WEBVTT 00:00:00.000 --> 00:00:02.140 I want you to close your eyes for a second. Imagine 00:00:02.140 --> 00:00:03.940 you're standing in the middle of a floodplain. 00:00:04.339 --> 00:00:08.320 It's hot, really hot. The air is thick, humid, 00:00:08.500 --> 00:00:13.699 maybe smelling a bit like pine resin and rotting 00:00:13.699 --> 00:00:16.739 ferns. You look around and there's no grass. 00:00:16.980 --> 00:00:22.399 Just ferns, cycads, call conifers. A very alien 00:00:22.399 --> 00:00:24.899 world. And in the distance you hear a sound. 00:00:25.149 --> 00:00:27.850 It's not a roar exactly. It's a low frequency 00:00:27.850 --> 00:00:30.269 rumble, something you feel in your chest more 00:00:30.269 --> 00:00:32.030 than you hear with your ears. You've just stepped 00:00:32.030 --> 00:00:34.649 out of the time machine about 155 million years 00:00:34.649 --> 00:00:37.149 ago. Welcome to the late Jurassic. Right. And 00:00:37.149 --> 00:00:38.869 if I'm standing there looking at the top of the 00:00:38.869 --> 00:00:41.429 food chain, who am I looking at? Because if I 00:00:41.429 --> 00:00:43.369 ask most people to name the scariest dinosaur, 00:00:43.729 --> 00:00:46.929 they immediately shout. T -Rex. Of course. But 00:00:46.929 --> 00:00:48.609 we are way too early for the Tarrant Lizard King. 00:00:48.710 --> 00:00:50.929 Way too early. It's a great point. You are closer 00:00:50.929 --> 00:00:53.950 in time to the T -Rex today than the T -Rex was 00:00:53.950 --> 00:00:56.109 to the animal we're talking about. That fact 00:00:56.109 --> 00:00:58.490 always blows my mind. Yeah. So the animal you 00:00:58.490 --> 00:01:00.390 are looking at, the one making that rumble, is 00:01:00.390 --> 00:01:02.570 the Allosaurus. The Lion of the Jurassic. Yeah. 00:01:02.630 --> 00:01:05.230 That's the nickname. And it's earned. For millions 00:01:05.230 --> 00:01:08.069 of years, this animal was the absolute ruler 00:01:08.069 --> 00:01:11.209 of what is now North America. It was the most 00:01:11.209 --> 00:01:14.250 abundant, the most successful large predator. 00:01:14.379 --> 00:01:16.579 of its time. Abundant is the key word there, 00:01:16.620 --> 00:01:18.879 right? It is. If you look at the Morrison Formation, 00:01:18.939 --> 00:01:22.420 this massive stretch of sedimentary rock in the 00:01:22.420 --> 00:01:26.140 western U .S., it is absolutely packed with Allosaurus 00:01:26.140 --> 00:01:28.579 bones. They are everywhere. And that's what we 00:01:28.579 --> 00:01:30.980 are unpacking today. Yeah. Because I think Allosaurus 00:01:30.980 --> 00:01:33.900 gets a bad rap. It's often treated as the generic 00:01:33.900 --> 00:01:36.760 meat eater. You know, the player two dinosaur. 00:01:36.959 --> 00:01:39.939 The default theropod. Exactly. It's not as big 00:01:39.939 --> 00:01:42.340 as T -Rex, not as weird as Spinosaurus. It's 00:01:42.340 --> 00:01:45.379 just... Yeah. But reading through these sources, 00:01:45.439 --> 00:01:48.280 I realized this animal is actually a biomechanical 00:01:48.280 --> 00:01:51.239 masterpiece, a completely terrifying piece of 00:01:51.239 --> 00:01:52.900 engineering. It really is. It's a completely 00:01:52.900 --> 00:01:54.900 different engineering solution to the problem 00:01:54.900 --> 00:01:57.219 of how to kill a giant animal compared to what 00:01:57.219 --> 00:01:59.159 came later with the tyrannosaurs. So that's our 00:01:59.159 --> 00:02:00.920 mission today. We're going to talk about that 00:02:00.920 --> 00:02:02.859 engineering, specifically the hatchet attack 00:02:02.859 --> 00:02:05.250 theory. which is one of the most violent concepts 00:02:05.250 --> 00:02:07.129 I've ever come across in nature. It's brutal. 00:02:07.390 --> 00:02:09.909 We're going to look at the Bone Wars, which is 00:02:09.909 --> 00:02:12.449 the chaotic human drama behind its discovery. 00:02:12.729 --> 00:02:14.349 And we're going to spend some time with Big Al. 00:02:14.490 --> 00:02:18.340 Ah, Big Al. the most famous and perhaps the most 00:02:18.340 --> 00:02:21.219 tragic Allosaurus we've ever found. His life 00:02:21.219 --> 00:02:23.479 story is essentially a series of unfortunate 00:02:23.479 --> 00:02:25.740 events written in calcium. It's just staggering. 00:02:26.000 --> 00:02:28.419 It really is a window into what life was actually 00:02:28.419 --> 00:02:30.500 like for these animals. But before we get to 00:02:30.500 --> 00:02:32.500 the tragedy, let's start with the identity, the 00:02:32.500 --> 00:02:36.219 name itself, Allosaurus. Different lizard. It 00:02:36.219 --> 00:02:38.159 doesn't exactly strike fear into your heart, 00:02:38.180 --> 00:02:40.240 does it? It really doesn't. Tyrannosaurus Rex 00:02:40.240 --> 00:02:43.199 means tyrant lizard king. Velociraptor means 00:02:43.199 --> 00:02:45.620 swift Caesar. And then we have different lizard. 00:02:46.000 --> 00:02:48.879 Why did Othniel Charles Marsh, who named it in 00:02:48.879 --> 00:02:54.610 1877, go with something so, uh... So vague. Well, 00:02:54.669 --> 00:02:56.330 you have to look at it from his perspective in 00:02:56.330 --> 00:02:58.530 the 19th century. He was just getting these bones 00:02:58.530 --> 00:03:00.990 from his collectors out west and he was examining 00:03:00.990 --> 00:03:03.930 the vertebrae, the backbone of this new find. 00:03:04.110 --> 00:03:06.810 And he noticed something that at the time was 00:03:06.810 --> 00:03:10.069 revolutionary. The vertebrae weren't solid blocks 00:03:10.069 --> 00:03:12.750 of bone like, you know, crocodiles or lizards. 00:03:12.849 --> 00:03:16.830 They were hourglass shaped inside with deep hollows 00:03:16.830 --> 00:03:20.129 and cavities. Hollow bones. Exactly. Marsh looked 00:03:20.129 --> 00:03:23.280 at them and thought, this is weird. This is different 00:03:23.280 --> 00:03:25.979 from any reptile I've ever seen, hence Allosaurus. 00:03:26.199 --> 00:03:29.000 It was a literal description of his first impression. 00:03:29.240 --> 00:03:31.740 So it was an aha moment for him. A huge one. 00:03:32.219 --> 00:03:34.960 But today we know exactly what those hollows 00:03:34.960 --> 00:03:36.879 were for. It's a feature called pneumatization. 00:03:37.599 --> 00:03:41.419 Pneumatization, like pneumatic tires? Air. Precisely. 00:03:41.639 --> 00:03:44.259 These cavities held air sacs that were part of 00:03:44.259 --> 00:03:46.479 the respiratory system. It's a system we see 00:03:46.479 --> 00:03:48.879 in modern birds, their closest living relatives. 00:03:49.159 --> 00:03:50.740 And what's the advantage of that? Two big ones. 00:03:50.960 --> 00:03:53.259 First, it makes the skeleton incredibly lightweight 00:03:53.259 --> 00:03:55.800 without sacrificing too much strength. You get 00:03:55.800 --> 00:03:58.539 a bigger animal for less biological cost. Second, 00:03:58.780 --> 00:04:01.659 it suggests a very efficient one -way respiratory 00:04:01.659 --> 00:04:04.750 system. What do you mean one way? So when a mammal 00:04:04.750 --> 00:04:07.550 like us breathes, we breathe in, the air goes 00:04:07.550 --> 00:04:10.449 to our lungs, we extract oxygen, and we breathe 00:04:10.449 --> 00:04:13.770 the same air back out. We're mixing old deoxygenated 00:04:13.770 --> 00:04:16.709 air with new air. Birds and likely Allosaurus 00:04:16.709 --> 00:04:19.910 had a system where air flowed in one continuous 00:04:19.910 --> 00:04:22.810 loop through the lungs in these air sacs. It 00:04:22.810 --> 00:04:25.889 means they had a constant supply of fresh, fully 00:04:25.889 --> 00:04:28.290 oxygenated air. It's like having a turbocharger. 00:04:28.490 --> 00:04:30.290 Which is high -performance machinery. Absolutely. 00:04:30.449 --> 00:04:32.939 Built for an active lifestyle. But that leads 00:04:32.939 --> 00:04:35.519 to the second part of its name, the species epithet, 00:04:35.540 --> 00:04:40.319 Allosaurus fragilis. Fragilis. Fragile. You have 00:04:40.319 --> 00:04:42.660 the top predator of the ecosystem, a two -ton 00:04:42.660 --> 00:04:45.899 killer, and you name it fragile, was marsh trolling. 00:04:45.939 --> 00:04:48.439 It does seem incredibly ironic, but it refers 00:04:48.439 --> 00:04:50.699 specifically to those same weight -saving features 00:04:50.699 --> 00:04:53.660 in the vertebrae. The bone walls of these hollows 00:04:53.660 --> 00:04:56.319 were thin. Ah, so the different and the fragile 00:04:56.319 --> 00:04:58.920 are pointing at the same thing. Exactly. Marsh 00:04:58.920 --> 00:05:00.639 wasn't saying the animal is weak or delicate. 00:05:00.740 --> 00:05:03.680 He was highlighting how elegantly and, yes, fragilly 00:05:03.680 --> 00:05:05.920 constructed the spine was. It's the difference 00:05:05.920 --> 00:05:08.399 between a tank and a fighter jet. A tank is just 00:05:08.399 --> 00:05:11.339 heavy armor. A fighter jet is fragile in the 00:05:11.339 --> 00:05:14.360 sense that it's light and highly tuned, but it's 00:05:14.360 --> 00:05:16.980 still an incredibly dangerous weapon. I like 00:05:16.980 --> 00:05:19.939 that analogy. So Allosaurus is the F -16 of the 00:05:19.939 --> 00:05:23.410 Jurassic. Speed and maneuverability over brute 00:05:23.410 --> 00:05:25.449 force. That's a great way to think about it. 00:05:25.550 --> 00:05:27.769 Now, you mentioned Marsh, and you can't talk 00:05:27.769 --> 00:05:30.110 about O .C. Marsh without talking about his nemesis. 00:05:30.209 --> 00:05:34.110 Edward Drinker Cope. The Bone Wars. I feel like 00:05:34.110 --> 00:05:36.370 we could do 10 deep dives just on these two guys. 00:05:36.689 --> 00:05:39.889 They hated each other. Hate is a mild word for 00:05:39.889 --> 00:05:42.810 it. This was a bitter, scorched earth rivalry 00:05:42.810 --> 00:05:46.250 in the late 1800s. It was personal. It was professional. 00:05:46.449 --> 00:05:48.970 It was nasty. It was all about ego, wasn't it? 00:05:49.009 --> 00:05:51.649 Completely. They were racing to name new species, 00:05:51.790 --> 00:05:54.189 to fill up the museums back east, to cement their 00:05:54.189 --> 00:05:56.730 own legacies. And in their rush, they made a 00:05:56.730 --> 00:05:59.850 complete mess of the science. How so? They were 00:05:59.850 --> 00:06:02.110 getting crates of bones from Colorado, Wyoming, 00:06:02.329 --> 00:06:05.050 Utah. often very fragmentary stuff. And every 00:06:05.050 --> 00:06:07.189 time they found a toe or a tooth that looked 00:06:07.189 --> 00:06:09.629 even slightly different, they slapped a new name 00:06:09.629 --> 00:06:12.069 on it to claim priority. They were naming things 00:06:12.069 --> 00:06:13.910 so fast they weren't even properly describing 00:06:13.910 --> 00:06:16.310 them. So we ended up with this clutter of names 00:06:16.310 --> 00:06:19.790 like creosaurus, labrosaurus, epentereus. And 00:06:19.790 --> 00:06:22.389 dozens more. And most of those, after decades 00:06:22.389 --> 00:06:24.769 of patient work by later paleontologists, turned 00:06:24.769 --> 00:06:27.230 out to be just allosaurus. Different individuals, 00:06:27.430 --> 00:06:29.449 maybe different ages or slightly different sizes, 00:06:29.449 --> 00:06:31.730 but the same animal. The rush for glory just 00:06:31.730 --> 00:06:34.759 created... confusion. It did, but it also led 00:06:34.759 --> 00:06:37.920 to one of the most painful what -if stories in 00:06:37.920 --> 00:06:41.120 the history of paleontology. It involves a specific 00:06:41.120 --> 00:06:44.519 crate of fossils. The unopened box. The unopened 00:06:44.519 --> 00:06:48.459 box. So Cope's team is out in Como Bluff, Wyoming, 00:06:48.740 --> 00:06:52.879 a legendary site. In 1879, they excavate a massive 00:06:52.879 --> 00:06:55.019 block of matrix containing a nearly complete 00:06:55.019 --> 00:06:58.240 theropod dinosaur. A huge find. A career -making 00:06:58.240 --> 00:07:00.160 find. They crate it up, ship it back to Cope 00:07:00.160 --> 00:07:02.699 in Philadelphia, and he just ignores it. It sits 00:07:02.699 --> 00:07:05.379 in his collection unopened. Why? Was he too busy 00:07:05.379 --> 00:07:07.860 sabotaging Marsh, selling him mislabeled fossils? 00:07:08.220 --> 00:07:10.139 Probably. That was a real tactic they both used. 00:07:10.279 --> 00:07:12.420 He was so obsessed with volume, with finding 00:07:12.420 --> 00:07:15.319 the next big thing, that he didn't properly analyze 00:07:15.319 --> 00:07:17.500 what he already had. He just wanted to publish 00:07:17.500 --> 00:07:20.240 a name and move on. He died in 1897. having never 00:07:20.240 --> 00:07:22.800 opened that crate. So what happened to it? After 00:07:22.800 --> 00:07:24.980 his death, his collection was sold to the American 00:07:24.980 --> 00:07:28.860 Museum of Natural History. And in 1903, six years 00:07:28.860 --> 00:07:32.300 after he died, they finally opened it. And inside 00:07:32.300 --> 00:07:38.360 was specimen AMNH 5753. And that is? It is one 00:07:38.360 --> 00:07:41.300 of the most spectacular, complete allosaurus 00:07:41.300 --> 00:07:44.259 skeletons ever found. It's a cornerstone of our 00:07:44.259 --> 00:07:46.060 understanding of the animal. Is that the one 00:07:46.060 --> 00:07:49.060 in the famous painting? The green dinosaur crouching 00:07:49.060 --> 00:07:51.139 over the Apatosaurus carcass? That's the one. 00:07:51.399 --> 00:07:54.420 The iconic Charles R. Knight painting from 1907. 00:07:54.819 --> 00:07:57.540 That image, which defined what a predatory dinosaur 00:07:57.540 --> 00:08:00.100 looked like for generations of people, came from 00:08:00.100 --> 00:08:02.339 the box Cope couldn't be bothered to open. Wow. 00:08:02.459 --> 00:08:04.819 If he had just looked inside, he might have described 00:08:04.819 --> 00:08:07.759 the definitive Allosaurus specimen and completely 00:08:07.759 --> 00:08:10.040 stolen Marsh's thunder. It was right there in 00:08:10.040 --> 00:08:12.939 his hands. That is just, it's paleontological 00:08:12.939 --> 00:08:15.300 tragedy. It is. But the confusion didn't end 00:08:15.300 --> 00:08:17.399 with Marsh and Cope. For a long time, the public 00:08:17.399 --> 00:08:19.899 didn't even know the name Allosaurus. My grandfather, 00:08:20.100 --> 00:08:21.800 for example, might have gone to a museum and 00:08:21.800 --> 00:08:24.279 seen a label that said Antrodemus. What happened 00:08:24.279 --> 00:08:27.420 there? That is a classic case of taxonomic bureaucracy. 00:08:27.920 --> 00:08:30.160 It's all about the rule of priority. Meaning 00:08:30.160 --> 00:08:33.019 whoever names it first wins. Exactly. Back in 00:08:33.019 --> 00:08:36.440 1870, seven years before Marsh named Allosaurus, 00:08:36.820 --> 00:08:40.200 a paleontologist named Joseph Lady, who was really 00:08:40.200 --> 00:08:43.279 the grandfather of American paleontology, a much 00:08:43.279 --> 00:08:46.000 more careful scientist than Marsh or Cope. Right. 00:08:46.100 --> 00:08:49.509 Lady described a tail vertebra. Just half a tailbone, 00:08:49.649 --> 00:08:51.870 really, that was sent to him from Colorado. He 00:08:51.870 --> 00:08:54.129 named it Antrodemus. On the basis of one bone? 00:08:54.230 --> 00:08:57.480 One partial bone. So... Decades later, in the 00:08:57.480 --> 00:09:00.440 1920s, another paleontologist named Charles Gilmore 00:09:00.440 --> 00:09:02.899 was studying the material. He looked at Leidy's 00:09:02.899 --> 00:09:05.399 bone and said, hey, this looks identical to the 00:09:05.399 --> 00:09:07.860 tail bones on Marsha's Allosaurus. Okay, so they're 00:09:07.860 --> 00:09:10.019 the same animal. Right. And since Leidy named 00:09:10.019 --> 00:09:13.799 his bone first, 1870 versus 1877, the strict 00:09:13.799 --> 00:09:17.299 rules of taxonomy say the older name wins. Antrodemus 00:09:17.299 --> 00:09:19.740 has priority. So because of one half -broken 00:09:19.740 --> 00:09:22.299 tail bone, the name Allosaurus was thrown in 00:09:22.299 --> 00:09:24.379 the trash. For about 50 years, yes, from the 00:09:24.379 --> 00:09:26.590 1920s all the way to... the 1970s, scientific 00:09:26.590 --> 00:09:29.289 papers and museum exhibits used the name Antrodemus. 00:09:29.309 --> 00:09:31.389 It's a real shame. So what brought Allosaurus 00:09:31.389 --> 00:09:34.279 back from the dead? A man named James Madsen, 00:09:34.480 --> 00:09:37.720 he published this massive exhaustive monograph 00:09:37.720 --> 00:09:40.480 on the fossils from the Cleveland Lloyd Quarry 00:09:40.480 --> 00:09:43.860 in the 70s. And he successfully argued, look, 00:09:44.080 --> 00:09:46.879 Antrodemus is based on garbage material. It's 00:09:46.879 --> 00:09:49.899 a nomin dubium. A dubious name. Exactly. You 00:09:49.899 --> 00:09:52.360 can't define an entire genus on half a tailbone 00:09:52.360 --> 00:09:54.799 that could belong to anything. He made the case 00:09:54.799 --> 00:09:57.019 that Allosaurus was based on much better, more 00:09:57.019 --> 00:09:59.639 complete and more diagnostic material. And the 00:09:59.639 --> 00:10:02.720 scientific community finally agreed. He resurrected 00:10:02.720 --> 00:10:05.639 the name. Thank goodness. Allosaurus just sounds 00:10:05.639 --> 00:10:07.639 better. It has a flow to it. It does. It rolls 00:10:07.639 --> 00:10:09.639 off the tongue. Now, you mentioned the Cleveland 00:10:09.639 --> 00:10:11.179 Lloyd Quarry, and we're going to get deep into 00:10:11.179 --> 00:10:12.960 that later because it sounds like a prehistoric 00:10:12.960 --> 00:10:16.299 crime scene. But first, let's establish where 00:10:16.299 --> 00:10:18.580 this animal lived. We know it's an American icon, 00:10:18.820 --> 00:10:22.240 Utah, Wyoming, Colorado, the Morrison Formation. 00:10:22.240 --> 00:10:24.120 But I saw in the notes that there's a Portuguese 00:10:24.120 --> 00:10:27.159 connection. Yes, this is fascinating. We have 00:10:27.159 --> 00:10:29.500 confirmed Allosaurus remains from the Laurinium 00:10:29.500 --> 00:10:32.299 Formation in Portugal. How does a dinosaur get 00:10:32.299 --> 00:10:34.779 from Utah to Portugal? Do they swim the Atlantic? 00:10:35.039 --> 00:10:37.360 No swimming involved. You have to remember your 00:10:37.360 --> 00:10:40.299 paleogeography. In the late Jurassic, the Atlantic 00:10:40.299 --> 00:10:43.059 Ocean was just a baby. It was a narrow seaway, 00:10:43.200 --> 00:10:45.720 a rift that was just starting to open up. So 00:10:45.720 --> 00:10:48.100 North America and Europe were still connected. 00:10:48.379 --> 00:10:50.759 Much closer, certainly. There were likely land 00:10:50.759 --> 00:10:52.980 bridges or shallow island chains connecting them, 00:10:53.120 --> 00:10:55.200 especially during periods of lower sea level, 00:10:55.279 --> 00:10:58.100 so animals could just... walk across. So it's 00:10:58.100 --> 00:11:01.000 basically the same ecosystem on both sides. Remarkably 00:11:01.000 --> 00:11:03.720 similar. It's almost a mirror image. In the U 00:11:03.720 --> 00:11:06.340 .S., you have Allosaurus hunting prey like Stegosaurus 00:11:06.340 --> 00:11:09.379 and Camptosaurus. In Portugal, you have Allosaurus 00:11:09.379 --> 00:11:12.340 hunting, well, Merigaea, which is a type of Stegosaur, 00:11:12.559 --> 00:11:15.820 and Draconix, a type of Camptosaur. It shows 00:11:15.820 --> 00:11:18.539 that Allosaurus was a dominant transcontinental 00:11:18.539 --> 00:11:21.299 success story. And it's the state fossil of Utah, 00:11:21.460 --> 00:11:24.940 right? It is. Designated in 1988 purely because 00:11:24.940 --> 00:11:27.509 of the sheer volume of bones found there, especially 00:11:27.509 --> 00:11:29.549 at Cleveland Lloyd. Okay, let's get a good look 00:11:29.549 --> 00:11:32.750 at this animal. Physically, if I'm standing next 00:11:32.750 --> 00:11:35.610 to an adult Allosaurus fragilis, how small do 00:11:35.610 --> 00:11:38.269 I feel? You feel very, very small. An average 00:11:38.269 --> 00:11:41.309 adult is about 8 .5 meters long. That's 28 feet. 00:11:41.529 --> 00:11:44.169 That's a decent -sized yacht or a large moving 00:11:44.169 --> 00:11:46.750 truck. Good comparison. And the big ones, the 00:11:46.750 --> 00:11:48.769 ones that live long enough to really bulk up, 00:11:48.870 --> 00:11:52.370 could hit 9 .7 meters, maybe even 10 meters, 00:11:52.490 --> 00:11:55.789 so 32 feet or more. And weight. The weight estimates 00:11:55.789 --> 00:11:57.590 are all over the place, as they always are with 00:11:57.590 --> 00:12:00.509 extinct animals. But a good ballpark is 1 .5 00:12:00.509 --> 00:12:04.370 to 2 metric tons. So maybe 4 ,000 pounds? So 00:12:04.370 --> 00:12:07.169 significantly smaller than a T -Rex, which is 00:12:07.169 --> 00:12:09.830 like 7 to 9 tons. Oh, much lighter. A completely 00:12:09.830 --> 00:12:11.850 different weight class. But again, remember the 00:12:11.850 --> 00:12:14.309 fighter jet analogy. Allosaurus was built for 00:12:14.309 --> 00:12:17.269 athleticism. It had a massive skull, a short 00:12:17.269 --> 00:12:19.830 neck, and a long, stiff tail that acted as a 00:12:19.830 --> 00:12:21.950 counterbalance. And unlike the Tyrannosaurus, 00:12:22.250 --> 00:12:24.740 it had functional arms. It really did. to ask 00:12:24.740 --> 00:12:26.860 about that. T -Rex gets endlessly mocked for 00:12:26.860 --> 00:12:29.379 its tiny two -fingered arms, but Allosaurus was 00:12:29.379 --> 00:12:31.740 packing some serious heat in the upper body department. 00:12:31.980 --> 00:12:34.980 Oh, absolutely. The arms were robust, powerful, 00:12:35.159 --> 00:12:37.740 and about 35 % of the length of the legs. That 00:12:37.740 --> 00:12:40.059 is a very useful reach. And they ended in three 00:12:40.059 --> 00:12:42.740 fingers, each one tipped with a massive recurved 00:12:42.740 --> 00:12:45.580 claw. How big were the claws? The innermost claw, 00:12:45.840 --> 00:12:47.980 the thumb essentially, was huge. It could be 00:12:47.980 --> 00:12:51.159 over six inches long following the curve. They 00:12:51.159 --> 00:12:53.740 were like meat hooks. What were they doing with 00:12:53.740 --> 00:12:55.440 them? Were they slashing with them? Probably 00:12:55.440 --> 00:12:58.100 not slashing so much as grappling. The range 00:12:58.100 --> 00:13:00.139 of motion studies show they could reach forward 00:13:00.139 --> 00:13:03.220 and pull inwards with a lot of force. Imagine 00:13:03.220 --> 00:13:06.220 a linebacker grabbing you. Allosaurus could hook 00:13:06.220 --> 00:13:08.419 onto the side of a prey animal, digging those 00:13:08.419 --> 00:13:11.179 claws in to anchor itself, while the mouth did 00:13:11.179 --> 00:13:14.240 the real work. That's a horrifying image. Being 00:13:14.240 --> 00:13:16.759 hugged to death by three -inch hooks. It creates 00:13:16.759 --> 00:13:19.360 a stable platform for the bite. Which is good, 00:13:19.419 --> 00:13:22.279 because, speaking of the bite... Yeah. We need 00:13:22.279 --> 00:13:24.580 to talk about the skull, because this is where 00:13:24.580 --> 00:13:27.120 Allosaurus gets really, really weird. The horns 00:13:27.120 --> 00:13:29.200 first. Let's start with the decorations. It has 00:13:29.200 --> 00:13:31.320 those little horns over the eyes. The lacrimal 00:13:31.320 --> 00:13:33.679 horns, yeah. They sit right above and in front 00:13:33.679 --> 00:13:35.860 of the eye sockets. They give it that distinct, 00:13:36.019 --> 00:13:38.299 angry eyebrow look. Were they weapons? Could 00:13:38.299 --> 00:13:40.940 they headbutt with them? Unlikely. The bone itself 00:13:40.940 --> 00:13:43.299 is a bit too thin and hollow for high -impact 00:13:43.299 --> 00:13:45.440 smashing. If you headbutted another Allosaurus 00:13:45.440 --> 00:13:47.559 or a Stegosaurus, you might break your own skull. 00:13:47.799 --> 00:13:50.720 So what were they for? Sunshades. That's one 00:13:50.720 --> 00:13:53.480 idea. Maybe they helped keep the sun out of its 00:13:53.480 --> 00:13:56.179 eyes. But the leading theory is that they were 00:13:56.179 --> 00:13:59.399 for display. Like antlers on a deer. Precisely. 00:13:59.480 --> 00:14:02.200 In life, they would have been covered in a sheath 00:14:02.200 --> 00:14:05.059 of keratin, the same stuff as your fingernails 00:14:05.059 --> 00:14:08.580 or a bird's beak. That keratin sheath could have 00:14:08.580 --> 00:14:12.019 been much larger, pointier, and almost certainly 00:14:12.019 --> 00:14:14.299 brightly colored. So it could have had bright 00:14:14.299 --> 00:14:17.159 red eyebrows to say, look at me, I'm healthy, 00:14:17.259 --> 00:14:20.840 I'm dangerous. Or, I'm single and ready to mingle. 00:14:21.279 --> 00:14:24.179 It's all about signaling fitness to mates and 00:14:24.179 --> 00:14:26.539 rivals. Okay, so it had decent eyesight to see 00:14:26.539 --> 00:14:29.159 those displays. Pretty good, yeah. It's binocular 00:14:29.159 --> 00:14:31.559 vision. The area where the two eyes' fields of 00:14:31.559 --> 00:14:33.879 view overlap to give you depth perception was 00:14:33.879 --> 00:14:36.590 about 20 degrees wide. How does that compare? 00:14:36.830 --> 00:14:39.669 It's less than modern crocodilians, but it's 00:14:39.669 --> 00:14:41.830 definitely enough to judge distance for an attack. 00:14:42.049 --> 00:14:44.230 It wasn't just relying on spell. Okay, but the 00:14:44.230 --> 00:14:45.789 most important thing about the skull isn't the 00:14:45.789 --> 00:14:47.690 decoration, it's the mechanics. You called it 00:14:47.690 --> 00:14:51.250 cranial kinesis. Yes, cranial kinesis. It means 00:14:51.250 --> 00:14:54.429 moving skull. And that's different from a T -Rex. 00:14:54.929 --> 00:14:58.769 Completely different. A T -Rex skull is akinetic. 00:14:59.009 --> 00:15:02.159 It's fused. It's a solid block of bone, like 00:15:02.159 --> 00:15:04.759 a sledgehammer, designed to withstand massive 00:15:04.759 --> 00:15:08.600 crushing forces. An Allosaurus skull is not. 00:15:08.840 --> 00:15:11.580 Not at all. The joints between the different 00:15:11.580 --> 00:15:13.980 bones of the skull were loose. They could flex 00:15:13.980 --> 00:15:16.539 and move against each other. And the lower jaw 00:15:16.539 --> 00:15:19.899 was even stranger. It had a hinge, a joint, right 00:15:19.899 --> 00:15:21.600 in the middle that allowed it to bow outward. 00:15:21.940 --> 00:15:24.879 Bow outward. Think of a snake swallowing an egg, 00:15:24.960 --> 00:15:27.840 though not quite that extreme. As it opened its 00:15:27.840 --> 00:15:30.320 mouth, the lower jaws could splay out to the 00:15:30.320 --> 00:15:32.320 sides. Why would it do that? It dramatically 00:15:32.320 --> 00:15:34.759 increased the gait. It allowed the throat to 00:15:34.759 --> 00:15:37.179 widen and the animal to encompass a huge volume 00:15:37.179 --> 00:15:39.879 of flesh. In fact, studies show Allosaurus could 00:15:39.879 --> 00:15:42.779 open its jaws to an angle of 79 to 92 degrees. 00:15:43.059 --> 00:15:45.360 92 degrees? That's wider than a right angle. 00:15:45.500 --> 00:15:48.139 It's basically unhinging its face. It's a gaping 00:15:48.139 --> 00:15:51.110 maw of teeth. That's terrifying. But here's the 00:15:51.110 --> 00:15:52.870 thing that doesn't add up. Here's the paradox. 00:15:53.149 --> 00:15:55.649 Lay it on me. You have this massive gape. You 00:15:55.649 --> 00:15:58.929 have these scary serrated teeth. But when scientists 00:15:58.929 --> 00:16:01.029 ran the numbers on bite force, how hard it could 00:16:01.029 --> 00:16:04.309 actually clamp down, it came back shockingly 00:16:04.309 --> 00:16:06.730 low. Yeah, shockingly weak for an animal its 00:16:06.730 --> 00:16:09.009 size. How about low are we talking? Well, the 00:16:09.009 --> 00:16:11.350 estimates vary, but the highest are around 8 00:16:11.350 --> 00:16:15.250 ,700 newtons. The lowest are around 800. For 00:16:15.250 --> 00:16:18.309 comparison, a modern lion is about 4 ,000. A 00:16:18.309 --> 00:16:21.389 saltwater crocodile is over 16 ,000. And a T 00:16:21.389 --> 00:16:24.450 -Rex. A T -Rex is way up in the 30 ,000 to 50 00:16:24.450 --> 00:16:26.629 ,000 newton range. It's not even in the same 00:16:26.629 --> 00:16:29.230 league. So wait, let me get this straight. It's 00:16:29.230 --> 00:16:31.870 the top predator. It hunts giant long -necked 00:16:31.870 --> 00:16:36.070 dinosaurs. But it has the bite force of a large 00:16:36.070 --> 00:16:38.350 dog. That doesn't make any sense. It seems like 00:16:38.350 --> 00:16:40.690 a massive contradiction, doesn't it? If I'm an 00:16:40.690 --> 00:16:42.730 allosaurus and I bite a stegosaurus and I can't 00:16:42.730 --> 00:16:44.470 crush bone, isn't the stegosaurus going to shake 00:16:44.470 --> 00:16:46.929 me off and laugh? That's exactly what paleontologists 00:16:46.929 --> 00:16:49.649 asked for decades. How does this thing kill? 00:16:49.889 --> 00:16:52.730 And that question, that paradox, led to the hatchet 00:16:52.730 --> 00:16:54.789 attack theory. This is the Robert Baker theory, 00:16:54.889 --> 00:16:56.470 right? He's always coming up with these wild 00:16:56.470 --> 00:16:59.570 ideas. Yes, and it was later refined and tested 00:16:59.570 --> 00:17:02.629 by Emily Rayfield using a technique called finite 00:17:02.629 --> 00:17:05.359 element analysis. What's that? It's basically 00:17:05.359 --> 00:17:08.519 engineering software used to test stress on bridges 00:17:08.519 --> 00:17:11.779 or airplane wings. You build a digital model 00:17:11.779 --> 00:17:14.380 of the skull and apply forces to it to see where 00:17:14.380 --> 00:17:16.559 it's strong and where it's weak. And what did 00:17:16.559 --> 00:17:18.859 she find? She found that while the jaw muscles 00:17:18.859 --> 00:17:21.480 were relatively weak for biting, the skull itself 00:17:21.480 --> 00:17:25.299 was incredibly strong. But only in one specific 00:17:25.299 --> 00:17:28.359 direction. Vertical impact. Vertical impact, 00:17:28.660 --> 00:17:31.220 meaning top down, like a hammer striking a nail. 00:17:31.440 --> 00:17:35.559 Exactly. The skull could withstand over 55 ,000 00:17:35.559 --> 00:17:38.480 newtons of force, that's six times its own bite 00:17:38.480 --> 00:17:41.660 force, if that force came from the teeth slamming 00:17:41.660 --> 00:17:43.920 straight down into something. Okay, I think I 00:17:43.920 --> 00:17:45.599 see where this is going. So the theory goes like 00:17:45.599 --> 00:17:47.839 this. Allosaurus doesn't bite you like a dog 00:17:47.839 --> 00:17:50.140 or a lion. It doesn't clamp and hold. It's not 00:17:50.140 --> 00:17:52.579 a grappler. It's a slasher. It opens its mouth 00:17:52.579 --> 00:17:55.880 to that insane 92 degree angle. It rears its... 00:17:55.880 --> 00:17:58.180 its head high using its powerful neck muscles 00:17:58.180 --> 00:18:00.319 and then it swings its head down like a medieval 00:18:00.319 --> 00:18:02.960 battle axe. So it's face slamming the prey. It 00:18:02.960 --> 00:18:05.720 is driving the upper jaw, the maxilla, into the 00:18:05.720 --> 00:18:07.980 flesh. And you have to remember the teeth. The 00:18:07.980 --> 00:18:10.339 teeth of Allosaurus are serrated and recurved, 00:18:10.380 --> 00:18:12.980 but they're also laterally compressed. They're 00:18:12.980 --> 00:18:15.539 like steak knives. They aren't round spikes for 00:18:15.539 --> 00:18:18.420 crushing. They're flat blades for slicing. Precisely. 00:18:18.480 --> 00:18:21.900 So it slams the teeth in, anchors them, and then 00:18:21.900 --> 00:18:24.559 uses those powerful neck muscles to pull back, 00:18:24.759 --> 00:18:27.599 ripping out a massive chunk of meat. That sounds 00:18:27.599 --> 00:18:30.079 incredibly violent. But I have a physics question. 00:18:30.480 --> 00:18:33.220 If I slam my open mouth into a solid wall of 00:18:33.220 --> 00:18:36.660 muscle, am I not going to get a concussion or 00:18:36.660 --> 00:18:40.019 just break my jaw? That's where the cranial kinesis 00:18:40.019 --> 00:18:43.079 comes back in. The flexibility isn't a bug. It's 00:18:43.079 --> 00:18:46.180 a feature. When the skull hits the prey, all 00:18:46.180 --> 00:18:49.480 those loose joints flex slightly. The whole structure 00:18:49.480 --> 00:18:51.559 gives a little. It acts like a shock absorber, 00:18:51.599 --> 00:18:53.720 dissipating the energy of the impact across the 00:18:53.720 --> 00:18:55.640 whole skull so the bone doesn't shatter. It's 00:18:55.640 --> 00:18:58.769 a crumple zone for your face. Exactly. It's a 00:18:58.769 --> 00:19:00.970 beautifully engineered system for high speed, 00:19:01.089 --> 00:19:03.369 high impact slashing. You don't need a strong 00:19:03.369 --> 00:19:06.250 bite. It's a slash and bleed strategy. You don't 00:19:06.250 --> 00:19:08.869 crush the windpipe. You open a massive wound 00:19:08.869 --> 00:19:11.410 and let the prey go into shock or bleed out from 00:19:11.410 --> 00:19:14.109 a safe distance. It's surgical. Well, messy surgical. 00:19:14.410 --> 00:19:18.029 It's ruthlessly efficient. But it opens up a 00:19:18.029 --> 00:19:20.710 really, really disturbing possibility that some 00:19:20.710 --> 00:19:23.369 paleontologists have raised. And that's a strategy 00:19:23.369 --> 00:19:25.990 we might call flesh grazing. I hate the sound 00:19:25.990 --> 00:19:27.769 of that already. And you should. Think about 00:19:27.769 --> 00:19:30.289 the ecosystem. You have these giant sauropods 00:19:30.289 --> 00:19:32.710 wandering around, Diplodocus, Brachiosaurus, 00:19:32.990 --> 00:19:36.210 Apatosaurus. These things weigh 30, 50, maybe 00:19:36.210 --> 00:19:38.470 even 80 tons. They're walking mountains. Right. 00:19:38.569 --> 00:19:40.950 Even for a group of Allosaurus, trying to kill 00:19:40.950 --> 00:19:43.569 a healthy adult is incredibly hard work and very, 00:19:43.650 --> 00:19:45.309 very dangerous. You could get stepped on. You 00:19:45.309 --> 00:19:47.799 could get hit by a tank. It's a huge risk. So, 00:19:47.920 --> 00:19:51.480 what if you don't kill it? You just snack on 00:19:51.480 --> 00:19:54.240 it. You're a two -ton predator. You're hungry. 00:19:54.599 --> 00:19:57.880 You see a 50 -ton sauropod. You run up, use the 00:19:57.880 --> 00:20:00.440 hatchet attack to rip off a 50 -pound chunk of 00:20:00.440 --> 00:20:02.720 flesh from its flank or its tail. Then you just 00:20:02.720 --> 00:20:05.480 leave. And the sauropod is so big it just... 00:20:05.660 --> 00:20:09.460 It survives. The wound is serious, but not fatal. 00:20:09.660 --> 00:20:13.000 It scabs over, it heals. You come back three 00:20:13.000 --> 00:20:15.359 months later and do it again. So you're treating 00:20:15.359 --> 00:20:19.079 the prey like a renewable resource, like a parasitic 00:20:19.079 --> 00:20:22.259 relationship on a gigantic scale. Exactly. It 00:20:22.259 --> 00:20:25.299 changes the dynamic from predator versus prey 00:20:25.299 --> 00:20:27.799 to something more like host versus parasite. 00:20:29.059 --> 00:20:31.440 Imagine living your life as a sauropod, knowing 00:20:31.440 --> 00:20:34.619 that at any moment a lion of the Jurassic might 00:20:34.619 --> 00:20:37.220 come screaming out of the ferns, rip a piece 00:20:37.220 --> 00:20:38.900 of you off, and then just leave you to bleed. 00:20:39.059 --> 00:20:41.859 That is pure psychological horror. It's worse 00:20:41.859 --> 00:20:43.940 than being eaten alive. It's being eaten alive 00:20:43.940 --> 00:20:46.480 in installments. That is going to stick with 00:20:46.480 --> 00:20:49.640 me. It's speculation, of course, but the anatomy 00:20:49.640 --> 00:20:51.640 allows for it. Is everyone on board with the 00:20:51.640 --> 00:20:54.319 hatchet theory, though? Not entirely. There are 00:20:54.319 --> 00:20:56.660 alternative theories. Some researchers point 00:20:56.660 --> 00:20:58.880 out that there are no modern animals that hunt 00:20:58.880 --> 00:21:01.940 this way, which makes it hard to test. They suggest 00:21:01.940 --> 00:21:04.160 the strong neck was for resisting the pull of 00:21:04.160 --> 00:21:07.240 struggling prey. The big cat clam. Sort of, yeah. 00:21:07.460 --> 00:21:10.420 The idea is that they'd use those strong forelimbs 00:21:10.420 --> 00:21:13.420 to grapple the prey, hold it steady, and then 00:21:13.420 --> 00:21:16.619 use the jaws for a more conventional muscle -driven 00:21:16.619 --> 00:21:19.690 bite to the throat or soft underbelly. The wide 00:21:19.690 --> 00:21:21.809 gape isn't for a hatchet swing. It's just to 00:21:21.809 --> 00:21:24.109 get their mouth around a bigger chunk of animal. 00:21:24.289 --> 00:21:26.990 So the debate is still active. Very active. But 00:21:26.990 --> 00:21:29.470 the hatchet model does a great job of explaining 00:21:29.470 --> 00:21:32.049 the paradox of the weak bite and the strong skull. 00:21:32.269 --> 00:21:34.509 And we do know for a fact that they got into 00:21:34.509 --> 00:21:36.609 fights where the prey definitely fought back. 00:21:36.869 --> 00:21:39.049 Yeah. We have to talk about the Stegosaurus evidence. 00:21:39.329 --> 00:21:41.589 Yes. The ultimate Jurassic showdown. We have 00:21:41.589 --> 00:21:44.109 direct fossil evidence of their conflicts. It's 00:21:44.109 --> 00:21:46.849 like a prehistoric crime scene. Exhibit A. The 00:21:46.849 --> 00:21:49.450 thagomizer. The thagomizer. Yeah. That four -spike 00:21:49.450 --> 00:21:53.009 tail is a nasty, nasty weapon. And we found an 00:21:53.009 --> 00:21:55.730 Allosaurus tail vertebra, a bone from the base 00:21:55.730 --> 00:21:58.230 of the tail, with a massive puncture wound that 00:21:58.230 --> 00:22:00.569 goes straight through the bone. A hole. A perfectly 00:22:00.569 --> 00:22:03.089 circular hole. And when they measured it, the 00:22:03.089 --> 00:22:05.410 shape and size of the hole are a perfect match 00:22:05.410 --> 00:22:07.789 for a Stegosaurus tail spike. So an Allosaurus 00:22:07.789 --> 00:22:11.150 got smacked. Heart. Right in the tail. Probably 00:22:11.150 --> 00:22:13.190 as it was chasing the Stegosaurus. But here's 00:22:13.190 --> 00:22:16.869 the kicker. The bone had healed. There was smooth, 00:22:16.869 --> 00:22:19.950 rounded bone growth around the hole. The Allosaurus 00:22:19.950 --> 00:22:22.630 survived the fit. It limped away from that encounter. 00:22:23.079 --> 00:22:26.140 But on the flip side, we have a Stegosaurus neckplate, 00:22:26.400 --> 00:22:29.099 one of those big bony plates on its back with 00:22:29.099 --> 00:22:32.480 a huge U -shaped bite mark taken out of it. And 00:22:32.480 --> 00:22:34.720 that U -shape is a perfect fit for the snout 00:22:34.720 --> 00:22:37.079 of an Allosaurus. So these weren't just ships 00:22:37.079 --> 00:22:39.380 passing in the night. They were actively brawling. 00:22:39.480 --> 00:22:42.359 It was a brutal world. And nothing, absolutely 00:22:42.359 --> 00:22:45.359 nothing, illustrates just how brutal it was better 00:22:45.359 --> 00:22:47.380 than the story of Big Al. Let's talk about Al, 00:22:47.500 --> 00:22:49.599 because usually when we see a fossil, it's just 00:22:49.599 --> 00:22:52.519 a cool skeleton. An anatomical specimen. But 00:22:52.519 --> 00:22:56.460 Big Al is a biography. He is. He's specimen MOR693, 00:22:56.779 --> 00:23:00.759 found in Wyoming in 1991, about 95 % complete, 00:23:00.900 --> 00:23:02.700 which is incredible. And he wasn't fully grown, 00:23:02.839 --> 00:23:04.980 was he? No, he was a sub -adult. A teenager, 00:23:05.180 --> 00:23:08.019 really. Maybe 87 % grown, about 8 meters long. 00:23:08.359 --> 00:23:10.319 And when they examined his bones, they found 00:23:10.319 --> 00:23:12.500 that this animal lived a life of almost constant 00:23:12.500 --> 00:23:14.359 agony. What was the damage report? What did they 00:23:14.359 --> 00:23:17.579 find? He had 19 separate pathological injuries. 00:23:18.119 --> 00:23:21.759 19 documented traumas. 19. That's unbelievable. 00:23:21.859 --> 00:23:24.319 What kind of injuries? Let's see. He had several 00:23:24.319 --> 00:23:27.119 broken ribs that had healed, but healed poorly 00:23:27.119 --> 00:23:30.480 with big calluses. He had damage to his vertebrae. 00:23:30.599 --> 00:23:33.160 But the thing that likely led to his death was 00:23:33.160 --> 00:23:35.559 his right foot. The toe infection? The toe infection. 00:23:35.940 --> 00:23:38.579 His right middle toe, the main weight -bearing 00:23:38.579 --> 00:23:41.559 digit, was massively swollen. It had a condition 00:23:41.559 --> 00:23:44.829 called an involucrum. What's that? It's a shell 00:23:44.829 --> 00:23:47.410 of new bone that grows around a site of chronic 00:23:47.410 --> 00:23:50.890 festering infection. It suggests he had a raging 00:23:50.890 --> 00:23:54.910 case of osteomyelitis, a bone infection. So paint 00:23:54.910 --> 00:23:56.950 the picture for me. He is walking on this. He's 00:23:56.950 --> 00:23:59.529 trying to. Imagine a deep, throbbing infection 00:23:59.529 --> 00:24:03.089 in your foot filled with pus, the bone literally 00:24:03.089 --> 00:24:05.349 rotting from the inside out. And every time he 00:24:05.349 --> 00:24:07.470 took a step, he was putting tons of weight directly 00:24:07.470 --> 00:24:09.769 on that infection. The pain would have been blinding. 00:24:09.789 --> 00:24:11.799 And he survived with this for a while. The amount 00:24:11.799 --> 00:24:14.160 of bone growth suggests the infection was active 00:24:14.160 --> 00:24:16.599 for months, maybe as long as six months. How? 00:24:16.920 --> 00:24:19.460 I mean, how is that even possible? We just said 00:24:19.460 --> 00:24:21.279 this is a high -performance athletic predator. 00:24:21.619 --> 00:24:24.440 If you have a severe limp, you can't hunt. You 00:24:24.440 --> 00:24:27.259 starve. How does a crippled teenager survive 00:24:27.259 --> 00:24:29.819 for six months in the Jurassic? This is one of 00:24:29.819 --> 00:24:31.480 the great questions, and this is where we get 00:24:31.480 --> 00:24:33.559 into the debate about social behavior. Right. 00:24:33.619 --> 00:24:36.779 One theory, the heartwarming one, is that he 00:24:36.779 --> 00:24:40.059 had help. Maybe his family, his pack, brought 00:24:40.059 --> 00:24:42.680 him food. Maybe they protected him from other 00:24:42.680 --> 00:24:45.220 predators while he was vulnerable. The pack theory, 00:24:45.380 --> 00:24:47.599 it suggests a level of social care, maybe even 00:24:47.599 --> 00:24:51.799 altruism. It does, but I have to say, I'm skeptical. 00:24:52.099 --> 00:24:54.259 Why? You don't want to believe dinosaurs had 00:24:54.259 --> 00:24:56.799 feelings. I try to avoid anthropomorphizing. 00:24:57.609 --> 00:25:00.250 The alternative is that he was just incredibly, 00:25:00.269 --> 00:25:02.849 incredibly resilient. Maybe he switched to scavenging. 00:25:03.029 --> 00:25:05.329 Maybe he found a drying waterhole with trapped 00:25:05.329 --> 00:25:07.990 fish or dying animals he could eat without a 00:25:07.990 --> 00:25:10.150 fight. Or bullied smaller predators off their 00:25:10.150 --> 00:25:12.210 kills. Exactly. He might have spent those six 00:25:12.210 --> 00:25:14.230 months in a state of slow starvation, getting 00:25:14.230 --> 00:25:16.690 weaker and weaker, the infection spreading, until 00:25:16.690 --> 00:25:19.130 he finally just laid down at a dry riverbed and 00:25:19.130 --> 00:25:21.630 never got up. That's where they found him. That 00:25:21.630 --> 00:25:24.750 is just. It's a bleak story. But it brings us 00:25:24.750 --> 00:25:26.970 to the bigger question. Do they have friends? 00:25:27.289 --> 00:25:30.029 We see movies where allosaurs hunt in coordinated 00:25:30.029 --> 00:25:32.990 packs like wolves. Is there any truth to that? 00:25:33.170 --> 00:25:37.309 The evidence is tricky and very controversial. 00:25:37.490 --> 00:25:39.730 The main argument for packs comes from the Cleveland 00:25:39.730 --> 00:25:42.450 Lloyd Dinosaur Quarry in Utah. The place we mentioned 00:25:42.450 --> 00:25:44.470 earlier. This is the bone bed that's just off 00:25:44.470 --> 00:25:45.890 the charts, right? Completely off the charts. 00:25:45.970 --> 00:25:49.170 We have found over 12 ,000 individual bones there. 00:25:49.650 --> 00:25:53.529 And of all the dinosaurs found, 67 % of the bones 00:25:53.529 --> 00:25:56.309 are allosaurus. Two -thirds of all the fossils 00:25:56.309 --> 00:25:59.349 are from one species of predator. Yes. We have 00:25:59.349 --> 00:26:01.869 the remains of at least 46 individual allosaurus 00:26:01.869 --> 00:26:04.329 in one spot. We have babies. We have teenagers 00:26:04.329 --> 00:26:06.829 like Big Al. We have full -grown adults. So someone 00:26:06.829 --> 00:26:08.769 like Robert Baker looks at that and says, see? 00:26:08.970 --> 00:26:11.769 A pack. They lived together. They died together. 00:26:12.029 --> 00:26:14.430 Exactly. He argued it was a social group that 00:26:14.430 --> 00:26:16.829 got trapped, maybe trying to bring down a large 00:26:16.829 --> 00:26:19.369 herbivore that was stuck in the mud. He even 00:26:19.369 --> 00:26:21.970 suggested they had lairs and brought food back 00:26:21.970 --> 00:26:24.819 to the young. It's a nice image. It is. But modern 00:26:24.819 --> 00:26:26.680 interpretations are leaning towards something 00:26:26.680 --> 00:26:30.500 else. The predator trap concept is now seen less 00:26:30.500 --> 00:26:33.599 as a single event and more like sticky flypaper. 00:26:33.859 --> 00:26:36.880 Explain that model. So imagine a seasonal waterhole 00:26:36.880 --> 00:26:39.880 that during the dry season turns into a thick, 00:26:39.980 --> 00:26:43.980 sticky mud bog. Quicksand, essentially. A herbivore, 00:26:43.980 --> 00:26:46.910 like a Camarasaurus, comes to drink. gets stuck 00:26:46.910 --> 00:26:49.509 and starts panicking. It's bellowing, struggling. 00:26:49.849 --> 00:26:51.490 You have dinner bell. The loudest dinner bell 00:26:51.490 --> 00:26:54.190 in the Jurassic. An allosaurus hears it, comes 00:26:54.190 --> 00:26:56.990 in for an easy meal and gets stuck itself. Now 00:26:56.990 --> 00:26:59.430 you have two dying animals making even more noise. 00:26:59.549 --> 00:27:02.990 That attracts more predators and more. They get 00:27:02.990 --> 00:27:04.970 stuck, they die, they attract scavengers who 00:27:04.970 --> 00:27:07.309 then also get stuck. So it's not a social gathering, 00:27:07.369 --> 00:27:10.390 it's a pileup caused by greed. A feeding frenzy 00:27:10.390 --> 00:27:12.450 that went wrong for everyone involved. They aren't 00:27:12.450 --> 00:27:14.009 there because they like each other, they're there 00:27:14.009 --> 00:27:17.059 because they're opportunistic. And possibly cannibalistic. 00:27:17.240 --> 00:27:20.539 Oh, yes. There is clear evidence for cannibalism. 00:27:20.539 --> 00:27:22.940 We have allosaurus bones from the Morrison Formation 00:27:22.940 --> 00:27:25.279 that have bite marks on them, and the spacing 00:27:25.279 --> 00:27:27.539 of the serrations in those bite marks perfectly 00:27:27.539 --> 00:27:29.819 matches the teeth of other allosaurus. So they 00:27:29.819 --> 00:27:32.240 were eating each other. No doubt about it. We 00:27:32.240 --> 00:27:35.440 even find shed allosaurus teeth inside the rib 00:27:35.440 --> 00:27:38.779 cages of other allosaurus skeletons. This all 00:27:38.779 --> 00:27:41.740 supports the Komodo dragon model of social behavior, 00:27:42.059 --> 00:27:45.589 the mob. The mob. If you watch Komodo dragons 00:27:45.589 --> 00:27:48.289 today, they don't hunt in coordinated packs. 00:27:48.490 --> 00:27:50.490 But if there's a carcass, they all converge on 00:27:50.490 --> 00:27:52.789 it. They eat together, but it's not friendly. 00:27:52.930 --> 00:27:56.329 It's a violent, chaotic hierarchy. The big ones 00:27:56.329 --> 00:27:58.910 eat first. If a little one gets in the way, the 00:27:58.910 --> 00:28:01.710 big one kills it and eats it too. So if Big Al 00:28:01.710 --> 00:28:04.670 was limping around a carcass with a mob of other 00:28:04.670 --> 00:28:07.089 allosaurs... He was probably in more danger of 00:28:07.089 --> 00:28:09.170 becoming the main course than getting a handout. 00:28:09.529 --> 00:28:12.009 It paints a picture of the Jurassic that is much 00:28:12.009 --> 00:28:15.140 less... The land before time and much more Mad 00:28:15.140 --> 00:28:17.680 Max. A world of just constant, brutal competition. 00:28:18.099 --> 00:28:20.119 Exactly. And that competition wasn't just with 00:28:20.119 --> 00:28:22.359 their own kind. Let's zoom out a little bit from 00:28:22.359 --> 00:28:24.460 the behavior to the neighborhood. The Morrison 00:28:24.460 --> 00:28:27.440 Formation Ecosystem. We know Allosaurus was the 00:28:27.440 --> 00:28:29.380 most common predator, but it wasn't the only 00:28:29.380 --> 00:28:31.920 killer in town. No, it had some very serious 00:28:31.920 --> 00:28:35.859 competition. The two other main large theropods 00:28:35.859 --> 00:28:38.799 that lived alongside were Ceratosaurus and Torvosaurus. 00:28:39.259 --> 00:28:42.140 Torvosaurus. That name just sounds heavy. Savage 00:28:42.140 --> 00:28:44.940 lizard. And it was. Torvosaurus was a monster. 00:28:45.160 --> 00:28:47.660 It was rarer than Allosaurus, but it was bigger, 00:28:47.819 --> 00:28:50.440 maybe 10 meters long, and much more robustly 00:28:50.440 --> 00:28:54.400 built. It had a massive skull, huge dagger -like 00:28:54.400 --> 00:28:57.099 teeth. If Allosaurus is the wolf or the leopard 00:28:57.099 --> 00:28:59.160 of the Morrison... Torvosaurus is the grizzly 00:28:59.160 --> 00:29:01.779 bear. Perfect analogy. The brute force apex predator. 00:29:02.079 --> 00:29:04.640 And what about Ceratosaurus? Ceratosaurus is 00:29:04.640 --> 00:29:07.859 the weird one, the horned lizard. It had a prominent 00:29:07.859 --> 00:29:10.420 horn on its nose and two smaller horns over its 00:29:10.420 --> 00:29:13.539 eyes. It was smaller than Allosaurus, stockier, 00:29:13.680 --> 00:29:16.500 with a very deep, flexible tail that looks almost 00:29:16.500 --> 00:29:18.920 crocodile -like, and its teeth were disproportionately 00:29:18.920 --> 00:29:21.700 huge. So how do you have three top -tier predators 00:29:21.700 --> 00:29:23.880 living in the same zip code without them constantly 00:29:23.880 --> 00:29:26.799 fighting and wiping each other out? Niche partitioning. 00:29:26.799 --> 00:29:28.839 It's the roommate agreement of nature. I like 00:29:28.839 --> 00:29:31.140 that. You take the top shelf, I take the crisper 00:29:31.140 --> 00:29:33.240 drawer, and we don't fight over the leftovers. 00:29:33.680 --> 00:29:35.680 They were likely specializing in different prey 00:29:35.680 --> 00:29:37.559 or different environments. So what was the breakdown? 00:29:38.009 --> 00:29:40.430 The general thinking is that Allosaurus was the 00:29:40.430 --> 00:29:42.609 generalist. It had longer legs. It was probably 00:29:42.609 --> 00:29:45.369 faster. It was adaptable. It likely patrolled 00:29:45.369 --> 00:29:48.029 the open floodplains, hunting a wide variety 00:29:48.029 --> 00:29:50.970 of prey like Camptosaurus or young sauropods. 00:29:51.069 --> 00:29:53.549 And the others. Ceratosaurus, with that flexible 00:29:53.549 --> 00:29:56.829 tail and lower -slung body, probably stuck closer 00:29:56.829 --> 00:29:59.710 to the waterways, the rivers, and lakes. Maybe 00:29:59.710 --> 00:30:02.230 it hunted fish, crocodiles, or ambushed prey 00:30:02.230 --> 00:30:04.769 that came to drink. And the bear. Torvosaurus. 00:30:05.109 --> 00:30:07.710 Torvosaurus was likely the specialist in hunting 00:30:07.710 --> 00:30:10.730 giants. It used its immense size and power to 00:30:10.730 --> 00:30:13.529 tackle the largest prey, maybe adult stegosaurs 00:30:13.529 --> 00:30:16.470 or subadult sauropods that Allosaurus might have 00:30:16.470 --> 00:30:19.279 hesitated to attack alone. But in the end? Allosaurus 00:30:19.279 --> 00:30:22.259 won the numbers game. By a landslide. In most 00:30:22.259 --> 00:30:25.299 parts of the Morrison, something like 75 % of 00:30:25.299 --> 00:30:27.480 the theropod fossils we find are Allosaurus. 00:30:28.140 --> 00:30:30.619 It was a coyote of the Jurassic. It could live 00:30:30.619 --> 00:30:33.000 anywhere, eat anything, and recover from these 00:30:33.000 --> 00:30:35.599 crazy, life -threatening injuries. It was the 00:30:35.599 --> 00:30:37.759 ultimate survivor. I have to ask about one more 00:30:37.759 --> 00:30:39.460 name before we wrap up because it gets thrown 00:30:39.460 --> 00:30:42.380 around a lot. Saurificanax? The lord of lizard 00:30:42.380 --> 00:30:44.880 eaters. It sounds like a final boss in a video 00:30:44.880 --> 00:30:47.500 game. For a long time, people said this was a 00:30:47.500 --> 00:30:50.059 separate, even bigger predator. What's the current 00:30:50.059 --> 00:30:52.700 thinking? It's messy, and it's a perfect example 00:30:52.700 --> 00:30:55.559 of how science is always updating itself. Saur 00:30:55.559 --> 00:30:58.119 faginax was found in Oklahoma from rocks of the 00:30:58.119 --> 00:31:01.140 same age. The bones are huge, indicating an animal 00:31:01.140 --> 00:31:04.359 over 10 meters, maybe 11 or 12, a true giant. 00:31:04.880 --> 00:31:08.630 For years, the debate was. is it its own unique 00:31:08.630 --> 00:31:11.589 genus or is it just a really really big allosaurus 00:31:11.589 --> 00:31:14.309 what some called allosaurus maximus meaning the 00:31:14.309 --> 00:31:16.589 greatest different lizard right but a study came 00:31:16.589 --> 00:31:19.890 out very recently in 2024 that threw a massive 00:31:19.890 --> 00:31:22.430 wrench in the works they re -examined the holotype 00:31:22.430 --> 00:31:24.950 the original defining specimen and found that 00:31:24.950 --> 00:31:27.619 it was a chimera a chimera, like the mythological 00:31:27.619 --> 00:31:30.319 beast. In mythology, a chimera is a beast made 00:31:30.319 --> 00:31:32.880 of different animal parts. In paleontology, it 00:31:32.880 --> 00:31:35.200 means the person who collected or described the 00:31:35.200 --> 00:31:37.099 bones accidentally mixed up two different animals 00:31:37.099 --> 00:31:39.019 and thought they were one. No way. It happens. 00:31:39.339 --> 00:31:41.700 It turns out some of the bones originally assigned 00:31:41.700 --> 00:31:46.000 to sauropod bones that got mixed in. Big oops. 00:31:46.500 --> 00:31:49.660 So the validity of the name sauropod is on very 00:31:49.660 --> 00:31:52.440 shaky ground now. However, the actual theropod 00:31:52.440 --> 00:31:54.599 bones that are in the mix are distinct enough 00:31:54.599 --> 00:31:57.819 from allosaurus to likely be their own species. 00:31:58.279 --> 00:32:00.799 So the current thinking is pushing toward renaming 00:32:00.799 --> 00:32:05.039 it Allosaurus Anax. Allosaurus Anax, King Allosaurus. 00:32:05.440 --> 00:32:08.839 Exactly. It confirms that this body plan, the 00:32:08.839 --> 00:32:11.619 hatchet -wielding, loose -skulled, fast -slashing 00:32:11.619 --> 00:32:14.700 design, was scalable. It could get truly massive 00:32:14.700 --> 00:32:16.940 and challenge even something like Torvosaurus 00:32:16.940 --> 00:32:19.480 for the title of heavyweight champion. So when 00:32:19.480 --> 00:32:21.359 we step back into our time machine and leave 00:32:21.359 --> 00:32:23.799 the Jurassic... What is the lasting image we 00:32:23.799 --> 00:32:25.940 should have of Allosaurus? It's not the T -Rex. 00:32:26.099 --> 00:32:28.299 It's not the bone crusher. No, it's the slasher. 00:32:28.400 --> 00:32:30.319 It's the ultimate opportunist. It's an animal 00:32:30.319 --> 00:32:32.299 that lived fast, died young, and threw its body 00:32:32.299 --> 00:32:34.859 into the fray with reckless abandon. Think of 00:32:34.859 --> 00:32:38.220 Big Al. It survived 19 major traumas. It dominated 00:32:38.220 --> 00:32:40.099 its world, not because it was the biggest or 00:32:40.099 --> 00:32:42.200 the strongest, but because it was the most adaptable, 00:32:42.200 --> 00:32:44.680 aggressive, and widespread engineering marvel 00:32:44.680 --> 00:32:47.599 of its time. And for me, the image that's going 00:32:47.599 --> 00:32:50.769 to stick is that idea of flesh grazing. It's 00:32:50.769 --> 00:32:53.170 so much more terrifying than a clean kill. The 00:32:53.170 --> 00:32:55.630 idea of a predator that doesn't even grant you 00:32:55.630 --> 00:32:58.710 the mercy of death, but just farms you. It's 00:32:58.710 --> 00:33:03.089 a grim world. Nature isn't cruel, but it is profoundly, 00:33:03.190 --> 00:33:06.390 deeply indifferent. And for 10 million years, 00:33:06.650 --> 00:33:08.890 Allosaurus was the master of that indifference. 00:33:09.170 --> 00:33:10.670 Well, on that cheerful note, we're going to wrap 00:33:10.670 --> 00:33:12.549 up this deep dive. Whether you're Team Hatchet 00:33:12.549 --> 00:33:15.230 Attack or Team Big Cat Clamp, there is no denying 00:33:15.230 --> 00:33:17.960 that the Different lizard deserves way more respect 00:33:17.960 --> 00:33:20.619 than just being T -Rex's opening act. Absolutely. 00:33:20.660 --> 00:33:23.220 A true king in its own right for its own time. 00:33:23.420 --> 00:33:25.279 Thanks for listening. Keep those questions coming. 00:33:25.339 --> 00:33:27.660 Keep digging. And as always, stay curious. We'll 00:33:27.660 --> 00:33:28.380 see you on the next dive.