WEBVTT 00:00:00.000 --> 00:00:03.339 If you were to ask a committee of say fantasy 00:00:03.339 --> 00:00:06.679 illustrators to design a dragon but the catch 00:00:06.679 --> 00:00:08.300 is they weren't allowed to talk to each other 00:00:08.300 --> 00:00:10.460 and then you just sort of mashed all their drawings 00:00:10.460 --> 00:00:12.519 together you might end up with something that 00:00:12.519 --> 00:00:15.160 looks a little bit like Carnotaurus. Yeah that's 00:00:15.160 --> 00:00:17.739 a pretty good analogy. It is a creature of just 00:00:17.739 --> 00:00:21.019 absolute contradictions. Right. It just doesn't 00:00:21.019 --> 00:00:23.480 seem like it should be real. It really is the 00:00:23.480 --> 00:00:25.879 platypus of the Cretaceous theropods, you know. 00:00:26.120 --> 00:00:29.260 You have these legitimate horns of a bull, a 00:00:29.260 --> 00:00:31.739 face that looks like it ran into a wall. A clug 00:00:31.739 --> 00:00:34.420 -smashed face. Yeah, exactly. And then you have 00:00:34.420 --> 00:00:36.600 these legs that are, I mean, they look like they're 00:00:36.600 --> 00:00:39.560 biologically engineered for Olympic sprinting. 00:00:39.619 --> 00:00:43.409 Yeah. And then the arms. The arms make a T -Rex 00:00:43.409 --> 00:00:46.289 look like a bodybuilder. A serious weightlifter. 00:00:46.750 --> 00:00:48.729 And that's the thing. Usually when we see designs 00:00:48.729 --> 00:00:51.770 like that in movies or games, we kind of roll 00:00:51.770 --> 00:00:54.090 our eyes. We say, okay, that's a movie monster. 00:00:54.109 --> 00:00:56.170 That's not a real animal. Right. It's over -designed. 00:00:56.329 --> 00:00:59.929 But Carnotaurus is the reality. Yeah. It is, 00:00:59.990 --> 00:01:02.350 and I don't think this is an exaggeration, arguably 00:01:02.350 --> 00:01:06.590 the most specialized, derived, and frankly bizarre 00:01:06.590 --> 00:01:09.590 predator to ever come out of the Southern Hemisphere. 00:01:09.849 --> 00:01:11.989 It absolutely challenges our assumptions about 00:01:11.989 --> 00:01:14.010 what an apex predator is even supposed to look 00:01:14.010 --> 00:01:17.189 like. We are so, so conditioned by the Tyrannosaurus 00:01:17.189 --> 00:01:20.150 model. You know, the big head, the massive bone 00:01:20.150 --> 00:01:22.370 crushing bite, that sort of generalist heavy 00:01:22.370 --> 00:01:25.049 duty build. And then you look at Carnotaurus, 00:01:25.170 --> 00:01:27.049 which went down a completely different evolutionary 00:01:27.049 --> 00:01:30.510 path. And it just it looks alien. But that's 00:01:30.510 --> 00:01:32.230 exactly what we're going to do today. We're going 00:01:32.230 --> 00:01:37.689 to try and move past the caricature. The villain 00:01:37.689 --> 00:01:39.370 from the Disney movie. Yeah, the movie monster. 00:01:39.370 --> 00:01:41.310 So we really dig into the biomechanics. We're 00:01:41.310 --> 00:01:43.670 going to look at the fluid dynamics of its speed, 00:01:43.769 --> 00:01:45.930 the structural engineering of that wild skull, 00:01:46.010 --> 00:01:49.069 and maybe the ecological pressures that force 00:01:49.069 --> 00:01:52.129 a dinosaur to evolve into, well, a meat -eating 00:01:52.129 --> 00:01:54.489 bull. And the incredible thing is that we can 00:01:54.489 --> 00:01:57.790 do that. We can base this deep dive on the holotype, 00:01:57.909 --> 00:02:00.879 the original specimen. Because unlike so many 00:02:00.879 --> 00:02:02.680 other dinosaurs where we're, you know, we're 00:02:02.680 --> 00:02:05.420 pasting together a toe bone from here and a jaw 00:02:05.420 --> 00:02:07.439 fragment from there. Right, a Frankenstein's 00:02:07.439 --> 00:02:09.979 monster of fossils. Exactly. Carnotaurus gave 00:02:09.979 --> 00:02:13.460 us almost everything in one single package. Including 00:02:13.460 --> 00:02:16.710 the skin. Mm -hmm. Which... We have to talk about 00:02:16.710 --> 00:02:19.169 the skin because that discovery back in 1984, 00:02:19.430 --> 00:02:22.169 it didn't just tell us what this one animal looked 00:02:22.169 --> 00:02:24.169 like. It feels like it fundamentally changed 00:02:24.169 --> 00:02:27.229 the whole field of paleo art and our understanding 00:02:27.229 --> 00:02:29.389 of theropod skin in general. It did. It was a 00:02:29.389 --> 00:02:31.270 landmark find. It was really the first time we 00:02:31.270 --> 00:02:33.090 could look at a large predator and say, with 00:02:33.090 --> 00:02:35.870 certainty, this is the texture of a killer. Not 00:02:35.870 --> 00:02:39.650 just scales, but this specific complex texture. 00:02:39.849 --> 00:02:41.569 Okay, so let's set the stage. Where does this 00:02:41.569 --> 00:02:44.409 story begin? It starts in 1984. The location 00:02:44.409 --> 00:02:46.870 is the Chubut province in Argentina, Patagonia, 00:02:46.969 --> 00:02:49.669 and the man in charge is the absolute legend, 00:02:49.909 --> 00:02:53.090 Jose Bonaparte. Now, Bonaparte is a titan in 00:02:53.090 --> 00:02:54.810 South American paleontology. I mean, he's the 00:02:54.810 --> 00:02:57.009 one who really put the southern continents on 00:02:57.009 --> 00:02:59.590 the map, especially during a time when all the 00:02:59.590 --> 00:03:01.509 money and attention was focused on North American 00:03:01.509 --> 00:03:04.289 dig sites. Absolutely. He was leading this huge 00:03:04.289 --> 00:03:07.289 project, the Jurassic and Cretaceous terrestrial 00:03:07.289 --> 00:03:09.310 vertebrates of South America project. It was 00:03:09.310 --> 00:03:11.629 a massive undertaking. And they were working 00:03:11.629 --> 00:03:14.469 in a geological unit called the La Colonia Formation. 00:03:14.610 --> 00:03:16.169 And for those who haven't been to Patagonia, 00:03:16.210 --> 00:03:18.490 the La Colonia outcrops are, I mean, they're 00:03:18.490 --> 00:03:21.180 beautiful. but they are geologically unforgiving. 00:03:21.319 --> 00:03:23.439 That's a good way to put it. And that unforgiving 00:03:23.439 --> 00:03:26.280 nature is actually a key detail here. The preservation 00:03:26.280 --> 00:03:29.479 of this specific animal was dictated by the rock 00:03:29.479 --> 00:03:32.099 it was buried in. We aren't talking about, you 00:03:32.099 --> 00:03:34.539 know, soft mudstone or loose sand where bones 00:03:34.539 --> 00:03:36.580 get crushed. Right. No, we are talking about 00:03:36.580 --> 00:03:40.539 hematite concretions, iron, iron. The skeleton 00:03:40.539 --> 00:03:43.199 was found encased in this massive iron -rich 00:03:43.199 --> 00:03:47.039 rock. Hematite is an iron oxide. So when it forms 00:03:47.039 --> 00:03:50.039 a compression around a fossil, it basically creates 00:03:50.039 --> 00:03:52.379 a sarcophagus that is incredibly, incredibly 00:03:52.379 --> 00:03:54.960 hard. It's much denser than the surrounding rock. 00:03:55.120 --> 00:03:56.699 Which sounds like a double -edged sword, right? 00:03:56.759 --> 00:03:59.039 I mean, on the one hand, that iron tomb protects 00:03:59.039 --> 00:04:01.000 the fossil from being flattened from weathering. 00:04:01.000 --> 00:04:02.979 It's perfect protection. But on the other hand... 00:04:03.180 --> 00:04:05.360 Getting the bones out of that rock must be an 00:04:05.360 --> 00:04:07.919 absolute preparation nightmare. Nightmare is 00:04:07.919 --> 00:04:10.879 the right word. It took years and years of mechanical 00:04:10.879 --> 00:04:13.639 preparation. You can't just chip away at hematite 00:04:13.639 --> 00:04:16.160 with a little brush. You risk destroying the 00:04:16.160 --> 00:04:20.100 bone. But that hardness, that perfect casing, 00:04:20.259 --> 00:04:24.029 is exactly why we have the skin. The mineral 00:04:24.029 --> 00:04:26.889 replacement was so fine and the casing was so 00:04:26.889 --> 00:04:29.709 rigid that it preserved the three -dimensional 00:04:29.709 --> 00:04:32.870 structure of the soft tissues before they could 00:04:32.870 --> 00:04:35.370 decompose or get flattened by sediment. It's 00:04:35.370 --> 00:04:38.110 a geological miracle, really. And this wasn't 00:04:38.110 --> 00:04:40.550 the only major find from that expedition, was 00:04:40.550 --> 00:04:42.850 it? They found it alongside Amargosaurus, right? 00:04:43.269 --> 00:04:46.170 The sauropod with the crazy double row of necks 00:04:46.170 --> 00:04:48.389 binds? Yes, it was a banner expedition for them. 00:04:48.470 --> 00:04:51.230 They found both Amargosaurus and Carnotaurus 00:04:51.230 --> 00:04:54.199 in the same general time frame. But Carnotaurus 00:04:54.199 --> 00:04:55.980 was the showstopper because it wasn't just a 00:04:55.980 --> 00:04:58.279 pile of bones. It was an articulated skeleton. 00:04:58.779 --> 00:05:01.959 Found in the death pose. Correct. Lying on its 00:05:01.959 --> 00:05:05.019 right side with the neck arched way, way back 00:05:05.019 --> 00:05:07.899 over the torso. That epistatonic posture. Which 00:05:07.899 --> 00:05:10.000 we see a lot in theropod fossils. What causes 00:05:10.000 --> 00:05:12.600 that exactly? It's caused by the desiccation 00:05:12.600 --> 00:05:14.639 and shrinking of the heavy neutral ligaments 00:05:14.639 --> 00:05:17.000 that run along the spine after the animal dies. 00:05:17.220 --> 00:05:19.939 As they dry out, they contract and they're so 00:05:19.939 --> 00:05:22.240 strong they pull the head and neck back over 00:05:22.240 --> 00:05:25.199 the body. But seeing it in Carnotaurus, seeing 00:05:25.199 --> 00:05:28.800 that massive bulldog neck wrenched back, it's 00:05:28.800 --> 00:05:31.459 just a very visceral, powerful connection to 00:05:31.459 --> 00:05:33.279 the moment of its death. And because of that 00:05:33.279 --> 00:05:36.589 hematite sarcophagus. The skeleton was incredibly 00:05:36.589 --> 00:05:39.449 complete. We have the skull, the vertebrae, the 00:05:39.449 --> 00:05:42.350 arms, the pelvis. What are we missing? We're 00:05:42.350 --> 00:05:44.990 missing the lower legs, so the shins and feet 00:05:44.990 --> 00:05:47.290 and the very tip of the tail. And that's just 00:05:47.290 --> 00:05:49.689 due to weathering where that part of the concretion 00:05:49.689 --> 00:05:51.889 was exposed at the surface for thousands of years. 00:05:52.310 --> 00:05:54.910 But otherwise, this is basically an autopsy of 00:05:54.910 --> 00:05:56.529 a specific individual. And we know it was an 00:05:56.529 --> 00:06:00.079 adult. An adult, yes. We can tell because the 00:06:00.079 --> 00:06:02.579 sutures in the brain case, the lines where the 00:06:02.579 --> 00:06:05.720 skull bones meet, were fused together. In a juvenile, 00:06:06.000 --> 00:06:08.319 those are still separate to allow for growth. 00:06:08.420 --> 00:06:10.379 So this wasn't an animal going through a growth 00:06:10.379 --> 00:06:13.459 spurt. This is the finished, final product of 00:06:13.459 --> 00:06:16.180 its evolution. So Bonaparte gets this incredible 00:06:16.180 --> 00:06:19.220 specimen, and he names it Carnotaurus sastre, 00:06:19.439 --> 00:06:24.319 which means... Flesh bull. Carno for flesh, torus 00:06:24.319 --> 00:06:27.790 for bull. And Sastry is in honor of Angel Sastry, 00:06:27.850 --> 00:06:29.689 the owner of the ranch where the fossil was found. 00:06:29.829 --> 00:06:32.949 A fitting tribute. And Fleshbulk just, I mean, 00:06:33.009 --> 00:06:35.029 it captures the essence of it perfectly. It's 00:06:35.029 --> 00:06:37.430 not just the horns. It's the whole vibe, the 00:06:37.430 --> 00:06:40.129 bulk, the power. It's perfect. But let's circle 00:06:40.129 --> 00:06:41.990 back to that skin because you mentioned it changed 00:06:41.990 --> 00:06:44.829 everything. And it really did. Before this discovery, 00:06:45.050 --> 00:06:47.779 a lot of... dinosaur skin reconstruction was, 00:06:47.860 --> 00:06:49.779 you know, it was pretty speculative. Right. It 00:06:49.779 --> 00:06:51.740 was based on these tiny postage stamp -sized 00:06:51.740 --> 00:06:54.339 patches from other dinosaurs or just people inferring, 00:06:54.339 --> 00:06:56.240 well, they're reptiles, so they must have scales. 00:06:56.620 --> 00:06:59.000 Exactly. It was a lot of guesswork. But Carnotaurus 00:06:59.000 --> 00:07:01.620 provided a roadmap. It provided a whole landscape. 00:07:01.899 --> 00:07:04.100 A landscape. I like that. So we have impressions 00:07:04.100 --> 00:07:06.279 from all over the body. All over. The neck, the 00:07:06.279 --> 00:07:08.959 shoulder, the thorax, the tail. And the very 00:07:08.959 --> 00:07:11.100 first thing it told us, loud and clear, is... 00:07:11.420 --> 00:07:14.439 No feathers. Which is a really significant data 00:07:14.439 --> 00:07:17.180 point. Because by this time, especially later, 00:07:17.399 --> 00:07:20.199 we know that many cholerasaurs, that's the lineage 00:07:20.199 --> 00:07:22.060 that leads to birds and includes tyrannosaurs, 00:07:22.339 --> 00:07:26.319 were feathery. So Carnotaurus, which is an abelosaur, 00:07:26.560 --> 00:07:29.100 a totally different branch of the theropod family 00:07:29.100 --> 00:07:31.699 tree. Yeah. It went hard in the other direction. 00:07:31.839 --> 00:07:33.899 Completely staley. But here's the cool part. 00:07:34.040 --> 00:07:36.160 It's not just scales. It's the complexity of 00:07:36.160 --> 00:07:39.220 the skin. The base layer, the background texture, 00:07:39.339 --> 00:07:41.959 is made of these small, non -overlapping scales. 00:07:42.279 --> 00:07:43.720 Non -overlapping. That's interesting. So not 00:07:43.720 --> 00:07:45.620 like a snake or a fish where they overlap like 00:07:45.620 --> 00:07:48.079 shingles on a roof? Exactly. These are polygonal 00:07:48.079 --> 00:07:50.199 scales that fit together perfectly, like a mosaic 00:07:50.199 --> 00:07:53.120 floor or, you know, cracked mud. They range from 00:07:53.120 --> 00:07:56.600 about 5 to maybe 12 millimeters across. It creates 00:07:56.600 --> 00:08:00.310 this... really tough but flexible hide. Okay, 00:08:00.389 --> 00:08:03.189 so that's the base layer. That's the base. But 00:08:03.189 --> 00:08:05.449 then, interrupting this field of small scales, 00:08:05.689 --> 00:08:09.629 you have these large conical protuberances, the 00:08:09.629 --> 00:08:12.850 feature scales. The bumps, the studs. This is 00:08:12.850 --> 00:08:14.129 the part that always shows up in the artwork. 00:08:14.389 --> 00:08:16.689 These are the studs. They're big, four to five 00:08:16.689 --> 00:08:19.269 centimeters in diameter. And they're surrounded 00:08:19.269 --> 00:08:21.790 by a little rosette of slightly larger basement 00:08:21.790 --> 00:08:25.610 scales. Now, for decades, paleo artists drew 00:08:25.610 --> 00:08:28.430 these bumps in these neat, orderly rows running 00:08:28.430 --> 00:08:30.790 along the length of the body. I can picture it 00:08:30.790 --> 00:08:32.429 now. It looks like it has racing stripes made 00:08:32.429 --> 00:08:36.090 of osteoderms. Very tidy, very, you know, designed. 00:08:36.450 --> 00:08:39.169 And it turns out it's very wrong. There was a 00:08:39.169 --> 00:08:42.309 major study in 2021 by Christoph Hendricks and 00:08:42.309 --> 00:08:44.789 Phil Bell. They reexamined the skin impressions 00:08:44.789 --> 00:08:47.269 using modern imaging techniques, and they found 00:08:47.269 --> 00:08:48.850 that the distribution of these feature scales 00:08:48.850 --> 00:08:52.200 is actually... Random. Random. So no rows at 00:08:52.200 --> 00:08:54.779 all. No neat rows. It's a chaotic, irregular 00:08:54.779 --> 00:08:57.200 distribution, which when you think about it, 00:08:57.220 --> 00:08:59.360 looks much more organic. That does make more 00:08:59.360 --> 00:09:02.480 sense. Nature rarely does perfect geometric rows 00:09:02.480 --> 00:09:04.539 unless there's a very specific reason, like, 00:09:04.580 --> 00:09:06.580 you know, segmentation in an insect or something. 00:09:07.339 --> 00:09:09.820 Exactly. And they also found that the little 00:09:09.820 --> 00:09:12.100 basement scales, the small ones, they change 00:09:12.100 --> 00:09:14.019 shape depending on where they are on the body. 00:09:14.200 --> 00:09:16.460 On the chest, they might be sort of conical. 00:09:16.980 --> 00:09:19.440 Elsewhere, they're more lens shaped or polygonal. 00:09:19.440 --> 00:09:23.000 It shows a really high degree of regionalization 00:09:23.000 --> 00:09:25.679 in the skin. So what's the function of the bumps? 00:09:25.899 --> 00:09:29.659 I mean, what's the why? Is it just armor? Protection 00:09:29.659 --> 00:09:32.740 is definitely the leading hypothesis. The best 00:09:32.740 --> 00:09:35.419 modern analogs we have are things like the green 00:09:35.419 --> 00:09:37.940 iguana or the marine iguana. They have these 00:09:37.940 --> 00:09:41.220 large, bumpy, tubercular scales often on their 00:09:41.220 --> 00:09:42.980 neck and back. And they use them for fighting. 00:09:43.360 --> 00:09:46.340 They do. They serve to protect against bites 00:09:46.340 --> 00:09:48.639 and scratches during what we call intraspecific 00:09:48.639 --> 00:09:51.120 combat. So fighting with other members of their 00:09:51.120 --> 00:09:53.080 own species. And we are going to get to the combat 00:09:53.080 --> 00:09:55.740 later, but given the horns on this thing, it's 00:09:55.740 --> 00:09:57.559 a safe bet these animals were getting up close 00:09:57.559 --> 00:09:59.340 and personal with each other. That's the idea. 00:09:59.559 --> 00:10:04.360 There's also a secondary hypothesis about thermoregulation. 00:10:04.440 --> 00:10:08.159 Heat regulation. Yeah. A large, active animal 00:10:08.159 --> 00:10:10.019 living in the Cretaceous, which is a greenhouse 00:10:10.019 --> 00:10:12.940 world much warmer than today, needs to be able 00:10:12.940 --> 00:10:15.620 to dump heat efficiently, especially an active 00:10:15.620 --> 00:10:18.940 hunter. The varied surface area between the flat 00:10:18.940 --> 00:10:21.019 scales and the projecting bumps might have created 00:10:21.019 --> 00:10:23.600 microturbulence in the air flowing over the skin, 00:10:23.799 --> 00:10:26.139 helping to shed heat. Almost like cooling fins 00:10:26.139 --> 00:10:29.399 on an engine. In a way, yeah. But the skin story 00:10:29.399 --> 00:10:31.580 gets even wilder when you look at the face. Right. 00:10:31.639 --> 00:10:33.940 The texture of the facial bones, the maxilla, 00:10:34.080 --> 00:10:36.960 the nasal, the jugule is incredibly rough and 00:10:36.960 --> 00:10:39.879 hummocky. It's not smooth. And in paleontology, 00:10:39.879 --> 00:10:42.100 that rough bone texture usually implies a specific 00:10:42.100 --> 00:10:44.039 kind of covering, right? It's not just skin. 00:10:44.240 --> 00:10:48.399 It implies a cornified pad, a thick, horny keratinous 00:10:48.399 --> 00:10:50.779 layer. Think of the texture on a rhino's face 00:10:50.779 --> 00:10:53.100 near its horn or the beak of a turtle but spread 00:10:53.100 --> 00:10:56.009 all over the snout. Wow. Carnotaurus likely had 00:10:56.009 --> 00:10:58.269 a face that was covered in tough, horny armor. 00:10:58.429 --> 00:11:01.269 It wasn't soft skin. Its face was a helmet. A 00:11:01.269 --> 00:11:04.950 helmet with horns on it. That transitions us 00:11:04.950 --> 00:11:07.909 perfectly to the skull itself. The demon's head. 00:11:08.269 --> 00:11:10.370 Because if you look at a Carnotaurus skull in 00:11:10.370 --> 00:11:13.090 profile, and then you look at, say, a Giganotosaurus 00:11:13.090 --> 00:11:15.570 or a T -Rex, the difference is just jarring. 00:11:16.149 --> 00:11:19.980 Carnotaurus looks squashed. Pug -nosed is the 00:11:19.980 --> 00:11:22.220 common descriptor you hear, but I think bulldog 00:11:22.220 --> 00:11:24.519 is probably more accurate, just given the ferocity 00:11:24.519 --> 00:11:27.279 it implies. The skull is incredibly short for 00:11:27.279 --> 00:11:29.179 its height. It's only about 60 centimeters long, 00:11:29.340 --> 00:11:32.279 but it is very, very deep vertically. It gives 00:11:32.279 --> 00:11:35.360 it a very distinct box -like head shape. It does. 00:11:35.419 --> 00:11:37.740 And the snout isn't long and tapered like most 00:11:37.740 --> 00:11:40.539 other big varipods. It's moderately broad. But 00:11:40.539 --> 00:11:42.840 the features that really jump out at you, besides 00:11:42.840 --> 00:11:45.620 the horns, are the orbits, the eye sockets. They're 00:11:45.620 --> 00:11:47.899 weird shaped. They're keyhole shaped. And the 00:11:47.899 --> 00:11:50.080 upper margin of the eye socket projects outward, 00:11:50.320 --> 00:11:52.080 like a bony eyebrow, which would have protected 00:11:52.080 --> 00:11:53.700 the eye from above. And the eyes themselves, 00:11:54.000 --> 00:11:55.600 they're not facing out to the sides, are they? 00:11:55.700 --> 00:11:58.519 They're not. They are rotated forward. There 00:11:58.519 --> 00:12:00.960 is a definite overlap in the visual fields. This 00:12:00.960 --> 00:12:04.000 implies binocular vision. So, stereoscopic sight. 00:12:04.700 --> 00:12:07.500 Depth perception. Exactly. Now, it's not to the 00:12:07.500 --> 00:12:10.639 extreme degree of a T -Rex, which had truly phenomenal 00:12:10.639 --> 00:12:13.700 eagle -like depth perception, but it was certainly 00:12:13.700 --> 00:12:16.860 enough to judge distance accurately, which... 00:12:17.080 --> 00:12:19.220 You know, if you are a predator that moves at 00:12:19.220 --> 00:12:21.659 high speeds, that's a non -negotiable requirement. 00:12:22.000 --> 00:12:24.120 You do not want to run into a tree at 30 miles 00:12:24.120 --> 00:12:26.720 an hour. Or miss the prey you're trying to ambush. 00:12:27.000 --> 00:12:29.059 Yeah. But okay, let's talk about the main event. 00:12:29.460 --> 00:12:32.360 The horns. These aren't just little bumps in 00:12:32.360 --> 00:12:35.220 the skin. These are actual extensions of the 00:12:35.220 --> 00:12:37.679 frontal bones of the skull. So solid bone. Solid 00:12:37.679 --> 00:12:40.059 bone cores, yeah. They're about 15 centimeters 00:12:40.059 --> 00:12:43.309 long. And they project diagonally upward and 00:12:43.309 --> 00:12:45.570 outward from right above the eyes. You have to 00:12:45.570 --> 00:12:47.789 remember that's just the bone core. Right. In 00:12:47.789 --> 00:12:49.590 life, it would have been covered in keratin. 00:12:49.669 --> 00:12:52.649 A keratinous sheath, just like the horns of a 00:12:52.649 --> 00:12:55.450 bull or a ram today. And that sheath would have 00:12:55.450 --> 00:12:57.950 made them even longer, thicker, and almost certainly 00:12:57.950 --> 00:13:00.340 sharper. There was a lot of debate about these 00:13:00.340 --> 00:13:02.440 for a while, right? Were they just for display, 00:13:02.659 --> 00:13:05.080 like a peacock's tail, or were they actual weapons? 00:13:05.659 --> 00:13:08.179 But the structure seems pretty robust. They are 00:13:08.179 --> 00:13:10.500 incredibly robust. They're flattened from top 00:13:10.500 --> 00:13:13.539 to bottom, dorsiventrally, and their internal 00:13:13.539 --> 00:13:15.860 cross -section suggests they were built to take 00:13:15.860 --> 00:13:18.840 impact. This isn't a delicate, paper -thin crest 00:13:18.840 --> 00:13:21.419 like you see on a Dilophosaurus. These are functional 00:13:21.419 --> 00:13:23.659 structures. And that leads us straight into the 00:13:23.659 --> 00:13:26.799 behavioral questions. Why have horns? I mean, 00:13:26.820 --> 00:13:28.419 the neat -eating bull nickname isn't just... 00:13:28.429 --> 00:13:31.350 aesthetic. It implies a behavior. It does. And 00:13:31.350 --> 00:13:34.309 for Carnotaurus, we have three main theories 00:13:34.309 --> 00:13:36.389 for how they might have used them in combat against 00:13:36.389 --> 00:13:39.110 each other. Okay, what's theory A? Theory A is 00:13:39.110 --> 00:13:42.149 the ram theory. Straight up, like, bighorn sheep. 00:13:42.610 --> 00:13:45.029 Two Carnotaurus run at each other from a distance 00:13:45.029 --> 00:13:48.409 and collet coquet, a massive head -on collision. 00:13:49.039 --> 00:13:50.860 But does the skull mechanic support that? I mean, 00:13:50.860 --> 00:13:53.460 that's a huge shockwave to send through your 00:13:53.460 --> 00:13:55.340 skull. The brain is right there. And that's the 00:13:55.340 --> 00:13:57.399 main criticism of the theory. While the neck 00:13:57.399 --> 00:14:00.220 is incredibly strong and muscular, the cranial 00:14:00.220 --> 00:14:03.200 roof, the top of the skull, isn't quite as thickened 00:14:03.200 --> 00:14:05.860 or dome -like as, say, a Pachycephalosaur, those 00:14:05.860 --> 00:14:09.379 dinosaurs that definitely had butters. So a high 00:14:09.379 --> 00:14:12.440 -speed direct impact might have been a bit too 00:14:12.440 --> 00:14:15.419 risky. Okay, so that brings us to Theory B. Theory 00:14:15.419 --> 00:14:18.929 B is shoving. Think of it as a sumo match. Just 00:14:18.929 --> 00:14:21.889 slow push. Exactly. They lock horns or maybe 00:14:21.889 --> 00:14:24.149 press the flat tops of their heads together and 00:14:24.149 --> 00:14:27.570 they just push. It becomes a pure test of strength, 00:14:27.789 --> 00:14:30.649 leveraging that massive neck musculature we talked 00:14:30.649 --> 00:14:33.029 about, but without the high impulse shock of 00:14:33.029 --> 00:14:35.330 a full -on collision. More like a shoving match 00:14:35.330 --> 00:14:38.610 between marine iguanas. Precisely. A way to establish 00:14:38.610 --> 00:14:41.309 dominance without risking brain damage. And what's 00:14:41.309 --> 00:14:43.649 Theory C? Theory C for me is the most compelling. 00:14:43.830 --> 00:14:46.230 It's the giraffe method. Or you could call it 00:14:46.230 --> 00:14:49.049 neck flanking. I've seen videos of giraffes fighting. 00:14:49.210 --> 00:14:51.850 It's brutal. It is absolutely brutal. They fight 00:14:51.850 --> 00:14:54.750 by swinging their long necks and slamming their 00:14:54.750 --> 00:14:58.110 ossicones, their horns, into the side, the neck, 00:14:58.149 --> 00:15:00.230 or the flanks of their opponent. And we know 00:15:00.230 --> 00:15:02.929 Carnotaurus had a powerful muscular neck that 00:15:02.929 --> 00:15:05.929 was capable of rapid lateral or sideways movement. 00:15:06.210 --> 00:15:07.889 So it could swing its head like a club. Like 00:15:07.889 --> 00:15:10.500 a warhammer with two spikes on it. A sideways 00:15:10.500 --> 00:15:12.960 swipe with those horns could easily break ribs 00:15:12.960 --> 00:15:15.740 or tear huge gashes in the skin. And that makes 00:15:15.740 --> 00:15:17.740 so much sense in the context of the skin armor 00:15:17.740 --> 00:15:20.960 we just discussed. If you're evolving these brutal 00:15:20.960 --> 00:15:24.500 sideways horn attacks, you also co -evolve the 00:15:24.500 --> 00:15:26.440 studded leather jacket to help you survive the 00:15:26.440 --> 00:15:28.539 fight. Precisely. It's an evolutionary arms race 00:15:28.539 --> 00:15:30.980 happening within the species itself. The offense 00:15:30.980 --> 00:15:33.960 and defense evolving in lockstep. Wow. Okay, 00:15:34.000 --> 00:15:36.440 so we've got the horns, the armor. Now we have 00:15:36.440 --> 00:15:39.039 to address the bite. This is probably the most 00:15:39.039 --> 00:15:42.200 contentious part of Carnotaurus anatomy in the 00:15:42.200 --> 00:15:44.960 scientific literature. You have one group of 00:15:44.960 --> 00:15:47.059 scientists saying it had this flexible, almost 00:15:47.059 --> 00:15:49.759 snake -like jaw, and another group saying it 00:15:49.759 --> 00:15:52.190 had a surprisingly crushing bite. it's a classic 00:15:52.190 --> 00:15:54.909 case of biomechanical modeling versus morphological 00:15:54.909 --> 00:15:57.929 interpretation it's a real puzzle so on one side 00:15:57.929 --> 00:16:00.769 you have the kinetic jaw hypothesis this was 00:16:00.769 --> 00:16:03.269 largely championed by researchers like mazetta 00:16:03.269 --> 00:16:05.830 and his colleague kinetic meaning mobile yeah 00:16:05.830 --> 00:16:08.190 they looked at the joints and contacts between 00:16:08.190 --> 00:16:10.389 the different bones in the skull and importantly 00:16:10.389 --> 00:16:13.289 in the lower jaw there's a joint halfway down 00:16:13.289 --> 00:16:15.549 the lower jaw called the intramandibular joint 00:16:15.549 --> 00:16:18.409 they argued that this joint and others made the 00:16:18.409 --> 00:16:21.389 jaw flexible that the bones could move relative 00:16:21.389 --> 00:16:24.450 to one another. Kinda like how a snake can unhinge 00:16:24.450 --> 00:16:27.429 its jaw to swallow a huge egg. A bit less extreme 00:16:27.429 --> 00:16:30.340 than that, but it's a similar principle. They 00:16:30.340 --> 00:16:32.580 suggested this flexibility allowed Carnotaurus 00:16:32.580 --> 00:16:35.220 to do a couple of things. One, absorb the shock 00:16:35.220 --> 00:16:38.179 of struggling prey. Two, it might have allowed 00:16:38.179 --> 00:16:40.779 the lower jaw to bow outward slightly to accommodate 00:16:40.779 --> 00:16:43.779 and swallow smaller prey whole or in very large 00:16:43.779 --> 00:16:46.279 chunks. But that paints a picture of Carnotaurus 00:16:46.279 --> 00:16:50.799 as a hunter of small game. A giant 1 .5 ton dinosaur 00:16:50.799 --> 00:16:53.039 running around eating lizards and tiny mammals. 00:16:53.220 --> 00:16:55.500 Or small dinosaurs, yeah. But it does feel a 00:16:55.500 --> 00:16:57.440 little underwhelming for an animal this size. 00:16:57.779 --> 00:17:00.940 And biomechanically... A kinetic jaw is a structurally 00:17:00.940 --> 00:17:04.059 weaker jaw. If you bite down on a large, struggling 00:17:04.059 --> 00:17:06.960 herbivore with a loose, flexible jaw, you risk 00:17:06.960 --> 00:17:09.460 dislocation or fracture. Which is where the second 00:17:09.460 --> 00:17:11.680 cam comes in, the bite force modelers. Right. 00:17:11.779 --> 00:17:13.980 This is work by people like Francois Therrien. 00:17:14.140 --> 00:17:16.880 They use a technique called finite element analysis, 00:17:17.299 --> 00:17:20.660 it's an engineering method, to model the stresses 00:17:20.660 --> 00:17:24.859 on a digital skull of Carnotaurus. And their 00:17:24.859 --> 00:17:27.039 results were completely different. What did they 00:17:27.039 --> 00:17:29.160 find? They found that the bite force was actually 00:17:29.160 --> 00:17:32.240 quite high, potentially double that of a modern 00:17:32.240 --> 00:17:35.220 American alligator. They argued the skull was 00:17:35.220 --> 00:17:37.920 actually built for stress absorption, not for 00:17:37.920 --> 00:17:40.279 flexibility. And this aligns much better with 00:17:40.279 --> 00:17:42.339 the hatchet theory that Robert Baker proposed 00:17:42.339 --> 00:17:45.299 years ago, doesn't it? It fits perfectly. Baker 00:17:45.299 --> 00:17:47.559 looked at the whole picture, the short, deep, 00:17:47.680 --> 00:17:50.660 reinforced skull, and especially the neck. The 00:17:50.660 --> 00:17:53.180 neck of Carnotaurus is enormous. The muscle attachment 00:17:53.180 --> 00:17:55.880 sites are just huge. And Baker proposed that 00:17:55.880 --> 00:17:58.200 the animal didn't rely on jaw muscle power alone 00:17:58.200 --> 00:18:00.359 to kill? He's saying it's not about the squeeze. 00:18:00.660 --> 00:18:02.380 It's not about the squeeze. Instead, it used 00:18:02.380 --> 00:18:05.500 its entire head and neck as a weapon. The jaw 00:18:05.500 --> 00:18:08.279 was like a serrated axe head. So it would open 00:18:08.279 --> 00:18:10.930 its mouth wide. Open its mouth wide, probably 00:18:10.930 --> 00:18:13.470 raise its head up high, and then bring the entire 00:18:13.470 --> 00:18:16.849 head crashing down, slamming the upper teeth 00:18:16.849 --> 00:18:19.430 into the prey using the power of those immense 00:18:19.430 --> 00:18:22.950 neck muscles. Driving the teeth in like a pickaxe. 00:18:23.339 --> 00:18:26.160 A dental pickaxe. Exactly. And then you pull 00:18:26.160 --> 00:18:28.880 back, and the serrated teeth create a massive, 00:18:28.920 --> 00:18:32.299 deep slashing wound. This hit -and -run slashing 00:18:32.299 --> 00:18:34.680 tactic is also supported by the teeth themselves. 00:18:34.799 --> 00:18:38.039 They're relatively slender and blade -like, perfect 00:18:38.039 --> 00:18:40.220 for slicing meat, not for crushing bone like 00:18:40.220 --> 00:18:42.680 the thick, robust teeth of a T -Rex. It's a completely 00:18:42.680 --> 00:18:45.059 different killing style. It's a surgical strike. 00:18:45.140 --> 00:18:47.759 You inflict a massive wound, you slash the prey, 00:18:47.980 --> 00:18:51.539 let it bleed out, and just wait. And that strategy 00:18:51.539 --> 00:18:53.460 fits perfectly with the rest of the anatomy we 00:18:53.460 --> 00:18:55.700 haven't even gotten to yet. Specifically, it's 00:18:55.700 --> 00:18:57.319 incredible speed. You don't want to grapple with 00:18:57.319 --> 00:18:59.440 prey if you were built like Carnotaurus. You 00:18:59.440 --> 00:19:02.160 want to ambush, slash, and retreat before it 00:19:02.160 --> 00:19:04.920 can fight back. Okay, speaking of speed, we've 00:19:04.920 --> 00:19:06.960 thrown around the term Olympic sprinter, but 00:19:06.960 --> 00:19:09.000 let's actually look at the hardware. This dinosaur 00:19:09.000 --> 00:19:11.660 is often cited as being one of, if not the fastest, 00:19:11.779 --> 00:19:14.500 large theropod. The Ferrari of the Cretaceous 00:19:14.500 --> 00:19:16.579 is the go -to analogy, and it's not far off. 00:19:16.980 --> 00:19:19.599 We are talking about top speed estimates that 00:19:19.599 --> 00:19:22.900 fall somewhere between 48 and 56 kilometers per 00:19:22.900 --> 00:19:26.119 hour. That's about 30 to 35 miles per hour. For 00:19:26.119 --> 00:19:29.339 an animal weighing over a ton, that is terrifying 00:19:29.339 --> 00:19:31.480 velocity. It's incredible, and the question is 00:19:31.480 --> 00:19:35.109 how? What allows a bipedal animal of that size 00:19:35.109 --> 00:19:37.750 to move that fast? And the answer really comes 00:19:37.750 --> 00:19:40.230 down to its tail. The tail. Okay, so the tail 00:19:40.230 --> 00:19:42.910 isn't just a counterbalance. Not at all. In sauropods, 00:19:42.970 --> 00:19:45.369 the tail is the engine room. It's the anchor 00:19:45.369 --> 00:19:47.650 for a critically important muscle called the 00:19:47.650 --> 00:19:50.309 caudofemoralis longus. Okay. Break that down 00:19:50.309 --> 00:19:52.950 for us. Caudo femoralis. Caudo refers to the 00:19:52.950 --> 00:19:55.289 tail, the caudal vertebrae, and femoralis refers 00:19:55.289 --> 00:19:57.549 to the femur, the thigh bone. So it's a muscle 00:19:57.549 --> 00:19:59.430 that connects the tail to the thigh. And this 00:19:59.430 --> 00:20:01.130 is the muscle that retracts the leg. It pulls 00:20:01.130 --> 00:20:04.230 it backwards. Precisely. It attaches to the tail 00:20:04.230 --> 00:20:06.990 vertebrae, runs down the leg, and attaches to 00:20:06.990 --> 00:20:10.019 a prominence on the femur. When that muscle contracts, 00:20:10.380 --> 00:20:13.740 it pulls the leg back with immense force. That 00:20:13.740 --> 00:20:15.779 is your power stroke when you're running. So 00:20:15.779 --> 00:20:18.259 the bigger and more powerful the cata femoralis 00:20:18.259 --> 00:20:20.579 muscle is, the more power you can put into each 00:20:20.579 --> 00:20:23.079 and every stride. And Carnotaurus, I'm guessing, 00:20:23.140 --> 00:20:26.500 has a supersized cata femoralis. It has a monstrous 00:20:26.500 --> 00:20:29.400 one. And we know this because of a really unique 00:20:29.400 --> 00:20:32.700 anatomical quirk in its tail bones. This was 00:20:32.700 --> 00:20:35.119 a discovery by Scott Persons and Phil Curry. 00:20:35.400 --> 00:20:37.960 They noticed that in most theropods, the caudal 00:20:37.960 --> 00:20:39.839 ribs, the little ribs that stick out from the 00:20:39.839 --> 00:20:42.259 sides of the tail vertebrae, they stick straight 00:20:42.259 --> 00:20:44.819 out sideways, kind of like a T -shape. But in 00:20:44.819 --> 00:20:47.279 Carnotaurus, these ribs are angled sharply upwards, 00:20:47.440 --> 00:20:50.279 forming a V -shape instead of a T. A V -shape. 00:20:50.299 --> 00:20:52.240 So instead of having a flat top to the tail, 00:20:52.339 --> 00:20:54.589 you'd have a deep groove on top. No, it's the 00:20:54.589 --> 00:20:58.069 opposite. The V creates a massive amount of space 00:20:58.069 --> 00:21:00.410 on the sides of the vertebrae underneath the 00:21:00.410 --> 00:21:03.769 upward angled ribs. By angling those ribs up, 00:21:03.829 --> 00:21:06.589 you create this huge sub -rectangular channel 00:21:06.589 --> 00:21:08.869 running along the sides of the tail vertebrae. 00:21:08.990 --> 00:21:12.170 And that entire space was filled by the patofemoralis 00:21:12.170 --> 00:21:14.509 muscle. Ah, I see. So the tail is effectively 00:21:14.509 --> 00:21:17.009 thicker, just packed with more muscle. Way more 00:21:17.009 --> 00:21:19.009 muscle. Based on their models, they estimated 00:21:19.009 --> 00:21:22.970 the muscle mass was between 111 and 137 kilograms. 00:21:23.240 --> 00:21:25.880 per leg. That is just an absurd amount of horsepower. 00:21:26.259 --> 00:21:29.740 It's an incredible engine, but there's always 00:21:29.740 --> 00:21:32.559 a catch. Engineering, especially biological engineering, 00:21:32.740 --> 00:21:34.900 is always about trade -offs. If you build a car 00:21:34.900 --> 00:21:37.920 for pure straight -line speed like a drag racer, 00:21:37.960 --> 00:21:40.240 you can't really turn corners very well. And 00:21:40.240 --> 00:21:42.640 that is the Carnotaurus problem. That is the 00:21:42.640 --> 00:21:44.579 carnotaurus problem. To support that massive 00:21:44.579 --> 00:21:46.720 muscle and handle the forces involved, the tail 00:21:46.720 --> 00:21:48.819 vertebrae themselves have these very complex 00:21:48.819 --> 00:21:51.880 interlocking joints that make the tail extremely 00:21:51.880 --> 00:21:55.299 rigid. It was stiff. It wasn't a flexible whipping 00:21:55.299 --> 00:21:57.460 tail like you see in other dinosaurs. No, it 00:21:57.460 --> 00:21:59.480 can't use its tail like a rudder, whipping it 00:21:59.480 --> 00:22:02.579 around to help it turn. No, not at all. And turning 00:22:02.579 --> 00:22:05.500 at speed, making tight corners, requires rotational 00:22:05.500 --> 00:22:08.380 inertia and flexibility. If your body is basically 00:22:08.380 --> 00:22:11.119 a stiff, heavy rocket, you're going to have a 00:22:11.119 --> 00:22:13.480 very, very wide turning radius. So Carnotaurus 00:22:13.480 --> 00:22:15.559 was a straight -line specialist. A drag racer, 00:22:15.559 --> 00:22:18.980 not a slalom skier. Perfect analogy. It could 00:22:18.980 --> 00:22:21.559 run you down in a sprint across an open plain, 00:22:21.640 --> 00:22:24.059 but if you were able to zigzag between trees, 00:22:24.319 --> 00:22:28.240 it would have to slow down significantly to reorient 00:22:28.240 --> 00:22:30.660 its entire body to follow you. It really solidifies 00:22:30.660 --> 00:22:33.619 that ambush predator hypothesis then. It's not 00:22:33.619 --> 00:22:35.380 a pursuit predator that's going to chase you 00:22:35.380 --> 00:22:37.799 for miles. It sees you, it bursts out of the 00:22:37.799 --> 00:22:40.019 tree line at incredible speed, hits you with 00:22:40.019 --> 00:22:42.099 that hatchet bite, and then it's gone before 00:22:42.099 --> 00:22:43.880 you even know what happened. That seems to be 00:22:43.880 --> 00:22:46.059 the most likely strategy, yes. It's all about 00:22:46.059 --> 00:22:48.720 that initial explosive burst of speed. Now, we 00:22:48.720 --> 00:22:51.019 cannot do a deep dive on Carnotaurus without 00:22:51.019 --> 00:22:53.539 discussing the arms. Because, you know, we all 00:22:53.539 --> 00:22:56.279 mock T. rex for its small arms. But Carnotaurus 00:22:56.279 --> 00:22:58.799 arms are, I mean, they are barely there. They 00:22:58.799 --> 00:23:01.539 are vestigial in the truest sense of the word. 00:23:01.859 --> 00:23:04.839 They're not just small. They're bizarrely proportioned 00:23:04.839 --> 00:23:08.359 and structured. The forearm is only 25 % of the 00:23:08.359 --> 00:23:10.819 length of the upper arm, the humerus. So it's 00:23:10.819 --> 00:23:12.980 mostly just an upper arm with a tiny little stub 00:23:12.980 --> 00:23:15.079 at the end? Pretty much. And it gets weirder. 00:23:15.500 --> 00:23:18.440 The hand attaches directly to the forearm. There 00:23:18.440 --> 00:23:21.740 are no wrist bones. Wait, no wrist at all? No 00:23:21.740 --> 00:23:25.259 ossified carpal bones. The metacarpals, the hand 00:23:25.259 --> 00:23:27.779 bones, articulate directly with the radius and 00:23:27.779 --> 00:23:30.440 ulna. It's like having your hand glued directly 00:23:30.440 --> 00:23:33.480 onto your forearm with no flexible joint in between. 00:23:33.680 --> 00:23:36.640 That's wild. And what about the fingers? It had 00:23:36.640 --> 00:23:39.579 four digits, which is already strange for a theropod, 00:23:39.660 --> 00:23:42.079 but digit number four was just a little splint 00:23:42.079 --> 00:23:44.940 of bone, a spur. And the other fingers, especially 00:23:44.940 --> 00:23:47.440 the middle two, were fused together. They couldn't 00:23:47.440 --> 00:23:49.380 move independently. And they almost certainly 00:23:49.380 --> 00:23:51.400 lacked claws. So let me get this straight. You 00:23:51.400 --> 00:23:54.339 have a tiny, immobile hand that can't grab, can't 00:23:54.339 --> 00:23:56.440 slash, can't reach the mouth. And it's attached 00:23:56.440 --> 00:23:58.900 to a stiff arm with no wrist. It's a nubbin. 00:23:59.000 --> 00:24:01.380 It's basically a decorative nubbin. For a long, 00:24:01.480 --> 00:24:04.339 long time, people tried to invent uses for them. 00:24:04.480 --> 00:24:06.160 You know, maybe they're for display. Maybe they 00:24:06.160 --> 00:24:09.720 help brace during mating. But a 2009 study analyzed 00:24:09.720 --> 00:24:12.119 the position of the shoulder socket and the actual 00:24:12.119 --> 00:24:14.900 range of motion. And the arms were locked in 00:24:14.900 --> 00:24:17.460 this outward flaring position. They were basically 00:24:17.460 --> 00:24:20.539 doing a permanent jazz hands pose out to the 00:24:20.539 --> 00:24:22.819 side. They couldn't even reach forward, let alone 00:24:22.819 --> 00:24:24.799 touch each other. And surely the neurological 00:24:24.799 --> 00:24:27.480 evidence must seal the deal on them being useless. 00:24:27.599 --> 00:24:30.160 It does. When you look at the vertebrae, the 00:24:30.160 --> 00:24:32.940 neural canals, the holes for the nerves that 00:24:32.940 --> 00:24:35.339 would have gone to the arm muscles are extremely 00:24:35.339 --> 00:24:38.359 reduced. This tells us the animal had very poor 00:24:38.359 --> 00:24:41.380 motor control and sensation in these limbs. They 00:24:41.380 --> 00:24:43.880 were on their way out, evolutionarily speaking. 00:24:44.200 --> 00:24:46.859 It's such a classic example of an energetic tradeoff. 00:24:47.420 --> 00:24:49.539 Evolution doesn't like to maintain expensive 00:24:49.539 --> 00:24:53.000 tissue that it doesn't need. Exactly. Why waste 00:24:53.000 --> 00:24:55.480 calories and developmental resources on arms? 00:24:55.960 --> 00:24:58.480 If you are putting all of your evolutionary points 00:24:58.480 --> 00:25:01.039 into building a massive skull, a huge neck, and 00:25:01.039 --> 00:25:03.599 a turbocharged tail, you have to save energy 00:25:03.599 --> 00:25:07.180 somewhere. The arms were the budget cut. So here's 00:25:07.180 --> 00:25:09.660 a thought. If the lineage had continued, say, 00:25:09.740 --> 00:25:12.279 for another 10 or 20 million years, do you think 00:25:12.279 --> 00:25:15.299 the arms would have disappeared entirely? I think 00:25:15.299 --> 00:25:17.400 it's almost certain. We see this today in animals 00:25:17.400 --> 00:25:20.680 like skinks and some snakes. The limbs get smaller 00:25:20.680 --> 00:25:22.839 and smaller over generations until they just 00:25:22.839 --> 00:25:25.759 vanish. Carnotaurus was just caught in the middle 00:25:25.759 --> 00:25:28.000 of that deletion process when the asteroid hit. 00:25:28.180 --> 00:25:30.240 Okay, so we've built the animal. We have this 00:25:30.240 --> 00:25:32.940 hyper -specialized armored horned speed demon 00:25:32.940 --> 00:25:35.759 with useless arms. Let's place it in its world, 00:25:35.920 --> 00:25:38.839 the La Colonia Formation. What does this ecosystem 00:25:38.839 --> 00:25:41.059 look like? So we are in the late Cretaceous, 00:25:41.079 --> 00:25:43.619 specifically the Mastrichtian stage, which is 00:25:43.619 --> 00:25:45.700 the very last stage of the age of dinosaurs. 00:25:45.940 --> 00:25:49.099 We're talking around 69 to 66 million years ago. 00:25:49.339 --> 00:25:51.319 This is the end of the line. And at this point, 00:25:51.339 --> 00:25:53.319 South America is an island continent, right? 00:25:53.480 --> 00:25:56.039 Gondwana has mostly broken up. Correct. So the 00:25:56.039 --> 00:25:58.779 fauna here is isolated. It's evolved on its own. 00:25:58.859 --> 00:26:02.140 There's no T. rex here, no Triceratops. This 00:26:02.140 --> 00:26:04.619 is a completely different world. And the environment 00:26:04.619 --> 00:26:07.099 itself? The environment of the Lachlonia formation. 00:26:07.339 --> 00:26:10.839 is coastal. We're talking about estuaries, tidal 00:26:10.839 --> 00:26:14.519 flats, lagoons, basically a coastal plain that's 00:26:14.519 --> 00:26:17.680 facing the Atlantic Ocean, which was transgressing 00:26:17.680 --> 00:26:21.140 or moving inland at the time. It was a wet, lush 00:26:21.140 --> 00:26:23.500 environment, but there's evidence of seasonal 00:26:23.500 --> 00:26:25.519 dry spells as well. So who are the neighbors? 00:26:25.680 --> 00:26:29.259 Who is Carnotaurus living with and probably eating? 00:26:29.740 --> 00:26:31.980 Well, in the water, you have plesiosaurs and 00:26:31.980 --> 00:26:34.140 a lot of different kinds of turtles. On land, 00:26:34.160 --> 00:26:36.460 you have some early mammals, tiny things like 00:26:36.460 --> 00:26:39.559 Rigotherium. But the other big dinosaurs are 00:26:39.559 --> 00:26:42.140 the key to understanding Carnotaurus's role. 00:26:42.640 --> 00:26:45.420 So... The prey animals. The prey animals. The 00:26:45.420 --> 00:26:47.359 main herbivore we know of from this formation 00:26:47.359 --> 00:26:50.619 is a sauropod called Titanomachia. A titanosaur, 00:26:50.720 --> 00:26:53.420 so a long neck. A titanosaur, yes, but a relatively 00:26:53.420 --> 00:26:55.640 small one for a titanosaur. It was probably around 00:26:55.640 --> 00:26:57.819 six tons. Now, that's still a big animal, but 00:26:57.819 --> 00:26:59.579 for carnivores, that is the perfect prey size. 00:26:59.819 --> 00:27:02.099 It's too big to swallow whole, obviously. But 00:27:02.099 --> 00:27:04.359 it's just the right size for that hatchet strategy 00:27:04.359 --> 00:27:07.339 to be effective. Exactly. You run in, you deliver 00:27:07.339 --> 00:27:10.099 one or two of those massive slashing bites to 00:27:10.099 --> 00:27:11.859 the flanks or the legs. You weaken it and you 00:27:11.859 --> 00:27:13.779 just wait for it to drop from blood loss. It's 00:27:13.779 --> 00:27:16.480 the perfect prey. Are there any other predators 00:27:16.480 --> 00:27:19.059 in this environment? There are. We have other 00:27:19.059 --> 00:27:21.599 ablosaurids, including the recently described 00:27:21.599 --> 00:27:25.519 colican. But based on the fossils we have, Carnotaurus 00:27:25.519 --> 00:27:28.059 seems to be the largest predator in this specific 00:27:28.059 --> 00:27:31.269 niche. It was the apex. It's just fascinating 00:27:31.269 --> 00:27:33.470 to me to compare the southern hemisphere to the 00:27:33.470 --> 00:27:35.630 northern hemisphere at the end of the Cretaceous. 00:27:35.690 --> 00:27:38.170 In the north, you have the Tyrannosaurs, which 00:27:38.170 --> 00:27:41.430 are these massive, bone -crushing generalists. 00:27:41.529 --> 00:27:43.609 And in the south, you have the Avosaurs, these 00:27:43.609 --> 00:27:46.910 speedy, short -faced slicers. Why the completely 00:27:46.910 --> 00:27:48.930 different approaches to being an apex predator? 00:27:49.440 --> 00:27:52.259 It all comes down to biogeography and the prey 00:27:52.259 --> 00:27:55.099 that was available when the supercontinent Pangaea 00:27:55.099 --> 00:27:57.920 broke up and then Gondwana after it. The ancestors 00:27:57.920 --> 00:28:00.680 of these different predator groups were separated. 00:28:00.900 --> 00:28:03.480 They were isolated. And they evolved to deal 00:28:03.480 --> 00:28:06.579 with their local food sources. Precisely. In 00:28:06.579 --> 00:28:09.000 the south, the dominant large herbivores were 00:28:09.000 --> 00:28:11.509 the titanosaurs. And as we discussed, you don't 00:28:11.509 --> 00:28:14.130 necessarily need to crush massive bones to kill 00:28:14.130 --> 00:28:15.990 a titanosaur. You just need to bleed it out. 00:28:16.430 --> 00:28:18.650 In the north, tyrannosaurs were dealing with 00:28:18.650 --> 00:28:21.430 heavily armored prey like hadrosaurs and especially 00:28:21.430 --> 00:28:24.930 ceratopsians, the horned dinosaurs. That might 00:28:24.930 --> 00:28:26.970 have required a different tactic, one based on 00:28:26.970 --> 00:28:29.690 overwhelming bone shattering force. So it's a 00:28:29.690 --> 00:28:31.869 case of convergent evolution for the role of 00:28:31.869 --> 00:28:34.869 apex predator, but completely divergent solutions 00:28:34.869 --> 00:28:37.390 to the problem of how to kill. That's a great 00:28:37.390 --> 00:28:39.609 way to put it. And Carnotaurus really represents 00:28:39.609 --> 00:28:42.109 the absolute pinnacle of the Abelisaurid line, 00:28:42.230 --> 00:28:45.470 specifically a group within them called the Brachyrostra, 00:28:45.549 --> 00:28:49.170 which means short snouts. It took the basic Abelisaur 00:28:49.170 --> 00:28:52.130 blueprint fast, short -faced, and just pushed 00:28:52.130 --> 00:28:54.470 every single slider to the maximum. The shortest 00:28:54.470 --> 00:28:56.289 skull? The shortest skull, the longest and most 00:28:56.289 --> 00:28:58.809 powerful legs, and by far the smallest arms. 00:28:58.970 --> 00:29:01.650 It's the extreme athlete of the family. It is. 00:29:01.710 --> 00:29:04.069 And that's why it's so incredibly important to 00:29:04.069 --> 00:29:07.089 paleontology. It shows us just how plastic and 00:29:07.089 --> 00:29:09.730 adaptable the dinosaur body plan really was. 00:29:10.009 --> 00:29:12.650 There wasn't one single way to be a successful 00:29:12.650 --> 00:29:15.849 giant predator. So as we start to wrap this up, 00:29:15.890 --> 00:29:17.470 I want to go back to that idea you mentioned 00:29:17.470 --> 00:29:19.509 at the start of the evolutionary experiment. 00:29:20.009 --> 00:29:22.190 When you look at the whole picture of Carnotaurus, 00:29:22.490 --> 00:29:26.049 what is the big overarching takeaway for you? 00:29:26.109 --> 00:29:29.430 For me, it has to be the concept of hyperspecialization. 00:29:30.109 --> 00:29:32.589 Carnotaurus wasn't trying to be good at everything. 00:29:32.710 --> 00:29:34.970 It really, really wasn't. It sacrificed agility 00:29:34.970 --> 00:29:37.630 for pure straight -line speed. It sacrificed 00:29:37.630 --> 00:29:40.549 raw bite strength for bite speed and the shock 00:29:40.549 --> 00:29:43.210 -absorbing properties of its skull. And it sacrificed 00:29:43.210 --> 00:29:46.549 its arms for, well, for everything else. It went 00:29:46.549 --> 00:29:48.910 all in on a very specific strategy. Very specific 00:29:48.910 --> 00:29:51.589 lifestyle. It did. And, you know, usually in 00:29:51.589 --> 00:29:53.509 evolutionary history, hyperspecialists are the 00:29:53.509 --> 00:29:55.769 most vulnerable to extinction. They're fragile. 00:29:55.890 --> 00:29:58.089 When the environment changes, they often can't 00:29:58.089 --> 00:29:59.710 adapt because they're too locked into one way 00:29:59.710 --> 00:30:02.490 of life. But Carnotaurus was thriving. It was 00:30:02.490 --> 00:30:04.390 incredibly successful right up until the very 00:30:04.390 --> 00:30:06.849 end, right up until the asteroid hit. Which, 00:30:06.890 --> 00:30:09.509 it always makes you wonder, if the Chicxulub 00:30:09.509 --> 00:30:12.589 impact hadn't happened, if that one asteroid 00:30:12.589 --> 00:30:15.640 on that one day had just missed. That is the 00:30:15.640 --> 00:30:18.240 ultimate what if in all of paleontology, isn't 00:30:18.240 --> 00:30:20.319 it? It is. But specifically for this lineage, 00:30:20.519 --> 00:30:22.519 where would it have gone? I mean, you mentioned 00:30:22.519 --> 00:30:24.140 the arms would have likely disappeared completely. 00:30:24.279 --> 00:30:26.690 What about the head? Could it have become even 00:30:26.690 --> 00:30:29.049 shorter, even more specialized for that hatchet 00:30:29.049 --> 00:30:30.950 bite? It's certainly possible. I mean, you follow 00:30:30.950 --> 00:30:33.549 that trend to its logical conclusion. You might 00:30:33.549 --> 00:30:35.289 have ended up with a dinosaur that was essentially 00:30:35.289 --> 00:30:38.630 just a giant mouth on two legs with a massive 00:30:38.630 --> 00:30:41.069 tail engine propelling it. The Pac -Man dinosaur. 00:30:41.369 --> 00:30:43.829 The Pac -Man dinosaur, yes. A mouth with a turbo 00:30:43.829 --> 00:30:46.529 engine attached to the back. That is a genuinely 00:30:46.529 --> 00:30:48.769 terrifying image to leave our listeners with. 00:30:49.009 --> 00:30:52.890 A two -ton Pac -Man sprinting at 35 miles per 00:30:52.890 --> 00:30:55.250 hour through the ancient... Argentine jungle. 00:30:55.450 --> 00:30:58.150 I think we're all very lucky we missed that particular 00:30:58.150 --> 00:31:01.609 timeline. I have to agree. Carnotaurus is cool 00:31:01.609 --> 00:31:04.130 enough as a fossil. I don't think I'd want to 00:31:04.130 --> 00:31:05.869 meet the version that got to evolve for another 00:31:05.869 --> 00:31:08.210 10 million years. Definitely not. Well, that 00:31:08.210 --> 00:31:10.809 is the story of the meat -eating bull, a creature 00:31:10.809 --> 00:31:13.829 of contradictions, of bizarre anatomy, and of 00:31:13.829 --> 00:31:16.549 incredible specialized violence. Thank you for 00:31:16.549 --> 00:31:18.690 joining us on this deep dive. Always a pleasure 00:31:18.690 --> 00:31:20.970 to unpack the weird ones. And to our listeners, 00:31:21.089 --> 00:31:23.049 keep exploring and we will see you on the next 00:31:23.049 --> 00:31:23.630 deep dive.