WEBVTT 00:00:00.000 --> 00:00:01.740 Okay, close your eyes for a second. I want you 00:00:01.740 --> 00:00:04.459 to picture the single most majestic dinosaur 00:00:04.459 --> 00:00:07.240 you can think of. You're probably imagining that 00:00:07.240 --> 00:00:10.779 one scene, you know, from 1993. The paleontologists 00:00:10.779 --> 00:00:14.619 are just stunned that John Williams' score swells. 00:00:14.640 --> 00:00:17.000 The Jeep stops. The Jeep stops, and there it 00:00:17.000 --> 00:00:21.980 is. This towering, gentle giant rearing up to 00:00:21.980 --> 00:00:24.000 get the highest leaves, and then it comes down 00:00:24.000 --> 00:00:26.280 with this ground -shaking thud. It's probably 00:00:26.280 --> 00:00:29.820 the most recognizable dinosaur silhouette. in 00:00:29.820 --> 00:00:31.960 movie history, the Brachiosaurus. It was the 00:00:31.960 --> 00:00:34.579 first fully computer -generated dinosaur most 00:00:34.579 --> 00:00:36.820 of us ever saw. It's like the ambassador of the 00:00:36.820 --> 00:00:39.520 Jurassic. It is. It's the pop culture icon. But, 00:00:39.539 --> 00:00:42.119 and this is where I might have to ruin your childhood 00:00:42.119 --> 00:00:44.219 just a little bit. Uh -oh. What if I told you 00:00:44.219 --> 00:00:46.119 that the dinosaur you're picturing, the one in 00:00:46.119 --> 00:00:47.939 the movie, the one in that famous Berlin museum, 00:00:48.000 --> 00:00:50.159 the one on all the lunchboxes, isn't actually 00:00:50.159 --> 00:00:53.200 Brachiosaurus? That is the big twist. Yeah. The 00:00:53.200 --> 00:00:55.460 animal that everyone pictures is almost certainly 00:00:55.460 --> 00:00:58.240 Giraffatitan, which is an African cousin. The 00:00:58.240 --> 00:01:00.840 true Brachiosaurus, Brachiosaurus altithorax, 00:01:01.039 --> 00:01:04.359 is this rare North American animal that honestly 00:01:04.359 --> 00:01:06.700 looked pretty different. So it's a total imposter 00:01:06.700 --> 00:01:08.700 situation. Yeah. We've been cheering for the 00:01:08.700 --> 00:01:11.819 wrong dinosaur for, what, 30 years? Pretty much. 00:01:11.840 --> 00:01:15.019 So today, on this deep dive, we're going to set 00:01:15.019 --> 00:01:16.920 the record straight. We are going to find the 00:01:16.920 --> 00:01:20.280 real... And in doing that, we're going to uncover 00:01:20.280 --> 00:01:23.180 just this masterpiece of biological engineering. 00:01:23.439 --> 00:01:26.079 I mean, we're talking about an animal that defied 00:01:26.079 --> 00:01:28.540 gravity with its blood pressure, had a respiratory 00:01:28.540 --> 00:01:31.819 system more like a bird's than a reptile's. Wow. 00:01:31.980 --> 00:01:36.640 And grew from a tiny two meter long baby into 00:01:36.640 --> 00:01:39.859 a 40 ton Titan. Let's unpack this whole case 00:01:39.859 --> 00:01:41.640 of mistaken identity. But first, we have to go 00:01:41.640 --> 00:01:44.040 back to where it all started, not on some island 00:01:44.040 --> 00:01:46.620 off Costa Rica, but in the Colorado River Valley. 00:01:46.969 --> 00:01:48.890 right around the turn of the 20th century. The 00:01:48.890 --> 00:01:52.549 year is 1900. Paleontologist Elmer S. Riggs and 00:01:52.549 --> 00:01:54.849 his crew, they're out from the Field Columbian 00:01:54.849 --> 00:01:56.730 Museum, what we now call the Field Museum in 00:01:56.730 --> 00:01:59.769 Chicago. And they're prospecting near Grand Junction, 00:01:59.810 --> 00:02:01.969 Colorado. And the funny thing is, they weren't 00:02:01.969 --> 00:02:03.849 even looking for dinosaurs. They were hoping 00:02:03.849 --> 00:02:07.030 to find Eocene mammals, like prehistoric horses. 00:02:07.719 --> 00:02:10.419 That is classic scientific serendipity. You go 00:02:10.419 --> 00:02:12.259 out looking for a little horse, you find a monster. 00:02:12.560 --> 00:02:15.860 Exactly. So Riggs' assistant, a guy named Harold 00:02:15.860 --> 00:02:18.159 Minka, he's out walking and he stumbles on a 00:02:18.159 --> 00:02:21.819 bone. But not just any bone. It's the upper arm 00:02:21.819 --> 00:02:26.080 bone, the humerus, and it is just absurdly large. 00:02:26.300 --> 00:02:28.520 How large are we talking? We're talking over 00:02:28.520 --> 00:02:30.620 two meters long. That's about six and a half 00:02:30.620 --> 00:02:32.500 feet. Just the upper arm bone. That's taller 00:02:32.500 --> 00:02:34.860 than me. Taller than the average person. And 00:02:34.860 --> 00:02:37.419 this leads to my favorite little story from the 00:02:37.419 --> 00:02:41.479 original material. Riggs sees this bone and he's 00:02:41.479 --> 00:02:44.020 totally baffled. He actually thinks it's a femur, 00:02:44.020 --> 00:02:47.080 a thigh bone that's just been, you know, squashed 00:02:47.080 --> 00:02:49.300 and deformed over time. Well, that's an understandable 00:02:49.300 --> 00:02:51.819 mistake, right? I mean, for other big sauropods 00:02:51.819 --> 00:02:54.439 like Diplodocus, the back legs were the huge 00:02:54.439 --> 00:02:56.539 ones. They're the powerhouses. The front legs 00:02:56.539 --> 00:02:58.460 are always shorter. Yeah. Those animals were 00:02:58.460 --> 00:03:01.599 built like a... like suspension bridges, sloping 00:03:01.599 --> 00:03:03.740 down towards the head, finding an arm bone that 00:03:03.740 --> 00:03:06.219 was bigger than a thigh bone. It was unheard 00:03:06.219 --> 00:03:08.560 of. It just broke all the rules of dinosaur architecture. 00:03:08.960 --> 00:03:11.620 It completely broke the mold. Riggs eventually 00:03:11.620 --> 00:03:14.000 figured it out, and he famously declared he'd 00:03:14.000 --> 00:03:16.659 found the largest land animal ever. And that 00:03:16.659 --> 00:03:18.780 weird proportion, that's what gives us the name, 00:03:18.919 --> 00:03:22.280 Brachiosaurus. It comes from the Greek. Brachion 00:03:22.280 --> 00:03:25.889 means arm, and soros means lizard. Arm lizard. 00:03:26.090 --> 00:03:28.509 Arm lizard. Makes sense. And the specific name 00:03:28.509 --> 00:03:31.310 Altothorax is from Latin and Greek, meaning deep 00:03:31.310 --> 00:03:34.449 chest. Which also fits. If your front legs are 00:03:34.449 --> 00:03:36.669 longer than your back legs, your whole body angles 00:03:36.669 --> 00:03:38.590 up. You don't look like that suspension bridge 00:03:38.590 --> 00:03:41.750 anymore. You look more like a giraffe. Precisely. 00:03:41.750 --> 00:03:45.069 That deep chest and those long arms gave it this 00:03:45.069 --> 00:03:47.949 steeply inclined trunk. It was a completely radical 00:03:47.949 --> 00:03:50.810 body plan. But this is where the confusion starts. 00:03:51.110 --> 00:03:54.050 Okay. Riggs finds this thing in 1900. It's huge, 00:03:54.169 --> 00:03:56.250 but it's not complete. They only have about 20 00:03:56.250 --> 00:04:00.490 % of the skeleton. So Chicago's got this fragmentary 00:04:00.490 --> 00:04:02.250 giant. They know it's a big deal, but they don't 00:04:02.250 --> 00:04:05.189 have the whole picture. But then, a few years 00:04:05.189 --> 00:04:07.969 later, German expeditions head to Tanzania. Right, 00:04:08.030 --> 00:04:10.629 to what was then German East Africa. And they 00:04:10.629 --> 00:04:14.129 hit the absolute motherlode, the Tenduguru expedition. 00:04:14.830 --> 00:04:17.189 And what do they find there? They find tons of 00:04:17.189 --> 00:04:20.189 dinosaur material, including these nearly complete 00:04:20.189 --> 00:04:22.670 skeletons that look remarkably similar to what 00:04:22.670 --> 00:04:25.850 Riggs found in Colorado. A paleontologist named 00:04:25.850 --> 00:04:28.550 Werner Janensch studies them and decides, OK, 00:04:28.730 --> 00:04:31.209 these are close enough. And he names the African 00:04:31.209 --> 00:04:35.269 species Brachiosaurus branchi. And because the 00:04:35.269 --> 00:04:37.629 African skeletons were so complete, I mean, you 00:04:37.629 --> 00:04:40.009 could build a whole thing in a museum. They become 00:04:40.009 --> 00:04:42.569 the model for what a Brachiosaurus is. They became 00:04:42.569 --> 00:04:45.529 the default, the poster child. The original specimen 00:04:45.529 --> 00:04:48.730 in Chicago was kind of forgotten by the public 00:04:48.730 --> 00:04:50.990 because it was just a few bones. But the one 00:04:50.990 --> 00:04:54.629 in Berlin, that was a full standing skeleton. 00:04:54.649 --> 00:04:57.730 So every movie, every toy, every poster was based 00:04:57.730 --> 00:05:00.170 on the African one. For a century, yeah. But 00:05:00.170 --> 00:05:02.649 even then, there were some whispers in the paleontological 00:05:02.649 --> 00:05:05.110 community. Are these really the same animal? 00:05:05.370 --> 00:05:07.509 And those whispers got a lot louder in 2009. 00:05:07.889 --> 00:05:10.370 They became a shout. A researcher, Michael P. 00:05:10.389 --> 00:05:12.389 Taylor, did his own deep dive, and he realized, 00:05:12.509 --> 00:05:14.589 wait a minute, these aren't just different species, 00:05:14.910 --> 00:05:16.589 they're different genera. How different are we 00:05:16.589 --> 00:05:21.069 talking? He found 26 distinct anatomical differences, 00:05:21.509 --> 00:05:24.189 which is a lot. In fact, they were more different 00:05:24.189 --> 00:05:26.750 from each other than, say, Diplodocus and Beresaurus 00:05:26.750 --> 00:05:30.370 are. So the African one got a new name, Giraffatitan. 00:05:30.970 --> 00:05:33.029 Giraffatitan. I love that name. It's very fitting. 00:05:33.170 --> 00:05:35.750 It is. So, okay, the star of Jurassic Park is 00:05:35.750 --> 00:05:38.819 technically a Giraffatitan. So what makes our 00:05:38.819 --> 00:05:41.600 original American Brachiosaurus Altothorax different? 00:05:42.079 --> 00:05:44.839 If I put them side by side, what do I see? The 00:05:44.839 --> 00:05:47.060 American Brachiosaurus is the heavy duty model. 00:05:47.279 --> 00:05:50.660 Its trunk, its torso is about 25 to 30 percent 00:05:50.660 --> 00:05:53.600 longer than Giraffitans. So it's just bulkier, 00:05:53.639 --> 00:05:56.459 a longer body. Much bulkier, longer, deeper. 00:05:56.779 --> 00:06:00.399 And the tail was probably 20, maybe 25 percent 00:06:00.399 --> 00:06:02.720 longer and taller at the base. But the biggest 00:06:02.720 --> 00:06:05.519 visual cue might be the stance. The stance. Yeah. 00:06:09.879 --> 00:06:12.620 Brachiosaurus had arms that were slightly sprawled 00:06:12.620 --> 00:06:14.600 at the shoulder. Sprawled? You mean like a bulldog? 00:06:14.860 --> 00:06:17.000 A little bit, yeah. Not that extreme, but it 00:06:17.000 --> 00:06:20.500 gave it this wider, more robust posture. It was 00:06:20.500 --> 00:06:23.199 wider in the hips, wider in the shoulders. If 00:06:23.199 --> 00:06:26.439 Giraffatian is a graceful giraffe, Brachiosaurus 00:06:26.439 --> 00:06:29.980 is a tank. A very, very tall tank. And it's funny 00:06:29.980 --> 00:06:31.720 you say that because in the place they found 00:06:31.720 --> 00:06:34.889 it... The Morrison Formation out west Brachiosaurus 00:06:34.889 --> 00:06:37.769 is actually incredibly rare. That's a huge point. 00:06:37.850 --> 00:06:39.629 If you were walking around in the Jurassic, you'd 00:06:39.629 --> 00:06:41.850 be tripping over a Camarasaurus or Diplodocus. 00:06:41.949 --> 00:06:44.589 They're everywhere in the fossil record. Spotting 00:06:44.589 --> 00:06:46.310 a Brachiosaurus would have been a really special 00:06:46.310 --> 00:06:49.810 event. So we have this rare, massive, deep -chested, 00:06:49.810 --> 00:06:53.389 slightly sprawling American giant. Let's talk 00:06:53.389 --> 00:06:56.220 numbers. How big are we really talking? The estimates 00:06:56.220 --> 00:06:58.720 do vary a bit, and that's mainly because the 00:06:58.720 --> 00:07:00.740 original specimen Riggs found probably wasn't 00:07:00.740 --> 00:07:02.439 even fully grown. It was a sub -adult. It was 00:07:02.439 --> 00:07:05.319 still growing. Yeah. But based on what we have, 00:07:05.399 --> 00:07:08.560 we're looking at an animal about 18 to 22 meters 00:07:08.560 --> 00:07:11.259 long, so up to 72 feet. And the weight? That's 00:07:11.259 --> 00:07:13.560 all over the place. The low end is around 28 00:07:13.560 --> 00:07:17.079 tons. The high end is close to 47 tons. So let's 00:07:17.079 --> 00:07:20.180 say a safe bet is somewhere in the 40 to 50 ton 00:07:20.180 --> 00:07:23.480 range. Okay, that's just mind -boggling. Yeah. 00:07:23.560 --> 00:07:26.009 And that's what gets me. You can't just scale 00:07:26.009 --> 00:07:28.370 up a lizard to that size and expect it to work. 00:07:28.949 --> 00:07:32.170 Gravity becomes this huge enemy. The square cube 00:07:32.170 --> 00:07:35.250 law. Right. Your volume and your weight increase 00:07:35.250 --> 00:07:38.490 way faster than your bone strength. So how did 00:07:38.490 --> 00:07:41.589 it not just collapse into a pile of goo? The 00:07:41.589 --> 00:07:45.120 answer is air. Lots and lots of air. And we're 00:07:45.120 --> 00:07:47.379 not just talking about big lungs here. No, not 00:07:47.379 --> 00:07:49.139 at all. We're talking about a respiratory system 00:07:49.139 --> 00:07:51.600 that was incredibly similar to modern birds. 00:07:51.819 --> 00:07:54.800 They had this whole system of air sacs in the 00:07:54.800 --> 00:07:56.980 abdomen, in the chest, even running up the neck. 00:07:57.199 --> 00:07:59.319 And these didn't just help it breathe. They actually 00:07:59.319 --> 00:08:01.779 invaded the bones. What do you mean invaded the 00:08:01.779 --> 00:08:04.839 bones? The vertebrae, the ribs. They were hollowed 00:08:04.839 --> 00:08:07.040 out by these air sacs. The technical term is 00:08:07.040 --> 00:08:08.980 pneumaticity. It's like building with carbon 00:08:08.980 --> 00:08:11.939 fiber instead of solid steel. It drastically 00:08:11.939 --> 00:08:13.800 cut down the weight of the skeleton without losing 00:08:13.800 --> 00:08:16.439 strength. So if its bones were solid like ours, 00:08:16.579 --> 00:08:18.680 it would have been too heavy to even move. It 00:08:18.680 --> 00:08:20.439 might have been too heavy to lift its own neck. 00:08:20.680 --> 00:08:23.699 Seriously. But this system did more than just 00:08:23.699 --> 00:08:26.259 lighten the load. It also gave it a supercharged 00:08:26.259 --> 00:08:29.680 engine. Hell so. Well, mammals like us, we breathe 00:08:29.680 --> 00:08:32.539 in, we breathe out. It's called bidirectional 00:08:32.539 --> 00:08:34.980 flow. You're always mixing fresh air with stale 00:08:34.980 --> 00:08:38.980 air. But sauropods, like birds, had unidirectional 00:08:38.980 --> 00:08:41.179 airflow. So the air only moves in one direction 00:08:41.179 --> 00:08:43.379 through the lungs. Exactly. It's a continuous 00:08:43.379 --> 00:08:46.620 loop. The air sacs act like bellows, constantly 00:08:46.620 --> 00:08:49.139 pumping fresh air across the lung tissue, whether 00:08:49.139 --> 00:08:52.299 the animal is inhaling or exhaling. It's incredibly 00:08:52.299 --> 00:08:54.899 efficient at extracting oxygen, which you absolutely 00:08:54.899 --> 00:08:57.539 need to fuel a body that big. To fuel a body 00:08:57.539 --> 00:09:00.059 that big, you need a high metabolism. For a long 00:09:00.059 --> 00:09:02.320 time, the thinking was that dinosaurs were cold 00:09:02.320 --> 00:09:05.059 -blooded, slow -moving lizards. Yeah, that idea 00:09:05.059 --> 00:09:08.220 is long gone. The consensus now is that Brachiosaurus 00:09:08.220 --> 00:09:11.220 was homeothermic. It kept a stable internal temperature, 00:09:11.440 --> 00:09:14.120 and endothermic, or warm -blooded, it had to 00:09:14.120 --> 00:09:16.379 be to grow that fast and move that actively. 00:09:16.700 --> 00:09:19.200 But wouldn't it have the opposite problem? A 00:09:19.200 --> 00:09:22.659 40 -ton... warm -blooded animal must have generated 00:09:22.659 --> 00:09:25.519 a crazy amount of internal heat. It would have 00:09:25.519 --> 00:09:28.320 been like a biological furnace. And that's where 00:09:28.320 --> 00:09:31.120 those air sacs come in again. They likely worked 00:09:31.120 --> 00:09:33.340 as a cooling system, helping to radiate excess 00:09:33.340 --> 00:09:36.320 heat away from the body's core. And some theories 00:09:36.320 --> 00:09:38.740 suggest that big crest on its head also helped 00:09:38.740 --> 00:09:41.159 cool blood going to the brain. Okay, let's go 00:09:41.159 --> 00:09:44.039 there. The neck. You can't talk about brachiosaurus 00:09:44.039 --> 00:09:46.740 without talking about that neck. In all the movies, 00:09:46.840 --> 00:09:49.100 it's held high, almost vertical, like a swan. 00:09:50.059 --> 00:09:51.779 But I remember a while back, scientists were 00:09:51.779 --> 00:09:54.080 saying, no, they held their necks straight out, 00:09:54.139 --> 00:09:57.240 horizontally. Ah, yes, the great neck posture 00:09:57.240 --> 00:10:00.259 debate. That was a 1999 study that argued the 00:10:00.259 --> 00:10:02.320 vertebrae weren't flexible enough to curve upwards 00:10:02.320 --> 00:10:04.299 like that. They said it would have broken its 00:10:04.299 --> 00:10:06.840 own back. It caused a huge stir, ruined a lot 00:10:06.840 --> 00:10:10.320 of museum displays. I bet. Excuse me, sir, could 00:10:10.320 --> 00:10:12.320 you please lower your multi -million dollar dinosaur 00:10:12.320 --> 00:10:15.179 display? So where are we now? Is it up or is 00:10:15.179 --> 00:10:17.620 it down? The pendulum has swung back, thankfully. 00:10:18.240 --> 00:10:21.879 The current view is an inclined posture, maybe 00:10:21.879 --> 00:10:26.039 60 to 70 degrees. So not a perfect vertical swan 00:10:26.039 --> 00:10:28.659 neck, but definitely high. They were specialized 00:10:28.659 --> 00:10:31.840 high browsers. So they were eating leaves about 00:10:31.840 --> 00:10:34.820 30 feet up in the air. Exactly. It makes no sense 00:10:34.820 --> 00:10:36.480 to have front legs that long if you're just going 00:10:36.480 --> 00:10:38.539 to hold your head near the ground. Okay, phew. 00:10:38.960 --> 00:10:41.480 But that brings us to a massive physics problem, 00:10:41.720 --> 00:10:44.590 the heart. It's the ultimate plumbing challenge. 00:10:44.830 --> 00:10:47.669 To get blood from your chest all the way up to 00:10:47.669 --> 00:10:49.669 a brain that high, you're fighting an incredible 00:10:49.669 --> 00:10:52.210 amount of gravitational pressure. A giraffe's 00:10:52.210 --> 00:10:54.470 heart is already huge, and its blood pressure 00:10:54.470 --> 00:10:57.509 is sky high compared to ours. And this animal 00:10:57.509 --> 00:10:59.830 would need a heart that could generate maybe 00:10:59.830 --> 00:11:01.789 double the blood pressure of a giraffe's. We're 00:11:01.789 --> 00:11:02.970 talking about a heart that could have weighed 00:11:02.970 --> 00:11:06.889 400 kilograms. That's almost 900 pounds. The 00:11:06.889 --> 00:11:08.950 heart weighed as much as a piano. Just to keep 00:11:08.950 --> 00:11:11.210 its brain from passing out. It was a cardiovascular 00:11:11.210 --> 00:11:14.350 marvel every single second of its life. Okay, 00:11:14.409 --> 00:11:17.070 so let's picture this animal day to day. The 00:11:17.070 --> 00:11:18.929 old image was always the swamp thing, right? 00:11:19.029 --> 00:11:21.519 Right. The 19th century idea was they were just 00:11:21.519 --> 00:11:23.620 too heavy for a land. So they must have lived 00:11:23.620 --> 00:11:25.720 in the water to support all that weight. You 00:11:25.720 --> 00:11:27.820 see all those old paintings of them submerged 00:11:27.820 --> 00:11:30.240 in a swamp with their heads sticking out. Which 00:11:30.240 --> 00:11:32.340 is funny because Riggs, the guy who discovered 00:11:32.340 --> 00:11:34.899 it, was calling that out back in 1904. He was 00:11:34.899 --> 00:11:37.299 way ahead of his time. He pointed to the feet. 00:11:37.379 --> 00:11:39.779 They're compact, like an elephant's foot, built 00:11:39.779 --> 00:11:42.679 for solid ground, not splayed out for mud. He 00:11:42.679 --> 00:11:45.580 pointed to the deep, narrow chest and those hollow 00:11:45.580 --> 00:11:48.539 vertebrae. He knew it was a land animal from 00:11:48.539 --> 00:11:51.019 day one. It just took science 50 years to catch 00:11:51.019 --> 00:11:52.899 up with them. Pretty much. So it's walking on 00:11:52.899 --> 00:11:56.019 land through these semi -arid fern savannas. 00:11:56.240 --> 00:11:58.340 What's it eating up there? It's a highbrowser, 00:11:58.440 --> 00:12:01.759 so it's going for conifers, ginkgos, tree ferns. 00:12:01.799 --> 00:12:04.700 And its eating style was very efficient. It was 00:12:04.700 --> 00:12:07.419 all nip and swallow. No chewing. Zero chewing. 00:12:07.620 --> 00:12:10.500 Their teeth were like chisels just for stripping 00:12:10.500 --> 00:12:12.659 vegetation off a branch. They'd just swallow 00:12:12.659 --> 00:12:15.419 it all whole and let their enormous gut do all 00:12:15.419 --> 00:12:17.320 the hard work of fermentation. It's basically 00:12:17.320 --> 00:12:19.600 a walking fermentator. One that needed something 00:12:19.600 --> 00:12:24.179 like 200 to 400 kilograms of plants every single 00:12:24.179 --> 00:12:27.299 day. That is a lot of ferns. Now, the Jurassic 00:12:27.299 --> 00:12:30.419 Park question. Could it rear up on its hind legs 00:12:30.419 --> 00:12:33.639 like in the movie? Ah. Another great myth to 00:12:33.639 --> 00:12:36.980 bust. While some sauropods, like Diplodocus, 00:12:37.259 --> 00:12:39.580 might have been able to rear up, Brachiosaurus 00:12:39.580 --> 00:12:43.200 was uniquely bad at it. Why? Remember that body 00:12:43.200 --> 00:12:46.419 shape? Long front legs, deep chest. Its center 00:12:46.419 --> 00:12:49.679 of mass was way too far forward. If it tried 00:12:49.679 --> 00:12:51.480 to rear up, it would have been incredibly unstable 00:12:51.480 --> 00:12:53.240 and would have probably just tipped over. Plus, 00:12:53.500 --> 00:12:55.740 it was already 30 feet tall. It didn't need to. 00:12:55.799 --> 00:12:57.720 It evolved the height so it wouldn't have to 00:12:57.720 --> 00:13:00.519 do the gymnastics. Good point. Okay, let's talk 00:13:00.519 --> 00:13:03.000 about its face. The skull of Brachiosaurus is 00:13:03.000 --> 00:13:05.860 really distinctive. It has that huge crest right 00:13:05.860 --> 00:13:08.620 on top of its head. A nasal bar, yeah. It creates 00:13:08.620 --> 00:13:11.539 this big bony arch high up on the skull. And 00:13:11.539 --> 00:13:14.980 for years people said, aha, that's a snorkel. 00:13:15.120 --> 00:13:17.679 Which ties right back into the swamp myth. The 00:13:17.679 --> 00:13:20.139 idea was its nostrils were on top of its head 00:13:20.139 --> 00:13:22.620 so it could hide underwater. But we know now 00:13:22.620 --> 00:13:24.360 that water pressure would have made it impossible 00:13:24.360 --> 00:13:27.039 to inflate its lungs at that depth. But the hole 00:13:27.039 --> 00:13:29.139 in the skull is on top. The bony opening is on 00:13:29.139 --> 00:13:33.039 top, yes. But in 2001, a researcher named Lawrence 00:13:33.039 --> 00:13:36.179 Whitmer did a great study. He looked at modern 00:13:36.179 --> 00:13:39.120 animals and found that the fleshy nostril, the 00:13:39.120 --> 00:13:41.960 part you actually breathe through, is almost 00:13:41.960 --> 00:13:44.860 always at the front of that bony opening. So 00:13:44.860 --> 00:13:47.179 even though the hole in the skull is high up, 00:13:47.360 --> 00:13:50.379 the fleshy nostril tubes probably ran down its 00:13:50.379 --> 00:13:52.460 face. Exactly. The nostrils you could actually 00:13:52.460 --> 00:13:55.059 see were probably low on the snout near the mouth. 00:13:55.279 --> 00:13:56.980 So what was the point of the big crest then? 00:13:57.679 --> 00:14:00.100 if it's not a snorkel mount? That's the million 00:14:00.100 --> 00:14:02.279 -dollar question. Maybe a heightened sense of 00:14:02.279 --> 00:14:04.720 smell. Maybe it was a resonating chamber to make 00:14:04.720 --> 00:14:07.399 deep, booming calls that could travel for miles. 00:14:07.679 --> 00:14:09.360 Or, like you said, a radiator for the brain. 00:14:09.480 --> 00:14:11.320 Or a radiator for the brain. It was probably 00:14:11.320 --> 00:14:13.620 a combination of all those things. I love the 00:14:13.620 --> 00:14:15.879 idea of them just rumbling to each other across 00:14:15.879 --> 00:14:18.440 the plains. Now, before we finish, we have to 00:14:18.440 --> 00:14:21.120 talk about the babies. Finding a baby sauropod 00:14:21.120 --> 00:14:23.600 has to be incredibly rare. It's like finding 00:14:23.600 --> 00:14:27.309 a needle in a continent -sized haystack. But 00:14:27.309 --> 00:14:30.070 they did describe one, a juvenile specimen nicknamed 00:14:30.070 --> 00:14:32.669 Tony. It was only about two meters long. So the 00:14:32.669 --> 00:14:36.269 size of a pony. A pony, yeah. But a pony that 00:14:36.269 --> 00:14:38.210 was shaped very differently from its parents. 00:14:38.549 --> 00:14:41.389 This shows us they had allometric growth. They 00:14:41.389 --> 00:14:43.730 changed shape as they got bigger. Like how a 00:14:43.730 --> 00:14:46.990 human baby has a giant head. Exactly. Tony had 00:14:46.990 --> 00:14:49.149 a much shorter neck compared to its body than 00:14:49.149 --> 00:14:51.809 an adult did. Its arm bones were more robust. 00:14:52.440 --> 00:14:54.639 And the bones hadn't become fully hollowed out 00:14:54.639 --> 00:14:57.179 yet. That pneumaticity increased as they grew. 00:14:57.379 --> 00:14:59.620 So they literally shapeshifted from this pony 00:14:59.620 --> 00:15:02.960 -sized short -necked thing into a 40 -ton long 00:15:02.960 --> 00:15:05.620 -necked hollow -boned giant. And they did it 00:15:05.620 --> 00:15:08.159 incredibly fast. They probably hit sexual maturity 00:15:08.159 --> 00:15:10.620 when they were only at about 40 % of their maximum 00:15:10.620 --> 00:15:12.879 size. They were just built to grow at an explosive 00:15:12.879 --> 00:15:14.879 rate. Okay, let's bring this all together. We 00:15:14.879 --> 00:15:17.139 started with the movie Monster. We've ended up 00:15:17.139 --> 00:15:19.639 with something that is, well, it's quite different. 00:15:20.090 --> 00:15:23.090 It is. The real Brachiosaurus Altothorax was 00:15:23.090 --> 00:15:26.289 a rare North American specialist. Not the slender, 00:15:26.289 --> 00:15:28.850 vertical -necked animal from Africa. It was beefier, 00:15:28.929 --> 00:15:31.549 deeper in the chest, with those slightly sprawled 00:15:31.549 --> 00:15:34.549 front limbs. A warm -blooded, air -sack -filled, 00:15:34.769 --> 00:15:38.070 land -walking biological machine that pumped 00:15:38.070 --> 00:15:40.909 blood three stories into the air and ate half 00:15:40.909 --> 00:15:43.730 a ton of food a day without chewing. And it really 00:15:43.730 --> 00:15:45.750 shows us that getting the names right matters. 00:15:46.029 --> 00:15:48.970 By separating it from Girafatetan, we get to 00:15:48.970 --> 00:15:50.419 appreciate... I appreciate Brachiosaurus for 00:15:50.419 --> 00:15:52.799 what it uniquely was. It really makes you wonder 00:15:52.799 --> 00:15:56.320 if maybe the most famous dinosaur in cinema is 00:15:56.320 --> 00:16:00.200 actually a case of mistaken identity, an imposter. 00:16:00.480 --> 00:16:03.019 How many other prehistoric animals that we have 00:16:03.019 --> 00:16:06.070 in our heads are just... That is the problem 00:16:06.070 --> 00:16:08.970 with iconic images. They tend to stick even long 00:16:08.970 --> 00:16:11.250 after the science has moved on. Well, next time 00:16:11.250 --> 00:16:13.389 you're watching that 1993 classic, you could 00:16:13.389 --> 00:16:15.570 be that person on the couch who pushes up their 00:16:15.570 --> 00:16:18.029 glasses and says, actually, that's a Giraffatidon. 00:16:18.029 --> 00:16:19.490 Just don't blame us if you don't get invited 00:16:19.490 --> 00:16:21.490 back for movie night. Worth it for the accuracy. 00:16:21.789 --> 00:16:23.769 Thanks for taking this deep dive with us. Keep 00:16:23.769 --> 00:16:26.350 questioning the icons. And keep looking for the 00:16:26.350 --> 00:16:28.169 real story that's in the bones. See you next 00:16:28.169 --> 00:16:28.389 time.