WEBVTT 00:00:00.000 --> 00:00:03.100 I want you to picture something. You're walking 00:00:03.100 --> 00:00:06.299 through this really dense, semi -arid floodplain. 00:00:06.320 --> 00:00:08.880 OK, to set in the sea. Yeah. And the air is just 00:00:08.880 --> 00:00:11.919 thick. There are these slow, meandering rivers 00:00:11.919 --> 00:00:15.320 everywhere. And suddenly, stepping right out 00:00:15.320 --> 00:00:18.859 from the reeds is an absolute monster. A real 00:00:18.859 --> 00:00:21.460 nightmare. Exactly. We're talking about a 30 00:00:21.460 --> 00:00:24.500 -foot long apex predator. It's got this massive 00:00:24.500 --> 00:00:26.980 sail jutting out of its back. four limbs that 00:00:26.980 --> 00:00:30.320 are thick enough to wrestle a boulder and this 00:00:30.320 --> 00:00:34.460 really long, narrow snout that looks, well, looks 00:00:34.460 --> 00:00:37.200 incredibly similar to a crocodile's. Which is 00:00:37.200 --> 00:00:39.520 terrifying in its own right. Right. It is just 00:00:39.520 --> 00:00:41.899 a completely dominant giant of its ecosystem. 00:00:42.820 --> 00:00:44.740 But here is the paradox we're exploring today 00:00:44.740 --> 00:00:47.079 for you. Practically everything we know about 00:00:47.079 --> 00:00:48.979 this massive creature comes from something so 00:00:48.979 --> 00:00:50.719 small, you could literally just close your hand 00:00:50.719 --> 00:00:53.259 around it. Yeah, it's actually kind of wild when 00:00:53.259 --> 00:00:55.280 you think about it. It really is. Because we 00:00:55.280 --> 00:00:57.460 were talking about just a scattering of isolated 00:00:57.460 --> 00:00:59.899 teeth. Right, it's a total master class in forensic 00:00:59.899 --> 00:01:01.880 reconstruction. I mean, we are looking at an 00:01:01.880 --> 00:01:04.400 animal that is essentially a ghost built entirely 00:01:04.400 --> 00:01:07.719 out of these tiny dental scraps. So our mission 00:01:07.719 --> 00:01:10.239 for this deep dive is to explore the Wikipedia 00:01:10.239 --> 00:01:14.159 article on Siamisaurus, which literally translates 00:01:14.159 --> 00:01:17.719 to Siam Lizard. A very fitting name. Yeah, and 00:01:17.719 --> 00:01:19.599 we're going straight into the mechanics of how 00:01:19.599 --> 00:01:23.000 paleontologists can take a handful of these fluted 00:01:23.000 --> 00:01:26.239 teeth and somehow reverse engineer an entire 00:01:26.239 --> 00:01:28.640 tree historic lifestyle. Not to mention a highly 00:01:28.640 --> 00:01:31.319 specialized diet. Exactly, and even a global 00:01:31.319 --> 00:01:34.760 ecosystem. And, you know, inevitably we have 00:01:34.760 --> 00:01:36.799 to talk about the fierce scientific debates that 00:01:36.799 --> 00:01:39.140 break out when you try to construct a 30 -foot 00:01:39.140 --> 00:01:42.239 dinosaur without an actual skull. The drama of 00:01:42.239 --> 00:01:44.439 paleontology. Oh, there's always drama. OK, let's 00:01:44.439 --> 00:01:47.120 unpack this. To set the stage, we are in early 00:01:47.120 --> 00:01:51.319 Cretaceous Thailand, so roughly 113 to 129 million 00:01:51.319 --> 00:01:53.780 years ago. Right, during the Boromian to Aption 00:01:53.780 --> 00:01:55.879 ages. Yep. And the story starts in the early 00:01:55.879 --> 00:01:59.299 1980s with two paleontologists, Eric Buffetot 00:01:59.299 --> 00:02:02.120 and Rucha Ingavat, working in the Salkufa formation. 00:02:02.299 --> 00:02:04.260 They were doing some incredible field work there. 00:02:04.359 --> 00:02:06.560 They really were. and they pull some teeth out 00:02:06.560 --> 00:02:09.240 of the dirt and immediately, instantly, the scientific 00:02:09.240 --> 00:02:11.500 community is thrown into a debate over whether 00:02:11.500 --> 00:02:14.280 these teeth even belong to a dinosaur. And to 00:02:14.280 --> 00:02:16.620 be fair, the skepticism was entirely justified. 00:02:16.759 --> 00:02:19.819 Really? Just from teeth? Oh yeah. In paleontology, 00:02:20.000 --> 00:02:22.020 if a creature is known confidently only from 00:02:22.020 --> 00:02:24.960 teeth, so without a skull, without a skeletal 00:02:24.960 --> 00:02:27.379 frame attached to it, it gets slapped with the 00:02:27.379 --> 00:02:31.919 label of a dubious genus. Ouch. Dubious. That 00:02:31.919 --> 00:02:35.599 sounds like a diss. Kind of is. So when Buffetot 00:02:35.599 --> 00:02:38.719 and Ingevat formally described Psymosaurus suthothorny 00:02:38.719 --> 00:02:42.139 in 1986, it was this massive claim because it 00:02:42.139 --> 00:02:44.699 was the first reported spinosaurid from Asia. 00:02:44.780 --> 00:02:47.759 Which is a huge deal. A huge deal. But critics 00:02:47.759 --> 00:02:49.800 looked at the teeth and argued, well, they could 00:02:49.800 --> 00:02:53.159 easily belong to a crocodilian. Or maybe a long 00:02:53.159 --> 00:02:55.719 -necked marine reptile like a plesiosaur. Oh, 00:02:55.719 --> 00:02:58.319 wow. Or perhaps even just a giant prehistoric 00:02:58.319 --> 00:03:01.110 fish. I love that initial debate, honestly, because 00:03:01.110 --> 00:03:04.050 it captures how messy this science can be. I 00:03:04.050 --> 00:03:05.689 mean, it's kind of like wandering into the woods, 00:03:05.789 --> 00:03:09.009 finding a strange rusted hubcap in the dirt and 00:03:09.009 --> 00:03:11.090 having to prove beyond a shadow of a doubt that 00:03:11.090 --> 00:03:14.169 it fell off a highly specific rare Italian sports 00:03:14.169 --> 00:03:16.949 car. Right. And not just, you know, some local 00:03:16.949 --> 00:03:19.289 farmer's tractor. You have to find that exact 00:03:19.289 --> 00:03:21.930 engineering signature. That is a brilliant way 00:03:21.930 --> 00:03:25.849 to visualize it because form absolutely follows 00:03:25.849 --> 00:03:29.229 function in biology. What's fascinating here 00:03:29.229 --> 00:03:32.669 is the concept of convergent evolution. Right, 00:03:32.830 --> 00:03:35.849 which is, remind me, that's when different animals 00:03:35.849 --> 00:03:38.930 evolve the same traits. Exactly. If different 00:03:38.930 --> 00:03:41.729 animals are doing the exact same job, nature 00:03:41.729 --> 00:03:44.250 tends to equip them with the exact same tools. 00:03:45.189 --> 00:03:47.490 So if you make your living catching slippery 00:03:47.490 --> 00:03:51.270 fish in a river, a long, narrow snout and cone 00:03:51.270 --> 00:03:53.629 -shaped teeth are going to evolve. Regardless 00:03:53.629 --> 00:03:55.710 of what you started at? Yes. whether you are 00:03:55.710 --> 00:03:58.810 a theropod dinosaur, a crocodilian, or some swimming 00:03:58.810 --> 00:04:01.229 reptile. So to separate the sports car from the 00:04:01.229 --> 00:04:04.229 tractor, Bufatot and Engavat had to look past 00:04:04.229 --> 00:04:06.090 the obvious shape. They had to really analyze 00:04:06.090 --> 00:04:07.610 the microarchitecture of the teeth. And they 00:04:07.610 --> 00:04:09.629 went deep into it. Yeah, from the source material, 00:04:09.870 --> 00:04:11.650 it seems the key difference was in the geometry. 00:04:12.530 --> 00:04:14.250 Like, crocodilian teeth and plesiosaur teeth 00:04:14.250 --> 00:04:16.589 typically have this distinct curve to them. They 00:04:16.589 --> 00:04:18.509 hook backward, right? Right, to keep prey from 00:04:18.509 --> 00:04:20.410 pulling away. Both the simosaurs' teeth were 00:04:20.410 --> 00:04:23.370 straighter. much straighter, and their base indicated 00:04:23.370 --> 00:04:26.069 they were inserted vertically into the jaw rather 00:04:26.069 --> 00:04:28.610 than angled outward like you often see in those 00:04:28.610 --> 00:04:31.449 long, snouted, fish -eating crocodilians. OK, 00:04:31.449 --> 00:04:33.629 so that's one clue. But the real smoking gun 00:04:33.629 --> 00:04:37.269 was the texture. These teeth featured these highly 00:04:37.269 --> 00:04:40.709 specific lengthwise grooves running down the 00:04:40.709 --> 00:04:43.069 crown, which we call flutes. Flutes, yeah. There 00:04:43.069 --> 00:04:46.089 were about 15 of these flutes on each side of 00:04:46.089 --> 00:04:48.750 the tooth, running almost the entire length down 00:04:48.750 --> 00:04:51.290 to the dentin. I was reading about those flutes, 00:04:52.029 --> 00:04:54.290 and structurally, they act almost like the ridges 00:04:54.290 --> 00:04:56.949 on a Roman column, don't they? Like, adding incredible 00:04:56.949 --> 00:04:59.689 strength to a relatively thin tooth. Exactly. 00:04:59.769 --> 00:05:02.509 So it doesn't snap when a heavy fish is thrashing 00:05:02.509 --> 00:05:04.350 around in its mouth. That makes so much sense. 00:05:04.569 --> 00:05:06.930 That biomechanical scaffolding is exactly what 00:05:06.930 --> 00:05:09.310 gave them away. Plus, the researchers analyzed 00:05:09.310 --> 00:05:11.829 the cross -section. Crocodiles and plesiosaurs 00:05:11.829 --> 00:05:14.850 have different, often more de -shaped or flattened 00:05:14.850 --> 00:05:16.970 profiles. Whereas these were different. Yeah, 00:05:17.110 --> 00:05:19.769 these teeth were oval to near circular. So when 00:05:19.769 --> 00:05:22.009 you stack up all those subtle geometric clues, 00:05:22.149 --> 00:05:24.410 the vertical alignment, the circular cross section, 00:05:24.509 --> 00:05:28.370 the 15 flutes, they point entirely away from 00:05:28.370 --> 00:05:31.550 marine reptiles. And firmly toward a spinosaur 00:05:31.550 --> 00:05:34.449 and dinosaur. Bingo. OK, so the hubcap definitely 00:05:34.449 --> 00:05:36.870 belongs to the sports car. We have a dinosaur. 00:05:37.910 --> 00:05:40.490 But I mean, that brings up an even bigger logical 00:05:40.490 --> 00:05:42.970 leap for me. OK, what's that? We still just have 00:05:42.970 --> 00:05:45.709 teeth. How do we get from a handful of straight 00:05:45.709 --> 00:05:49.009 fluted teeth to picturing this animal with massive 00:05:49.009 --> 00:05:52.290 robust forelimbs and a giant sail on its back? 00:05:52.509 --> 00:05:54.589 That feels like, I don't know, drawing a whole 00:05:54.589 --> 00:05:56.629 house just because you found a doorknob. It does 00:05:56.629 --> 00:05:58.290 sound like a massive leap until you understand 00:05:58.290 --> 00:06:00.730 the strict comparative anatomy paleontologists 00:06:00.730 --> 00:06:03.439 rely on. Okay, walk me through it. Once you constantly 00:06:03.439 --> 00:06:06.000 identify those teeth as belonging to a spinosaurid, 00:06:06.220 --> 00:06:07.939 you can essentially pull the blueprints of its 00:06:07.939 --> 00:06:10.600 closest relatives. Ah, I see. The teeth of cymosaurs 00:06:10.600 --> 00:06:13.300 completely lack the jagged, steak -knife serrations 00:06:13.300 --> 00:06:16.560 you see on an apex predator like a T. rex. Furthermore, 00:06:16.959 --> 00:06:19.579 they had a very specific, finely wrinkled, almost 00:06:19.579 --> 00:06:22.660 granular enamel texture. And that matches something 00:06:22.660 --> 00:06:25.439 else we already know about. Exactly. Those exact 00:06:25.439 --> 00:06:28.040 traits perfectly matched well -known, much more 00:06:28.040 --> 00:06:30.160 complete spinosaurids that had been discovered 00:06:30.160 --> 00:06:32.660 in other parts of the world. Like baryonyx found 00:06:32.660 --> 00:06:35.579 in Europe, right? Yeah. Or the really famous 00:06:35.579 --> 00:06:38.319 one, spinosaurus from Africa. Yes. We have a 00:06:38.319 --> 00:06:41.680 substantial articulated skeletons of those animals. 00:06:42.040 --> 00:06:44.680 So we know exactly what kind of body goes with 00:06:44.680 --> 00:06:47.500 that specific dental hardware. Because, like 00:06:47.500 --> 00:06:50.279 you said, form follows function. Right, and biology 00:06:50.279 --> 00:06:53.560 doesn't operate in a vacuum. If cymosaurus possesses 00:06:53.560 --> 00:06:56.139 the identical, highly specialized dental hardware 00:06:56.139 --> 00:06:59.139 of its cousins, it requires the same biological 00:06:59.139 --> 00:07:01.339 software and skeletal framing to operate it. 00:07:01.500 --> 00:07:03.660 Meaning you need the right muscles. Exactly. 00:07:03.860 --> 00:07:06.699 You cannot wield a heavy fish -smashing jaw without 00:07:06.699 --> 00:07:08.959 the specific neck musculature to strike quickly. 00:07:09.379 --> 00:07:12.360 And you need the powerful, robust forelimbs characteristic 00:07:12.360 --> 00:07:15.060 of the spinosaur family to pin down the heavy 00:07:15.060 --> 00:07:17.139 aquatic prey you're pulling out of the water. 00:07:17.500 --> 00:07:20.660 So, therefore, scientists can confidently infer 00:07:20.660 --> 00:07:23.560 the broader anatomy. Okay, I understand the logic 00:07:23.560 --> 00:07:26.259 of the blueprint. But wait, the fossil record 00:07:26.259 --> 00:07:28.839 did eventually throw us a bone, didn't it? Literally. 00:07:29.300 --> 00:07:32.240 Oh, yes, it did. I want to talk about the 2004 00:07:32.240 --> 00:07:34.620 discovery in the co -crued formation because, 00:07:34.839 --> 00:07:37.730 honestly, This part of the story drove me crazy. 00:07:38.490 --> 00:07:41.730 Ah, specimen SMKK 14. Yes. This is arguably one 00:07:41.730 --> 00:07:44.170 of the most agonizing teases in the history of 00:07:44.170 --> 00:07:46.250 the field. It's so frustrating. In a younger 00:07:46.250 --> 00:07:49.129 rock formation, an incomplete skeleton was finally 00:07:49.129 --> 00:07:53.149 excavated. It had neck and back vertebrae, hip 00:07:53.149 --> 00:07:56.470 fragments, and, crucially, a massive neural spine 00:07:56.470 --> 00:07:59.069 measuring over 60 centimeters tall. Which is 00:07:59.069 --> 00:08:01.410 the exact bone structure that creates a giant 00:08:01.410 --> 00:08:04.189 sail on the back. It clearly belonged to a massive 00:08:04.189 --> 00:08:06.629 spinosaur, matching the exact physical profile 00:08:06.629 --> 00:08:08.529 we just talked about. It's a perfect match, physically, 00:08:08.709 --> 00:08:10.910 yes. And more importantly, they found a cymosaurus 00:08:10.910 --> 00:08:13.250 tooth sitting right nearby in the exact same 00:08:13.250 --> 00:08:15.250 immediate area. So I have to push back here. 00:08:15.370 --> 00:08:17.610 I figured you might. I mean, you predict a sail 00:08:17.610 --> 00:08:20.009 -backed dinosaur. You find a sail -backed skeleton. 00:08:20.350 --> 00:08:22.209 You find a cymosaurus tooth right next to it. 00:08:22.600 --> 00:08:25.720 How is this not an open and shut case? Why does 00:08:25.720 --> 00:08:27.779 the scientific community still insist on calling 00:08:27.779 --> 00:08:31.220 cymosaurus a dubious genus known only from teeth? 00:08:31.420 --> 00:08:34.000 Isn't that just paleontology being, I don't know, 00:08:34.200 --> 00:08:37.000 overly pedantic? I completely understand the 00:08:37.000 --> 00:08:39.980 frustration. But this raises an important question 00:08:39.980 --> 00:08:43.000 about the burden of proof in science. Because 00:08:43.000 --> 00:08:45.200 while it absolutely could be the skeleton of 00:08:45.200 --> 00:08:48.659 a cymosaurus, it could also be a prehistoric 00:08:48.659 --> 00:08:51.500 crime scene. A crime scene? What, you mean the 00:08:51.500 --> 00:08:53.600 skeleton and the tooth belong to two entirely 00:08:53.600 --> 00:08:55.960 different animals interacting? Precisely. The 00:08:55.960 --> 00:08:58.759 tooth they found was isolated? It was not rooted 00:08:58.759 --> 00:09:01.340 in a jawbone attached to that spine. Oh, wow. 00:09:01.500 --> 00:09:04.600 Yeah. We know that theropod dinosaurs shed their 00:09:04.600 --> 00:09:06.759 teeth frequently, especially when feeding or 00:09:06.759 --> 00:09:09.480 tearing at bone. Right, like sharks. Exactly. 00:09:09.940 --> 00:09:12.899 So the alternative hypothesis, which is just 00:09:12.899 --> 00:09:16.000 as statistically likely, is that this massive 00:09:16.000 --> 00:09:18.940 sail -backed skeleton belongs to a completely 00:09:18.940 --> 00:09:21.480 different as yet unknown animal. And the cymosaurus 00:09:21.480 --> 00:09:23.179 was just there for dinner. A cymosaurus might 00:09:23.179 --> 00:09:25.539 have simply wandered by after that animal died, 00:09:25.799 --> 00:09:27.659 started scavenging on the carcass. and snapped 00:09:27.659 --> 00:09:30.580 off a tooth in the process. That is wild. Without 00:09:30.580 --> 00:09:32.879 teeth directly rooted into the skull of that 00:09:32.879 --> 00:09:35.240 specific skeleton, you cannot scientifically 00:09:35.240 --> 00:09:36.980 prove they are the same entity. You just have 00:09:36.980 --> 00:09:40.460 to accept the ambiguity. OK, that is maddening. 00:09:40.940 --> 00:09:43.519 But I have to admit, the logic absolutely holds 00:09:43.519 --> 00:09:45.940 up. And you know, it also highlights just how 00:09:45.940 --> 00:09:47.840 specialized these teeth were. How do you mean? 00:09:48.200 --> 00:09:50.279 Well, if they're snapping off while scavenging, 00:09:50.659 --> 00:09:52.600 it proves they weren't designed for tearing into 00:09:52.600 --> 00:09:56.730 heavy dinosaur flanks. Ah, yes. Very true. So 00:09:56.730 --> 00:09:58.950 let's look at the mechanics of survival. Yeah. 00:09:59.210 --> 00:10:01.889 If those straight, unsurrated teeth would snap 00:10:01.889 --> 00:10:04.710 when trying to tear flesh like a standard raptor, 00:10:05.230 --> 00:10:07.710 how is this 30 -foot animal getting enough calories 00:10:07.710 --> 00:10:10.370 to sustain itself? Think about the physics of 00:10:10.370 --> 00:10:13.549 a fishing spear. OK. A spear is not designed 00:10:13.549 --> 00:10:16.649 to slice or tear. It is meant to penetrate quickly, 00:10:16.909 --> 00:10:19.529 puncture deeply, and hold on to a thrashing, 00:10:19.809 --> 00:10:22.049 slippery target without snapping. Which is exactly 00:10:22.049 --> 00:10:24.389 what a straight, conical, unsurrated tooth does. 00:10:24.629 --> 00:10:27.850 Exactly. This strongly points to a highly paciferous 00:10:27.850 --> 00:10:31.509 or fish -eating lifestyle. To support this, biomechanical 00:10:31.509 --> 00:10:33.830 models suggest they likely had a snat tip that 00:10:33.830 --> 00:10:36.509 flared out into a rosette shape. A rosette shape? 00:10:36.590 --> 00:10:38.690 Yeah, very similar to modern gharials living 00:10:38.690 --> 00:10:42.009 in India today. Oh, right! And that rosette shape 00:10:42.009 --> 00:10:44.350 basically creates a wider snare at the end of 00:10:44.350 --> 00:10:47.149 the jaw, giving them a larger surface area to 00:10:47.149 --> 00:10:49.570 snap up quick aquatic prey darting through the 00:10:49.570 --> 00:10:51.929 water. It's a perfect fish trap. But they weren't 00:10:51.929 --> 00:10:54.610 exclusively eating fish, right? Because the source 00:10:54.610 --> 00:10:57.490 notes mentioned the Wat Sakawan locality, where 00:10:57.490 --> 00:10:59.809 cymosaurus teeth were found mixed in with the 00:10:59.809 --> 00:11:03.429 remains of massive long -necked sauropod dinosaurs. 00:11:04.529 --> 00:11:06.990 The terrestrial giants. Which perfectly ties 00:11:06.990 --> 00:11:09.690 back to our scavenger hypothesis from earlier. 00:11:09.929 --> 00:11:12.590 The presence of their teeth alongside sauropod 00:11:12.590 --> 00:11:15.350 bones proves they were highly opportunistic. 00:11:15.470 --> 00:11:17.350 So they wouldn't turn down a free meal? Never. 00:11:17.669 --> 00:11:19.870 They were primary fish eaters, but if a drought 00:11:19.870 --> 00:11:22.250 hit, or if they stumbled across the carcass of 00:11:22.250 --> 00:11:25.149 a terrestrial giant, or perhaps even actively 00:11:25.149 --> 00:11:28.009 hunted young ones, they possessed the size and 00:11:28.009 --> 00:11:30.250 the leverage to take advantage of it. Here's 00:11:30.250 --> 00:11:33.149 where it gets really interesting for me. If I'm 00:11:33.149 --> 00:11:35.909 visualizing this, we are basically talking about 00:11:35.909 --> 00:11:39.009 a 30 -foot, heavily armed, sail -backed heron 00:11:39.009 --> 00:11:41.190 that also occasionally snacks on long -necked 00:11:41.190 --> 00:11:43.629 dinosaurs. That is quite the image. It's an incredible 00:11:43.629 --> 00:11:48.490 image. But a heron is a waiting bird. How do 00:11:48.490 --> 00:11:51.029 we actually know Psymosaurus spent the majority 00:11:51.029 --> 00:11:54.029 of its life in the water, rather than just hunting 00:11:54.029 --> 00:11:56.409 from the riverbank? This is where the investigation 00:11:56.409 --> 00:11:59.860 shifts from anatomy to chemistry. Specifically, 00:12:00.679 --> 00:12:03.019 oxygen isotope analysis. Oh, I love this part. 00:12:03.340 --> 00:12:05.559 Researchers took the enamel from cymosaurus teeth 00:12:05.559 --> 00:12:08.879 and analyzed the ratio of different oxygen isotopes 00:12:08.879 --> 00:12:11.620 locked inside the crystalline structure of the 00:12:11.620 --> 00:12:13.879 tooth itself. And this relies on the concept 00:12:13.879 --> 00:12:16.289 that you are what you drink, correct? Exactly 00:12:16.289 --> 00:12:18.769 that principle. To get slightly technical for 00:12:18.769 --> 00:12:20.669 a moment, there are different weights of oxygen 00:12:20.669 --> 00:12:23.389 atoms. Okay, tracking. Oxygen -16 is lighter 00:12:23.389 --> 00:12:26.370 and oxygen -18 is heavier. Right. When water 00:12:26.370 --> 00:12:28.909 evaporates from the leaves of plants, the lighter 00:12:28.909 --> 00:12:32.049 oxygen -16 evaporates faster, leaving the plant 00:12:32.049 --> 00:12:35.370 rich in the heavy oxygen -18. So the plants get 00:12:35.370 --> 00:12:39.169 heavier chemically speaking. Yes. Therefore terrestrial 00:12:39.169 --> 00:12:41.769 plant eating dinosaurs and the meat eaters that 00:12:41.769 --> 00:12:45.149 prey on them accumulate a very specific heavy 00:12:45.149 --> 00:12:47.690 isotope signature in their bodies. But an animal 00:12:47.690 --> 00:12:50.509 in the water wouldn't have that. Precisely. An 00:12:50.509 --> 00:12:52.929 animal that spends its life submerged drinking 00:12:52.929 --> 00:12:55.929 directly from rivers and lakes will have a completely 00:12:55.929 --> 00:12:58.490 different much lighter isotopic fingerprint. 00:12:58.750 --> 00:13:02.289 So the water an animal ingests leaves a permanent 00:13:02.539 --> 00:13:05.299 readable chemical signature in the enamel as 00:13:05.299 --> 00:13:08.320 the tooth grows. That is just amazing. It really 00:13:08.320 --> 00:13:10.340 is. And when researchers compared the oxygen 00:13:10.340 --> 00:13:13.639 isotope ratios of cymosaurus teeth to other animals 00:13:13.639 --> 00:13:16.419 pulled from the exact same rock layers, the results 00:13:16.419 --> 00:13:18.759 were definitive. Did they match the other dinosaurs? 00:13:19.120 --> 00:13:22.259 Not at all. The cymosaurus ratios did not match 00:13:22.259 --> 00:13:24.580 the other land -dwelling, meat -eating dinosaurs 00:13:24.580 --> 00:13:27.440 even slightly. Instead, their chemical signature 00:13:27.440 --> 00:13:29.940 aligned almost perfectly with freshwater turtles 00:13:29.940 --> 00:13:32.440 and crocodilians. That is a brilliant use of 00:13:32.440 --> 00:13:34.220 chemistry. I mean, it proves they weren't just 00:13:34.220 --> 00:13:36.679 visiting the shoreline. They were deeply embedded 00:13:36.679 --> 00:13:40.039 in a semi -aquatic lifestyle. And from an evolutionary 00:13:40.039 --> 00:13:42.620 standpoint, adopting that lifestyle is a stroke 00:13:42.620 --> 00:13:45.899 of ecological genius. Why is that? It's a textbook 00:13:45.899 --> 00:13:49.149 example of niche partitioning. If you are a massive 00:13:49.149 --> 00:13:51.649 theropod, you require a massive amount of calories. 00:13:52.110 --> 00:13:54.889 If you stay on land and compete directly with 00:13:54.889 --> 00:13:57.289 other giant predators for the same terrestrial 00:13:57.289 --> 00:14:00.190 prey, you run a huge risk of starvation. Too 00:14:00.190 --> 00:14:03.429 many cooks in the kitchen. Exactly. But by evolving 00:14:03.429 --> 00:14:07.129 to hunt in the water, Siamisaurus entirely bypassed 00:14:07.129 --> 00:14:09.509 that competition. They essentially carved out 00:14:09.509 --> 00:14:12.470 their own exclusive lane in the food web. But 00:14:12.470 --> 00:14:14.669 wait, if they moved into the rivers to avoid 00:14:14.669 --> 00:14:17.289 terrestrial dinosaurs, wouldn't they just end 00:14:17.289 --> 00:14:19.970 up in direct competition with the giant crocodilians 00:14:19.970 --> 00:14:22.129 that were already dominating the water? They 00:14:22.129 --> 00:14:25.210 absolutely did compete with them. But Siamisaurus 00:14:25.210 --> 00:14:28.730 possessed a massive anatomical trump card. Oh. 00:14:29.120 --> 00:14:31.440 What was that? You have to remember the environment 00:14:31.440 --> 00:14:34.779 of early Cretaceous Thailand. It wasn't a lush, 00:14:34.779 --> 00:14:37.659 endless jungle. It was a semi -arid floodplain. 00:14:37.700 --> 00:14:40.240 Right. With wet and dry seasons. Yes. And during 00:14:40.240 --> 00:14:42.419 seasonal droughts, the meandering rivers would 00:14:42.419 --> 00:14:45.399 dry up, living behind isolated, shrinking pools 00:14:45.399 --> 00:14:48.159 of mud. Oh no. So the aquatic animals get stuck. 00:14:48.279 --> 00:14:51.120 Exactly. Obligate aquatic predators, like the 00:14:51.120 --> 00:14:53.379 long -snouted crocodilians, would get trapped 00:14:53.379 --> 00:14:55.700 in these muddy pools and eventually die out. 00:14:56.100 --> 00:14:58.620 But Psymosaurus was, at its core, a dinosaur. 00:14:58.509 --> 00:15:02.570 It had legs. It had robust, powerful hind legs. 00:15:03.049 --> 00:15:06.070 When a river dried up, it could simply walk across 00:15:06.070 --> 00:15:08.809 the dry land to the next active river system. 00:15:08.909 --> 00:15:11.250 So they basically beat the crocodiles at their 00:15:11.250 --> 00:15:13.690 own game just by having the ability to hike. 00:15:13.980 --> 00:15:17.019 The ability to migrate overland during a drought 00:15:17.019 --> 00:15:20.259 is a massive evolutionary advantage. Researchers 00:15:20.259 --> 00:15:22.639 actually hypothesized that cymosaurus was so 00:15:22.639 --> 00:15:25.159 successful at this water -hopping lifestyle that 00:15:25.159 --> 00:15:28.019 it completely out -competed and replaced long 00:15:28.019 --> 00:15:30.600 -snouted crocodilians in that specific ecosystem 00:15:30.600 --> 00:15:34.080 for millions of years. A dinosaur displacing 00:15:34.080 --> 00:15:36.799 crocodiles in the water is a staggering concept. 00:15:37.360 --> 00:15:39.779 Okay, so we know they ruled the local environments. 00:15:39.879 --> 00:15:42.700 This semi -arid floodplain shared with turtles, 00:15:42.960 --> 00:15:45.870 sharks, flying pterosaurs and those iguanodonchian 00:15:45.870 --> 00:15:48.629 dinosaurs. A very busy neighborhood. Extremely. 00:15:48.730 --> 00:15:50.789 Right. But this highly specialized water -hopping 00:15:50.789 --> 00:15:53.409 lifestyle didn't just allow them to survive locally. 00:15:53.850 --> 00:15:55.809 It is the key to understanding how they conquered 00:15:55.809 --> 00:15:58.850 the globe. So what does this all mean for the 00:15:58.850 --> 00:16:01.269 broader map of the ancient world? If we connect 00:16:01.269 --> 00:16:03.389 this to the bigger picture. The discovery of 00:16:03.389 --> 00:16:06.129 cymosaurus in Thailand created a massive crisis 00:16:06.129 --> 00:16:08.769 for geologists and paleontologists. Because it 00:16:08.769 --> 00:16:10.909 didn't fit the map, right? It forced them to 00:16:10.909 --> 00:16:13.629 entirely redraw their maps of the ancient Earth. 00:16:14.389 --> 00:16:16.610 Before Buffetot and Ingevat found those first 00:16:16.610 --> 00:16:19.129 fluted teeth, spinosaurids were only known from 00:16:19.129 --> 00:16:22.149 the Western Hemisphere, specifically from Europe, 00:16:22.629 --> 00:16:25.230 Africa, and South America. And the scientific 00:16:25.230 --> 00:16:27.269 consensus was that they were strictly restricted 00:16:27.269 --> 00:16:30.009 to those land masses. Exactly. And geographically, 00:16:30.090 --> 00:16:32.549 just as a refresher, Africa and South America 00:16:32.549 --> 00:16:34.950 were part of the giant southern supercontinent 00:16:34.950 --> 00:16:37.710 known as Gondwana, while Asia was part of the 00:16:37.710 --> 00:16:39.929 northern supercontinent, Laurasia. Correct. And 00:16:39.929 --> 00:16:42.409 those two massive supercontinents were separated 00:16:42.409 --> 00:16:44.970 by the Tethys Ocean. Right. And you do not just 00:16:44.970 --> 00:16:48.250 swim a 30 -foot multi -ton dinosaur across an 00:16:48.250 --> 00:16:50.509 ocean. You really don't. So finding a spinosaurid 00:16:50.509 --> 00:16:52.830 firmly established in Asia completely shatters 00:16:52.830 --> 00:16:55.429 that geographic boundary. And the mystery deepened, 00:16:55.610 --> 00:16:57.490 didn't it? It did. Because once researchers knew 00:16:57.490 --> 00:17:00.990 the specific signature of those fluted, rated 00:17:00.990 --> 00:17:03.690 teeth, they started identifying them elsewhere. 00:17:04.289 --> 00:17:06.549 Teeth potentially related to Siamisaurus were 00:17:06.549 --> 00:17:09.549 suddenly recognized in China, and even a specimen 00:17:09.549 --> 00:17:11.930 in Japan that had previously been misidentified 00:17:11.930 --> 00:17:14.849 as a marine reptile. Meaning, these water -hopping 00:17:14.849 --> 00:17:17.170 predators had managed to spread across the entire 00:17:17.170 --> 00:17:19.230 northern hemisphere as well. Which implies one 00:17:19.230 --> 00:17:22.339 of two massive paradigm shifts in geology. OK, 00:17:22.420 --> 00:17:24.640 let's hear them. The first hypothesis is that 00:17:24.640 --> 00:17:27.160 there was a massive faunal interchange during 00:17:27.160 --> 00:17:30.299 the early Cretaceous. This forces geologists 00:17:30.299 --> 00:17:33.680 to theorize the existence of temporary, previously 00:17:33.680 --> 00:17:37.000 unknown land bridges spanning across the Tethys 00:17:37.000 --> 00:17:39.839 Ocean, allowing these heavy predators to migrate 00:17:39.839 --> 00:17:43.259 between Gondwana and Laurasia. Wow. land bridges 00:17:43.259 --> 00:17:46.640 we never knew existed, or... Or the alternative 00:17:46.640 --> 00:17:49.240 hypothesis is that the spinosaur family evolved 00:17:49.240 --> 00:17:51.819 much earlier than the fossil record currently 00:17:51.819 --> 00:17:55.259 shows. How much earlier? Millions of years. They 00:17:55.259 --> 00:17:57.539 might have achieved a cosmopolitan worldwide 00:17:57.539 --> 00:18:00.339 distribution across the megacontinent of Pangaea 00:18:00.339 --> 00:18:02.759 before the landmass broke apart into north and 00:18:02.759 --> 00:18:05.220 south. So they were already everywhere. Right. 00:18:05.470 --> 00:18:07.849 If that is true, cymosaurus isn't a migrant, 00:18:08.130 --> 00:18:10.309 it is the descendant of an ancient lineage that 00:18:10.309 --> 00:18:12.410 was already living in Asia when the continents 00:18:12.410 --> 00:18:15.329 split. The scale of that deduction is mind -boggling. 00:18:15.509 --> 00:18:18.250 I mean, you pick up one weird, grooved tooth 00:18:18.250 --> 00:18:20.789 from the dirt in Thailand, and suddenly, the 00:18:20.789 --> 00:18:23.450 entire scientific community is forced to literally 00:18:23.450 --> 00:18:26.490 reconstruct the tectonic plates, the migration 00:18:26.490 --> 00:18:28.430 routes, and the connecting land bridges of the 00:18:28.430 --> 00:18:31.039 Earth, just to explain how it got there. It perfectly 00:18:31.039 --> 00:18:33.420 illustrates the interconnectedness of all scientific 00:18:33.420 --> 00:18:35.940 disciplines. Identifying the subtle texture of 00:18:35.940 --> 00:18:38.460 enamel on a single -tooth crown can literally 00:18:38.460 --> 00:18:40.680 alter our understanding of continental drift 00:18:40.680 --> 00:18:43.440 and planetary geology. We started this deep dive 00:18:43.440 --> 00:18:46.400 with a single, highly debated piece of fossilized 00:18:46.400 --> 00:18:49.680 dentin. And by reading the geometric shape, the 00:18:49.680 --> 00:18:51.680 biomechanical flutes, and the isotopic chemistry 00:18:51.680 --> 00:18:54.420 locked inside it, we have watched a 30 -foot 00:18:54.420 --> 00:18:57.539 sail -backed, fish -impaling giant rise out of 00:18:57.539 --> 00:18:59.420 the ancient rivers of Thailand. That's an amazing 00:18:59.420 --> 00:19:02.180 journey. We've seen how they used a rosette snout 00:19:02.180 --> 00:19:05.200 to catch aquatic prey, how their internal chemistry 00:19:05.200 --> 00:19:07.859 proved they live side by side with turtles, and 00:19:07.859 --> 00:19:10.940 how their sheer ability to hike across dry floodplains 00:19:10.940 --> 00:19:13.920 allowed them to out -survive crocodiles. And 00:19:13.920 --> 00:19:16.539 to top it all off, their mere presence in Asia 00:19:16.539 --> 00:19:19.920 rewrote the tectonic maps of the ancient supercontinents. 00:19:20.420 --> 00:19:23.319 It is a profound reminder that no detail in nature 00:19:23.319 --> 00:19:26.049 is too small to matter. Absolutely. Often the 00:19:26.049 --> 00:19:29.170 most seemingly insignificant fragment, a tiny 00:19:29.170 --> 00:19:31.509 anomaly that doesn't quite fit the established 00:19:31.509 --> 00:19:34.589 pattern, is the exact key required to unlock 00:19:34.589 --> 00:19:38.250 a massive unseen reality. I think it is an incredible 00:19:38.250 --> 00:19:40.650 takeaway for you listening today. The profound 00:19:40.650 --> 00:19:43.289 value of looking closely at the tiny details, 00:19:43.609 --> 00:19:46.990 the anomalies in your own work or life. But as 00:19:46.990 --> 00:19:49.150 we wrap up this deep dive, I want to leave you 00:19:49.150 --> 00:19:52.890 with one final lingering mystery to mull over 00:19:52.890 --> 00:19:55.759 on your own. Oh, this is a good one. If an entire 00:19:55.759 --> 00:19:59.119 family of massive, dominant, 30 -foot apex predators, 00:19:59.579 --> 00:20:01.960 creatures that completely ruled the river systems 00:20:01.960 --> 00:20:04.640 of ancient Asia, can be reduced to just a scattered 00:20:04.640 --> 00:20:07.220 handful of isolated teeth in the fossil record, 00:20:08.019 --> 00:20:10.380 what else did we miss? Makes you wonder. It really 00:20:10.380 --> 00:20:13.440 does. Because if Siamasaurus barely managed to 00:20:13.440 --> 00:20:15.920 scrape by in the fossilization lottery, just 00:20:15.920 --> 00:20:18.660 imagine the other bizarre, terrifying, incredible 00:20:18.660 --> 00:20:20.920 monsters that missed out entirely, leaving no 00:20:20.920 --> 00:20:23.039 teeth behind, remaining nothing but ghosts of 00:20:23.039 --> 00:20:24.039 the ancient Earth forever.