fossil, most dinosaur species.

There's maybe about 2,000 species of dinosaurs that have been named and described by scientists. I would say roughly half of those, maybe even more, only a single fossil, one representative. And usually that's not going to be a skeleton. That's going to be a few backbones, part of a leg, a claw, you know. So to have a lot of skeletons and to have skeletons of juveniles up to adults,

For T. rex, that means as paleontologists, we're very privileged because we actually have data. We have evidence. These fossils are the archives, you know, for the historians listening. The archives are so important for historical research. For paleontologists, the fossils are the archives. And with T. rex, we have a lot. And Steve, I must also say, also a quick shout out to Iguanodon, my favorite dinosaur, which of course you have the thumb spikes and everything. That's an acceptable favorite dinosaur, I must say. That's plausible.

It's a plant eater, but you know, even so, that's important historically, by the way, Tristan. Yes, yes. I know, man, I will go too much of a tangent there. We don't have much time, but it's because one of my family relatives was Gideon and Mary Mantel. Are you kidding? Yeah, no, yeah, yeah, yeah. Oh my goodness, the royalty. Your paleontology royalty.

So one day on the entrance in the future, we'll have to do one on the iguanodon and the thumb spikes. Absolutely. But we have to keep on T-Rex today. But one thing I'd like to ask before going on from, I mean, this kind of source material we have for T-Rex is, I mean, Steve, I've got to ask about T-Rex poo. Because I've got this in my notes and I'm guessing we do have poo surviving. You know what? This sounds like a conversation with my four-year-old right now. This is about every conversation we have.

I hope he doesn't listen because then he'll realize that we actually have T-Rex fossil poo. We do. Fossilized poo is some of, I would say, some of the least heralded fossils, maybe. They're a little bit weird to think about it, but actually...

When you do think about it, a dinosaur like a T-Rex, an individual, would have had a single skeleton. What are the odds that skeleton would ever be buried in sand or mud and turn into a fossil? But I don't know how many times a T-Rex individual over the course of his life would have had to stop

and relieve itself. So you can imagine that actually there is quite a lot of fossil poo and this sort of stuff in the fossil record. We call these fossils coprolites. That's the fancy name for fossilized fecal matter. And we have them for various dinosaurs.

It can be hard to tell which dinosaur dropped it, if you find a coprolite. But there is a really famous one that was found out in Saskatchewan in Canada that almost certainly was made by T. rex because it was found in the same rocks that T. rex skeletons are found in.

Because it was huge this thing was like over a foot long and because it was chock full of chunks of broken bone so it had to have been made by a meat-eater and a big meat-eater and a meat-eater that had the types of powerful teeth and jaws that could actually crush bone so all the evidence points to T-Rex and And that's a remarkable fossil this thing was published in the journal nature in the late 90s I mean the world's eminent scientific journal. That's how

important this fossil was. And it's a novelty in a way to say, oh, here's a piece of fossilized T. rex crap, you know. Oh, OK, that's pretty cool. But the neat thing scientifically is that it was full of those chunks of bone

That was some of the first definitive proof that T. rex really was powerful enough, its bite was strong enough, that it could literally crush the bones of its prey. And later on, scientists also started to find bones of triceratops, of duck-billed dinosaurs, shattered, broken, with tooth marks that matched the jaws of T. rex.

These fossils give us insight into the life of T. rex. They tell us about what it was like as a hunter, as a predator, what kind of food it ate, and that's really unusual. You don't have a whole lot of animals today that just crush through the bones of their prey. Maybe some things like hyenas and maybe some big cats, you know, might occasionally do it. But to do that regularly, constantly, is part of the way

integral part of the way that you feed, that is one of those things that sets T-Rex apart. After Dark, Myths, Misdeeds and the Paranormal is a podcast that delves into the dark side of history. Expect murder and conspiracy, ghosts and witches.

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Well, we're going to talk more about kind of the hunting and what types of dinosaurs T-Rex hunted as we go on. But I think just before we get there and we kind of focus on the head and its great crushing power of its teeth and so on, let's talk about the whole anatomy of the Tyrannosaurus Rex. You've already mentioned its massive size when it's full size, double deca bus size. But can we also kind of almost work our way through the anatomy of the Tyrannosaurus Rex?

let's say an adult T-Rex, Steve, let's say start at the tail, because this is another part of the T-Rex that sometimes we overlook. But if we work from the tail and then all the way up to the head, can you talk us through the whole anatomy of a T-Rex? I would love to, because really, fundamentally, that's what I do. That's the science that I study. I really am an anatomist. That's the crux of a lot of my research is finding and scrutinizing and describing fossil bones and using those bones to...

reconstruct what these animals would have been like millions of years ago.

About a decade ago, we did a show that I was a part of on National Geographic. It was called T-Rex Autopsy. And some of you out there maybe have heard of it. It's kind of gone into the niche corners of the internet now. But check it out if you're interested in this topic because the producers of that show and the artist built a life-size T-Rex from the skeleton on out, fleshed it out, put in plausible organs and skin and feathers and all this stuff. And then we

dissected it. We did a mock dissection on TV. And so that really led us through the anatomy of T. rex. And if we start with, first of all, we know T. rex is really big. We know it's really bulky. We know it's really strong. But if we start at the back of the animal, it had a really, really, really long tail. And that tail was

It used to be thought that that tail just kind of was some noodley appendage that dragged along the ground as T-Rex walked. And if you see photographs of old museum exhibits or artwork in older dinosaur books, even some dinosaur books that reached into the 90s when I was in school, you see that image of a T-Rex just plodding along, dragging around.

its tail, but we know that wasn't the case. We have footprints of dinosaurs, trackways showing that they walked upright and they didn't drag their tails. And in fact that tail, it wasn't just long, it was very, very, very muscular. And it acted as kind of a balance beam, as a seesaw. The head of T. rex was so huge, the tail helped counterbalance that. And the muscles that powered the legs of T. rex

actually attached to the tail. Now this is very different from us. We don't have a tail. The muscles that we use to walk and our legs are very different. But a T-Rex, when it was walking, the biggest, most important muscles that moved its legs attached all along the tail. So you have that tail. The tail is integrally animal. Then if you move forward, you have those big legs. Big, sturdy, bulky legs. Legs that we can tell from the lengths of the bones

actually evolved from earlier ancestors that were pretty fast runners, that were probably sprinters. We can just tell from the proportions of the lower leg relative to the upper leg and the shape of the foot. There's features of the arch of the foot that are really distinctive for fast-moving dinosaurs. And we have fossils of the ancestors of T. rex, and they were smaller and they were more slender and they could probably move fast.

T-Rex itself became so big and so bulky that it probably could not run very fast on those really muscular legs. And people have done computer modeling studies using animation software, kind of like what movie makers use. They've done laser scans of T-Rex skeletons, put them into the software, fleshed them out with the muscles and the skin and so on, and just put them through gymnastics routines to see what they were capable of.

And that really shows that T. rex probably couldn't have moved faster than about 10 or 15 miles an hour. It could not sprint. It could not run simply because it was so big. But its ancestors were runners. And you can see that in the legs. If you move forward on the animal, I think the next thing that you would immediately notice is the pathetic puny little arms. Absolutely.

jokers those arms. I mean, it's absurd. It's like T-Rex was designed by some mad cartoonist or something. It's like you have this seven-ton animal the size of a bus,

And its arms are the size of our arms. I mean, it's like imagine like our arms sticking off the front of a London double-decker bus is just complete absurdity. But we know a few things. We know, again, the ancestors of T-Rex that were smaller. They had proportionally much longer arms relative to their body.

And those arms had more fingers and those arms had bigger claws. So the ancestors of T. rex probably used their arms to grab prey and to dispatch prey and to cut up prey. And then as T. rex and its immediate kin became really big,

The head took over most of that work. The head became huge, the arms shrunk in size, but the arms did not totally disappear. And that's important because in evolution we often see over time if part of a body becomes completely useless it disappears. I mean that's why whales don't have hind legs. They don't need them. Sometimes there might be a little remnant or something like our appendix, let's say, is a famous example of that. That it used to be part of a bigger structure. We don't really use it anymore.

and it's barely there. So the arms of T. rex are still there. They're still quite muscular even though they are short. So they're the length of our arms, give or take, but they're much more muscular than our arms. We can see that because we see the scars and the ridges and the grooves on the bones where the muscles attach. And we know from birds and crocodiles today

which are close relatives of dinosaurs, what muscles were there. So that tells us that these arms, they probably weren't being used to grab prey anymore, but they were being used for something, and they were probably really good at holding on to things, at bracing the T. rex when it was feeding, let's say. You know, it was biting through the bones of its prey, it was generating obscene strength and power in its jaws.

Just by the laws of physics, it would have needed to brace itself. Each action has an opposite reaction. So the arms might have been useful for that. They could have been useful in mating. They could have been useful in grappling. T-Rex was probably a social animal. We have bone beds where multiple Tyrannosaurs are found together. It's hard to do that unless they were living together. It's hard to preserve a bunch of fossils of the same species together unless they were living together. So maybe they used their arms.

in little grappling matches it's hard to know but they were doing something and then of course we come to the business end of the animal but still so i see so keeping on that so you you do then think it's your opinion that those little hands although as you say it's quite easy to envisage almost a human putting out their hand of a bus today to give a sense of the insane size comparison but you do think that there was they still did have a function for t-rex yes as difficult as it is yeah yeah

I know it's so weird to envision that because those arms are so famously, infamously pathetic. But they are there, they are still there, and the muscles are really powerful. So they were doing something.

but not the same thing as in the ancestors that were using those arms to grab prey. At least that's what we think. Of course, we are always dependent here on the fossils. We make these hypotheses based on what we see in the fossils. We draw comparisons to modern day animals. We look at what the muscles are like in crocodiles and birds, for instance. You know, we have levels of inference and we are kind of like detectives or like, you know, historians that are going through the archive and looking for connections between things. And

There's always a bit of circumstantial evidence here. None of us were around to see T-Rex hunting its prey, using its arms, seeing what it was doing with them. But we can make, I think, some reasonable inferences. And the same with the head. I mean, that head is now at the front of the animal. It's huge. It really is the size of a bathtub. I could fit inside of its jaws. I'd have to scrunch up a little bit, but I could fit inside. That's not a place I would want to be because of all those banana-sized teeth.

But those teeth were not only thick, they were sharp. They were like steak knives, like razors. T-Rex had huge jaw muscles.

We can also tell, though, that T. rex had quite a lot of intelligence and keen senses. And how do we know that? We can use some different lines of evidence. And one of those things is that we can CAT scan the skulls of T. rex and other dinosaurs, actually use the X-rays to see inside the brain cavity and build a digital model of what the brain would have looked like. And we can then compare that digital brain to the brains of modern day animals and just get a rough sense of what

of the braininess of T. rex. And what that tells us really is that for a reptilian type animal of its size, T. rex actually had a pretty big brain.

And it's hard to say, well, it was as smart as this or as smart as that. Some people sometimes will say, and I've done this before, when I've done some of my writings, I made a mistake in my book. I wrote a book called The Rise and Fall of the Dinosaurs, a pop science book. And I drew this parallel between T-Rex and chimpanzees in there. And I described it very awkwardly and very incorrectly. And it's the

the biggest regret I have in writing that book. But the point is, it's hard to make exact comparisons with modern day animals, but we can tell at least that T. rex had a pretty big brain for a reptilian creature of its size. Beyond that though, we can tell that brain had really large olfactory bulbs, the parts that control the sense of smell. So that means the smell was probably pretty good. We can also use the CAT scans to see inside the ear, and we can look at the cochlea, the part of the ear

that hears sound. And the cochlea of T. rex is really long. And we know from modern day animals that a cochlea of that length is really good at hearing a wide range of sounds, both low frequency and high frequency sounds. And we can tell a little bit about the eyesight too. The optic lobes of the brain look like they're pretty big, but more importantly, the area of the head where the eyeballs would have been, the eye sockets, are quite large.

Both of them point somewhat forward. So T-Rex would have had some stereo vision like us. Its left and right eyes would have had an overlapping field of vision. It could have seen in some depth, some 3D. That's really important. So you put all of this together. It's 3D? What?

And in many ways, it may have had better vision than us, or at least better vision than most mammals, because humans are a little bit odd for mammals. Most mammals can't even see in color. Mammals usually rely more on hearing and on smell than on vision.

vision. That's because our mammal ancestors were largely nocturnal, and so seeing color didn't mean very much to them. That's why most mammals have pretty drab brown or black or gray colorings, whereas if you look at birds, you see all the fantastic colors birds have because they could see

in color. I know that's a bit of a tangent, but the point is that, you know, we can look at the evidence in a T. rex fossil. We can CAT scan the skull. We can look at the brain cavity. We can look at the ear. We can look at the eye sockets. We can draw comparisons to modern animals, and we can start to tell a bit of a story. It's a story based on evidence, but we can start to flesh out what this animal would have behaved like.

a little bit about how it would have sensed its world. And I think that's absolutely fascinating that we can start to put ourselves in the mind of a 66 million year old super predator. - Obviously that is absolutely exciting. You said learning more about the behaviors of the T-Rex in many ways seen as the king of the dinosaurs.

I must, I mean, we've got about 10 minutes more of your time. So I'm going to do almost kind of some quick fire questions to you now, but still in that kind of same vein, keeping on the appearance a little longer. And you actually mentioned the word feathers earlier. And just before we started talking, I went down to the local shop and told the shopkeeper who I know very well that we're doing an interview on T-Rex and asked, does he have any questions he'd love to ask? And I think this is what we'd all love to ask. I mean, is it true that T-Rex had feathers?

Probably. And I say probably because nobody has found direct fossil evidence yet, but it's very hard to preserve feathers as fossils. Most fossils are the hard bits, bones and teeth and shells, the type of stuff that can get buried in sand or mud and turned into rock.

fairly easily. The softer bits - skin, muscles, tendons, guts, feathers, hair - that kind of stuff, it breaks down quite quickly, it decays, it's eaten away, and it's just harder to turn into fossils. So to get fossil soft bits, we usually need exceptional preservation. We need places where something strange has happened, where there's really good fossil preservation because of some quirk of the environment.

And we have that in a few places. In China, in northeastern China, a place called Liaoning Province, way up there, shares a long border with North Korea, far off the tourist trail. And about 25 years ago, actually almost 30 years ago now, farmers out working the land started to crack open some rocks and they started to see these skeletons of dinosaurs with feathers preserved all around their bones.

And it turns out there's basically an entire ecosystem there that was buried by volcanoes, almost Pompeii style. So you had these moments in time where a volcano would just blanket everything and it would lock that ecosystem in stone and those dinosaurs would turn into fossils so quickly that some of the soft bits could be preserved. And there are two Tyrannosaurs from China. One's called Eutyrannus, one's called DeLong. DeLong's the size of a little dog. It's a very primitive Tyrannosaur. Eutyrannus

is eight or nine meters long. It weighed about a ton. It was an apex predator. Those two tyrannosaur, which are essentially ancestors of T. rex, they are found covered in feathers. So we know that the ancestors of T. rex had feathers. However, those feathers were simple feathers. They look like little strands of hair, fluffy little down feathers. They were not flying with those feathers. Birds later

change their feathers, repurpose them into airfoils. But the feathers began as simple structures probably for keeping the bodies of these dinosaurs warm, for regulating their metabolism.

So the take-home point is, we know the ancestors of T. rex had very simple feathers, and that means that probably T. rex would have retained some of those feathers, too. And that doesn't mean it would have looked like Elton John at a concert with the feather boas all over itself or something. I mean, it could have had very restrained feathers. We know a lot of mammals today have hair, but if they're really big and if they live in hot environments, let's say elephants, they reduce that hair. So...

We don't know for sure, but my prediction is somebody will find somewhere out in Montana or Saskatchewan some local setting where some T-Rex was buried really quickly and some small little hairy feathers were preserved in stone. My prediction is that that will happen at some point. It will be on the cover of nature. It will be a big discovery.

And you can tell your friend at the shop that I told you, I told you so right here. All right, watch this space. All right, Steve, I'm going to try and get two more quick questions out of you before we completely wrap. And my first one is also something that I've thought about for some time. I think maybe since watching Walking with Dinosaurs almost like 20 years ago now.

female T-Rexes, were they bigger and stronger and more ferocious than the males? Do we know that? We don't know. Really, it's very challenging to tell male and female dinosaurs apart from fossils. It's not like, say, physical anthropology with humans, where at least in adult humans, based on things like the size of the pelvis and so on, you can make a pretty reasonable identification of a male or a female, although that's quite difficult for younger humans.

With dinosaurs, we just don't have the big enough sample sizes. We don't have the thousands of skeletons we need to do all the meticulous measurements to see statistically what differences there could be. So it's very hard to tell a male from a female. We really don't know. People have proposed this idea. There are different lines of evidence that maybe some dinosaur fossils are female or male.

This idea gained a lot of traction about 20, 25 years ago, but we honestly just don't know right now.

Fair enough indeed. Well, lastly, Steve, I'd like to ask a little bit about T-Rex hunting, because going back to the anatomy of a T-Rex, you've mentioned how muscly they were, how strong, how heavy they were, and also living in this landscape alongside other famous dinosaurs, let's say Triceratops with the three horns. I mean, would T-Rex to sustain itself, just itself, have to hunt a lot, a lot of prey and a lot of big prey in that?

Probably. Probably. You know, this was an animal that weighed seven or eight tons as an adult. It needed to keep itself going. It depends on what its metabolism was. Was it warm-blooded? Was it cold-blooded? Was it somewhere in between? Of course, warm-blooded animals that regulate their body temperature at a high degree and produce their own body heat, they require more food, more energy. So it all depends. But probably T. rexes would have had to eat, you know,

many, many dozens of kilos of meat a day, you know, on average to keep themselves going. And that means they probably did hunt larger prey. A triceratops, an average adult triceratops, probably weighed about twice as much.

as an adult T. rex. It was bulky. It was meaty. That would have been a great meal. So, probably T. rex would have hunted those animals, and we do have some direct evidence. We have bite marks on the bones of Triceratops, as I alluded to earlier. There's other big plant-eating dinosaurs, the duck-billed dinosaurs.

things like Edmontosaurus, which also lived in the same environment. We have bite marks on some of their bones. So we know that T-Rexes did feed on those animals. And you can only imagine T-Rex was probably a glutton because it needed to get a lot of food. And it makes sense. I mean, why have a head the size of a bathtub with teeth that can crush the bones of your prey if you're not going to use those things to hunt?

All right, Steve, absolutely fantastic. Well, you have graced us with your time for long enough now, and it's been absolutely fantastic. Last but certainly not least, I mean, you've written numerous books over your career, but the latest book you've written all about the dinosaurs, it is called? So I wrote The Rise and Fall of the Dinosaurs a few years ago. It's a pop science book that was really written for a general audience. I think people that are into history really will love it in the same way. I hope they'll love it. But I read a lot of history books, you know, and I'm relaxing and

I try to write it in that kind of style to be accessible. I did one on mammals, followed it up with what's called The Rise and Reign of the Mammals. That's all about our family, our ancestors, going all the way back to the time of the dinosaurs. And right now, as we speak, I'm doing the

the third one basically in the series, which is about birds. Yes. The origin and evolution of birds, how birds evolved from dinosaurs, how birds have changed over the last 150 million years. And it's been a whole lot of fun so far. And I have about another year or so to finish that one up. Well, good luck, Steve. And when that is done, we will get you back on to talk all about these early birds, which would be fantastic. We will do so. Steve, thank you so much for taking the time to come back on the podcast today.

As always, I really love talking to you guys and I look forward to talking about birds down the line.

Well, there you go. There was Dr. Steve Brassati talking all things Tyrannosaurus Rex. What a great episode that was. I hope you enjoyed. Thank you for listening. Please follow this show on Spotify or wherever you get your podcasts. It really helps us and you'll be doing us a big favour. And don't forget, you can also listen to us and all of History Hits podcasts ad-free and watch hundreds of TV documentaries when you subscribe at historyhit.com slash subscribe. And as a special gift...

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