WEBVTT 00:00:00.000 --> 00:00:02.680 If you close your eyes and picture a dinosaur, 00:00:02.919 --> 00:00:05.860 I mean just the archetypal textbook dinosaur, 00:00:06.219 --> 00:00:09.000 there are really only, what, three contenders. 00:00:09.140 --> 00:00:11.460 You've got the T -Rex, the Triceratops, and then 00:00:11.460 --> 00:00:14.000 you have the one we are diving into today. The 00:00:14.000 --> 00:00:15.960 one with the plates. The one with the kite -shaped 00:00:15.960 --> 00:00:18.239 plates along its back and the spikes on the tail. 00:00:18.420 --> 00:00:22.940 The Stegosaurus. It is an absolute icon of the 00:00:22.940 --> 00:00:25.420 Jurassic. It really is. It's one of those animals 00:00:25.420 --> 00:00:27.480 that's so visually distinct that even if you 00:00:27.480 --> 00:00:29.579 aren't a paleontology buff, you know exactly 00:00:29.579 --> 00:00:32.200 what it is. The Mohawk dinosaur. Exactly. Right. 00:00:32.579 --> 00:00:35.039 But here's the thing that really struck me while 00:00:35.039 --> 00:00:36.520 I was going through the research for this deep 00:00:36.520 --> 00:00:39.880 dive. Yeah. For an animal that is so instantly 00:00:39.880 --> 00:00:43.759 recognizable to us now, we spent arguably the 00:00:43.759 --> 00:00:45.640 first hundred years of our relationship with 00:00:45.640 --> 00:00:48.759 it getting almost every single detail wrong. 00:00:49.280 --> 00:00:51.600 That is a perfect way to frame it. It feels like 00:00:51.600 --> 00:00:53.920 the history of the Stegosaurus is basically a 00:00:53.920 --> 00:00:56.039 history of paleontologists just scratching their 00:00:56.039 --> 00:00:57.880 heads and saying, wait, that can't be right. 00:00:58.020 --> 00:01:00.719 It's a complete paradox. It's a pop culture celebrity. 00:01:00.780 --> 00:01:04.280 But scientifically, it has been a century long 00:01:04.280 --> 00:01:07.280 puzzle. We've had to assemble it, dismantle it, 00:01:07.319 --> 00:01:09.299 and then reassemble it multiple times. And it 00:01:09.299 --> 00:01:10.859 all starts with a name, right? You know what 00:01:10.859 --> 00:01:13.239 Stegosaurus actually translates to? Roof lizard. 00:01:13.519 --> 00:01:16.599 Roof lizard. Which... When you look at a modern 00:01:16.599 --> 00:01:18.640 reconstruction with those vertical plates, it 00:01:18.640 --> 00:01:21.200 makes zero sense. None at all. A roof is flat. 00:01:21.359 --> 00:01:23.680 It covers you. And these are standing straight 00:01:23.680 --> 00:01:27.459 up. Exactly. And that name is basically a fossil 00:01:27.459 --> 00:01:31.200 of a mistake. It goes back to 1877 and Othniel 00:01:31.200 --> 00:01:33.900 Charles Marsh. O .C. Marsh. When he found the 00:01:33.900 --> 00:01:36.700 first fossils in Colorado, nothing was articulated. 00:01:37.159 --> 00:01:40.159 The bones were a jumbled mess. He found these 00:01:40.159 --> 00:01:43.760 large, flat, bony slabs, the plates, and he just... 00:01:44.120 --> 00:01:46.459 He didn't have a reference point. So his best 00:01:46.459 --> 00:01:49.019 guess was that they lay flat against the animal's 00:01:49.019 --> 00:01:51.060 back. Like shingles on a house. Overlapping, 00:01:51.079 --> 00:01:52.920 just like shingles on a roof, yeah. So the name 00:01:52.920 --> 00:01:55.480 roof lizard is literally a description of construction 00:01:55.480 --> 00:01:57.200 error. He thought he was looking at some kind 00:01:57.200 --> 00:02:00.739 of giant armored turtle thing. He did. Marsha's 00:02:00.739 --> 00:02:03.040 early notes actually speculate that it might 00:02:03.040 --> 00:02:05.260 have been an aquatic animal, something like a 00:02:05.260 --> 00:02:07.739 turtle. Wow. It just shows you how difficult 00:02:07.739 --> 00:02:09.960 it is to reconstruct an animal when you're working 00:02:09.960 --> 00:02:11.919 with a jigsaw puzzle that's missing half the 00:02:11.919 --> 00:02:15.319 pieces, has no box, cover. And the pieces are 00:02:15.319 --> 00:02:17.840 150 million years old. And we have to add the 00:02:17.840 --> 00:02:19.699 context of the Bone Wars here. Oh, absolutely. 00:02:20.139 --> 00:02:22.759 Marsh wasn't just working in a vacuum. He was 00:02:22.759 --> 00:02:26.000 working in a, well, a war zone. This was the 00:02:26.000 --> 00:02:28.680 late 19th century. And he was locked in this 00:02:28.680 --> 00:02:31.870 bitter rivalry with Edward Drinker Cope. That 00:02:31.870 --> 00:02:35.250 context is crucial. The bone wars drove discovery, 00:02:35.310 --> 00:02:38.169 but they also drove haste. Marsh and Cope were 00:02:38.169 --> 00:02:40.969 racing to name species, trying to outpublish 00:02:40.969 --> 00:02:42.669 each other. They were sabotaging each other's 00:02:42.669 --> 00:02:44.889 dig sites, right? Oh, yeah. Sabotaging sites, 00:02:45.090 --> 00:02:48.030 bribing porters, shipping crates of bones back 00:02:48.030 --> 00:02:50.129 east before they were even fully prepped. So 00:02:50.129 --> 00:02:51.909 in that kind of environment, you don't really 00:02:51.909 --> 00:02:55.889 take the time to ponder the details. You just 00:02:55.889 --> 00:02:59.740 name it, claim it, and move on. Exactly. And 00:02:59.740 --> 00:03:02.639 that rush led to some wild theories. After the 00:03:02.639 --> 00:03:05.000 turtle phase, Marsh realized it was a dinosaur, 00:03:05.259 --> 00:03:07.259 but because the front legs were so much shorter 00:03:07.259 --> 00:03:09.340 than the back legs, he thought it was bipedal, 00:03:09.360 --> 00:03:12.530 walked on two legs. He briefly proposed it was 00:03:12.530 --> 00:03:14.870 bipedal. I mean, can you imagine a five -ton 00:03:14.870 --> 00:03:18.229 Stegosaurus trying to walk like a person? The 00:03:18.229 --> 00:03:20.669 physics just don't work. It would just face plant. 00:03:20.729 --> 00:03:22.330 It would be terrifying, but yeah, physically 00:03:22.330 --> 00:03:25.129 impossible. And it took decades to correct these 00:03:25.129 --> 00:03:27.610 assumptions. Even when the first skeleton of 00:03:27.610 --> 00:03:30.430 Stegosaurus undulatus was mounted in 1910. Way 00:03:30.430 --> 00:03:32.689 after Marsh described it. They set the plates 00:03:32.689 --> 00:03:35.349 in pairs, side by side. Like butterfly wings. 00:03:36.300 --> 00:03:39.479 Precisely. It wasn't until the 1960s, so nearly 00:03:39.479 --> 00:03:42.240 a century after the discovery, that the alternating 00:03:42.240 --> 00:03:44.979 row arrangement became the standard. The staggered 00:03:44.979 --> 00:03:47.000 pattern we see today. Right, that chiral pattern 00:03:47.000 --> 00:03:49.259 from Stegosaurus stenops, which is the species 00:03:49.259 --> 00:03:51.439 most of us know. So now that we've cleared up 00:03:51.439 --> 00:03:53.560 the shingle confusion, let's look at the actual 00:03:53.560 --> 00:03:57.000 animal. Because the anatomy is incredibly weird, 00:03:57.159 --> 00:03:59.919 even when you get it right. It's a lowrider. 00:04:00.319 --> 00:04:02.599 That is the best description for it. It's a quadruped, 00:04:02.699 --> 00:04:05.740 but the build is totally unique. The forelimbs 00:04:05.740 --> 00:04:08.439 are short and stocky, while the hind limbs are 00:04:08.439 --> 00:04:11.000 long and columnar. And that forces the whole 00:04:11.000 --> 00:04:13.419 body into this permanent downward slope. It does. 00:04:13.479 --> 00:04:15.759 It puts the head very close to the ground, about 00:04:15.759 --> 00:04:18.240 a meter high, and the tail way up in the air. 00:04:18.360 --> 00:04:20.500 But what about the movement? I was reading about 00:04:20.500 --> 00:04:23.519 the stride length, and it seems like that mismatch 00:04:23.519 --> 00:04:25.699 in leg size put a hard speed limit on the animal. 00:04:25.819 --> 00:04:28.959 It absolutely did. It's a biomechanical bottleneck. 00:04:28.959 --> 00:04:31.060 If you have long back legs and short front legs, 00:04:31.139 --> 00:04:33.680 you just can't gallop. The back legs would overtake 00:04:33.680 --> 00:04:35.860 the front legs. And the animal would, as you 00:04:35.860 --> 00:04:38.519 said, faceplant. It's the classic flat tire effect. 00:04:38.819 --> 00:04:41.899 Exactly. The estimated maximum speed is roughly, 00:04:42.079 --> 00:04:45.139 what, 15 to 17 kilometers per hour? So about 00:04:45.139 --> 00:04:48.949 9 to 11 miles per hour. A reasonably fit human 00:04:48.949 --> 00:04:52.449 could outrun a stegosaurus. Yeah. It wasn't built 00:04:52.449 --> 00:04:54.750 for speed. It was built for stability and for 00:04:54.750 --> 00:04:57.829 browsing on low vegetation. A tank, basically. 00:04:58.110 --> 00:05:01.290 But a tank with a famously small driver. Yeah. 00:05:01.610 --> 00:05:03.790 We have to talk about the brain. It is the most 00:05:03.790 --> 00:05:07.029 legendary insult in paleontology. The walnut 00:05:07.029 --> 00:05:09.649 comparison. The dumb dinosaur stereotype. It 00:05:09.649 --> 00:05:12.730 is legendary. And, well, unfortunately for the 00:05:12.730 --> 00:05:15.649 stegosaurus, it is factually accurate. How accurate? 00:05:16.060 --> 00:05:18.959 For an animal weighing around 4 .5 metric tons, 00:05:19.139 --> 00:05:21.459 that's bigger than an elephant, the brain weighed 00:05:21.459 --> 00:05:25.339 only about 80 grams. Which is roughly the size 00:05:25.339 --> 00:05:27.639 of a dog's brain. Yes. A walnut. But this is 00:05:27.639 --> 00:05:29.920 where the myth making comes in again. Because 00:05:29.920 --> 00:05:32.579 the brain was so comically small, early scientists, 00:05:32.959 --> 00:05:34.740 Marsh again, he couldn't believe it could run 00:05:34.740 --> 00:05:37.360 the whole body. Right. So he proposed the sacral 00:05:37.360 --> 00:05:39.620 brain. I remember learning this in school. The 00:05:39.620 --> 00:05:42.240 idea that it had a second brain in its butt to 00:05:42.240 --> 00:05:44.839 control the tail. That was a very popular theory 00:05:44.839 --> 00:05:48.160 for a very long time. Marsh found this huge canal 00:05:48.160 --> 00:05:51.160 in the hip vertebrae, the neural canal. It was 00:05:51.160 --> 00:05:53.410 massive, wasn't it? Almost 20 times larger. than 00:05:53.410 --> 00:05:56.089 the brain case in the skull. So the logic was 00:05:56.089 --> 00:05:58.810 the head is empty, so the hips must be doing 00:05:58.810 --> 00:06:00.889 the thinking. At least handling the reflexes. 00:06:00.930 --> 00:06:04.610 But modern science has debunked that. It wasn't 00:06:04.610 --> 00:06:07.949 a brain. Not nervous tissue. No. We can look 00:06:07.949 --> 00:06:10.269 at modern birds, which are living dinosaurs, 00:06:10.550 --> 00:06:12.670 for the answer. They have a similar structure 00:06:12.670 --> 00:06:15.569 called a glycogen body. Okay, what's that? It's 00:06:15.569 --> 00:06:17.910 a specialized organ for storing energy glycogen, 00:06:18.069 --> 00:06:20.990 and it possibly helps with balance. So not a 00:06:20.990 --> 00:06:23.610 second brain. It was a battery pack. A very well 00:06:23.610 --> 00:06:25.790 -stocked pantry for the nervous system. That's 00:06:25.790 --> 00:06:28.129 a good way to put it. So the stegosaurus really 00:06:28.129 --> 00:06:30.629 was operating on just that 80 -gram brain. It 00:06:30.629 --> 00:06:34.470 was. But... We need to be careful with our mammalian 00:06:34.470 --> 00:06:37.069 bias here. We tend to equate intelligence with 00:06:37.069 --> 00:06:39.750 evolutionary success. Sure. Sagasaurus didn't 00:06:39.750 --> 00:06:42.670 need to solve puzzles or hunt in packs. It needed 00:06:42.670 --> 00:06:45.850 to eat ferns, thermoregulate, and not get eaten 00:06:45.850 --> 00:06:49.149 by Allosaurus. And considering the genus lasted 00:06:49.149 --> 00:06:52.110 for millions of years... That walnut brain was 00:06:52.110 --> 00:06:54.470 perfectly adequate for the job. Absolutely. Speaking 00:06:54.470 --> 00:06:56.550 of not getting eaten, let's move to the defining 00:06:56.550 --> 00:07:00.019 feature, the plates. The Great Plate Debate. 00:07:00.060 --> 00:07:02.740 Right. We're talking about 17 to 22 of these 00:07:02.740 --> 00:07:06.879 structures. And anatomically, these are osteoderms, 00:07:06.879 --> 00:07:08.259 right? They aren't part of the skeleton proper. 00:07:08.540 --> 00:07:11.699 That's a key distinction. If you look at a skeleton 00:07:11.699 --> 00:07:15.000 in a museum, the plates are wired onto the vertebrae. 00:07:15.000 --> 00:07:16.800 But in life, they weren't attached to the bone. 00:07:16.860 --> 00:07:19.180 They were sort of floating in the skin. Bone 00:07:19.180 --> 00:07:22.740 skin. That's what osteoderm means. Crocodiles 00:07:22.740 --> 00:07:25.220 have them. Armadillos have them. But in those 00:07:25.220 --> 00:07:28.939 animals, osteoderms are clearly armor. They lay 00:07:28.939 --> 00:07:31.639 flat. They're a shield. And for a long time, 00:07:31.660 --> 00:07:33.899 that was the theory for Stegosaurus, too. That 00:07:33.899 --> 00:07:36.360 they were armor plates to stop a bite. Yeah, 00:07:36.459 --> 00:07:38.399 but that falls apart pretty quick when you look 00:07:38.399 --> 00:07:40.579 at the placement. It really does. If you were 00:07:40.579 --> 00:07:43.600 designing a tank, you wouldn't put a row of billboards 00:07:43.600 --> 00:07:45.819 on the roof and leave the sides completely exposed. 00:07:46.139 --> 00:07:49.300 Exactly. The flanks, the belly, the most vulnerable 00:07:49.300 --> 00:07:52.399 parts are wide open. Plus, the internal structure 00:07:52.399 --> 00:07:55.300 of the plates is surprisingly porous. they aren't 00:07:55.300 --> 00:07:58.060 dense solid bone like a turtle shell and allosaurus 00:07:58.060 --> 00:08:00.019 bites into one it would probably shatter okay 00:08:00.019 --> 00:08:02.360 so if it's not armor we move to theory number 00:08:02.360 --> 00:08:05.100 two which i find fascinating the radiator theory 00:08:05.100 --> 00:08:08.480 the thermoregulation hypothesis because the bone 00:08:08.480 --> 00:08:11.800 is so porous it suggests it was heavily vascularized 00:08:11.800 --> 00:08:14.480 filled with blood vessels so the idea is the 00:08:14.480 --> 00:08:16.439 animal could turn its broadside to the morning 00:08:16.439 --> 00:08:19.720 sun to warm up or face into the wind to cool 00:08:19.720 --> 00:08:22.079 down. Pretty much. It's like the ears of an African 00:08:22.079 --> 00:08:25.019 elephant. Exactly like that. And this led to 00:08:25.019 --> 00:08:27.699 that vivid imagery of the blushing Stegosaurus. 00:08:28.060 --> 00:08:30.480 The idea that they could pump blood into the 00:08:30.480 --> 00:08:33.820 plates to turn them bright red. Yeah, to scare 00:08:33.820 --> 00:08:36.500 off predators or maybe signal to mates. It's 00:08:36.500 --> 00:08:39.840 such a cool image. But my reading suggests this 00:08:39.840 --> 00:08:42.200 theory is kind of losing steam. It is, primarily 00:08:42.200 --> 00:08:45.259 because of its cousins. If you look at related 00:08:45.259 --> 00:08:48.139 stegosaurs, like Kentrosaurus, they don't have 00:08:48.139 --> 00:08:50.740 these big broad plates. They have spikes. And 00:08:50.740 --> 00:08:53.159 spikes are terrible radiators. Horrible. They 00:08:53.159 --> 00:08:56.200 don't have the surface area. So if thermoregulation 00:08:56.200 --> 00:08:58.240 was the main reason they evolved, why didn't 00:08:58.240 --> 00:09:00.720 all stegosaurs have flat plates? It suggests 00:09:00.720 --> 00:09:03.259 the cooling effect might have been a secondary 00:09:03.259 --> 00:09:06.059 benefit, not the main purpose. That's the thinking. 00:09:06.340 --> 00:09:08.460 Which brings us to the explanation that usually 00:09:08.460 --> 00:09:11.580 wins out in biology when nothing else makes sense. 00:09:11.720 --> 00:09:15.019 Sex. Sex. Display and dominance. It's almost 00:09:15.019 --> 00:09:18.639 always the answer when you see an extravagant, 00:09:18.639 --> 00:09:21.120 energy -expensive structure that doesn't seem 00:09:21.120 --> 00:09:23.360 to help with survival. It's the peacock's tail 00:09:23.360 --> 00:09:25.980 argument. You grow these massive things to say, 00:09:26.059 --> 00:09:28.480 look at me, I'm so healthy I can afford to grow 00:09:28.480 --> 00:09:31.450 these. giant billboards on my back. Precisely. 00:09:31.509 --> 00:09:34.149 And we have some fossil evidence for this. In 00:09:34.149 --> 00:09:36.750 Hesperosaurus, a very close relative, we see 00:09:36.750 --> 00:09:39.870 sexual dimorphism. Meaning males and females 00:09:39.870 --> 00:09:43.009 look different. Right. One morph has wide oval 00:09:43.009 --> 00:09:45.649 plates and the other has taller, pointier ones. 00:09:45.990 --> 00:09:49.149 That strongly suggests a male -female distinction. 00:09:49.610 --> 00:09:51.669 And there's a detail about their appearance that 00:09:51.669 --> 00:09:54.450 I think changes how we visualize them. The fossils 00:09:54.450 --> 00:09:56.149 are just the bone core, right? That's right. 00:09:56.210 --> 00:09:58.830 The bone is just the scaffold. In life, they 00:09:58.830 --> 00:10:00.450 would have been covered in a keratin sheath, 00:10:00.590 --> 00:10:02.889 same material as a bird's beak or your fingernails. 00:10:03.029 --> 00:10:04.710 So the plates would have been way bigger than 00:10:04.710 --> 00:10:07.309 the fossils suggest. Significantly larger and 00:10:07.309 --> 00:10:09.629 likely much sharper at the edges. And keratin 00:10:09.629 --> 00:10:12.549 holds pigment really well. So we should be picturing 00:10:12.549 --> 00:10:15.190 these things with bright, vibrant colors. Maybe 00:10:15.190 --> 00:10:18.730 patterns. A seven -ton animal with a neon billboard 00:10:18.730 --> 00:10:22.110 on its back. It changes the whole vibe of the 00:10:22.110 --> 00:10:25.009 Jurassic. Okay, so the plates are for show. But 00:10:25.009 --> 00:10:28.190 the tail? The tail means business. We have to 00:10:28.190 --> 00:10:30.210 talk about the Thagomizer. And I love that we 00:10:30.210 --> 00:10:32.429 can use that word in a serious scientific context. 00:10:32.769 --> 00:10:34.870 It is one of the rare times a cartoon changed 00:10:34.870 --> 00:10:38.389 science. Gary Larson, the far side. He drew a 00:10:38.389 --> 00:10:41.809 caveman pointing to the spikes and saying, now 00:10:41.809 --> 00:10:44.529 this end is called the Thagomizer, after the 00:10:44.529 --> 00:10:46.909 late Thag Simmons. And paleontologists thought 00:10:46.909 --> 00:10:48.710 it was so perfect that they adopted it. It's 00:10:48.710 --> 00:10:51.009 just perfect. Yeah. But the weapon itself is 00:10:51.009 --> 00:10:54.429 terrifying. Four spikes, two pairs, and unlike 00:10:54.429 --> 00:10:57.309 the vertical plates, these stuck out horizontally. 00:10:57.690 --> 00:11:00.330 That orientation is critical. They are positioned 00:11:00.330 --> 00:11:03.250 for a lateral swipe, and the engineering of the 00:11:03.250 --> 00:11:06.250 tail is key. How so? Most dinosaurs have ossified 00:11:06.250 --> 00:11:08.769 tendons, bony rods running down the tail to keep 00:11:08.769 --> 00:11:11.210 it stiff for balance. Stegosaurus lacks those 00:11:11.210 --> 00:11:13.149 in the tail section. Which means it wasn't a 00:11:13.149 --> 00:11:15.970 stiff rudder, it was a whip. A highly flexible 00:11:15.970 --> 00:11:18.149 muscular whip, and we have forensic evidence 00:11:18.149 --> 00:11:20.509 that they used it. This isn't just speculation. 00:11:20.889 --> 00:11:22.809 You mean the Allosaurus vertebra? That's the 00:11:22.809 --> 00:11:25.330 one. The top predator of the Morrison Formation. 00:11:25.929 --> 00:11:28.909 We found a tail vertebra with a puncture wound 00:11:28.909 --> 00:11:31.649 in it. A hole that perfectly matches a stegosaur 00:11:31.649 --> 00:11:35.889 spike. Perfectly. But here is the CSI part. The 00:11:35.889 --> 00:11:39.230 bone shows signs of healing and infection. Which 00:11:39.230 --> 00:11:41.830 means the Allosaurus didn't die immediately. 00:11:42.460 --> 00:11:45.200 It survived the hit. It survived, but it spent 00:11:45.200 --> 00:11:48.539 weeks or months in agony with a festering wound. 00:11:48.899 --> 00:11:51.980 That tells us two things. Okay. First, that Stegosaurus 00:11:51.980 --> 00:11:54.940 was actively fighting off apex predators. And 00:11:54.940 --> 00:11:57.179 second, that the weapon was incredibly effective. 00:11:57.600 --> 00:11:59.259 But they did break him sometimes, right? Oh, 00:11:59.259 --> 00:12:02.000 yeah. We find about 10 % of Stegosaurus spikes 00:12:02.000 --> 00:12:04.360 are trauma damage, like broken tips. So they 00:12:04.360 --> 00:12:06.340 were using them in combat and using them often. 00:12:06.399 --> 00:12:08.580 It completely reframes the animal. It's not a 00:12:08.580 --> 00:12:11.320 passive grazer. It's a samurai. It's got a display 00:12:11.320 --> 00:12:14.000 on its back and a sword in its, well, its tail. 00:12:14.139 --> 00:12:16.460 A samurai that eats bushes. Let's talk about 00:12:16.460 --> 00:12:18.779 that, the eating part. Because for a long time, 00:12:18.799 --> 00:12:21.200 the diet was another area where we underestimated 00:12:21.200 --> 00:12:23.840 this animal. Totally. The head is tiny. The teeth 00:12:23.840 --> 00:12:26.220 are little pegs. It has a beak. The assumption 00:12:26.220 --> 00:12:29.120 was it had an incredibly weak bite. That was 00:12:29.120 --> 00:12:32.440 the consensus as recently as 2010. A study came 00:12:32.440 --> 00:12:34.779 out suggesting the bite force was less than half 00:12:34.779 --> 00:12:36.960 that of a Labrador retriever. So it could only 00:12:36.960 --> 00:12:39.750 eat soft moss and cerns. Pretty much. But then 00:12:39.750 --> 00:12:42.309 came Sophie. Sophie changed everything. This 00:12:42.309 --> 00:12:44.929 is a specimen found in Wyoming in 2003, and it 00:12:44.929 --> 00:12:49.759 is a marvel. 85 % intact, 360 bones. The most 00:12:49.759 --> 00:12:52.279 well -preserved Stegosaurus ever found. And Sophie 00:12:52.279 --> 00:12:54.740 proved the wimpy bite theory wrong. Completely. 00:12:54.820 --> 00:12:57.759 When researchers modeled Sophie's skull in 2016, 00:12:57.940 --> 00:12:59.899 they found the bite force was actually comparable 00:12:59.899 --> 00:13:02.840 to a sheep or a cow. Now, a cow might not sound 00:13:02.840 --> 00:13:05.179 terrifying, but they can grind through very tough, 00:13:05.279 --> 00:13:08.919 fibrous material. Exactly. But Stegosaurus couldn't 00:13:08.919 --> 00:13:11.559 grind side to side. It likely used a shearing 00:13:11.559 --> 00:13:13.940 motion, like scissors, cropping and slicing. 00:13:14.299 --> 00:13:16.350 So it wasn't just eating mush. No, it was likely 00:13:16.350 --> 00:13:19.870 eating cycads, conifers, tougher woody plants. 00:13:20.190 --> 00:13:22.490 They were the mowers of the Jurassic, clearing 00:13:22.490 --> 00:13:24.750 out the underbrush. Sophie really was a revolution. 00:13:25.649 --> 00:13:28.090 But we can't talk about modern stegosaurus discoveries 00:13:28.090 --> 00:13:30.809 without talking about Apex. This is the dinosaur 00:13:30.809 --> 00:13:34.269 in the room. We have to discuss Apex. This specimen 00:13:34.269 --> 00:13:38.070 was discovered in 2022, and it's massive. But 00:13:38.070 --> 00:13:40.389 the headline wasn't just the size, it was the 00:13:40.389 --> 00:13:44.149 price tag. In July 2024, it sold at Sotheby's 00:13:44.149 --> 00:13:48.539 for... $44 .6 million. It's a staggering number. 00:13:48.600 --> 00:13:52.000 The most ever paid for a fossil. And this creates 00:13:52.000 --> 00:13:54.419 a huge tension in the scientific community. It 00:13:54.419 --> 00:13:57.299 creates a crisis, frankly. When a fossil of that 00:13:57.299 --> 00:13:59.899 importance goes into a private collection, it 00:13:59.899 --> 00:14:02.799 effectively disappears from science. Right. Even 00:14:02.799 --> 00:14:05.539 if the owner says researchers can visit, there's 00:14:05.539 --> 00:14:08.129 no guarantee of access forever. Science relies 00:14:08.129 --> 00:14:11.049 on reproducibility. If I write a paper on Apex's 00:14:11.049 --> 00:14:13.590 growth wings, and 50 years from now another scientist 00:14:13.590 --> 00:14:16.350 wants to verify my work. But Apex is locked in 00:14:16.350 --> 00:14:19.029 a vault or was sold to another anonymous buyer, 00:14:19.289 --> 00:14:21.990 the science becomes unverifiable. It essentially 00:14:21.990 --> 00:14:24.730 privatizes the data. It takes a piece of natural 00:14:24.730 --> 00:14:26.909 history and turns it into an asset class. And 00:14:26.909 --> 00:14:29.750 museums simply cannot compete. The Natural History 00:14:29.750 --> 00:14:32.470 Museum can't drop $45 million on one specimen. 00:14:32.690 --> 00:14:35.049 So we're seeing this trend where the best fossils 00:14:35.049 --> 00:14:37.309 are moving out of the public trust. It's a complicated 00:14:37.309 --> 00:14:40.629 legacy for such a magnificent find. And it really 00:14:40.629 --> 00:14:44.049 highlights how active this field still is. Stegosaurus 00:14:44.049 --> 00:14:47.029 isn't a solved dinosaur. Not at all. From the 00:14:47.029 --> 00:14:49.570 bone wars to the biomechanics of Sophie and now 00:14:49.570 --> 00:14:52.289 the ethics of the Apex auction, it's still generating 00:14:52.289 --> 00:14:54.759 debate. And it has stayed in the public eye the 00:14:54.759 --> 00:14:58.039 whole time, from the 1933 King Kong to becoming 00:14:58.039 --> 00:15:00.820 the state fossil of Colorado. I love that story. 00:15:00.919 --> 00:15:02.799 That was a fourth grade class, right? It was. 00:15:02.919 --> 00:15:05.279 A teacher and her students campaigned for two 00:15:05.279 --> 00:15:07.440 years to get the bill passed. It just shows you 00:15:07.440 --> 00:15:09.980 that this animal captures the imagination of 00:15:09.980 --> 00:15:13.059 children and adults in a way few others do. It's 00:15:13.059 --> 00:15:15.480 the combination of the weirdness and the coolness. 00:15:15.799 --> 00:15:17.919 So if we pull all of this together, we've come 00:15:17.919 --> 00:15:21.279 a very long way from O .C. Marsh's shingleback 00:15:21.279 --> 00:15:24.360 turtle. We have. We've moved from a clumsy, bipedal 00:15:24.360 --> 00:15:27.340 aquatic mistake to a sophisticated, well -adapted 00:15:27.340 --> 00:15:30.000 animal. We know it lived in her. protecting its 00:15:30.000 --> 00:15:32.600 young. We know it was a lowrider specialist clearing 00:15:32.600 --> 00:15:35.539 the forest floor. And we know it had a deadly 00:15:35.539 --> 00:15:38.500 whip -like tail that could fend off the top predators 00:15:38.500 --> 00:15:41.360 of its time. And we know that despite that tiny 00:15:41.360 --> 00:15:44.919 brain, it was an evolutionary success story. 00:15:45.139 --> 00:15:47.159 It didn't need to do calculus. It just needed 00:15:47.159 --> 00:15:50.059 to survive. Evolution doesn't optimize for IQ 00:15:50.059 --> 00:15:53.500 points. It optimizes for passing on genes. And 00:15:53.500 --> 00:15:56.460 the Stegosaurus design just worked. So as we 00:15:56.460 --> 00:15:59.230 wrap up this redemption arc, What is the one 00:15:59.230 --> 00:16:00.950 thing that still sticks with you? What's the 00:16:00.950 --> 00:16:03.629 lingering mystery? For me, it's still the plates. 00:16:03.649 --> 00:16:07.950 We have decent theories display, maybe some thermoregulation. 00:16:08.429 --> 00:16:10.850 But we don't know. Were they different colors 00:16:10.850 --> 00:16:13.509 in different seasons? Did they pump blood to 00:16:13.509 --> 00:16:15.769 flash warnings? We're looking at rocks and trying 00:16:15.769 --> 00:16:18.769 to reconstruct behavior. Exactly. It reminds 00:16:18.769 --> 00:16:21.730 us that even with an animal as famous as this, 00:16:21.850 --> 00:16:24.610 we are essentially looking at shadows on a wall. 00:16:24.730 --> 00:16:27.210 We are piecing together a life from fragments 00:16:27.210 --> 00:16:30.169 of bone. And maybe, just maybe, somewhere in 00:16:30.169 --> 00:16:32.769 the Morrison Formation, there's another Sophie 00:16:32.769 --> 00:16:34.889 waiting to be found that will finally tell us 00:16:34.889 --> 00:16:37.149 exactly why the roof lizard decided to wear a 00:16:37.149 --> 00:16:39.539 mohawk. I certainly hope so. Thanks for diving 00:16:39.539 --> 00:16:41.159 deep with us. Keep questioning what you think 00:16:41.159 --> 00:16:42.500 you know, and we'll catch you on the next one.