1 00:00:01,920 --> 00:00:04,320 Speaker 1: Welcome to brain Stuff, a production of I Heart Radio, 2 00:00:06,240 --> 00:00:11,400 Speaker 1: Hey brain Stuff, Lauren Bogobaum. Here words can become fossils 3 00:00:11,440 --> 00:00:15,560 Speaker 1: in their own right. Triceratops means three horned face, and 4 00:00:15,680 --> 00:00:21,000 Speaker 1: philociraptor translates to speedy plunderer. Abok genus names fit the 5 00:00:21,040 --> 00:00:24,680 Speaker 1: dinosaurs they belong to. We know Triceratops had a trio 6 00:00:24,720 --> 00:00:27,880 Speaker 1: of horns on its skull, while Velociraptor was a lightly 7 00:00:27,920 --> 00:00:33,960 Speaker 1: built carnivore. The case of Stegosaurus isn't so straightforward. Rooted 8 00:00:34,000 --> 00:00:38,360 Speaker 1: in Greek, this Jurassic plant gobbler's name means roofed lizard, 9 00:00:38,760 --> 00:00:40,839 Speaker 1: which made a lot more sense when the animal was 10 00:00:40,880 --> 00:00:45,239 Speaker 1: first discovered over a hundred and forty years ago. But 11 00:00:45,479 --> 00:00:48,400 Speaker 1: let's back up a little. A Stegosaurus belonged to a 12 00:00:48,400 --> 00:00:52,800 Speaker 1: suborder of dinosaurs called what else the stegosaurs found in 13 00:00:52,800 --> 00:00:57,000 Speaker 1: North America, Europe, Asia, and mainland Africa. The stegosaurs walked 14 00:00:57,000 --> 00:01:00,680 Speaker 1: on four legs and had long, beak tipped skulls, but 15 00:01:00,920 --> 00:01:05,039 Speaker 1: it's the ornaments that really grab your attention. The spikes 16 00:01:05,040 --> 00:01:08,960 Speaker 1: were a stegosaur mainstay, adorning the tails of every known species. 17 00:01:09,600 --> 00:01:13,960 Speaker 1: Many of these creatures like Africa's Kentrosaurus also rocked big 18 00:01:13,959 --> 00:01:18,160 Speaker 1: old spikes on the shoulders and lower back, and where 19 00:01:18,200 --> 00:01:21,080 Speaker 1: the back spikes came to an end, a much weirder 20 00:01:21,120 --> 00:01:25,120 Speaker 1: feature took over. A Stegosaurus and its kin are characterized 21 00:01:25,160 --> 00:01:30,679 Speaker 1: by the vertical plates above their spines. The paleontologist Othniol 22 00:01:30,800 --> 00:01:35,199 Speaker 1: Charles Marsh named Stegosaurus in eighteen seventy seven. He chose 23 00:01:35,200 --> 00:01:38,959 Speaker 1: this name, which again means roofed lizard, because he figured 24 00:01:38,959 --> 00:01:41,839 Speaker 1: the plates were sheets of armor that laid flat against 25 00:01:41,880 --> 00:01:47,560 Speaker 1: the animal's backside. Instead, later discoveries proved the objects stood upright, 26 00:01:47,960 --> 00:01:52,720 Speaker 1: leaving the flanks on these dinosaurs exposed. We may never 27 00:01:52,760 --> 00:01:56,680 Speaker 1: know how these things functioned. Because the plates contained blood vessels, 28 00:01:56,680 --> 00:01:59,880 Speaker 1: experts used to think that they helped Stegosaurus chill out. 29 00:02:00,520 --> 00:02:03,480 Speaker 1: The heat would supposedly dissipate from blood as it entered 30 00:02:03,520 --> 00:02:07,800 Speaker 1: the tall fan like structures. When the chilled blood circulated elsewhere, 31 00:02:07,880 --> 00:02:10,280 Speaker 1: it would stay cool for a little while lowering the 32 00:02:10,360 --> 00:02:16,080 Speaker 1: overall body temperature. This hypothesis is no longer popular. According 33 00:02:16,120 --> 00:02:18,040 Speaker 1: to a study published in two thousand five in the 34 00:02:18,120 --> 00:02:22,440 Speaker 1: journal Paleobiology, The blood carrying networks and Stegosaurus. As plates 35 00:02:22,560 --> 00:02:25,720 Speaker 1: were there to promote healthy bone growth, but they played 36 00:02:25,720 --> 00:02:30,480 Speaker 1: no role in dissipating body heat. Or maybe Stegosaurus and 37 00:02:30,480 --> 00:02:33,320 Speaker 1: its kin were just showing off a made of bone 38 00:02:33,400 --> 00:02:36,480 Speaker 1: and encased in horny sheats. The plates could have made 39 00:02:36,560 --> 00:02:42,000 Speaker 1: these dinos look bigger than more intimidating. Capable of hitting 40 00:02:42,000 --> 00:02:44,560 Speaker 1: over twenty nine feet that's nine meters in length and 41 00:02:44,680 --> 00:02:47,720 Speaker 1: weighing about five tons or four and a half metric tons, 42 00:02:47,720 --> 00:02:52,040 Speaker 1: a stegosaurus would loom large over today's land mammals. Even 43 00:02:52,040 --> 00:02:55,120 Speaker 1: by stegosaur standards, it was a biggie, and most of 44 00:02:55,120 --> 00:02:57,800 Speaker 1: the dinosaurs in that group were only thirteen to twenty 45 00:02:57,840 --> 00:03:01,320 Speaker 1: three feet long that's about four to seven ms. Yet 46 00:03:01,440 --> 00:03:04,880 Speaker 1: in the late Jurassic, when these species lived, the Stegosaurus 47 00:03:04,919 --> 00:03:09,200 Speaker 1: was in the shadows of behemoths. Sauropods, or long necked 48 00:03:09,200 --> 00:03:13,440 Speaker 1: dinosaurs like the sixty foot or eighteen meter Kmarasaurus and 49 00:03:13,560 --> 00:03:17,000 Speaker 1: the eighty foot or twenty four meter Diplodocus were some 50 00:03:17,160 --> 00:03:23,040 Speaker 1: of the creatures neighbors, but the Tyrannosaurus rex wasn't, and 51 00:03:23,120 --> 00:03:26,320 Speaker 1: despite movies like Fantasia and The Camp Classic Planet of 52 00:03:26,360 --> 00:03:29,520 Speaker 1: Dinosaurs showing Stegosaurus duking it out with the t Rex. 53 00:03:29,919 --> 00:03:34,600 Speaker 1: Those two dinos never crossed paths in real life. Tyrannosaurus 54 00:03:34,639 --> 00:03:37,480 Speaker 1: had a fairly short rain that lasted from sixty eight 55 00:03:37,560 --> 00:03:40,120 Speaker 1: to sixty five and a half million years ago. The 56 00:03:40,200 --> 00:03:45,240 Speaker 1: Stegosaurus came and went much much earlier. The oldest specimens 57 00:03:45,240 --> 00:03:47,800 Speaker 1: on record are around a hundred and fifty five million 58 00:03:47,880 --> 00:03:50,920 Speaker 1: years of age, while the youngest were fossilized hundred and 59 00:03:51,000 --> 00:03:54,560 Speaker 1: fifty billion years before the present, So the mighty t 60 00:03:54,720 --> 00:03:57,480 Speaker 1: Rex actually lived closer to the dawn of mankind than 61 00:03:57,560 --> 00:04:02,160 Speaker 1: it did to the Stegosaurus is heyday. The Jurassic Period, 62 00:04:02,200 --> 00:04:04,720 Speaker 1: which lasted from a hundred and ninety nine point six 63 00:04:04,760 --> 00:04:07,160 Speaker 1: million to a hundred and forty five point five million 64 00:04:07,240 --> 00:04:11,000 Speaker 1: years ago, was drawing to a close when Stegosaurus roamed 65 00:04:11,040 --> 00:04:15,080 Speaker 1: the earth. Although its range included modern day Portugal, the 66 00:04:15,120 --> 00:04:18,600 Speaker 1: beast is mainly known from fossil sites in western North America, 67 00:04:19,839 --> 00:04:22,640 Speaker 1: and while Stegosaurus didn't have to worry about t Rex, 68 00:04:22,960 --> 00:04:28,360 Speaker 1: a rogues gallery of Jurassic predators stalked its ecosystem. Allosaurus 69 00:04:28,480 --> 00:04:31,560 Speaker 1: was especially common, measuring up to twenty eight feet that's 70 00:04:31,600 --> 00:04:34,760 Speaker 1: eight and a half meters long. This carnivore had serrated 71 00:04:34,800 --> 00:04:37,920 Speaker 1: teeth and jaws that could open wide at a terrifying 72 00:04:38,040 --> 00:04:42,679 Speaker 1: seventy nine degree angle. Good things. Diegosaurus had four tail 73 00:04:42,720 --> 00:04:46,120 Speaker 1: spikes at its disposal. We know they saw action once 74 00:04:46,120 --> 00:04:48,800 Speaker 1: in a while too. A study published in two thousand 75 00:04:48,839 --> 00:04:52,440 Speaker 1: one in the Armored Dinosaurs by the Indiana University Press 76 00:04:52,760 --> 00:04:55,960 Speaker 1: found clear evidence of trauma on ten percent of the 77 00:04:56,000 --> 00:05:00,240 Speaker 1: fifty one tail spikes that they studied, and apparently the 78 00:05:00,400 --> 00:05:04,159 Speaker 1: roofed lizard hit below the belt. One Allosaurus pubic bone 79 00:05:04,279 --> 00:05:06,600 Speaker 1: shows a deep wound thought to have been made by 80 00:05:06,600 --> 00:05:12,279 Speaker 1: a Stegosaurus tailspike. The stegosaurus had another line of defense. 81 00:05:12,640 --> 00:05:15,640 Speaker 1: The underside of its throat was covered in tiny pebble 82 00:05:15,640 --> 00:05:19,880 Speaker 1: shaped chunks of bone called Ghouler armor. It helped protect 83 00:05:19,960 --> 00:05:22,840 Speaker 1: the dinosaur when Allosaurus and other carnivores went for the 84 00:05:22,880 --> 00:05:29,320 Speaker 1: jugular Paleontologists think Stegosaurus browsed on low lying vegetation. A 85 00:05:30,240 --> 00:05:33,080 Speaker 1: computer simulation found that the animals bite force would have 86 00:05:33,160 --> 00:05:37,520 Speaker 1: rivaled that of a sheep or cow, but however, it 87 00:05:37,560 --> 00:05:41,400 Speaker 1: processed its food. This dinosaur didn't need much gray matter. 88 00:05:41,920 --> 00:05:44,920 Speaker 1: A Stegosaurus had a brain cavity that was long narrow 89 00:05:45,160 --> 00:05:49,120 Speaker 1: and tiny, tipping the scales at twenty ounces, that's eighty 90 00:05:49,160 --> 00:05:52,279 Speaker 1: grams or so. The actual brain only made up about 91 00:05:52,360 --> 00:05:55,880 Speaker 1: zero point zero zero one percent of the creature's total 92 00:05:55,880 --> 00:06:01,279 Speaker 1: body weight. And note that we said brain, not brains. 93 00:06:02,360 --> 00:06:04,839 Speaker 1: As absurd as it might sound, there was a rumor 94 00:06:04,920 --> 00:06:08,240 Speaker 1: that Stegosaurus had a second brain located where the sun 95 00:06:08,240 --> 00:06:12,680 Speaker 1: don't shine. Writing in one Marsh drew attention to the 96 00:06:12,800 --> 00:06:16,080 Speaker 1: enlarged cavity that we find in the backbones above this 97 00:06:16,200 --> 00:06:19,520 Speaker 1: dinosaurs hip region. Then he went and called it a 98 00:06:19,560 --> 00:06:23,680 Speaker 1: posterior brain case. No one knows for sure what this 99 00:06:23,760 --> 00:06:27,480 Speaker 1: opening was for, though some researchers think it stored glycogen, 100 00:06:28,160 --> 00:06:31,840 Speaker 1: sugar that provides cells with energy. Regardless, there is no 101 00:06:31,920 --> 00:06:35,920 Speaker 1: reason to think that Steatosaurus or any dinosaur had multiple brains. 102 00:06:37,520 --> 00:06:40,360 Speaker 1: The Stegosaurus did have some pretty cool bragging rights though. 103 00:06:40,960 --> 00:06:44,280 Speaker 1: Not only is the Jurassic her Before Colorado's official state fossil, 104 00:06:44,560 --> 00:06:47,720 Speaker 1: but it was also the inspiration for Godzilla's dorsal plates, 105 00:06:47,960 --> 00:06:56,159 Speaker 1: as we have discussed on the show before. Today's episode 106 00:06:56,160 --> 00:06:58,960 Speaker 1: is based on the article Stegosaurus body like a bus, 107 00:06:59,040 --> 00:07:01,520 Speaker 1: tiny little brain on how Stuff Works dot com, written 108 00:07:01,560 --> 00:07:04,080 Speaker 1: by Mark Mancini Breen Stuff is production of by heart 109 00:07:04,160 --> 00:07:06,240 Speaker 1: Radio in partnership with how stuff works dot Com and 110 00:07:06,360 --> 00:07:09,200 Speaker 1: is produced by Tyler Klang. Four more podcasts from my 111 00:07:09,240 --> 00:07:12,320 Speaker 1: heart Radio. Visit the iHeart Radio app, Apple Podcasts, or 112 00:07:12,360 --> 00:07:14,040 Speaker 1: wherever you listen to your favorite shows.