WEBVTT - How Did Stegosaurus Work? 0:00:01.920 --> 0:00:04.320 Welcome to brain Stuff, a production of I Heart Radio, 0:00:06.240 --> 0:00:11.400 Hey brain Stuff, Lauren Bogobaum. Here words can become fossils 0:00:11.440 --> 0:00:15.560 in their own right. Triceratops means three horned face, and 0:00:15.680 --> 0:00:21.000 philociraptor translates to speedy plunderer. Abok genus names fit the 0:00:21.040 --> 0:00:24.680 dinosaurs they belong to. We know Triceratops had a trio 0:00:24.720 --> 0:00:27.880 of horns on its skull, while Velociraptor was a lightly 0:00:27.920 --> 0:00:33.960 built carnivore. The case of Stegosaurus isn't so straightforward. Rooted 0:00:34.000 --> 0:00:38.360 in Greek, this Jurassic plant gobbler's name means roofed lizard, 0:00:38.760 --> 0:00:40.839 which made a lot more sense when the animal was 0:00:40.880 --> 0:00:45.239 first discovered over a hundred and forty years ago. But 0:00:45.479 --> 0:00:48.400 let's back up a little. A Stegosaurus belonged to a 0:00:48.400 --> 0:00:52.800 suborder of dinosaurs called what else the stegosaurs found in 0:00:52.800 --> 0:00:57.000 North America, Europe, Asia, and mainland Africa. The stegosaurs walked 0:00:57.000 --> 0:01:00.680 on four legs and had long, beak tipped skulls, but 0:01:00.920 --> 0:01:05.039 it's the ornaments that really grab your attention. The spikes 0:01:05.040 --> 0:01:08.960 were a stegosaur mainstay, adorning the tails of every known species. 0:01:09.600 --> 0:01:13.960 Many of these creatures like Africa's Kentrosaurus also rocked big 0:01:13.959 --> 0:01:18.160 old spikes on the shoulders and lower back, and where 0:01:18.200 --> 0:01:21.080 the back spikes came to an end, a much weirder 0:01:21.120 --> 0:01:25.120 feature took over. A Stegosaurus and its kin are characterized 0:01:25.160 --> 0:01:30.679 by the vertical plates above their spines. The paleontologist Othniol 0:01:30.800 --> 0:01:35.199 Charles Marsh named Stegosaurus in eighteen seventy seven. He chose 0:01:35.200 --> 0:01:38.959 this name, which again means roofed lizard, because he figured 0:01:38.959 --> 0:01:41.839 the plates were sheets of armor that laid flat against 0:01:41.880 --> 0:01:47.560 the animal's backside. Instead, later discoveries proved the objects stood upright, 0:01:47.960 --> 0:01:52.720 leaving the flanks on these dinosaurs exposed. We may never 0:01:52.760 --> 0:01:56.680 know how these things functioned. Because the plates contained blood vessels, 0:01:56.680 --> 0:01:59.880 experts used to think that they helped Stegosaurus chill out. 0:02:00.520 --> 0:02:03.480 The heat would supposedly dissipate from blood as it entered 0:02:03.520 --> 0:02:07.800 the tall fan like structures. When the chilled blood circulated elsewhere, 0:02:07.880 --> 0:02:10.280 it would stay cool for a little while lowering the 0:02:10.360 --> 0:02:16.080 overall body temperature. This hypothesis is no longer popular. According 0:02:16.120 --> 0:02:18.040 to a study published in two thousand five in the 0:02:18.120 --> 0:02:22.440 journal Paleobiology, The blood carrying networks and Stegosaurus. As plates 0:02:22.560 --> 0:02:25.720 were there to promote healthy bone growth, but they played 0:02:25.720 --> 0:02:30.480 no role in dissipating body heat. Or maybe Stegosaurus and 0:02:30.480 --> 0:02:33.320 its kin were just showing off a made of bone 0:02:33.400 --> 0:02:36.480 and encased in horny sheats. The plates could have made 0:02:36.560 --> 0:02:42.000 these dinos look bigger than more intimidating. Capable of hitting 0:02:42.000 --> 0:02:44.560 over twenty nine feet that's nine meters in length and 0:02:44.680 --> 0:02:47.720 weighing about five tons or four and a half metric tons, 0:02:47.720 --> 0:02:52.040 a stegosaurus would loom large over today's land mammals. Even 0:02:52.040 --> 0:02:55.120 by stegosaur standards, it was a biggie, and most of 0:02:55.120 --> 0:02:57.800 the dinosaurs in that group were only thirteen to twenty 0:02:57.840 --> 0:03:01.320 three feet long that's about four to seven ms. Yet 0:03:01.440 --> 0:03:04.880 in the late Jurassic, when these species lived, the Stegosaurus 0:03:04.919 --> 0:03:09.200 was in the shadows of behemoths. Sauropods, or long necked 0:03:09.200 --> 0:03:13.440 dinosaurs like the sixty foot or eighteen meter Kmarasaurus and 0:03:13.560 --> 0:03:17.000 the eighty foot or twenty four meter Diplodocus were some 0:03:17.160 --> 0:03:23.040 of the creatures neighbors, but the Tyrannosaurus rex wasn't, and 0:03:23.120 --> 0:03:26.320 despite movies like Fantasia and The Camp Classic Planet of 0:03:26.360 --> 0:03:29.520 Dinosaurs showing Stegosaurus duking it out with the t Rex. 0:03:29.919 --> 0:03:34.600 Those two dinos never crossed paths in real life. Tyrannosaurus 0:03:34.639 --> 0:03:37.480 had a fairly short rain that lasted from sixty eight 0:03:37.560 --> 0:03:40.120 to sixty five and a half million years ago. The 0:03:40.200 --> 0:03:45.240 Stegosaurus came and went much much earlier. The oldest specimens 0:03:45.240 --> 0:03:47.800 on record are around a hundred and fifty five million 0:03:47.880 --> 0:03:50.920 years of age, while the youngest were fossilized hundred and 0:03:51.000 --> 0:03:54.560 fifty billion years before the present, So the mighty t 0:03:54.720 --> 0:03:57.480 Rex actually lived closer to the dawn of mankind than 0:03:57.560 --> 0:04:02.160 it did to the Stegosaurus is heyday. The Jurassic Period, 0:04:02.200 --> 0:04:04.720 which lasted from a hundred and ninety nine point six 0:04:04.760 --> 0:04:07.160 million to a hundred and forty five point five million 0:04:07.240 --> 0:04:11.000 years ago, was drawing to a close when Stegosaurus roamed 0:04:11.040 --> 0:04:15.080 the earth. Although its range included modern day Portugal, the 0:04:15.120 --> 0:04:18.600 beast is mainly known from fossil sites in western North America, 0:04:19.839 --> 0:04:22.640 and while Stegosaurus didn't have to worry about t Rex, 0:04:22.960 --> 0:04:28.360 a rogues gallery of Jurassic predators stalked its ecosystem. Allosaurus 0:04:28.480 --> 0:04:31.560 was especially common, measuring up to twenty eight feet that's 0:04:31.600 --> 0:04:34.760 eight and a half meters long. This carnivore had serrated 0:04:34.800 --> 0:04:37.920 teeth and jaws that could open wide at a terrifying 0:04:38.040 --> 0:04:42.679 seventy nine degree angle. Good things. Diegosaurus had four tail 0:04:42.720 --> 0:04:46.120 spikes at its disposal. We know they saw action once 0:04:46.120 --> 0:04:48.800 in a while too. A study published in two thousand 0:04:48.839 --> 0:04:52.440 one in the Armored Dinosaurs by the Indiana University Press 0:04:52.760 --> 0:04:55.960 found clear evidence of trauma on ten percent of the 0:04:56.000 --> 0:05:00.240 fifty one tail spikes that they studied, and apparently the 0:05:00.400 --> 0:05:04.159 roofed lizard hit below the belt. One Allosaurus pubic bone 0:05:04.279 --> 0:05:06.600 shows a deep wound thought to have been made by 0:05:06.600 --> 0:05:12.279 a Stegosaurus tailspike. The stegosaurus had another line of defense. 0:05:12.640 --> 0:05:15.640 The underside of its throat was covered in tiny pebble 0:05:15.640 --> 0:05:19.880 shaped chunks of bone called Ghouler armor. It helped protect 0:05:19.960 --> 0:05:22.840 the dinosaur when Allosaurus and other carnivores went for the 0:05:22.880 --> 0:05:29.320 jugular Paleontologists think Stegosaurus browsed on low lying vegetation. A 0:05:30.240 --> 0:05:33.080 computer simulation found that the animals bite force would have 0:05:33.160 --> 0:05:37.520 rivaled that of a sheep or cow, but however, it 0:05:37.560 --> 0:05:41.400 processed its food. This dinosaur didn't need much gray matter. 0:05:41.920 --> 0:05:44.920 A Stegosaurus had a brain cavity that was long narrow 0:05:45.160 --> 0:05:49.120 and tiny, tipping the scales at twenty ounces, that's eighty 0:05:49.160 --> 0:05:52.279 grams or so. The actual brain only made up about 0:05:52.360 --> 0:05:55.880 zero point zero zero one percent of the creature's total 0:05:55.880 --> 0:06:01.279 body weight. And note that we said brain, not brains. 0:06:02.360 --> 0:06:04.839 As absurd as it might sound, there was a rumor 0:06:04.920 --> 0:06:08.240 that Stegosaurus had a second brain located where the sun 0:06:08.240 --> 0:06:12.680 don't shine. Writing in one Marsh drew attention to the 0:06:12.800 --> 0:06:16.080 enlarged cavity that we find in the backbones above this 0:06:16.200 --> 0:06:19.520 dinosaurs hip region. Then he went and called it a 0:06:19.560 --> 0:06:23.680 posterior brain case. No one knows for sure what this 0:06:23.760 --> 0:06:27.480 opening was for, though some researchers think it stored glycogen, 0:06:28.160 --> 0:06:31.840 sugar that provides cells with energy. Regardless, there is no 0:06:31.920 --> 0:06:35.920 reason to think that Steatosaurus or any dinosaur had multiple brains. 0:06:37.520 --> 0:06:40.360 The Stegosaurus did have some pretty cool bragging rights though. 0:06:40.960 --> 0:06:44.280 Not only is the Jurassic her Before Colorado's official state fossil, 0:06:44.560 --> 0:06:47.720 but it was also the inspiration for Godzilla's dorsal plates, 0:06:47.960 --> 0:06:56.159 as we have discussed on the show before. Today's episode 0:06:56.160 --> 0:06:58.960 is based on the article Stegosaurus body like a bus, 0:06:59.040 --> 0:07:01.520 tiny little brain on how Stuff Works dot com, written 0:07:01.560 --> 0:07:04.080 by Mark Mancini Breen Stuff is production of by heart 0:07:04.160 --> 0:07:06.240 Radio in partnership with how stuff works dot Com and 0:07:06.360 --> 0:07:09.200 is produced by Tyler Klang. Four more podcasts from my 0:07:09.240 --> 0:07:12.320 heart Radio. Visit the iHeart Radio app, Apple Podcasts, or 0:07:12.360 --> 0:07:14.040 wherever you listen to your favorite shows.