1 00:00:05,410 --> 00:00:09,575 They say this is the most savage killer ever to have walked the earth. 2 00:00:12,866 --> 00:00:15,338 With teeth that could have sliced through steel. 3 00:00:16,886 --> 00:00:19,718 Jaws that could have crushed a car. 4 00:00:20,829 --> 00:00:25,272 They say it was a six tonne, twelve metre long killing machine. 5 00:00:30,169 --> 00:00:32,297 Or could they have got it all wrong? 6 00:00:35,754 --> 00:00:38,476 Now one scientist has uncovered evidence 7 00:00:38,648 --> 00:00:41,386 that tells a very different story. 8 00:00:43,811 --> 00:00:48,020 He claims the king of the dinosaurs wasn’t a hunter killer at all, 9 00:00:48,333 --> 00:00:51,118 but a stinking lumbering scavenger. 10 00:00:52,824 --> 00:00:55,233 He says T. rex was not a warrior 11 00:00:55,640 --> 00:00:56,578 but a wimp. 12 00:00:58,753 --> 00:01:00,818 Could he possibly be right? 13 00:01:02,337 --> 00:01:07,280 Horizon investigates the science that’s challenging the legend. 14 00:01:34,739 --> 00:01:39,839 Tyrannosaurus fever has infected people all over the world for generations. 15 00:01:47,099 --> 00:01:53,123 Children in particular seem to know more about T-Rex than any other beast, alive or dead. 16 00:01:54,344 --> 00:01:57,707 Because they’re fascinated by its viciousness. 17 00:02:05,155 --> 00:02:10,193 Extinct for over 65 million years yet T-Rex lives on, 18 00:02:11,120 --> 00:02:12,923 a ferocious killing machine. 19 00:02:13,624 --> 00:02:16,277 A tyrant monster we all love to hate. 20 00:02:16,904 --> 00:02:18,969 The king of killers. 21 00:02:27,129 --> 00:02:29,933 From the moment it was discovered in 1902, 22 00:02:30,496 --> 00:02:35,352 palaeontologists were agreed T-Rex must have been a ferocious killer. 23 00:02:36,811 --> 00:02:40,394 Yet the truth was it was all based on very little evidence. 24 00:02:43,211 --> 00:02:46,981 All scientists could tell from the twelve meagre specimens they had 25 00:02:47,388 --> 00:02:52,426 was that T-Rex had a formidable physique and enormous jaws. 26 00:02:53,740 --> 00:02:57,401 And exactly how deadly it was remained a mystery. 27 00:02:58,888 --> 00:03:06,131 To fully understand the beast, palaeontologists needed to get their hands on the perfect specimen. 28 00:03:07,353 --> 00:03:15,082 Only that way could they really know just how fast or strong or vicious T-Rex was. 29 00:03:17,601 --> 00:03:19,635 The search was on. 30 00:03:20,589 --> 00:03:23,108 Enter palaeontology’s bad boy. 31 00:03:42,507 --> 00:03:47,561 This is Pete Larson, dinosaur expert and fossil hunter. 32 00:03:49,517 --> 00:03:53,209 Palaeontologists don’t like him, for one big reason, 33 00:03:53,835 --> 00:03:56,683 he digs up fossils for money. 34 00:03:58,794 --> 00:04:01,079 But in thirty years dinosaur hunting 35 00:04:01,361 --> 00:04:07,635 he never dared dream he might be the one to find the T-Rex the world was waiting for. 36 00:04:11,437 --> 00:04:16,303 To Larson and his then girlfriend Susan, he 12th August 1990 37 00:04:16,491 --> 00:04:18,384 was a day like any other. 38 00:04:19,026 --> 00:04:24,298 We were out actually digging on a Triceratops skull that my ten year old son Matthew had found. 39 00:04:24,565 --> 00:04:28,617 And we were just having a grand old time, it was a very, very nice small Triceratops skull. 40 00:04:28,821 --> 00:04:32,090 And all of a sudden Susan walks, walked up with a couple of bone fragments. 41 00:04:32,325 --> 00:04:36,722 And I said is there more, and she said there's lots more. 42 00:04:39,678 --> 00:04:42,698 Nothing could have prepared them for what they’d found. 43 00:04:44,857 --> 00:04:49,316 I looked up the face of the cliff and I saw an expanse of about eight feet wide 44 00:04:49,317 --> 00:04:52,900 and perhaps two feet deep with bones jutting out everywhere. 45 00:04:52,901 --> 00:04:59,909 And as I crawled up to the top of the, this exposure, I saw three articulated vertebrae. 46 00:05:04,509 --> 00:05:09,391 I knew that they had to come from a T-Rex because of the size of the curve of those bones, 47 00:05:09,392 --> 00:05:13,787 they were obviously parts of vertebrae from a meat eating dinosaur. 48 00:05:15,903 --> 00:05:20,244 And when I saw those three articulated vertebrae I knew this was going to be the most 49 00:05:20,401 --> 00:05:24,625 important specimen I had ever dug up, I just knew it. 50 00:05:25,984 --> 00:05:30,541 Pete Larson marvelled at the size of the partially exposed killer dinosaur. 51 00:05:33,045 --> 00:05:37,113 And nicknamed it Sue, after his girlfriend. 52 00:05:38,090 --> 00:05:41,747 It was like clawing our way to the top of Mount Everest. 53 00:05:41,962 --> 00:05:44,934 And as we were uncovering it we could see the top. 54 00:05:45,032 --> 00:05:48,083 And as we got her out of the ground we were there, 55 00:05:48,338 --> 00:05:51,467 we had climbed the Mount Everest of palaeontology. 56 00:05:59,720 --> 00:06:04,335 We got the biggest, baddest of all the T-Rexs that ever was. 57 00:06:05,939 --> 00:06:08,207 And it got even better. 58 00:06:09,968 --> 00:06:17,908 Sue was extremely well preserved and nearly complete, exactly what Pete Larson had dreamed of finding. 59 00:06:18,279 --> 00:06:24,362 At long last here was a chance to study the world’s ultimate killing machine in extraordinary detail, 60 00:06:24,752 --> 00:06:28,096 and all from just this one specimen. 61 00:06:29,662 --> 00:06:33,378 Then for Larson at least the dream turned to a nightmare. 62 00:06:38,776 --> 00:06:42,805 Two weeks later I got up in the morning and was taking a shower 63 00:06:42,819 --> 00:06:48,662 and one of our employees knocked on my bathroom door and said get out here, this place is surrounded with FBI agents. 64 00:06:49,224 --> 00:06:53,600 And I walk out and literally there are 35 FBI agents with guns. 65 00:06:53,722 --> 00:06:56,338 Yellow police tape all over the place. 66 00:06:59,614 --> 00:07:06,801 And they had a search warrant demanding the surrender of the T-Rex known as Sue. 67 00:07:07,901 --> 00:07:14,844 The US government threw the book at Larson for taking the T-Rex away without the right type of permission. 68 00:07:15,259 --> 00:07:21,468 Larson countersued sparking the first ever legal battle for custody of a dinosaur. 69 00:07:22,201 --> 00:07:26,431 While the lawyers wrangled the world’s most important dinosaur was impounded, 70 00:07:27,017 --> 00:07:32,151 beyond the reach of science, incarcerated in a basement store room. 71 00:07:38,714 --> 00:07:45,608 Four years later Pete Larson was found guilty of minor offences, unrelated to Sue. 72 00:07:51,335 --> 00:07:57,618 From that conviction I was sentenced to two years in prison and two years probation. 73 00:08:04,608 --> 00:08:08,783 With Larsen behind bars Sue went under the hammer. 74 00:08:41,369 --> 00:08:47,359 It’s in the room, on the phone at seven million six. 75 00:08:48,874 --> 00:08:51,686 Seven million six hundred thousand. 76 00:08:53,250 --> 00:08:59,019 The big money behind the purchase, donated what was now the world’s most expensive dinosaur, 77 00:08:59,166 --> 00:09:02,686 to the prestigious Field Museum in Chicago. 78 00:09:03,248 --> 00:09:09,433 At long last everyone could admire this most perfectly preserved T-Rex. 79 00:09:34,353 --> 00:09:38,675 Now too palaeontologists could study its every bone. 80 00:09:39,282 --> 00:09:46,362 Science had waited almost a century to find out for real what the world’s most feared predator was capable of. 81 00:09:50,371 --> 00:09:52,210 The wait was over. 82 00:09:53,031 --> 00:09:55,397 And Sue didn’t disappoint. 83 00:09:58,859 --> 00:10:01,851 What was T-Rex like as a living animal? 84 00:10:03,474 --> 00:10:06,955 It stood approximately twelve feet at the hips. 85 00:10:07,424 --> 00:10:10,592 The top of a T-Rex hip would be about there. 86 00:10:11,980 --> 00:10:15,070 It was approximately forty feet long in an adult. 87 00:10:17,476 --> 00:10:20,194 That’s longer than a double-decker bus. 88 00:10:24,321 --> 00:10:29,581 T-Rex may have weighed as much as six tonnes, like these two ladies here combined. 89 00:10:31,557 --> 00:10:34,608 That kind of muscle could have defeated anybody. 90 00:10:36,740 --> 00:10:41,629 Look like a, you know a gigantic scaled up, you know, roadrunner from hell. 91 00:10:42,959 --> 00:10:46,674 A roadrunner that was twice the speed of the fastest man. 92 00:10:48,747 --> 00:10:52,130 I think if we’d met T-Rex we would have been blooming frightened of him. 93 00:11:03,962 --> 00:11:06,231 All this added up to one thing, 94 00:11:06,720 --> 00:11:11,218 T-Rex was every bit as deadly as they’d always thought. 95 00:11:12,821 --> 00:11:15,931 And because Sue was almost the perfect specimen, 96 00:11:16,068 --> 00:11:21,896 scientists couldn’t wait to dig deeper and find out precisely how this monstrous killer 97 00:11:21,935 --> 00:11:24,614 went about its deadly business. 98 00:11:32,319 --> 00:11:37,071 The man charged with getting in to the killer’s mindset was Chris Brochu. 99 00:11:39,144 --> 00:11:43,955 One of the first things he wanted to discover was how good was its sight. 100 00:11:45,050 --> 00:11:49,392 Because eyesight is often critical to how a predator works. 101 00:11:54,007 --> 00:12:00,167 A predator’s power lies in its eyesight’s ability to spot prey long distance. 102 00:12:01,810 --> 00:12:06,308 He can then guide it with pinpoint precision 103 00:12:06,582 --> 00:12:08,127 to the kill. 104 00:12:23,067 --> 00:12:27,409 Keen eyesight is a hallmark of a master predator. 105 00:12:30,519 --> 00:12:32,787 Too heavy to be mounted on its skeleton, 106 00:12:33,042 --> 00:12:36,640 Sue’s real skull had been encased behind glass. 107 00:12:39,613 --> 00:12:43,466 This is it, this is Sue’s skull. 108 00:12:44,052 --> 00:12:46,908 Skulls really are a thing of beauty when you look at them. 109 00:12:47,318 --> 00:12:53,655 There is a lot of delicate structure here that you might not appreciate if you just think of it as a big powerful Tyrannosaur. 110 00:12:53,969 --> 00:13:00,442 In terms of the senses, the eye would have been pretty much where that hole is there. 111 00:13:04,744 --> 00:13:08,538 It would have faced a little bit forward, and not just out to the side. 112 00:13:10,415 --> 00:13:16,165 They did have an improved amount of depth perception and ability to judge distance 113 00:13:16,166 --> 00:13:19,646 compared to their earlier relatives. 114 00:13:22,931 --> 00:13:27,449 At first glance the large forward facing eye opening in the skull 115 00:13:27,566 --> 00:13:31,732 suggested T-Rex probably had keen eyesight. 116 00:13:33,121 --> 00:13:38,518 But to be sure Brochu had to do more than examine the skull from the outside. 117 00:13:40,670 --> 00:13:43,115 He had to get inside the head. 118 00:13:45,305 --> 00:13:49,608 And to do that he needed the latest technology. 119 00:13:52,522 --> 00:13:56,374 Basically when it comes down to it I was told to describe the thing inside and out. 120 00:13:56,492 --> 00:13:59,914 I took that literally, I knew they wouldn’t let me break the skull apart, 121 00:14:00,325 --> 00:14:03,435 so CT scanning is the answer. 122 00:14:07,678 --> 00:14:12,137 CT scanning is an advance X-ray imaging technique. 123 00:14:13,858 --> 00:14:18,336 It allowed Chris Brochu to build up computer images of slices through the head, 124 00:14:18,591 --> 00:14:24,164 which he moulded together to produce a three dimensional likeness, of a T-Rex skull. 125 00:14:30,990 --> 00:14:38,070 Then painstakingly, millimetre by millimetre, he followed the contours on the inside of this skull 126 00:14:38,383 --> 00:14:42,098 to reveal the structure of a T-Rex brain. 127 00:14:53,089 --> 00:14:57,040 The first time I saw the individual slices themselves they didn’t seem all that exciting, 128 00:14:57,041 --> 00:15:03,024 it wasn’t ‘til I built the first animation, the first flip through a bunch of slices all going through the skull, 129 00:15:03,025 --> 00:15:06,857 that was when it really struck me that there were a lot of things here to see. 130 00:15:14,484 --> 00:15:17,906 It turns out we got really good data, we got great data. 131 00:15:21,661 --> 00:15:27,509 The CT scans revealed something scientists had never before been able to see in such detail. 132 00:15:31,831 --> 00:15:37,267 Protruding from the delicate network of brain tissue was the optic nerve. 133 00:15:40,378 --> 00:15:47,516 This nerve was responsible for relaying information from the eyes to the visual centres in the brain. 134 00:15:48,494 --> 00:15:51,779 And it was big enough to carry a lot of information. 135 00:15:54,537 --> 00:16:01,166 The scan seemed to confirm T-Rex did indeed have a key attribute to a skilled predator. 136 00:16:02,437 --> 00:16:10,044 It would have been able to seek out its prey at a distance, and destroy it with the accuracy of an assassin. 137 00:16:18,531 --> 00:16:22,286 Having established how this hunter tracked down its prey, 138 00:16:22,501 --> 00:16:26,804 scientists turned their attention to how it would have killed it. 139 00:16:29,418 --> 00:16:33,036 Just how powerful was the strength of that bite? 140 00:16:34,444 --> 00:16:38,101 The first place they began to look for clues were the jaws. 141 00:16:38,668 --> 00:16:41,093 But not T-Rex jaws. 142 00:17:00,572 --> 00:17:06,107 Greg Erickson is an expert on crocodilians, the animal group that includes crocodiles 143 00:17:06,263 --> 00:17:08,473 and their cousins the alligators. 144 00:17:13,478 --> 00:17:18,915 Erickson has studied the animals at the St Augustine Alligator reserve in Florida for 10 years. 145 00:17:19,228 --> 00:17:22,299 And likes to get up close and personal. 146 00:17:23,883 --> 00:17:26,524 Latcha, Latcha, Latcha. 147 00:17:31,041 --> 00:17:35,734 Erickson studies crocodilians so he can find out more about T-Rex 148 00:17:35,832 --> 00:17:39,919 and the dinosaur family to which it belongs, the theropods. 149 00:17:42,990 --> 00:17:47,019 Gators and crocodiles make a great model for studying the feeding biomechanics 150 00:17:47,020 --> 00:17:50,794 of extinct theropod dinosaurs, they have very similar musculature, 151 00:17:51,459 --> 00:17:57,796 and just the basic leverage of their jaws and things like that are actually just a good analogy for Tyrannosaur feeding. 152 00:18:01,551 --> 00:18:05,188 The similarity between crocodile jaws and T-Rex jaws 153 00:18:05,282 --> 00:18:09,021 makes these animals ideal for Erickson’s research. 154 00:18:11,383 --> 00:18:14,042 But it also makes them very dangerous. 155 00:18:16,858 --> 00:18:18,658 Ok grab that pole. 156 00:18:22,632 --> 00:18:24,729 Watch, watch your feet, watch your feet. 157 00:18:24,869 --> 00:18:28,624 Remember she can run forward. One, two, three, 158 00:18:28,922 --> 00:18:31,910 Go, go, go. Watch your feet. 159 00:18:32,614 --> 00:18:35,602 This is a female American crocodile, Stevie. 160 00:18:36,447 --> 00:18:40,937 A youngster at thirty one years old, she’s only half the size she could become. 161 00:18:41,126 --> 00:18:44,349 She may be small but her strength is obvious. 162 00:18:47,352 --> 00:18:49,856 Back up, back up, back up, back up, back up. 163 00:18:57,663 --> 00:19:02,607 It’s Erickson’s job to try to persuade her to take part in his research. 164 00:19:03,968 --> 00:19:07,848 Because her jaws are thought to work in a similar way to T-Rex jaws, 165 00:19:08,115 --> 00:19:14,874 Erickson plans to measure her bite to see what it may reveal about the power behind a T-Rex bite. 166 00:19:15,171 --> 00:19:18,331 Yet as she’s small, and he’s not tested her before, 167 00:19:18,660 --> 00:19:21,335 he has no idea what kind of results he’ll get. 168 00:19:21,414 --> 00:19:22,916 Pull the leg out of that. 169 00:19:23,948 --> 00:19:26,952 First Stevie is gently restrained. 170 00:19:28,000 --> 00:19:34,884 Her keeper covers her eyes, because it not only keeps her calm, but will prevent her biting too soon. 171 00:19:37,106 --> 00:19:42,238 Erickson needs to get the crocodile to crunch on to a specially designed pressure sensor, 172 00:19:42,598 --> 00:19:45,164 which will record the force of the bite. 173 00:19:47,478 --> 00:19:50,154 The tricky bit is getting the timing right. 174 00:19:51,030 --> 00:19:53,940 The bite needs to be a spontaneous one. 175 00:19:59,541 --> 00:20:01,075 Here we go, hang on. 176 00:20:07,207 --> 00:20:08,991 Eight hundred and nineteen pounds, 177 00:20:09,601 --> 00:20:10,790 good bite. 178 00:20:11,729 --> 00:20:14,780 Stevie’s bite results are impressive. 179 00:20:15,499 --> 00:20:19,692 We registered a very aggressive defensive bite from this American crocodile. 180 00:20:19,830 --> 00:20:23,006 I think the highest force we had was 820 pounds, 181 00:20:23,068 --> 00:20:25,462 which is you know is an incredible amount of force. 182 00:20:27,041 --> 00:20:28,856 It’s a remarkable bite, 183 00:20:29,153 --> 00:20:32,173 especially considering she’s not even fully grown. 184 00:20:35,530 --> 00:20:39,070 An eight hundred pound bite is comparable to what a lion can do, 185 00:20:39,089 --> 00:20:42,512 or a spotted hyena which is the bone crushing champion among mammals, so 186 00:20:42,551 --> 00:20:46,540 a very small crocodilian is capable of doing bite forces equal to what, 187 00:20:46,579 --> 00:20:49,708 you know some of these large carnivorian mammals do. 188 00:20:50,549 --> 00:20:53,776 If you matched up an equal sized crocodile say to a large lion, 189 00:20:53,854 --> 00:20:56,963 the crocodile will bite probably three times more forcefully. 190 00:20:57,570 --> 00:20:59,017 Watch your legs. 191 00:20:59,936 --> 00:21:05,373 If jaws like these give crocodiles a bite force well above what their weight implies, 192 00:21:05,490 --> 00:21:09,323 then Erickson believes the same must have been true of T-Rex jaws. 193 00:21:09,441 --> 00:21:10,751 Nice canine on this one. 194 00:21:10,790 --> 00:21:13,919 His work suggested the power of a T-Rex bite 195 00:21:14,037 --> 00:21:17,792 may have been on a scale beyond anything we have ever seen. 196 00:21:18,281 --> 00:21:22,114 It’s not a natural thing to stick your hand inside the mouth of a crocodile but. 197 00:21:22,564 --> 00:21:24,755 Perhaps you shouldn’t try this at home kids. 198 00:21:25,146 --> 00:21:27,981 To get an idea of how much more powerful 199 00:21:28,216 --> 00:21:31,951 Erickson worked on doing more than just scale up the bite. 200 00:21:31,991 --> 00:21:34,279 Snout width is fourteen point two. 201 00:21:34,377 --> 00:21:37,565 He measured every physical detail of his crocodiles 202 00:21:37,642 --> 00:21:44,487 to try to map the differences in skull shape and body weight compared to an animal the size and shape of a T-Rex. 203 00:21:44,780 --> 00:21:46,756 Fifty point two. 204 00:21:47,733 --> 00:21:51,215 Erickson’s preliminary maximum estimate of a T-Rex bite 205 00:21:51,508 --> 00:21:55,615 could be as much as forty thousand pounds of force. 206 00:21:57,845 --> 00:22:01,306 That’s about fifty times more powerful than our crocodile. 207 00:22:03,145 --> 00:22:09,833 T-Rex would have had easily the most powerful bite of any animal that has ever lived. 208 00:22:21,077 --> 00:22:24,441 So all those movies seemed to have got it about right. 209 00:22:24,656 --> 00:22:29,448 Scientists’ first assumptions about T-Rex appeared to have been proved correct. 210 00:22:29,682 --> 00:22:33,672 The facts were every bit as shocking as the popular fiction. 211 00:22:38,131 --> 00:22:40,497 With a predator like this around 212 00:22:41,044 --> 00:22:45,484 it would seem this Triceratops didn’t stand a chance. 213 00:22:53,302 --> 00:22:58,778 T-Rex, the most feared creature ever to have walked the earth. 214 00:23:12,331 --> 00:23:17,025 But there’s someone out there who thinks they’ve got it all wrong. 215 00:23:19,547 --> 00:23:23,801 Someone with a completely different view of T-Rex. 216 00:23:28,612 --> 00:23:33,648 This is Jack Horner, one of the world’s most respected palaeontologists. 217 00:23:33,893 --> 00:23:37,364 He’s a man used to standing out on his own. 218 00:23:40,615 --> 00:23:44,917 In a world of T-Rex fanatics, Horner is unique, 219 00:23:45,969 --> 00:23:48,315 he doesn’t even like the beast. 220 00:23:50,149 --> 00:23:58,607 Palaeontology is one of those kinds of sciences where you actually end up studying what you can find. 221 00:24:01,712 --> 00:24:07,873 I went out looking for duckbilled dinosaurs about five years ago and started finding nothing but T-Rex, 222 00:24:07,946 --> 00:24:19,289 and so I just kind of got, I guess I got kind of lured in to the, lured in to the mm, T-Rexs, I don't like them much. 223 00:24:24,447 --> 00:24:28,578 Jack Horner was lured in to the murky world of Tyrannosaurus Rex 224 00:24:28,872 --> 00:24:34,764 when an amateur fossil hunter named Cathy Wankel presented him with a single T-Rex bone. 225 00:24:35,008 --> 00:24:39,457 The rest of the beast was buried deep in the Montana Badlands. 226 00:24:41,486 --> 00:24:47,402 After years of excavation, without the fuss or fanfare associated with Tyrannosaurus Sue, 227 00:24:47,403 --> 00:24:50,703 the Wankel T-Rex emerged. 228 00:24:51,852 --> 00:24:58,452 Now and rather reluctantly, Jack Horner had a T-Rex in his backyard. 229 00:25:03,243 --> 00:25:10,259 If for the sake of science he had to study it, then he was going to do it thoroughly and impartially. 230 00:25:10,797 --> 00:25:17,911 Jack Horner would look at the T-Rex skeleton as if he’d heard nothing of the beast’s fearsome reputation. 231 00:25:20,918 --> 00:25:24,169 And it was then that he noticed something. 232 00:25:25,001 --> 00:25:30,061 It was the arms, something about the arms was not quite right. 233 00:25:32,456 --> 00:25:36,612 The upper arm bone is a little bit longer than my upper arm bone, 234 00:25:36,783 --> 00:25:43,188 and the ulna, the lower arm bone, is half the length of mine, I mean it is tiny. 235 00:25:45,363 --> 00:25:49,837 Then it struck him, something nobody else had dared consider. 236 00:25:50,228 --> 00:25:56,364 This tiny arm didn’t seem to be the arm of a creature that survived by killing. 237 00:26:01,399 --> 00:26:04,870 You start thinking about, you know, what T-Rex did for a living. 238 00:26:05,090 --> 00:26:08,023 What is this animal like as a living creature? 239 00:26:14,110 --> 00:26:18,730 Predatory animals have to grab things, they, I mean, they have to actually get a hold of them. 240 00:26:38,384 --> 00:26:45,131 But if you look at, at Tyrannosaurus Rex and you look at animals that, 241 00:26:45,400 --> 00:26:50,827 that we know to have been predatory animals, like Velociraptor. 242 00:26:57,330 --> 00:27:01,877 If you look at just the size of their arms compared to their bodies. 243 00:27:05,544 --> 00:27:09,259 It’s just this incredible difference. 244 00:27:10,922 --> 00:27:16,251 An adult Tyrannosaurus Rex is 12 meters long from nose to tail. 245 00:27:17,425 --> 00:27:25,321 Its arm is tiny. The lower arm bone is just 22 centimetres, that’s less than two percent of its body length. 246 00:27:25,687 --> 00:27:32,190 By comparison the predator Velociraptor has a lower arm bone that’s proportionally 3 times longer, 247 00:27:32,458 --> 00:27:35,465 a more useful six percent of its body length. 248 00:27:36,027 --> 00:27:42,286 T-Rex had arms far shorter for its size than any other predatory dinosaur. 249 00:27:42,652 --> 00:27:48,299 If we look at, you know the actual arms, we can see that T-Rex couldn’t put its arms together, 250 00:27:48,739 --> 00:27:54,509 has very little motion on them, probably couldn’t do any more than scratch its belly after it ate. 251 00:27:56,978 --> 00:28:01,012 Horner was now puzzled, this just didn’t add up. 252 00:28:01,745 --> 00:28:08,737 He began to wonder if for over a century the common perception of T-Rex had been wrong. 253 00:28:10,619 --> 00:28:16,510 For years people had just assumed that T-Rex was a killer, and no one had questioned it, 254 00:28:16,511 --> 00:28:24,040 I mean it just, it was sort of ingrained in to everyone’s minds from, from the time they were kids to grownups. 255 00:28:24,626 --> 00:28:29,491 But you know once we had the Wankel T-Rex and we could actually see a whole specimen 256 00:28:29,784 --> 00:28:35,822 it was really quite clear that it was very, very different than predatory dinosaurs. 257 00:28:40,198 --> 00:28:44,256 So Jack Horner continued his rigorous scientific investigation 258 00:28:44,329 --> 00:28:48,558 to find out if anything else about T-Rex didn’t add up. 259 00:28:51,077 --> 00:28:54,255 The next place Horner looked was the teeth. 260 00:28:55,868 --> 00:29:01,637 He looked not only at T-Rex teeth but at the teeth of other dinosaurs known to be predators. 261 00:29:01,784 --> 00:29:05,671 And again he noticed a significant difference. 262 00:29:08,653 --> 00:29:14,544 A T-Rex tooth is long, strong and slightly curved, a bit like a banana. 263 00:29:15,351 --> 00:29:22,709 In cross section it’s almost round. A very robust design, strong enough to pulverise bone. 264 00:29:23,389 --> 00:29:27,926 But the teeth of predators like Velociraptor, or Deinonychus are different. 265 00:29:28,708 --> 00:29:31,857 This Velociraptor tooth is blade like and serrated. 266 00:29:33,265 --> 00:29:37,724 Its cross section is laterally compressed, just like a steak knife. 267 00:29:39,483 --> 00:29:42,691 Which makes it ideal for slicing through flesh. 268 00:29:44,294 --> 00:29:48,773 It begs the question, if Velociraptor and Deinonychus 269 00:29:48,948 --> 00:29:55,695 are predatory dinosaurs and they have laterally compressed flattened teeth 270 00:29:55,852 --> 00:29:59,959 and T-Rex doesn’t, then T-Rex must be doing something different. 271 00:30:03,186 --> 00:30:07,566 To find out what meant turning not to the bones of T-Rex 272 00:30:07,976 --> 00:30:11,281 but to the remains of an animal eaten by one, 273 00:30:12,650 --> 00:30:14,743 a Triceratops. 274 00:30:15,251 --> 00:30:22,135 These animals were hefty herbivores, ten tonnes of muscle with a characteristic armoured head. 275 00:30:22,469 --> 00:30:26,673 And when scientists began to uncover bones baring huge tooth marks, 276 00:30:26,869 --> 00:30:31,054 they knew Triceratops had been T-Rex food. 277 00:30:32,735 --> 00:30:37,683 So Horner turned to a plaster cast of part of a Triceratops, the sacrum, 278 00:30:37,957 --> 00:30:43,530 fused vertebrae littered with nearly 60frenzied T-Rex tooth marks. 279 00:30:49,553 --> 00:30:55,538 Baring such terrible scars this enormous bone had been held up as conclusive proof of 280 00:30:55,772 --> 00:30:58,373 T-Rex as a predator. 281 00:30:59,488 --> 00:31:01,991 Horner wanted to reanalyse the specimen, 282 00:31:02,344 --> 00:31:06,001 to see if there was anything previous researchers had missed, 283 00:31:06,470 --> 00:31:07,956 and they had. 284 00:31:10,225 --> 00:31:16,581 It was not the size or the shape of the bite marks they’d overlooked, it was where they were. 285 00:31:21,451 --> 00:31:25,186 The sacrum is a well protected part of a Triceratops skeleton. 286 00:31:25,578 --> 00:31:28,511 It’s the reinforced bone at the base of the spine, 287 00:31:28,668 --> 00:31:32,872 enclosed by the heavy muscle of the legs and the belly. 288 00:31:34,124 --> 00:31:37,586 The bite marks were on the underside of this concealed bone. 289 00:31:37,859 --> 00:31:42,299 The one part of a Triceratops body, impossible for a T-Rex to get to 290 00:31:42,573 --> 00:31:45,330 if its meal was still alive and kicking. 291 00:31:46,210 --> 00:31:50,571 That animal had to be literally torn to pieces before, 292 00:31:50,904 --> 00:31:54,874 before you could, before a T-Rex could leave those puncture marks. 293 00:31:55,538 --> 00:32:00,427 To Jack Horner the pattern of the bite marks pointed to just one conclusion, 294 00:32:01,542 --> 00:32:05,238 a T-Rex hadn’t killed the Triceratops, 295 00:32:06,607 --> 00:32:08,347 something else had, 296 00:32:09,755 --> 00:32:13,119 and a T-Rex had simply chewed up the leftovers. 297 00:32:20,883 --> 00:32:26,065 Jack Horner was now certain T-Rex couldn’t have been the killer they said he was. 298 00:32:29,409 --> 00:32:33,262 The predator theory had been make believe, pure fantasy. 299 00:32:34,846 --> 00:32:38,425 Now there was evidence of arms that couldn’t grab on prey, 300 00:32:39,187 --> 00:32:42,981 teeth that couldn’t slice flesh, yet crush bone, 301 00:32:43,411 --> 00:32:47,557 and chew marks on an already dead Triceratops. 302 00:32:48,730 --> 00:32:53,580 The facts led Horner to believe there was only one thing a T-Rex could be. 303 00:32:58,039 --> 00:32:59,623 A scavenger. 304 00:33:07,308 --> 00:33:14,564 To see the king of the dinosaurs as nothing more regal than a giant vulture or hyena was heresy. 305 00:33:14,935 --> 00:33:17,340 Scavengers are nobody’s heroes, 306 00:33:18,416 --> 00:33:23,051 they feed on the abandoned carcasses of animals killed by real predators, 307 00:33:23,774 --> 00:33:26,864 they survive on leftovers. 308 00:33:29,739 --> 00:33:34,041 Jack Horner presented the case in favour of the scavenger theory. 309 00:33:34,941 --> 00:33:38,481 He was instantly dismissed as a crackpot. 310 00:33:42,118 --> 00:33:45,188 But then came some independent support, 311 00:33:45,697 --> 00:33:48,278 and from a most unlikely source. 312 00:34:04,412 --> 00:34:08,753 On the other side of the world, two scientists from the University of Glasgow 313 00:34:08,870 --> 00:34:12,176 couldn’t resist joining in the controversy. 314 00:34:12,645 --> 00:34:17,222 But David Houston and Graeme Ruxton knew nothing about T-Rex. 315 00:34:19,099 --> 00:34:22,580 What they did know about was scavenging. 316 00:34:24,652 --> 00:34:31,243 And they wanted to put Horner’s theory to the test by asking a question no palaeontologist had thought of. 317 00:34:32,846 --> 00:34:40,238 Was it even possible for an animal the size of T-Rex to survive just by scavenging scraps? 318 00:34:42,859 --> 00:34:47,553 Any animal can really only survive if the amount of energy that it uses in foraging each day 319 00:34:47,554 --> 00:34:50,408 is less than the amount of energy it’s able to get back from its food. 320 00:34:50,525 --> 00:34:55,454 So what we were doing was trying to calculate what the energy requirements would have been for a T-Rex, 321 00:34:55,455 --> 00:34:58,602 for locomotion and for general maintenance. 322 00:34:58,603 --> 00:35:03,216 And also to consider how much food would be available within that foraging range, 323 00:35:03,295 --> 00:35:08,027 and whether it would have been able to find enough carcasses to balance its energy budget. 324 00:35:08,692 --> 00:35:15,752 The first thing Ruxton and Houston wanted to do was to analyse each link in a cretaceous food chain. 325 00:35:16,222 --> 00:35:17,611 But they couldn’t, 326 00:35:18,041 --> 00:35:22,070 that ecosystem had disappeared 65 million years ago. 327 00:35:23,321 --> 00:35:26,333 So they searched for the next best thing, 328 00:35:27,683 --> 00:35:33,002 a largely unspoiled flourishing environment teeming with life. 329 00:35:34,586 --> 00:35:39,592 They found it in the Serengeti National Park in Africa. 330 00:35:54,513 --> 00:36:01,437 Here was an abundance of predators, prey and scavengers, all in the one ecosystem. 331 00:36:04,742 --> 00:36:10,178 We chose the Serengeti because there’s been much more work done there than almost any other area. 332 00:36:12,330 --> 00:36:15,811 The wildlife system is still relatively undisturbed. 333 00:36:20,778 --> 00:36:24,944 What Ruxton and Houston needed to determine from the Serengeti ecosystem 334 00:36:25,315 --> 00:36:29,793 was just how much dead meat might be available to a scavenger. 335 00:36:30,654 --> 00:36:34,096 The answer was more than you’d think. 336 00:36:35,172 --> 00:36:39,787 I think a lot of people think that the majority of animals when they die, die because they get killed by a predator, 337 00:36:39,944 --> 00:36:42,897 but in fact in systems like the Serengeti that really isn’t true. 338 00:36:43,014 --> 00:36:49,605 The majority of Animals which die will die from some other cause, mainly because of old age or food shortage, 339 00:36:49,606 --> 00:36:53,907 starvation, parasite burden, perhaps they just have an accident. 340 00:36:55,022 --> 00:36:58,483 In other words because animals just drop down dead 341 00:36:58,816 --> 00:37:02,668 more meat is available to a scavenger than most people assume. 342 00:37:03,216 --> 00:37:05,387 Yet this amount was still very low. 343 00:37:05,856 --> 00:37:11,625 The research suggested as little as 4 kilos of meat a day in every square kilometre. 344 00:37:12,896 --> 00:37:17,003 It seemed life might be tough for a scavenging T-Rex. 345 00:37:23,026 --> 00:37:25,764 But then Ruxton and Houston set up a computer model 346 00:37:25,979 --> 00:37:30,731 to calculate just how much food a T-Rex would have needed to survive. 347 00:37:32,805 --> 00:37:37,381 Based upon its weight and build they were expecting a figure to be high, 348 00:37:37,909 --> 00:37:40,256 but that’s not what they found. 349 00:37:41,899 --> 00:37:46,690 When they calculated its likely metabolic rate, similar to that of a reptile, 350 00:37:47,042 --> 00:37:50,582 they found T-Rex didn’t use much energy at all. 351 00:37:51,345 --> 00:37:58,659 Their estimate revealed T-Rex probably only needed to eat something the size of a human every five or six days. 352 00:38:01,475 --> 00:38:07,010 Despite the facts that it’s many, many times the size of us, the amount of energy it uses 353 00:38:07,244 --> 00:38:12,329 when it’s really not doing much, is only 5 or 6 times the amount of energy you and I spend. 354 00:38:12,779 --> 00:38:16,455 This thing doesn’t need to find an awful lot of food. 355 00:38:18,313 --> 00:38:23,730 And up here we have the density of carrion or food available to it in the environment. 356 00:38:23,887 --> 00:38:26,390 Ruxton and Houston’s calculation suggested 357 00:38:26,605 --> 00:38:31,279 there would have been enough food lying around for a T-Rex to survive by scavenging, 358 00:38:31,592 --> 00:38:33,509 but on one condition. 359 00:38:34,761 --> 00:38:38,066 That it could find the food in the first place. 360 00:38:38,536 --> 00:38:42,134 Everything about being a scavenger depends on being able to find carcasses 361 00:38:42,135 --> 00:38:45,381 which are going to be very widely dispersed, they’re going to be difficult to locate, 362 00:38:45,537 --> 00:38:49,879 so you clearly need to be able to detect carcasses from a considerable distance. 363 00:38:50,035 --> 00:38:51,952 And we get results from this graph here. 364 00:38:52,167 --> 00:38:57,271 The critical distance their calculations produced was 50 metres. 365 00:38:58,128 --> 00:39:04,668 All T-Rex needed to do was to see across a stretch of land half the length of a football pitch. 366 00:39:05,278 --> 00:39:10,520 And scientists already knew T-Rex was likely to have had excellent eyesight. 367 00:39:11,082 --> 00:39:15,103 I think given that it was likely to be preying on fairly large things, 368 00:39:16,305 --> 00:39:20,900 spotting things at a distance of 50 metres wouldn’t be too challenging. 369 00:39:24,284 --> 00:39:30,209 For the very first time Jack Horner’s theory had significant independent backup. 370 00:39:31,970 --> 00:39:38,951 Not only did the scavenger theory seem to fit the fossil evidence, it fitted the ecological evidence. 371 00:39:42,276 --> 00:39:45,894 T-Rex could have survived by scavenging alone. 372 00:39:52,466 --> 00:39:58,059 So if Jack Horner was right all those movies and most scientists had got it wrong. 373 00:40:00,249 --> 00:40:07,465 T-Rex wasn’t a terrifying predator, the truth was something altogether less glamorous. 374 00:40:12,940 --> 00:40:18,142 T-Rex may have been a king, but a king of scavengers. 375 00:40:29,153 --> 00:40:34,883 Jack Horner appeared to have won the argument, but then along came something and someone 376 00:40:35,235 --> 00:40:38,872 that would once again tear the debate wide open. 377 00:40:44,290 --> 00:40:49,062 Ken Carpenter is curator of the Denver Museum of Nature and Science, 378 00:40:49,296 --> 00:40:52,855 in charge of over three thousand dinosaur bones. 379 00:40:59,955 --> 00:41:03,788 Among his vast collection were Hadrosaurs. 380 00:41:06,428 --> 00:41:12,588 These gentle duckbilled vegetarians were likely to have formed a large proportion of a T-Rex diet. 381 00:41:15,326 --> 00:41:19,550 Herds of these placid beasts roamed the planes in vast numbers. 382 00:41:20,979 --> 00:41:23,619 They were the cows of the cretaceous. 383 00:41:28,805 --> 00:41:33,675 Ken Carpenter had never believed in Horner’s idea of T-Rex the scavenger, 384 00:41:34,105 --> 00:41:38,525 and it prompted him to take a closer look at one of his Hadrosaurs. 385 00:41:43,569 --> 00:41:47,305 It was then that he noticed something quite remarkable. 386 00:41:49,848 --> 00:41:56,399 It wasn’t until Jack Horner asked the question, was T-Rex a scavenger or a predator, that I thought mm, 387 00:41:56,731 --> 00:42:00,623 there is something about this specimen that’s very different and unique. 388 00:42:03,498 --> 00:42:07,976 It was something so obvious that everyone else had missed it. 389 00:42:08,582 --> 00:42:12,396 When I looked at the tail it’s rather unusual because 390 00:42:12,651 --> 00:42:15,682 one of the vertebrae is incomplete near the top. 391 00:42:17,481 --> 00:42:22,644 What’s missing is the top roughly third of that long bladelike bone that’s on the top. 392 00:42:22,645 --> 00:42:27,280 We can feel those same bones along our backs, those are the tops of the vertebrae. 393 00:42:27,397 --> 00:42:29,744 So part of this vertebrae is missing. 394 00:42:31,582 --> 00:42:37,781 I also noticed there were some little puncture rooms on some of the adjacent spines. 395 00:42:40,579 --> 00:42:47,893 They’re rather unusual in that they form a broad U shape which looks like, an awful lot like it was a bite mark. 396 00:42:49,027 --> 00:42:55,656 If the broad U shape was indeed a bite mark, then this Hadrosaur had been attacked by something with large 397 00:42:55,754 --> 00:42:58,981 and powerful bone crushing jaws, 398 00:42:59,333 --> 00:43:02,051 there could be only one suspect, 399 00:43:04,183 --> 00:43:07,645 and Ken Carpenter had the weapon to prove it. 400 00:43:08,075 --> 00:43:12,221 We can see that almost a third on one of these spines is missing. 401 00:43:12,436 --> 00:43:18,088 Also we can see that there’s some damage here, there’s actually some more damage on the back of this one, 402 00:43:18,363 --> 00:43:23,428 and damage here. But it’s this trough that’s been cut through this bone that’s most intriguing. 403 00:43:23,819 --> 00:43:28,904 Because we can actually take the tooth of a Tyrannosaurus Rex and put it right in there. 404 00:43:33,109 --> 00:43:35,260 It just fits so perfectly. 405 00:43:42,398 --> 00:43:47,952 The scavenger theory would dictate that the Hadrosaur must have been dead when this happened, 406 00:43:48,168 --> 00:43:51,199 but Ken Carpenter suspected otherwise. 407 00:43:52,138 --> 00:43:53,859 What was rather interesting, 408 00:43:53,957 --> 00:43:59,628 not only did we have this U shape groove but there was re-healed bone around it. 409 00:44:02,132 --> 00:44:05,671 The bone could only have re-healed if the animal was alive, 410 00:44:05,867 --> 00:44:10,854 and if the animal was alive that made the T-Rex a predator. 411 00:44:12,751 --> 00:44:17,015 It seemed T-Rex was capable of hunting after all. 412 00:44:19,733 --> 00:44:25,365 All this time the answer to the question of whether T-Rex was a scavenger or predator was just 413 00:44:25,796 --> 00:44:27,673 in my backyard practically. 414 00:44:33,501 --> 00:44:35,808 There was now a straight contradiction, 415 00:44:36,943 --> 00:44:41,754 Ken Carpenter’s evidence suggested T-Rex had been a predator. 416 00:44:45,118 --> 00:44:49,753 Jack Horner’s evidence suggested T-Rex had been a scavenger. 417 00:44:51,708 --> 00:44:54,388 Science was faced with a problem. 418 00:44:55,228 --> 00:44:58,963 But the fierce debate that once drove a rift through palaeontology 419 00:44:59,218 --> 00:45:02,562 has started to bring the two sides together. 420 00:45:07,373 --> 00:45:14,804 Because scientists have now begun to accept that the boundary between scavenger and predator can be blurred. 421 00:45:21,513 --> 00:45:24,212 Scavengers do kill. 422 00:45:28,006 --> 00:45:31,448 And predators aren’t above scavenging. 423 00:45:35,652 --> 00:45:40,756 I think it’s sometimes not very sensible to think of animals as being either scavengers or predators. 424 00:45:40,757 --> 00:45:43,866 If we think of modern carnivores, particularly mammalian carnivores, 425 00:45:44,022 --> 00:45:49,615 there really is no modern mammalian carnivore which is either a total scavenger or a total predator. 426 00:45:52,452 --> 00:45:57,302 So the suggestion now is that T-Rex was some kind of hybrid, 427 00:45:57,811 --> 00:46:01,898 an animal capable of both killing and scavenging. 428 00:46:04,695 --> 00:46:07,491 I think that we, we have evidence of, of both in this animal, 429 00:46:07,492 --> 00:46:10,816 so I think it probably was a predator sometimes and a scavenger at other times. 430 00:46:10,913 --> 00:46:13,436 I think the meaningful distinction we had to make here is, 431 00:46:13,514 --> 00:46:17,719 what was it doing most of the time, how did it get most of its meals. 432 00:46:18,833 --> 00:46:24,661 Just what the balance was between hunting and scavenging remains, for the moment at least, a mystery. 433 00:46:25,638 --> 00:46:27,437 But one thing is clear, 434 00:46:27,692 --> 00:46:31,447 T-Rex had a truly bizarre anatomy for a killer, 435 00:46:31,779 --> 00:46:34,419 so if it did on occasion hunt for a living 436 00:46:34,791 --> 00:46:39,289 then it seems it must have done so in a way different from any other predator. 437 00:46:45,254 --> 00:46:51,199 In the end Jack Horner may have been both right and wrong about T-Rex. 438 00:46:51,611 --> 00:46:59,062 But in raising the question he had done far more than help solve one small riddle within dinosaur biology. 439 00:46:59,199 --> 00:47:04,929 He had reminded palaeontologists what their science should be all about. 440 00:47:05,358 --> 00:47:09,719 We have to gather together evidence, and we have to test that evidence, 441 00:47:09,720 --> 00:47:17,249 we have to test the individual hypotheses that come out in order to come together with all this cumulative data. 442 00:47:21,453 --> 00:47:27,985 I think in one sense palaeontology had got in to a rut, and just automatically assumed that certain 443 00:47:28,553 --> 00:47:31,291 ideas that we had were automatically true. 444 00:47:31,487 --> 00:47:38,899 We can't do that, we have to go in there and, and address these questions, and, and come up with the evidence. 445 00:47:43,240 --> 00:47:48,931 Whether my colleagues believe that or not I think that in the end 446 00:47:49,831 --> 00:47:53,312 kids are going to learn more about how science works 447 00:47:54,230 --> 00:47:58,259 from this argument or this discussion. 448 00:47:59,178 --> 00:48:02,268 I think this engages them. 449 00:48:03,265 --> 00:48:07,490 And because of Horner’s work a new generation will grow up 450 00:48:07,783 --> 00:48:12,574 with a completely different view of T-Rex.