WEBVTT 00:00:00.000 --> 00:00:01.540 I want you to try a little experiment with me. 00:00:01.580 --> 00:00:04.240 Close your eyes for a second. Okay. Now, picture 00:00:04.240 --> 00:00:07.660 a dinosaur. Just let the very first image that 00:00:07.660 --> 00:00:09.880 pops into your brain float to the surface. Right. 00:00:10.380 --> 00:00:14.080 I am willing to bet good money that you aren't 00:00:14.080 --> 00:00:17.660 seeing a T -Rex snapping its jaws. No. And you 00:00:17.660 --> 00:00:21.000 aren't seeing a Triceratops. You are seeing a 00:00:21.000 --> 00:00:25.480 silhouette, a long horizontal neck, a heavy rounded 00:00:25.480 --> 00:00:28.559 body. and a tail that just stretches out forever. 00:00:28.760 --> 00:00:30.839 It's the default setting for the word dinosaur. 00:00:31.039 --> 00:00:33.600 It's the logo on the gas station sign. It's the 00:00:33.600 --> 00:00:36.320 cartoon on the cereal box. Exactly. It's the 00:00:36.320 --> 00:00:39.100 plastic toy in the sandbox. You are picturing 00:00:39.100 --> 00:00:42.240 the Diplodocus. It is the sheer ubiquity of this 00:00:42.240 --> 00:00:44.320 animal that makes us think we know it. It's the 00:00:44.320 --> 00:00:46.780 celebrity of the Jurassic. But here's the thing 00:00:46.780 --> 00:00:48.640 about celebrities. The public image isn't the 00:00:48.640 --> 00:00:50.899 whole story. It's usually a lot simpler and honestly 00:00:50.899 --> 00:00:53.119 a lot more boring than the reality. That is the 00:00:53.119 --> 00:00:55.200 perfect way to frame this because the actual 00:00:55.200 --> 00:00:58.219 animal, the living, breathing, biological machine 00:00:58.219 --> 00:01:00.560 that was walking around 150 million years ago 00:01:00.560 --> 00:01:04.540 is infinitely stranger than the museum mount 00:01:04.540 --> 00:01:07.049 we're all used to. We are talking about a creature 00:01:07.049 --> 00:01:09.829 that has been completely reinvented by science, 00:01:10.010 --> 00:01:13.049 specifically by studies that have come out as 00:01:13.049 --> 00:01:16.269 recently as 2024 and 2025. Yeah. We're talking 00:01:16.269 --> 00:01:20.390 sonic booms, iguana spines, sensory tails, and 00:01:20.390 --> 00:01:22.930 a scientific rivalry that was basically a soap 00:01:22.930 --> 00:01:25.849 opera with shovels. And we can't forget the diplomacy. 00:01:26.109 --> 00:01:28.390 This isn't just a biological success story. It's 00:01:28.390 --> 00:01:30.709 a cultural one. The reason you have that specific 00:01:30.709 --> 00:01:32.489 silhouette in your head is because of a very 00:01:32.489 --> 00:01:35.200 specific collision of Gilded Age wealth, international 00:01:35.200 --> 00:01:39.980 politics, and industrial manufacturing. So that 00:01:39.980 --> 00:01:42.000 is our mission for this deep dive. We're going 00:01:42.000 --> 00:01:45.019 to take that dusty gray plastic toy in your head 00:01:45.019 --> 00:01:48.519 and replace it with a high -definition technicolor 00:01:48.519 --> 00:01:51.540 reality. We have a massive stack of notes here 00:01:51.540 --> 00:01:54.900 from the 1870s right up to last year. Let's unpack 00:01:54.900 --> 00:01:56.959 the Diplodocus. Let's do it. And I think we have 00:01:56.959 --> 00:01:59.159 to start with the name itself. It sounds heavy. 00:01:59.679 --> 00:02:02.060 Diplodocus. It does sound heavy. It's a neo -Latin 00:02:02.060 --> 00:02:04.579 term derived from Greek. Diplos means double 00:02:04.579 --> 00:02:07.519 and dokos means beam. So literally the double 00:02:07.519 --> 00:02:09.439 beam. The double beam. It sounds like a gymnastics 00:02:09.439 --> 00:02:12.039 move or maybe a specific type of steel girder. 00:02:12.270 --> 00:02:14.090 Well, the steel girder comparison is actually 00:02:14.090 --> 00:02:17.330 pretty apt. When Othniel Charles Marsh named 00:02:17.330 --> 00:02:20.969 this animal in 1878, he was looking at the chevron 00:02:20.969 --> 00:02:23.969 bones. These are the small bones on the underside 00:02:23.969 --> 00:02:26.129 of the tail vertebrae that protect the blood 00:02:26.129 --> 00:02:28.229 vessels and nerves. Usually those look like a 00:02:28.229 --> 00:02:31.930 V, right? Hence the word chevron. Exactly. But 00:02:31.930 --> 00:02:34.710 in this new dinosaur, Marsh noticed something 00:02:34.710 --> 00:02:38.550 weird. The chevrons had these double protrusions, 00:02:38.550 --> 00:02:43.030 beams, sticking out both anteriorly and posteriorly. 00:02:43.069 --> 00:02:45.169 So forward and backward. Forward and backward. 00:02:45.250 --> 00:02:47.930 It looked like a double beam. And at the time, 00:02:47.949 --> 00:02:50.110 he thought this was the trademark feature. Like 00:02:50.110 --> 00:02:52.289 if you find the double beam, you found a dipologus. 00:02:52.409 --> 00:02:55.340 Right. He thought it was unique. As it turns 00:02:55.340 --> 00:02:57.560 out, paleontologists have since found similar 00:02:57.560 --> 00:03:00.120 structures in other sauropods, like Mementosaurus. 00:03:00.699 --> 00:03:03.460 So it wasn't as unique as he thought, but the 00:03:03.460 --> 00:03:06.159 name stuck. And functionally, it makes a lot 00:03:06.159 --> 00:03:08.580 of sense. When you have a tail that is 40 or 00:03:08.580 --> 00:03:11.580 50 feet long and incredibly heavy, you need structural 00:03:11.580 --> 00:03:14.759 support. Those beams likely acted as skids or 00:03:14.759 --> 00:03:17.759 guards to protect the delicate plumbing of the 00:03:17.759 --> 00:03:20.419 tail when the animal receded on the ground. So 00:03:20.419 --> 00:03:23.889 the name is all about the tail. But the reason 00:03:23.889 --> 00:03:25.930 this dinosaur is famous isn't because of its 00:03:25.930 --> 00:03:28.370 tail bones. It's because of a man named Andrew 00:03:28.370 --> 00:03:32.610 Carnegie. Oh, yeah. And I love this part of the 00:03:32.610 --> 00:03:35.169 story because it feels so modern. Yeah. It's 00:03:35.169 --> 00:03:37.409 basically branding. It is absolute branding. 00:03:37.530 --> 00:03:40.800 This is the Diplodocus diplomacy era. Andrew 00:03:40.800 --> 00:03:43.800 Carnegie, the steel tycoon, was one of the richest 00:03:43.800 --> 00:03:46.280 men in history. He was building his institute 00:03:46.280 --> 00:03:49.099 in Pittsburgh, and he wanted a centerpiece. He 00:03:49.099 --> 00:03:51.599 didn't just want a bone. No, he wanted a giant 00:03:51.599 --> 00:03:54.199 dinosaur. Go find me a monster, basically. Essentially, 00:03:54.340 --> 00:03:58.419 yes. In 1899, his team excavated a near -complete 00:03:58.419 --> 00:04:01.659 skeleton in Sheep Creek, Wyoming. And naturally, 00:04:01.819 --> 00:04:04.180 because he was writing the checks, they named 00:04:04.180 --> 00:04:07.379 the species Diplodocus carnegia. Which is a smart 00:04:07.379 --> 00:04:09.439 move if you want to keep your funding. Very smart. 00:04:09.560 --> 00:04:12.060 But Carnegie was a visionary in terms of influence. 00:04:12.199 --> 00:04:14.539 He realized that this skeleton was a sensation. 00:04:14.780 --> 00:04:16.860 So he didn't just put it in a hall in Pittsburgh. 00:04:17.120 --> 00:04:20.060 He commissioned a team to create plaster casts 00:04:20.060 --> 00:04:23.199 of the entire skeleton. And you have to pause 00:04:23.199 --> 00:04:25.839 and appreciate the scale of that. This is an 00:04:25.839 --> 00:04:29.040 animal nearly 85 feet long. Making a mold of 00:04:29.040 --> 00:04:32.100 that, casting it, and shipping it in 1905 was... 00:04:32.100 --> 00:04:34.279 A logistical nightmare. And he didn't just sell 00:04:34.279 --> 00:04:36.100 them. He gave them away, right? He gifted them 00:04:36.100 --> 00:04:39.160 to heads of state. King Edward VII of the UK 00:04:39.160 --> 00:04:41.399 asked for the first one for the Natural History 00:04:41.399 --> 00:04:44.680 Museum in London. Wow. Then he sent them to Kaiser 00:04:44.680 --> 00:04:47.879 Wilhelm II in Berlin, the president of France, 00:04:48.060 --> 00:04:50.660 the president of Mexico, the emperor of Austria. 00:04:50.959 --> 00:04:52.839 It's like the early 20th century equivalent of 00:04:52.839 --> 00:04:55.230 a friendship bracelet. But it weighs tons and 00:04:55.230 --> 00:04:57.629 takes up a ballroom. Exactly. But the result 00:04:57.629 --> 00:05:00.329 was that for millions of people across Europe 00:05:00.329 --> 00:05:03.230 and Latin America, Dippy, as the London cast 00:05:03.230 --> 00:05:06.110 was affectionately called, was the first dinosaur 00:05:06.110 --> 00:05:08.870 they ever saw. Right. Before T -Rex became famous, 00:05:08.930 --> 00:05:10.850 Diplodocus was the dinosaur because it was the 00:05:10.850 --> 00:05:13.089 one standing in the capital cities. I read a 00:05:13.089 --> 00:05:15.290 detail in the notes that really drove home just 00:05:15.290 --> 00:05:17.750 how famous this thing became. It involves World 00:05:17.750 --> 00:05:21.129 War I. Oh, the tank. Yes. In 1915, the French 00:05:21.129 --> 00:05:23.870 army was testing a new machine for crossing trenches. 00:05:24.149 --> 00:05:27.899 It was a prototype tank. Big, boxy, clumsy. And 00:05:27.899 --> 00:05:31.040 the soldiers nicknamed it what? Diplodocus Militares. 00:05:31.399 --> 00:05:34.339 That is wild. You know you've made it as a cultural 00:05:34.339 --> 00:05:37.339 icon when soldiers in the trenches are using 00:05:37.339 --> 00:05:40.399 your name as slang for giant lumbering beast. 00:05:40.680 --> 00:05:43.319 It shows that by 1915, the word diplodocus was 00:05:43.319 --> 00:05:46.519 already shorthand for leviathan. Speaking of 00:05:46.519 --> 00:05:48.480 leviathans, let's get into the actual anatomy. 00:05:48.819 --> 00:05:52.160 Because giant is a relative term. The classic 00:05:52.160 --> 00:05:55.790 dippy, the Carnegie specimen, is... Big. It's 00:05:55.790 --> 00:05:58.149 big. But it's not the biggest, is it? No. And 00:05:58.149 --> 00:06:00.509 this brings us to a really interesting scientific 00:06:00.509 --> 00:06:03.509 detective story involving a dinosaur formerly 00:06:03.509 --> 00:06:06.029 known as Seismosaurus. The Earthshaker. That 00:06:06.029 --> 00:06:08.370 is arguably the coolest name in paleontology. 00:06:08.470 --> 00:06:11.490 It's up there. In 1991, a partial skeleton was 00:06:11.490 --> 00:06:13.470 described in New Mexico. The researchers took 00:06:13.470 --> 00:06:15.470 a look at the vertebrae and did the math. They 00:06:15.470 --> 00:06:18.790 estimated this animal was 52 meters long. 52 00:06:18.790 --> 00:06:23.269 meters. That is over 170 feet. Which is, frankly, 00:06:23.529 --> 00:06:26.220 hard. to imagine it's half a football field it 00:06:26.220 --> 00:06:28.180 would have been the longest animal to ever walk 00:06:28.180 --> 00:06:30.660 the earth by a massive margin it became legendary 00:06:30.660 --> 00:06:33.860 overnight but uh science is a self -correcting 00:06:33.860 --> 00:06:36.740 process years later other paleontologists took 00:06:36.740 --> 00:06:39.519 a closer look at the spine yeah it turns out 00:06:39.949 --> 00:06:42.170 There was a mistake in the assembly. They put 00:06:42.170 --> 00:06:44.670 the puzzle together wrong. In a way. They had 00:06:44.670 --> 00:06:47.970 confused the 12th through 19th vertebrae for 00:06:47.970 --> 00:06:50.889 the 20th through 27th. They had basically slid 00:06:50.889 --> 00:06:53.149 the tail further back in the sequence. Ah, so 00:06:53.149 --> 00:06:55.410 they artificially stretched the animal out? Exactly. 00:06:55.410 --> 00:06:57.709 When you correct that alignment, the earth shaker 00:06:57.709 --> 00:07:01.529 shrinks. It's now classified as diplodocus hilarum. 00:07:01.610 --> 00:07:04.009 Okay. It is still the biggest of the diplodocids, 00:07:04.170 --> 00:07:07.410 coming in around 29 to 33 meters, so over 100 00:07:07.410 --> 00:07:10.689 feet. But it's not the mythical 50 -meter monster 00:07:10.689 --> 00:07:13.629 we once thought. Still, 33 meters. That is over 00:07:13.629 --> 00:07:15.750 100 feet of animal. And looking at the proportions, 00:07:16.029 --> 00:07:19.029 most of that length is just tail. It's an obsession 00:07:19.029 --> 00:07:21.870 with length. The tail makes up about 55 % of 00:07:21.870 --> 00:07:24.610 the total body. We are talking about 80 vertebrae 00:07:24.610 --> 00:07:28.329 in the tail alone. For comparison, earlier sauropods 00:07:28.329 --> 00:07:31.389 like Shunosaurus only had about 43. So Diplodocus 00:07:31.389 --> 00:07:33.750 took the tail strategy and doubled down on it. 00:07:33.910 --> 00:07:36.370 It really did. So the million -dollar question, 00:07:36.610 --> 00:07:40.750 why? Nature doesn't usually build 50 -foot tails 00:07:40.750 --> 00:07:42.970 for no reason. I've always heard the supersonic 00:07:42.970 --> 00:07:45.490 theory. The whip crack hypothesis. It's the most 00:07:45.490 --> 00:07:47.829 metal theory we have. The physics actually support 00:07:47.829 --> 00:07:50.629 it. The tail tapers down to a series of very 00:07:50.629 --> 00:07:53.569 small light bones at the tip, the whiplash. Right. 00:07:53.610 --> 00:07:55.649 Computer models suggest that if they flicked 00:07:55.649 --> 00:07:57.990 it correctly, the tip could travel faster than 00:07:57.990 --> 00:08:00.089 the speed of sound. Creating a literal sonic 00:08:00.089 --> 00:08:04.019 boom. Yes. a crack like a bullwhip but loud enough 00:08:04.019 --> 00:08:06.579 to deafen a predator or signal a mate across 00:08:06.579 --> 00:08:09.620 miles it's a compelling image but there's a new 00:08:09.620 --> 00:08:12.769 contender in the theory ring A study from 2021 00:08:12.769 --> 00:08:16.029 proposes something much quieter. But maybe more 00:08:16.029 --> 00:08:18.250 sophisticated. This is the sensor theory, right? 00:08:18.310 --> 00:08:20.709 The tactile sensory organ theory. Think about 00:08:20.709 --> 00:08:23.509 the logistics of being 100 feet long. Your head 00:08:23.509 --> 00:08:26.350 is way up front. You have zero visibility of 00:08:26.350 --> 00:08:28.449 your back half. Sure. You're maneuvering through 00:08:28.449 --> 00:08:31.410 forests around other herd members. The theory 00:08:31.410 --> 00:08:33.850 is that the tail acted like a curb feeler on 00:08:33.850 --> 00:08:36.409 a car or like a cat's whiskers. So they were 00:08:36.409 --> 00:08:38.950 using it to feel their way backward. Exactly. 00:08:39.190 --> 00:08:41.970 It allows them to maintain spatial awareness, 00:08:42.149 --> 00:08:45.289 knowing where the trees are, where the rest of 00:08:45.289 --> 00:08:47.570 the herd is, without having to constantly swing 00:08:47.570 --> 00:08:49.830 that long neck around to check. That makes so 00:08:49.830 --> 00:08:51.409 much sense. It's like having a backup camera, 00:08:51.470 --> 00:08:53.809 but it's a tail. Right. Now let's go to the other 00:08:53.809 --> 00:08:56.450 end, the neck. This seems to be the fight that 00:08:56.450 --> 00:08:59.509 never ends in paleontology, up or down. Are they 00:08:59.509 --> 00:09:02.240 giraffes or are they bridges? The giraffe imagery 00:09:02.240 --> 00:09:04.899 is very sticky because of, well, Jurassic Park. 00:09:05.039 --> 00:09:07.179 We all want to see the brachiosaur or Diplodocus 00:09:07.179 --> 00:09:09.919 reaching the top of the canopy. But for Diplodocus, 00:09:10.220 --> 00:09:13.440 modern biomechanics pushes hard against it. And 00:09:13.440 --> 00:09:15.039 it comes down to what? It really comes down to 00:09:15.039 --> 00:09:17.990 plumbing. Plumbing. Blood pressure. If Diplodocus 00:09:17.990 --> 00:09:20.830 held its head vertically, high above its heart, 00:09:20.970 --> 00:09:23.429 the pressure required to pump blood to the brain 00:09:23.429 --> 00:09:25.990 would be... Astronomical. Completely. One study 00:09:25.990 --> 00:09:27.789 estimated they would need a heart weighing 1 00:09:27.789 --> 00:09:31.190 .6 tons just to fight gravity. A 1 .6 ton heart. 00:09:31.330 --> 00:09:33.710 That's a Honda Civic beating inside your chest. 00:09:34.049 --> 00:09:37.179 It's physiologically improbable. The skeletal 00:09:37.179 --> 00:09:39.720 structure, the way the neck vertebrae articulate, 00:09:40.120 --> 00:09:43.620 suggests a neutral, horizontal posture. Think 00:09:43.620 --> 00:09:46.580 of a cantilever bridge. The massive tail sticks 00:09:46.580 --> 00:09:49.700 out back, the long neck sticks out front, and 00:09:49.700 --> 00:09:51.919 they balance over the hips. They weren't tree 00:09:51.919 --> 00:09:54.659 toppers. They were mowing machines. They swept 00:09:54.659 --> 00:09:57.500 that neck side to side, clearing out ferns and 00:09:57.500 --> 00:09:59.360 mid -level plants. Okay, I want to pivot back 00:09:59.360 --> 00:10:01.610 to the history for a second. We talked about 00:10:01.610 --> 00:10:03.909 Carnegie and the branding, but Diplodocus was 00:10:03.909 --> 00:10:06.309 actually discovered a bit earlier, right in the 00:10:06.309 --> 00:10:09.309 middle of the Bone Wars. And I feel like we can't 00:10:09.309 --> 00:10:11.649 do a dinosaur episode without mentioning how 00:10:11.649 --> 00:10:15.809 messy that era was. It was absolute chaos. The 00:10:15.809 --> 00:10:18.870 Bone Wars were the rivalry between Othniel Charles 00:10:18.870 --> 00:10:22.049 Marsh and Edward Drinker Cope in the late 19th 00:10:22.049 --> 00:10:24.539 century. These two... hated each other. I mean, 00:10:24.559 --> 00:10:26.419 really hated each other. They were sabotaging 00:10:26.419 --> 00:10:28.639 each other's digs, rushing descriptions to print, 00:10:28.700 --> 00:10:30.480 just trying to name more species than the other 00:10:30.480 --> 00:10:32.399 guy. And Diplodocus was caught in the crossfire. 00:10:32.600 --> 00:10:35.240 It was. Marsh named the original type species, 00:10:35.620 --> 00:10:39.659 Diplodocus longus, in 1878. But he based it on 00:10:39.659 --> 00:10:42.309 just two -tail vertebrae. Wait. Two bones, that's 00:10:42.309 --> 00:10:44.909 it. That's the entire basis for the species name. 00:10:45.110 --> 00:10:47.730 And that is a huge problem for modern scientists, 00:10:48.029 --> 00:10:50.629 because two -tailed vertebrae aren't really distinct 00:10:50.629 --> 00:10:53.169 enough to prove that a species is unique compared 00:10:53.169 --> 00:10:56.309 to other similar sauropods. So, strictly speaking, 00:10:56.610 --> 00:10:59.590 the original type species, Diplodocus longus, 00:10:59.730 --> 00:11:04.529 is now considered a, uh... Nomen dubium. Which 00:11:04.529 --> 00:11:07.909 means doubtful name. Correct. It means the foundation 00:11:07.909 --> 00:11:10.940 of the name is shaky. There was actually a petition 00:11:10.940 --> 00:11:13.120 fairly recently to the International Commission 00:11:13.120 --> 00:11:16.320 on Zoological Nomenclature. Oh, really? Paleontologists 00:11:16.320 --> 00:11:19.179 wanted to make Dippy Diplodocus Carnagee, the 00:11:19.179 --> 00:11:21.419 one with the beautiful complete skeleton, the 00:11:21.419 --> 00:11:23.440 new official reference point, just to clean up 00:11:23.440 --> 00:11:25.700 the taxonomy. Let me guess. The rules are the 00:11:25.700 --> 00:11:28.220 rules. Bureaucracy is undefeated. The petition 00:11:28.220 --> 00:11:30.799 was rejected. Of course. So we are in this weird 00:11:30.799 --> 00:11:33.000 position where the official original Diplodocus 00:11:33.000 --> 00:11:36.139 is a couple of nondescript bones that nobody 00:11:36.139 --> 00:11:38.340 really uses, but everyone just ignores that and 00:11:38.340 --> 00:11:40.399 uses the Carnegie skeleton as the real reference. 00:11:40.659 --> 00:11:42.659 Well, let's look at what that reference skeleton 00:11:42.659 --> 00:11:45.279 and the newer finds. Tell us about what they 00:11:45.279 --> 00:11:47.379 actually look like, because this is where the 00:11:47.379 --> 00:11:49.960 mental image update really happens. I grew up 00:11:49.960 --> 00:11:53.149 with the gray elephant skin giant. But the source 00:11:53.149 --> 00:11:55.490 material says that's wrong. It is very outdated. 00:11:55.710 --> 00:11:59.350 The image update started back in 1990. Paleontologists 00:11:59.350 --> 00:12:01.389 found skin impressions that showed Diplodocus, 00:12:01.690 --> 00:12:04.110 or at least its close relatives, didn't just 00:12:04.110 --> 00:12:06.779 have flat skin. So what did they have? They had 00:12:06.779 --> 00:12:10.580 a row of narrow, pointed keratinous spines running 00:12:10.580 --> 00:12:13.820 down the back, neck, and tail. Spines? Like an 00:12:13.820 --> 00:12:15.860 iguana? Very much like an iguana. Some of these 00:12:15.860 --> 00:12:18.679 spines were up to 18 centimeters long. That's 00:12:18.679 --> 00:12:22.019 over 7 inches. Yes. So break up that smooth silhouette 00:12:22.019 --> 00:12:25.509 in your mind. This animal was spiky. It had a 00:12:25.509 --> 00:12:27.929 punk rock ridge running down its spine. And the 00:12:27.929 --> 00:12:30.110 skin itself wasn't just wrinkly gray leather. 00:12:30.269 --> 00:12:32.389 No, the fossils from the Mother's Day Quarry, 00:12:32.490 --> 00:12:34.610 which is a great name for a site show. A huge 00:12:34.610 --> 00:12:37.149 variety of scale shapes. Rectangular scales, 00:12:37.610 --> 00:12:40.669 ovoid scales, arching rows of square scales. 00:12:40.929 --> 00:12:43.350 Bobular scales. Yeah, it wasn't a uniform hide. 00:12:43.450 --> 00:12:47.070 It was a complex tapestry of textures. And here 00:12:47.070 --> 00:12:49.590 is where it gets really interesting. The color. 00:12:50.029 --> 00:12:52.049 Usually when we talk about dinosaur color, it's 00:12:52.049 --> 00:12:54.960 a guessing game. Maybe it was green, maybe brown. 00:12:55.100 --> 00:12:57.539 Total guesswork. But you have a study here from 00:12:57.539 --> 00:13:01.720 2025 that is hot off the press. This is brand 00:13:01.720 --> 00:13:04.399 new science. A team led by Gallagher identified 00:13:04.399 --> 00:13:07.340 probable melanosomes in the skin of a juvenile 00:13:07.340 --> 00:13:10.759 Diplodocus. Explain melanosomes for us. Melanosomes 00:13:10.759 --> 00:13:13.679 are the microscopic cellular structures that 00:13:13.679 --> 00:13:16.340 hold pigment. Finding them is the holy grail 00:13:16.340 --> 00:13:18.399 because it gives us physical evidence of color 00:13:18.399 --> 00:13:21.059 patterns. So what did they find? The study suggests 00:13:21.059 --> 00:13:23.860 that, particularly as juveniles, they weren't 00:13:23.860 --> 00:13:26.580 just drab gray. They likely had diverse color 00:13:26.580 --> 00:13:28.679 patterning. Which makes sense. It tracks with 00:13:28.679 --> 00:13:31.179 what we see in modern reptiles. Baby Komodo dragons 00:13:31.179 --> 00:13:33.940 or iguanas often have bright stripes or spots 00:13:33.940 --> 00:13:36.519 for camouflage or display. So imagine a 20 -foot 00:13:36.519 --> 00:13:39.340 -long juvenile Diplodocus covered in spines with 00:13:39.340 --> 00:13:41.240 stripes or spots. It changes the whole vibe. 00:13:41.340 --> 00:13:43.379 It makes them feel like real animals living in 00:13:43.379 --> 00:13:45.440 a complex ecosystem, not just movie monsters. 00:13:45.879 --> 00:13:48.629 Which leads us to that ecosystem. The Morrison 00:13:48.629 --> 00:13:51.990 Formation, 150 million years ago. If I stepped 00:13:51.990 --> 00:13:54.309 out of a time machine, what am I seeing? You 00:13:54.309 --> 00:13:56.210 aren't seeing a tropical jungle. That's another 00:13:56.210 --> 00:13:59.870 movie trope. The Morrison was semi -arid. Think 00:13:59.870 --> 00:14:02.409 of a savanna. But instead of grass, because grass 00:14:02.409 --> 00:14:05.169 hadn't evolved yet, it's dominated by ferns, 00:14:05.169 --> 00:14:08.240 cycads, and horsetails. There are conifer forests 00:14:08.240 --> 00:14:10.759 along the rivers, but there are distinct wet 00:14:10.759 --> 00:14:13.519 and dry seasons. It's a harsh, demanding environment. 00:14:13.820 --> 00:14:16.000 And it's crowded. Incredibly crowded. This was 00:14:16.000 --> 00:14:18.580 the golden age of giants. You have Diplodocus, 00:14:18.860 --> 00:14:21.740 Apatosaurus, Brachiosaurus, Stegosaurus, Camarasaurus, 00:14:21.899 --> 00:14:24.659 all sharing the same space. And, of course, the 00:14:24.659 --> 00:14:26.879 predators like Allosaurus and Ceratosaurus hunting 00:14:26.879 --> 00:14:29.139 them. Right. The question I always have is, how? 00:14:30.139 --> 00:14:33.039 How did that many multi -ton animals survive 00:14:33.039 --> 00:14:36.200 in a semi -arid place without eating every leaf 00:14:36.200 --> 00:14:39.000 in sight and starving? That is the magic of niche 00:14:39.000 --> 00:14:41.559 partitioning. They all order off different parts 00:14:41.559 --> 00:14:43.679 of the menu. And this is where the Diplodocus 00:14:43.679 --> 00:14:46.100 teeth tell a fascinating story. Go on. If you 00:14:46.100 --> 00:14:48.379 look at their skull, they only have teeth in 00:14:48.379 --> 00:14:50.139 the front of the mouth, and they look like pegs 00:14:50.139 --> 00:14:52.860 or pencils. And they don't chew, right? No molars 00:14:52.860 --> 00:14:55.539 in the back. Zero chewing. If you are a Diplodocus, 00:14:55.700 --> 00:14:58.259 you don't have time to chew. You are a bulk browser. 00:14:59.060 --> 00:15:01.860 The wear patterns on the teeth suggest a technique 00:15:01.860 --> 00:15:05.240 called unilateral branch stripping. Unilateral 00:15:05.240 --> 00:15:07.519 branch stripping. It sounds like a gardening 00:15:07.519 --> 00:15:10.500 violation. It's brutally efficient. They would 00:15:10.500 --> 00:15:13.320 clamp onto a branch with those peg teeth and 00:15:13.320 --> 00:15:15.519 pull it through one side of the mouth, raking 00:15:15.519 --> 00:15:17.919 off all the leaves and stripping the soft bark. 00:15:18.139 --> 00:15:20.769 Then they'd swallow the whole mass. So they're 00:15:20.769 --> 00:15:23.850 basically giant rakes. Exactly. And because they 00:15:23.850 --> 00:15:26.870 didn't chew, they didn't need massive jaw muscles. 00:15:27.110 --> 00:15:29.649 This kept their heads small and light, which 00:15:29.649 --> 00:15:32.110 allowed them to have that incredibly long neck. 00:15:32.269 --> 00:15:34.570 It's all connected. And that's how they avoided 00:15:34.570 --> 00:15:37.070 competing with the neighbors. Right. Commersaurus, 00:15:37.210 --> 00:15:39.549 for example, lived right next door. But it had... 00:15:39.899 --> 00:15:42.899 Big, spoon -shaped teeth and a strong jaw. It 00:15:42.899 --> 00:15:45.980 was eating the tough, woody vegetation that Diplodocus 00:15:45.980 --> 00:15:48.360 couldn't handle. And Brachiosaurus was reaching 00:15:48.360 --> 00:15:51.279 the high canopy. Exactly. Diplodocus was sweeping 00:15:51.279 --> 00:15:54.159 the ferns and soft, mid -level branches. They 00:15:54.159 --> 00:15:55.940 split the buffet so they wouldn't start each 00:15:55.940 --> 00:15:57.899 other out. Now, we also have new information 00:15:57.899 --> 00:16:00.570 on their life cycle. The standard assumption 00:16:00.570 --> 00:16:03.929 with dinosaurs has been live fast, grow huge, 00:16:04.110 --> 00:16:07.570 die young. Generally, yes. The idea is that you 00:16:07.570 --> 00:16:10.450 need to sprint to adult size as fast as possible 00:16:10.450 --> 00:16:13.190 so the allosaurs can't eat you. Right. And for 00:16:13.190 --> 00:16:15.470 the classic Dacloticus carnegiei, that seems 00:16:15.470 --> 00:16:18.669 true, they likely reached sexual maturity in 00:16:18.669 --> 00:16:21.509 just over a decade, which is terrifyingly fast 00:16:21.509 --> 00:16:23.750 for an animal that size. But there's a twist 00:16:23.750 --> 00:16:26.620 in the 2024 study regarding the big one. The 00:16:26.620 --> 00:16:28.820 Obloticus Hallorum. This is a really fascinating 00:16:28.820 --> 00:16:31.159 divergence. A study by Woodruff and colleagues 00:16:31.159 --> 00:16:34.120 looked at the histology, the microscopic structure 00:16:34.120 --> 00:16:36.559 of the bone tissue of D. Hallorum. And what did 00:16:36.559 --> 00:16:38.480 they find? They found that this specific specimen 00:16:38.480 --> 00:16:41.679 was old, like really old. How old? They estimated 00:16:41.679 --> 00:16:44.659 around 60 years. Is that unusual? It's very old 00:16:44.659 --> 00:16:46.980 for a dinosaur. Most estimates put them in the 00:16:46.980 --> 00:16:50.600 30s or 40s. A 60 -year -old animal implies a 00:16:50.600 --> 00:16:53.179 much slower, more prolonged growth rate. Interesting. 00:16:53.200 --> 00:16:55.320 It suggests that D. Hallorum didn't just sprint 00:16:55.320 --> 00:16:57.509 to the finish. line it kept growing and lived 00:16:57.509 --> 00:17:01.230 a long sustained biological life. It adds a layer 00:17:01.230 --> 00:17:04.029 of complexity. It's not just one rule for all 00:17:04.029 --> 00:17:06.690 of them. Exactly. And speaking of complexity, 00:17:06.809 --> 00:17:08.930 we have to talk about the babies. We know that 00:17:08.930 --> 00:17:11.109 the juveniles didn't just look like miniature 00:17:11.109 --> 00:17:13.789 adults. They had different faces. Totally different 00:17:13.789 --> 00:17:17.750 faces. We found juvenile skulls where the snout 00:17:17.750 --> 00:17:21.250 isn't as blunt and square as the adult. The teeth 00:17:21.250 --> 00:17:23.910 weren't restricted just to the front. They extended 00:17:23.910 --> 00:17:26.349 further back in the jaw. Which means they were 00:17:26.349 --> 00:17:29.099 eating different things. Precisely. The babies 00:17:29.099 --> 00:17:31.920 were likely generalized browsers, maybe eating 00:17:31.920 --> 00:17:34.839 insects or more specific plants, while the adults 00:17:34.839 --> 00:17:37.039 were the specialized fern rigs. It's a brilliant 00:17:37.039 --> 00:17:39.380 evolutionary strategy. You don't have to fight 00:17:39.380 --> 00:17:42.180 your own children for dinner. That's it. So let's 00:17:42.180 --> 00:17:44.259 try to put this all together. When we strip away 00:17:44.259 --> 00:17:47.119 the museum lighting and the plastic toys, what 00:17:47.119 --> 00:17:49.220 are we left with? We are left with a sophisticated 00:17:49.220 --> 00:17:52.569 survivor. Diplodocus isn't just a pile of bones. 00:17:52.769 --> 00:17:55.710 It's a creature with a sensory -aware tail that 00:17:55.710 --> 00:17:58.690 acted like a navigation system. It's an animal 00:17:58.690 --> 00:18:01.549 covered in protective spines and complex camouflage 00:18:01.549 --> 00:18:04.470 patterns. It's a browser that engineered its 00:18:04.470 --> 00:18:08.589 own niche in a crowded ecosystem. And it's a 00:18:08.589 --> 00:18:12.130 reminder that science is never done. Absolutely. 00:18:12.490 --> 00:18:14.970 We've had these bones for 140 years. Carnegie 00:18:14.970 --> 00:18:17.930 cast them in plaster over a century ago. And 00:18:17.930 --> 00:18:20.089 yet we learned about their skin color last year. 00:18:20.309 --> 00:18:22.809 We learned about the aging of D. halorum two 00:18:22.809 --> 00:18:25.390 years ago. That is the beauty of paleontology. 00:18:25.549 --> 00:18:28.069 The fossils don't change. They sit in the drawer. 00:18:28.349 --> 00:18:31.809 But our technology changes. Our ability to ask 00:18:31.809 --> 00:18:34.589 questions changes. We can now look at melanosomes 00:18:34.589 --> 00:18:37.750 and bone histology in ways Martian Carnegie couldn't 00:18:37.750 --> 00:18:40.119 even dream of. Before we wrap up, I want to leave 00:18:40.119 --> 00:18:42.140 our listener with one final image to mull over. 00:18:42.440 --> 00:18:44.660 We've talked about the tail, the neck, the spines, 00:18:44.700 --> 00:18:47.019 but I want you to look at the hands. Yeah, the 00:18:47.019 --> 00:18:49.000 thumb claw. If you look at the front feet of 00:18:49.000 --> 00:18:51.480 the Diplodocus, they were arranged in a vertical 00:18:51.480 --> 00:18:53.759 column, almost like a horseshoe or an elephant's 00:18:53.759 --> 00:18:56.559 foot. But on the inner toe, there was one single, 00:18:56.640 --> 00:18:59.259 unusually large claw. Right. It's detached from 00:18:59.259 --> 00:19:01.039 the hand bones, just hanging there. And then 00:19:01.039 --> 00:19:03.339 the other toes have nothing, just pads. It looks 00:19:03.339 --> 00:19:06.160 bizarre, like a giant hook. And the best part, 00:19:06.339 --> 00:19:08.809 we have absolutely no idea what it was for. None. 00:19:09.269 --> 00:19:12.109 There are theories, of course. Maybe it was for 00:19:12.109 --> 00:19:14.109 digging up roots. Maybe it was for stripping 00:19:14.109 --> 00:19:16.730 bark. Some think it was a weapon for defense 00:19:16.730 --> 00:19:20.069 or used in grooming. To scratch those itchy spines. 00:19:20.109 --> 00:19:22.609 Yeah, but there is no consensus. No consensus. 00:19:22.650 --> 00:19:26.369 It's just there. It is a giant, mysterious hook 00:19:26.369 --> 00:19:28.750 on the hand of the world's most famous dinosaur. 00:19:29.730 --> 00:19:32.630 A little reminder that even with the celebrity 00:19:32.630 --> 00:19:35.009 of the Jurassic, there are still pieces of the 00:19:35.009 --> 00:19:36.950 puzzle missing. And that is why we keep digging. 00:19:37.440 --> 00:19:39.259 Thanks for joining us on this Deep Dives. We'll 00:19:39.259 --> 00:19:40.799 catch you on the next one. Keep exploring.