1 00:00:32,198 --> 00:00:34,257 Sixty-five million years ago, 2 00:00:34,401 --> 00:00:39,464 a world that belonged to the dinosaurs suffered a cosmic catastrophe, 3 00:00:40,273 --> 00:00:44,505 obliterating the kingdom of Tyrannosaurus rex. 4 00:01:12,105 --> 00:01:13,663 For sixty-five million years, 5 00:01:13,740 --> 00:01:17,107 the bones of the last king of the dinosaurs lay hidden. 6 00:01:17,777 --> 00:01:20,007 Then at the turn of the 20th Century, 7 00:01:20,146 --> 00:01:22,307 scientists began to coax the first 8 00:01:22,449 --> 00:01:25,885 fragments from the Badlands of western North America. 9 00:01:29,022 --> 00:01:30,922 It stood eighteen feet tall. 10 00:01:31,191 --> 00:01:33,591 Forty feet from head to tail. 11 00:01:33,860 --> 00:01:36,693 Today, the bones of Tyrannosaurus rex 12 00:01:36,796 --> 00:01:38,525 allow us to encounter the greatest 13 00:01:38,732 --> 00:01:42,498 meat-eating machine of the prehistoric world. 14 00:03:38,017 --> 00:03:42,010 Tyrannosaurus rex has become the most famous of the dinosaurs, 15 00:03:42,322 --> 00:03:45,917 the ultimate expression of savagery and power. 16 00:03:50,864 --> 00:03:52,991 For paleontologists like Phil Currie, 17 00:03:53,133 --> 00:03:56,694 who scour the bone yards of the North American Badlands in search 18 00:03:56,803 --> 00:04:02,503 of the real T. Rex, a close encounter is a rare and thrilling event. 19 00:04:03,676 --> 00:04:05,644 "The thing that allows Tyrannosaurus 20 00:04:05,745 --> 00:04:07,269 to be preserved in this part of the world 21 00:04:07,413 --> 00:04:11,645 is the fact that they were living on a coastal lowland, 22 00:04:12,018 --> 00:04:14,748 and there was a tremendous amount of sediment coming in from the 23 00:04:14,888 --> 00:04:17,254 mountains that were rising to the west at that time. 24 00:04:17,690 --> 00:04:20,215 So there were large rivers running across the coastal lowland. 25 00:04:20,360 --> 00:04:24,820 And if the Tyrannosaurus, ah, body happened to fall in the water, 26 00:04:24,964 --> 00:04:27,990 then it had a very good chance of being buried complete. 27 00:04:28,134 --> 00:04:32,161 And, ah, fast burial is one of the most critical factors in terms of, 28 00:04:32,305 --> 00:04:35,240 ah, preserving an animal that large." 29 00:04:46,219 --> 00:04:49,347 "So far, seventeen skeletons of Tyrannosaurus have been found, 30 00:04:49,489 --> 00:04:53,118 all of them from Wyoming north into Alberta and Saskatchewan. 31 00:04:53,259 --> 00:04:56,922 Now, Tyrannosaurus probably had a much more extensive range than that. 32 00:04:57,063 --> 00:05:01,227 It almost certainly lived all the way from, ah, the Arctic Ocean 33 00:05:01,367 --> 00:05:03,096 down to the Gulf of Mexico." 34 00:05:07,073 --> 00:05:10,338 Only seventeen skeletons have been unearthed of the many millions 35 00:05:10,476 --> 00:05:12,910 of animals that once lived and died, 36 00:05:13,179 --> 00:05:18,913 a handful of clues to the mysteries of this ferocious, but elusive, beast. 37 00:05:38,404 --> 00:05:43,068 The existence of the king of the dinosaurs was unknown until 1902, 38 00:05:43,209 --> 00:05:46,372 when a former Kansas farm boy named Barnum Brown, 39 00:05:46,512 --> 00:05:49,970 hunting dinosaurs for the American Museum of Natural History, 40 00:05:50,116 --> 00:05:52,311 discovered its remains. 41 00:05:54,787 --> 00:05:58,689 A dinosaur bone used as an offiice paperweight had caught his attention. 42 00:06:00,493 --> 00:06:04,122 Brown traced it back to Hell Creek in Montana. 43 00:06:04,664 --> 00:06:06,291 But what would he find there? 44 00:06:09,235 --> 00:06:12,295 Even the man who would become known as Mister Bones 45 00:06:12,438 --> 00:06:17,671 could hardly dare to hope for the rarest of the rare, a giant meat-eater. 46 00:06:19,679 --> 00:06:21,271 But that is exactly what he found, 47 00:06:21,414 --> 00:06:24,406 halfway up a steep and treacherous canyon wall. 48 00:06:26,819 --> 00:06:28,548 But six years of backbreaking work 49 00:06:28,688 --> 00:06:31,088 yielded only incomplete fragments. 50 00:06:31,891 --> 00:06:36,658 Then in 1908, Brown discovered the almost intact skeleton 51 00:06:36,729 --> 00:06:39,664 he would call "my favorite child". 52 00:06:42,068 --> 00:06:47,836 For Tyrannosaurus rex, the journey back to life and legend had begun. 53 00:06:57,550 --> 00:06:59,415 Back at the Museum in New York, 54 00:06:59,552 --> 00:07:02,385 Brown's boss, Henry Fairfield Osborn, 55 00:07:02,522 --> 00:07:07,152 was eager to show the world the animal he named Tyrannosaurus rex. 56 00:07:07,960 --> 00:07:09,791 While the bones were being prepared, 57 00:07:09,929 --> 00:07:14,298 Osborn and Brown used models to recreate a dynamic vision of 58 00:07:14,434 --> 00:07:16,902 the living tyrant lizard king. 59 00:07:18,671 --> 00:07:22,107 "Long, powerful hind legs carried the body upright, 60 00:07:22,241 --> 00:07:24,641 balanced by a long tail. 61 00:07:24,944 --> 00:07:26,434 The massive head was armed with 62 00:07:26,579 --> 00:07:30,481 thirteen dagger-like, saw-bladed teeth in each jaw. 63 00:07:30,683 --> 00:07:31,843 The Tyrannosaurus was capable of 64 00:07:31,984 --> 00:07:35,147 destroying any of the contemporary creatures, 65 00:07:35,288 --> 00:07:39,554 and was easily the king of the period and monarch of its race." 66 00:07:40,760 --> 00:07:44,287 But nearly two tons of bones could not be mounted to match Osborn 67 00:07:44,430 --> 00:07:48,799 and Brown's vision of an agile, almost bird-like beast. 68 00:07:51,904 --> 00:07:55,670 Their compromise design for an upright, more static pose, 69 00:07:55,742 --> 00:07:57,403 which we now believe to be wrong, 70 00:07:57,543 --> 00:08:01,070 dominated how we saw T. Rex for more than fifty years. 71 00:08:06,085 --> 00:08:10,681 The unveiling of T. Rex in 1915 created a popular sensation. 72 00:08:16,229 --> 00:08:17,696 The ages roll on and reptiles grow to monstrous size. 73 00:08:17,830 --> 00:08:18,797 The "tyrant giant Lizard" (Tyrannosaurus) 74 00:08:19,298 --> 00:08:23,394 The upright T. Rex became the horror movie superstar of a new Age 75 00:08:23,536 --> 00:08:24,696 of Dinosaurs. 76 00:08:25,438 --> 00:08:25,995 Through generations of life in the 77 00:08:26,139 --> 00:08:26,833 forests and bitter struggles among themselves, 78 00:08:26,973 --> 00:08:27,667 these powerful beasts develop hides like armor. 79 00:08:52,165 --> 00:08:54,133 Eighty years later in Montana, 80 00:08:54,267 --> 00:08:57,361 the painstaking search begun by Barnum Brown for the real 81 00:08:57,503 --> 00:08:59,368 T. Rex continues. 82 00:09:03,910 --> 00:09:07,471 Bill Garstka and his team are unearthing the first fragments of 83 00:09:07,647 --> 00:09:10,946 what he believes is a new and important skeleton. 84 00:09:13,085 --> 00:09:15,519 "This was the first piece of bone that I picked up at the site. 85 00:09:15,655 --> 00:09:22,993 This is distal end of fibula, the small bone of the leg. 86 00:09:23,129 --> 00:09:27,657 So it sits something like this into the ankle of the animal, 87 00:09:27,800 --> 00:09:29,290 and it is interesting in several respects. 88 00:09:29,435 --> 00:09:32,233 First of all, you see this iron core in the middle? 89 00:09:32,371 --> 00:09:34,305 Carnivorous dinosaur bones are hollow. 90 00:09:34,440 --> 00:09:37,500 This was the first indication that I had something really interesting." 91 00:09:38,010 --> 00:09:42,845 "We had not been here oh, even ten minutes picking up fragments 92 00:09:43,149 --> 00:09:47,415 when Shawn, who is the group leader, found this. 93 00:09:47,954 --> 00:09:51,117 And this is a Tyrannosaurus tooth. 94 00:09:51,457 --> 00:09:54,654 And this has the enamel weathered off. 95 00:09:54,760 --> 00:09:58,196 But it still has the ridges where the 96 00:09:58,564 --> 00:10:01,829 serrations on the enamel would have been. 97 00:10:02,268 --> 00:10:07,934 So we knew with these two pieces that we had a Tyrannosaur." 98 00:10:20,419 --> 00:10:22,319 Even with modern power tools, 99 00:10:22,455 --> 00:10:26,482 dinosaur hunting in hundred degree temperatures is backbreaking work, 100 00:10:26,859 --> 00:10:31,296 yet so delicate that removing an entire skeleton can take years. 101 00:10:41,073 --> 00:10:44,042 Today, just as they did one hundred years ago, 102 00:10:44,176 --> 00:10:46,337 the bones of T. Rex leave the Badlands 103 00:10:46,479 --> 00:10:50,916 as precious cargo, protected in plasterjackets. 104 00:10:54,554 --> 00:10:55,384 "Okay." 105 00:10:56,289 --> 00:10:57,381 "All right. Oh, good." 106 00:10:58,157 --> 00:10:59,317 "Ah! I got it." 107 00:11:10,303 --> 00:11:12,066 But fossilized bones are not the only 108 00:11:12,204 --> 00:11:15,401 remains that can shed light on the life of an animal. 109 00:11:15,708 --> 00:11:19,542 There are many other clues that can fill in some crucial details. 110 00:11:20,212 --> 00:11:21,907 "My concern is the world of T. Rex. 111 00:11:22,048 --> 00:11:23,208 What plants did it live with? 112 00:11:23,349 --> 00:11:27,308 What sort of foliage hit it while it stalked its prey? 113 00:11:28,254 --> 00:11:29,516 What had happened was the flowering 114 00:11:29,722 --> 00:11:31,451 plants appeared early in the Cretaceous period. 115 00:11:31,591 --> 00:11:32,922 And by the time of Tyrannosaurus rex, 116 00:11:33,059 --> 00:11:35,254 they were dominating the world's ecosystems. 117 00:11:35,394 --> 00:11:38,522 We find in North Dakota that ninety percent of our fossil leaves, 118 00:11:38,731 --> 00:11:40,926 and we now have over thirty thousand fossil leaves collected, 119 00:11:41,067 --> 00:11:42,694 over ninety percent of those fossil 120 00:11:42,768 --> 00:11:45,498 leaves are broad-leafed flowering plant leaves. 121 00:11:45,638 --> 00:11:50,098 What you see are, here broad-leaf relatives of the laurel and cinnamon. 122 00:11:50,409 --> 00:11:52,900 Relatives, two-lobed relatives of magnolia. 123 00:11:53,946 --> 00:11:55,811 Relatives of the modern sycamore. 124 00:11:56,782 --> 00:11:58,613 Relatives of the modern elm." 125 00:12:02,121 --> 00:12:05,522 "There are still a few conifers around in the time of Tyrannosaurus rex, 126 00:12:05,691 --> 00:12:07,488 the bald cypress and its relatives. 127 00:12:07,693 --> 00:12:09,558 So the look of the place was similar 128 00:12:09,695 --> 00:12:12,163 to say, perhaps, Florida or southern Georgia, 129 00:12:12,298 --> 00:12:14,664 where you have relatively small trees, 130 00:12:14,734 --> 00:12:17,532 maybe thirty or forty, fifty feet tall, trunks no more than 131 00:12:17,703 --> 00:12:19,671 maybe a foot in diameter." 132 00:12:35,621 --> 00:12:39,352 "By the time Tyrannosaurus was living in North America, 133 00:12:39,792 --> 00:12:42,955 most of the modern families of plants 134 00:12:43,095 --> 00:12:45,222 and animals had already appeared on the earth. 135 00:12:45,531 --> 00:12:49,934 Consequently, the world that Tyrannosaurus lived in may not have 136 00:12:50,069 --> 00:12:51,696 been as foreign as we think it is. 137 00:12:51,971 --> 00:12:54,531 In fact, we can almost go to parts of the world today 138 00:12:54,740 --> 00:12:59,302 and see representatives of those animals and plants still alive today. 139 00:12:59,745 --> 00:13:02,009 And you would have crocodiles and 140 00:13:02,148 --> 00:13:06,244 turtles and, ah, lizards and snakes and all these things. 141 00:13:06,552 --> 00:13:08,543 Ah, they would have been very familiar to us today. 142 00:13:08,688 --> 00:13:11,885 The difference would have been that the large animals which today 143 00:13:12,024 --> 00:13:15,755 are large mammals, at that time would have been dinosaurs." 144 00:13:20,900 --> 00:13:24,666 Just as plant-eating animals outnumber meat-eaters today, 145 00:13:24,837 --> 00:13:29,365 the plant-eating dinosaurs outnumbered carnivores millions of years ago. 146 00:13:32,912 --> 00:13:34,971 Phil Currie is leading a team of scientists 147 00:13:35,114 --> 00:13:39,414 excavating a herd of duckbilled plant-eaters called edmontosaurs. 148 00:13:40,052 --> 00:13:44,148 Dinosaurs like these probably were favorite dinners for T. Rex. 149 00:13:45,057 --> 00:13:48,356 "Well, we got about, ah, I would say sixty-five or so Tyrannosaur teeth, 150 00:13:48,627 --> 00:13:52,256 a few small theropods, lots of tooth-marked bone as well." 151 00:13:54,333 --> 00:13:56,927 "Do you think there is enough edmontosaurus material in here to, 152 00:13:57,069 --> 00:13:59,503 ah, indicate that this was a herd of edmontosaurus?" 153 00:13:59,839 --> 00:14:03,775 "Well, we have got at least, um, eight individuals, ee... big edmontosaurs. 154 00:14:03,909 --> 00:14:06,139 And we also have evidence of some very small animals based on 155 00:14:06,278 --> 00:14:07,438 some of the lower limb bones. 156 00:14:07,580 --> 00:14:10,242 So it appears that we have got older adults with smaller individuals 157 00:14:10,382 --> 00:14:13,180 which, to me, indicates we may have had a herd in this area." 158 00:14:13,986 --> 00:14:16,853 "Bone beds like this, ah, are pretty good indication that 159 00:14:16,989 --> 00:14:20,049 many of the prey species for animals like Tyrannosaurus rex were, 160 00:14:20,192 --> 00:14:21,489 in fact, herding animals. 161 00:14:21,994 --> 00:14:26,158 These, ah, animals, ah, were herding probably because they were 162 00:14:26,298 --> 00:14:27,424 moving from region to region, 163 00:14:27,566 --> 00:14:31,058 ah, as food resources changed over the course of the year. 164 00:14:31,203 --> 00:14:34,036 Ah, I would suspect that the Tyrannosaurs were, in fact, 165 00:14:34,173 --> 00:14:35,299 following these herds, 166 00:14:35,441 --> 00:14:39,002 and that the old individuals and that the young individuals that strayed 167 00:14:39,145 --> 00:14:42,171 too far from the herds were the most likely prey for the Tyrannosaurs. 168 00:14:42,314 --> 00:14:44,680 And these are the animals they actively hunted down." 169 00:15:11,911 --> 00:15:13,503 The discoveries of the past century 170 00:15:13,679 --> 00:15:16,546 have made Tyrannosaurus rex one of the most famous and the most 171 00:15:16,682 --> 00:15:19,242 fearsome of nature's creations. 172 00:15:20,085 --> 00:15:23,111 But how did such a ferocious giant come into being? 173 00:15:23,989 --> 00:15:27,152 Where does it fit in the history of life on earth? 174 00:15:28,294 --> 00:15:32,958 Today, we know that T. Rex's ancestry can be traced back to a tiny creature, 175 00:15:33,332 --> 00:15:36,733 whose skull can fit into the palm of your hand. 176 00:15:37,503 --> 00:15:40,199 "This is eoraptor, or the dawn stealer. 177 00:15:40,773 --> 00:15:42,968 It is the oldest and first predatory 178 00:15:43,108 --> 00:15:45,668 dinosaur that we know of in the fossil record. 179 00:15:46,378 --> 00:15:48,312 And it has some of the, ah, basic 180 00:15:48,447 --> 00:15:51,905 adaptations that were to carry predatory dinosaurs, 181 00:15:52,051 --> 00:15:54,519 ah, through a hundred and fifty million years of evolution 182 00:15:54,787 --> 00:15:57,347 to something like the Tyrannosaurus behind me. 183 00:15:57,890 --> 00:16:02,793 The skull shows some of the classic features of the predatory dinosaurs. 184 00:16:02,928 --> 00:16:05,658 Ah, one of those features involves the lowerjaw. 185 00:16:05,931 --> 00:16:08,331 At a, the mid-point of the lowerjaw, 186 00:16:08,467 --> 00:16:09,832 there is a joint that allowed the 187 00:16:09,969 --> 00:16:13,427 lowerjaw to flex, ah, like a flexible joint 188 00:16:13,572 --> 00:16:17,633 that if something was caught in the jaws, those jaws would clamp 189 00:16:17,710 --> 00:16:20,975 around, ah, something that might be a live prey item. 190 00:16:21,113 --> 00:16:24,640 And this kind of a lowerjaw is present in Tyrannosaurus. 191 00:16:24,783 --> 00:16:28,150 It is present in every other predatory dinosaur that we know of. 192 00:16:28,387 --> 00:16:32,653 And eoraptor is the first to show that adaptation in the fossil record." 193 00:16:38,230 --> 00:16:39,561 The body plan, road-tested in 194 00:16:39,698 --> 00:16:42,724 eoraptor, became an evolutionary best-seller. 195 00:16:43,602 --> 00:16:44,796 Even today's birds, 196 00:16:44,937 --> 00:16:47,462 themselves thought to be modified dinosaurs, 197 00:16:47,606 --> 00:16:51,474 owe much of their design to these long-tailed ancestors. 198 00:16:54,046 --> 00:16:55,673 But how did T. Rex evolve from the 199 00:16:55,748 --> 00:16:59,514 size of a small dog into a forty-foot giant? 200 00:17:02,087 --> 00:17:04,351 For decades, many scientists thought it had to be 201 00:17:04,490 --> 00:17:08,153 descended from other giant predators, like this allosaurus, 202 00:17:08,427 --> 00:17:12,864 the last in the line of ever-larger, ever-toothier dinosaurs. 203 00:17:16,502 --> 00:17:19,665 This was the super-carnosaur hypothesis. 204 00:17:19,905 --> 00:17:23,204 It may have seemed obvious, but it was wrong. 205 00:17:28,080 --> 00:17:30,173 "We used to have very simple views 206 00:17:30,516 --> 00:17:31,949 about how the different groups of 207 00:17:32,084 --> 00:17:34,644 meat-eating dinosaurs were related to each other. 208 00:17:35,020 --> 00:17:37,284 In recent years, though, as we have discovered more 209 00:17:37,423 --> 00:17:39,721 and more about the anatomy, these views have changed. 210 00:17:39,858 --> 00:17:43,021 Tyrannosaurus at one time was considered to be a carnosaur, 211 00:17:43,162 --> 00:17:45,824 that is, one of the large, meat-eating forms. 212 00:17:45,965 --> 00:17:50,197 And by its size, it was related to animals like allosaurus. 213 00:17:50,336 --> 00:17:53,897 But in recent years as we started to look more closely at the anatomy, 214 00:17:54,039 --> 00:17:58,703 there were a lot of things about Tyrannosaurs that did not fit that picture." 215 00:17:59,311 --> 00:18:01,973 "One example is the foot. 216 00:18:02,314 --> 00:18:07,217 And if we look at this, ah, pinched-out third toe, 217 00:18:07,353 --> 00:18:11,380 in fact, this is the kind of characteristic we see in many of 218 00:18:11,523 --> 00:18:13,718 the other late Cretaceous dinosaurs. 219 00:18:13,993 --> 00:18:15,620 But all of them are small dinosaurs. 220 00:18:15,761 --> 00:18:18,025 They are not these big meat-eaters that we are so familiar with, 221 00:18:18,163 --> 00:18:19,926 animals like allosaurus. 222 00:18:21,433 --> 00:18:25,392 Looking at the foot and a whole suite of other characters in the skeleton, 223 00:18:25,537 --> 00:18:30,497 we now realize that Tyrannosaurs are, in fact, small meat-eating dinosaurs 224 00:18:30,676 --> 00:18:32,371 that have grown extremely large, 225 00:18:32,511 --> 00:18:33,443 and they are not related to the other 226 00:18:33,579 --> 00:18:36,343 meat-eating dinosaurs that are large at all." 227 00:18:40,219 --> 00:18:43,655 Anatomical detective work can easily identify dinosaurs to whom 228 00:18:43,789 --> 00:18:45,984 T. Rex is not related. 229 00:18:47,693 --> 00:18:51,356 But tracing its family tree back through time is more diffiicult. 230 00:18:53,298 --> 00:18:54,890 A huge gap in the fossil record 231 00:18:55,034 --> 00:18:59,664 precedes the sudden appearance of T. Rex's first large predecessor. 232 00:19:20,659 --> 00:19:22,889 But recently, some of the missing clues have been 233 00:19:23,028 --> 00:19:26,987 found four thousand feet up in the mountains of Alberta, Canada, 234 00:19:27,366 --> 00:19:30,335 on a prehistoric beach frozen in time, 235 00:19:30,469 --> 00:19:33,632 thrust on its side over millions of years. 236 00:19:50,756 --> 00:19:52,986 "The richest dinosaur footprint site in all of Canada 237 00:19:53,125 --> 00:19:55,525 is in a coal mine in Grand Cache, Alberta. 238 00:19:56,261 --> 00:19:58,889 In these hundred million year-old rocks, 239 00:19:59,031 --> 00:20:02,933 we have evidence of, ah, armored dinosaurs, 240 00:20:03,068 --> 00:20:04,592 ah, meat-eating dinosaurs of different 241 00:20:04,736 --> 00:20:07,603 kinds, and large plant-eating dinosaurs." 242 00:20:10,242 --> 00:20:12,005 "The footprints are all in trackways, 243 00:20:12,144 --> 00:20:15,113 and they go across this, ah, enormous cliff face which, 244 00:20:15,247 --> 00:20:18,182 at one time, must have been a mud flat at the edge of the sea." 245 00:20:20,419 --> 00:20:22,649 "What is important about this site is 246 00:20:22,788 --> 00:20:24,983 that because of the age, a hundred million years ago, 247 00:20:25,457 --> 00:20:31,089 ah, we do not have equivalent bone sites in this part of the world. 248 00:20:31,363 --> 00:20:32,387 And so, we have to do a little bit of 249 00:20:32,531 --> 00:20:35,500 guesswork in terms of identifying the dinosaurs. 250 00:20:36,201 --> 00:20:38,795 And I do not think there is any question at all that these are 251 00:20:38,937 --> 00:20:40,632 not Tyrannosaur tracks. 252 00:20:40,772 --> 00:20:42,865 But their long, slender toes suggest to me that 253 00:20:43,008 --> 00:20:45,272 these were made by giant coelurosaurs. 254 00:20:45,511 --> 00:20:48,275 And we feel these days that giant coelurosaurs may have been the 255 00:20:48,413 --> 00:20:50,608 ancestor of Tyrannosaurus rex." 256 00:20:59,324 --> 00:21:04,091 The coelurosaur was a turning point in the evolution of Tyrannosaurus rex. 257 00:21:04,229 --> 00:21:06,754 Unlike other small predators of its time, 258 00:21:06,899 --> 00:21:11,427 it used its jaws rather than its front limbs for killing its victims. 259 00:21:17,109 --> 00:21:20,943 That adaptation would set the stage for the rise of T. Rex and its 260 00:21:21,079 --> 00:21:22,546 unique appearance. 261 00:21:22,881 --> 00:21:26,544 The earliest of the Tyrannosaur family is called alectrosaurus. 262 00:21:26,818 --> 00:21:30,720 It is a long, slender animal with relatively long front limbs. 263 00:21:33,425 --> 00:21:35,484 By the time albertosaurus evolved, 264 00:21:35,627 --> 00:21:38,790 its head was larger and its front limbs shorter. 265 00:21:43,135 --> 00:21:46,104 "There were certainly many species of Tyrannosaurs. 266 00:21:46,238 --> 00:21:49,696 We, at present, know of more than half a dozen species. 267 00:21:50,008 --> 00:21:52,306 The earliest fossil record of albertosaurus is about eighty 268 00:21:52,444 --> 00:21:53,502 million years old. 269 00:21:53,645 --> 00:21:56,910 This animal in its external features really is not all that different 270 00:21:57,049 --> 00:21:58,175 from Tyrannosaurus rex. 271 00:21:58,317 --> 00:22:00,717 But when you start looking at specific characteristics, 272 00:22:00,852 --> 00:22:03,912 there are features which suggest it is more primitive than 273 00:22:04,056 --> 00:22:05,956 Tyrannosaurus rex itself." 274 00:22:07,793 --> 00:22:10,728 But who was T. Rex's closest relative? 275 00:22:12,130 --> 00:22:15,065 Opinion is divided between two candidates, 276 00:22:16,235 --> 00:22:18,931 one from North America known as daspletosaurus 277 00:22:19,071 --> 00:22:22,165 and another from Asia known as tarbosaurus. 278 00:22:23,342 --> 00:22:25,207 "Tarbosaurus is an animal that 279 00:22:25,344 --> 00:22:27,471 originally was called Tyrannosaurus as well. 280 00:22:27,613 --> 00:22:30,138 It, ah, has a number of differences. 281 00:22:30,415 --> 00:22:32,679 But when you start looking at other specifics, 282 00:22:32,784 --> 00:22:35,218 ah, for example, the orientation of 283 00:22:35,354 --> 00:22:37,720 the back of the skull in relation to the neck, 284 00:22:37,856 --> 00:22:42,020 tarbosaurus shows a lot of characters that, ah, suggest to me, at least, 285 00:22:42,160 --> 00:22:46,324 that it may be more closely related to Tyrannosaurus rex." 286 00:22:47,599 --> 00:22:49,396 But a recent find from Montana 287 00:22:49,534 --> 00:22:53,334 convinces Jack Horner of T. Rex's American ancestry. 288 00:22:54,373 --> 00:22:58,503 "Daspletosaurus is the animal that, that I believe and, and, and 289 00:22:58,644 --> 00:23:00,578 some others also believe, was actually 290 00:23:00,746 --> 00:23:04,705 the predecessor of Tyrannosaurus rex, in other words, its ancestor. 291 00:23:05,017 --> 00:23:09,147 Tyrannosaurus rex was the descendant of daspletosaurus. 292 00:23:09,288 --> 00:23:13,156 Tyrannosaurs, they have a big horn over top of their eye. 293 00:23:13,692 --> 00:23:19,255 And we see, we see it very dominant in Tyrannosaurus rex. 294 00:23:19,398 --> 00:23:21,093 We see it less dominant in this 295 00:23:21,233 --> 00:23:24,430 particular animal that is related to daspletosaurus 296 00:23:24,569 --> 00:23:30,303 and even less so in the more primitive daspletosaurus." 297 00:23:31,810 --> 00:23:34,938 The ancestry puzzle may take a long time to solve. 298 00:23:35,080 --> 00:23:37,014 But one trend is clear. 299 00:23:37,282 --> 00:23:40,945 As the Tyrannosaur family evolved, they not only grew larger, 300 00:23:41,086 --> 00:23:44,283 they changed to cope with their increased size. 301 00:23:47,492 --> 00:23:48,516 "There are a lot of changes that are 302 00:23:48,727 --> 00:23:51,127 necessary if you are going to become a large animal. 303 00:23:51,430 --> 00:23:54,399 And, ah, this is particularly true when we are talking animals 304 00:23:54,533 --> 00:23:55,932 like the meat-eating dinosaurs, 305 00:23:56,068 --> 00:23:58,127 because essentially they were teeter-totters. 306 00:23:58,437 --> 00:24:01,929 They were animals where the front of the body was balanced by the tail 307 00:24:02,074 --> 00:24:04,474 on a fulcrum which was at the hips." 308 00:24:05,744 --> 00:24:07,302 "Now in Tyrannosaurus' case, 309 00:24:07,446 --> 00:24:11,405 as it got bigger, the head became disproportionately larger, 310 00:24:11,550 --> 00:24:15,782 and that is to house all those very large vicious-looking teeth. 311 00:24:16,188 --> 00:24:19,385 Consequently, we see a lot of specializations in Tyrannosaurus 312 00:24:19,524 --> 00:24:23,426 that are meant to bring the body weight down in front of the hips. 313 00:24:23,829 --> 00:24:27,265 The skull is, ah, a long, heavy skull. 314 00:24:27,566 --> 00:24:31,093 But many of the bones, in fact, are air-filled. 315 00:24:31,370 --> 00:24:33,531 The neck has been recurved, much 316 00:24:33,705 --> 00:24:36,333 more so that in earlier meat-eating dinosaurs, 317 00:24:36,475 --> 00:24:41,105 simply because by doing that it could bring the head back closer to the hips 318 00:24:41,246 --> 00:24:44,306 and shift the center of gravity further back as well." 319 00:24:46,284 --> 00:24:48,775 "Finally, and probably most conspicuously, if you look at 320 00:24:48,920 --> 00:24:51,013 the front limbs of Tyrannosaurus, 321 00:24:51,323 --> 00:24:54,019 they have become also extremely short. 322 00:24:54,826 --> 00:24:57,693 They were relying on their head to do the killing. 323 00:24:57,963 --> 00:24:59,396 The limbs could be shortened up 324 00:24:59,531 --> 00:25:04,696 and would give it a great savings in weight on the front end of the body. 325 00:25:04,836 --> 00:25:08,101 And it was one more of the adaptations that Tyrannosaurs picked up." 326 00:25:21,319 --> 00:25:25,483 Ever since the first skeleton of T. Rex was assembled eighty years ago, 327 00:25:25,690 --> 00:25:27,123 most people have assumed that the king 328 00:25:27,259 --> 00:25:30,922 of dinosaurs must have been a slow and lumbering beast. 329 00:25:31,263 --> 00:25:32,924 But that view is changing. 330 00:25:33,965 --> 00:25:34,897 "From this position, 331 00:25:35,033 --> 00:25:39,732 one gets a sense of what an enormous animal Tyrannosaurus rex really is. 332 00:25:40,105 --> 00:25:43,836 In fact, this animal is so big and so massive, 333 00:25:43,975 --> 00:25:45,966 that for a long time everybody thought 334 00:25:46,111 --> 00:25:48,739 that this had to be a slow-moving animal. 335 00:25:49,881 --> 00:25:53,112 In recent years, though, we have been looking more closely 336 00:25:53,251 --> 00:25:56,345 at the anatomy of the hind leg of these dinosaurs 337 00:25:56,488 --> 00:26:00,288 and what we see is not necessarily what we expected to see." 338 00:26:00,725 --> 00:26:04,252 The relative proportions of the individual leg bones of Tyrannosaurus 339 00:26:04,396 --> 00:26:07,456 give us an idea of how fast this animal could be. 340 00:26:07,766 --> 00:26:10,633 Now, in fast-moving animals like ostriches, 341 00:26:10,735 --> 00:26:15,069 the upper leg bone is relatively short compared to the lower leg bones. 342 00:26:15,407 --> 00:26:18,308 In Tyrannosaurus, we see the same kind of pattern. 343 00:26:18,443 --> 00:26:23,176 Lower bones are as long or longer than the upper bones. 344 00:26:24,249 --> 00:26:29,346 "This, ah, continues, in fact, down into the foot where, 345 00:26:29,488 --> 00:26:32,980 if we look at the flat of the foot, or what would be the flat of the 346 00:26:33,124 --> 00:26:37,026 foot in a human being, this unit is also very long. 347 00:26:37,395 --> 00:26:38,123 All in all, then, 348 00:26:38,263 --> 00:26:42,165 if we look at the characters that we see in the hind legs of Tyrannosaurs, 349 00:26:42,300 --> 00:26:46,498 I do not think there is any question at all that in spite of its massive size, 350 00:26:46,705 --> 00:26:49,697 this is an animal that was built for speed. And it is an animal that it, 351 00:26:49,841 --> 00:26:54,141 in fact, could outrun any of its potential prey in its world." 352 00:27:00,619 --> 00:27:03,986 But Jack Horner has studied the same evidence and drawn the opposite 353 00:27:04,122 --> 00:27:05,111 conclusion. 354 00:27:05,357 --> 00:27:09,157 He is convinced that T. Rex was a walker, not a runner. 355 00:27:10,328 --> 00:27:15,630 "If we look at the leg bones of a meat-eating dinosaur, ah, named troodon, 356 00:27:15,967 --> 00:27:21,906 what we see is a thigh bone and a shin bone that have different lengths. 357 00:27:22,040 --> 00:27:26,739 We see that the thigh bone is shorter than the shin bone, 358 00:27:27,045 --> 00:27:32,711 and this is true of every single one of the non-Tyrannosaurs. 359 00:27:32,851 --> 00:27:34,819 We see the same thing in ostriches. 360 00:27:34,953 --> 00:27:39,981 We see the same thing in emus and rheas and, and all these running birds." 361 00:27:40,292 --> 00:27:44,661 "Animals that run fast have a short thigh bone and a long shin bone. 362 00:27:44,963 --> 00:27:47,830 The primitive feature is running. 363 00:27:48,099 --> 00:27:54,038 That means, in evolution, you have to evolve legs for walking, 364 00:27:54,172 --> 00:27:58,404 because there were no dinosaurs that were adapted for walking before 365 00:27:58,543 --> 00:28:00,408 we get to the Tyrannosaurs. 366 00:28:00,545 --> 00:28:02,274 If we look at Tyrannosaurs, 367 00:28:02,414 --> 00:28:07,613 the thigh bone and the shin bone are either the same length or the thigh 368 00:28:07,719 --> 00:28:11,519 bone is a, is slightly longer than the shin bone. 369 00:28:11,856 --> 00:28:16,987 This is a feature that is good for walking." 370 00:28:24,002 --> 00:28:25,629 But the high plains of New Mexico 371 00:28:25,704 --> 00:28:30,835 may offer more direct evidence of exactly how fast T. Rex really moved. 372 00:28:39,050 --> 00:28:40,711 Martin Lockley follows the trail of 373 00:28:40,852 --> 00:28:43,650 fossilized footprints across North America. 374 00:28:44,789 --> 00:28:47,724 He has seen and cataloged thousands. 375 00:28:48,994 --> 00:28:51,485 But one footprint receives special treatment. 376 00:28:52,197 --> 00:28:55,928 It is so unique that its location is a tightly-guarded secret. 377 00:28:59,871 --> 00:29:04,205 "We are inside a high security area in the New Mexico back country. 378 00:29:04,442 --> 00:29:09,379 This fenced enclosure contains this extraordinary and unique fossil footprint. 379 00:29:09,514 --> 00:29:14,008 This the only Tyrannosaurus footprint anywhere in the world." 380 00:29:16,521 --> 00:29:21,618 "This footprint was probably made not far from some river in the mud, 381 00:29:21,893 --> 00:29:25,727 and then it was filled in when the river flooded and washed a sheet 382 00:29:25,864 --> 00:29:28,264 of sand over this trampled area." 383 00:29:31,002 --> 00:29:35,905 "This is the casting that was filled in by sand, now sandstone. 384 00:29:36,207 --> 00:29:41,804 This track is on the order of, um, three feet long. And it is, ah, two 385 00:29:41,946 --> 00:29:45,006 feet wide, and it is almost a, a foot deep. 386 00:29:45,350 --> 00:29:48,080 This was made by an animal that probably weighed in at around, 387 00:29:48,219 --> 00:29:49,652 ah, five tons. 388 00:29:50,188 --> 00:29:52,952 It is sitting on a block that is about nine feet long. 389 00:29:53,091 --> 00:29:55,651 There is not a second footprint in that space, 390 00:29:55,794 --> 00:29:59,787 so that this means a minimum step of about nine feet. 391 00:29:59,931 --> 00:30:02,900 And if we calculate or estimate the speed of this animal, 392 00:30:03,034 --> 00:30:07,027 it was probably moving along at, at least, ah, eleven kilometers, 393 00:30:07,172 --> 00:30:09,436 something like six or seven miles per hour, 394 00:30:09,574 --> 00:30:11,838 which, which is a, is pretty good, ah, clip. 395 00:30:11,976 --> 00:30:14,740 It would be a jog for a, a human being." 396 00:30:18,483 --> 00:30:22,852 The movements of modern birds can also shed light on how dinosaurs traveled. 397 00:30:26,157 --> 00:30:30,992 Jim Farlow studies Australian emus and their similarities to T. Rex. 398 00:30:32,063 --> 00:30:34,531 "It would be nice to know what Tyrannosaurus was like as 399 00:30:34,666 --> 00:30:35,360 a living animal, 400 00:30:35,500 --> 00:30:37,832 but it is very inconveniently extinct. 401 00:30:38,203 --> 00:30:41,798 And if you want to get a picture of how it moved, 402 00:30:41,940 --> 00:30:44,135 what it might have been like when it was alive, 403 00:30:44,275 --> 00:30:47,244 it is helpful to look at modern animals that give us an 404 00:30:47,378 --> 00:30:50,211 approximation to something like Tyrannosaurus. 405 00:30:50,348 --> 00:30:53,579 And of such modern animals, I think the emu is about as good 406 00:30:53,718 --> 00:30:55,686 a model as one could hope to find. 407 00:30:56,221 --> 00:30:59,349 I suspect it is probably faster than Tyrannosaurus was." 408 00:30:59,758 --> 00:31:04,991 "Ah, an emu in the wild can go what, ah, fifty, maybe sixty kilometers an hour? 409 00:31:06,030 --> 00:31:06,792 Tyrannosaurus, 410 00:31:06,931 --> 00:31:11,834 obviously we have no direct way of, of determining how fast it could go. 411 00:31:12,203 --> 00:31:15,661 But based on the calculations of the strength of its bones relative to 412 00:31:15,807 --> 00:31:17,536 the size of the animal, 413 00:31:17,909 --> 00:31:20,935 I would think that a, at a good ball-park figure for the top 414 00:31:21,079 --> 00:31:24,674 speed of Tyrannosaurus might be something on the order of thirty, 415 00:31:24,783 --> 00:31:26,774 forty kilometers per hour." 416 00:31:30,889 --> 00:31:32,584 "If you look at the way this emu walks, 417 00:31:32,724 --> 00:31:36,319 the way it puts its feet one in front of the other, it is a striding walker. 418 00:31:36,461 --> 00:31:38,588 It does not hop like a kangaroo. 419 00:31:38,897 --> 00:31:41,593 And if you look at the way it picks up its feet as it goes, 420 00:31:41,733 --> 00:31:42,927 I think this is about as close to a 421 00:31:43,067 --> 00:31:46,002 Tyrannosaurus as we can find in our modern world. 422 00:31:46,137 --> 00:31:48,935 And that is part of the fascination that emus have for me." 423 00:31:52,944 --> 00:31:54,536 But emus and other modern birds 424 00:31:54,746 --> 00:31:58,546 without tails may not provide a completely accurate model. 425 00:31:58,983 --> 00:32:01,918 Other scientists pursue a more distant cousin. 426 00:32:03,488 --> 00:32:06,150 "The animal I have here and the reason I think crocodilians are worth 427 00:32:06,291 --> 00:32:10,091 spending a lot of time looking at, ah, this is a salt-water crocodile 428 00:32:10,228 --> 00:32:13,925 and it retains many of the features that we think the primitive 429 00:32:14,065 --> 00:32:15,760 dinosaur ancestor might have had. 430 00:32:16,100 --> 00:32:19,331 We know that birds and crocodilians are dinosaurs' closest living relatives 431 00:32:19,470 --> 00:32:22,064 and so they are the logical place to look for information on how 432 00:32:22,207 --> 00:32:23,299 T. Rex works." 433 00:32:23,708 --> 00:32:26,768 The muscle that I have spent a lot of time looking at, ah, originates 434 00:32:26,911 --> 00:32:27,775 from the side of the tail. 435 00:32:27,912 --> 00:32:31,040 As you can see, crocodilians have a long, heavy, muscular tail. 436 00:32:31,349 --> 00:32:32,680 And along here where my fingers are 437 00:32:32,817 --> 00:32:36,981 is a large muscle that runs forward to attach onto the thigh bone, the femur. 438 00:32:37,288 --> 00:32:38,755 What we see in modern birds is that 439 00:32:38,890 --> 00:32:41,381 the tail itself has been reduced dramatically. 440 00:32:41,726 --> 00:32:43,091 Most of what we see in a bird tail is 441 00:32:43,228 --> 00:32:45,696 actually just feathers rather than muscle and bone. 442 00:32:46,030 --> 00:32:49,932 X-ray films prove that the presence or absence of a tail is a 443 00:32:50,068 --> 00:32:52,468 vital factor in the movement of an animal, 444 00:32:52,737 --> 00:32:55,865 be it bird, crocodilian or dinosaur. 445 00:32:57,108 --> 00:32:58,302 "What we are seeing in the X-ray films 446 00:32:58,443 --> 00:33:00,377 is that crocodilians and birds have 447 00:33:00,511 --> 00:33:02,672 very distinctive ways of moving their legs. 448 00:33:03,414 --> 00:33:05,507 The question was, which of those patterns can we apply back to a 449 00:33:05,683 --> 00:33:07,548 dinosaur like Tyrannosaurus? 450 00:33:08,753 --> 00:33:12,655 Birds use a lot of knee movement. The hip is very, very stable. 451 00:33:13,024 --> 00:33:16,118 Ah, whereas in crocodilians, they are using lots of hip movement, 452 00:33:16,261 --> 00:33:17,387 and that seems to be driven by this 453 00:33:17,528 --> 00:33:19,689 muscle running from the tail to the thigh bone." 454 00:33:20,431 --> 00:33:24,561 "Fortunately for this muscle, there is a very distinct scar, a bony 455 00:33:24,702 --> 00:33:29,503 attachment on the thigh bone that we can see in fossils like in T. Rex, 456 00:33:29,707 --> 00:33:32,972 suggesting that that muscle existed and probably was working in 457 00:33:33,111 --> 00:33:35,079 similar way in these forms. 458 00:33:35,513 --> 00:33:37,674 What I am suggesting is that in 459 00:33:37,815 --> 00:33:41,148 Tyrannosaurus we have a unique combination of features, 460 00:33:41,286 --> 00:33:44,551 a tail that is more similar to what we see in crocodilians 461 00:33:44,722 --> 00:33:46,019 and yet a bird-like lower limb, 462 00:33:46,391 --> 00:33:49,121 so a bird knee, a bird ankle and a bird foot 463 00:33:49,260 --> 00:33:50,921 with a kind of crocodilian hips." 464 00:33:51,262 --> 00:33:53,856 "And so in Tyrannosaurus rex, I am predicting then we would have 465 00:33:53,998 --> 00:33:55,829 a unique combination of features 466 00:33:55,967 --> 00:33:58,731 working in a way unlike any other living animal today." 467 00:34:30,902 --> 00:34:33,928 T. Rex was huge and its tail enormous. 468 00:34:34,072 --> 00:34:36,905 But it not only had to move, it had to mate. 469 00:34:38,710 --> 00:34:40,507 Again, modern crocodiles may offer 470 00:34:40,712 --> 00:34:44,148 us a glimpse of the mechanics of T. Rex sex. 471 00:35:11,275 --> 00:35:15,439 The examples of modern reptiles and birds, and a few rare fossils, 472 00:35:15,580 --> 00:35:19,710 suggest that T. Rex was a nesting animal and laid eggs. 473 00:35:20,451 --> 00:35:23,147 "Well, I have in front of me some dinosaur eggs from China. 474 00:35:23,721 --> 00:35:26,087 And these are very elongated, 475 00:35:26,224 --> 00:35:29,421 kind of the shape that we would expect for Tyrannosaurus rex. 476 00:35:29,727 --> 00:35:32,662 To give you a feel for its size, I have here a chicken egg." 477 00:35:35,066 --> 00:35:36,226 "But what it is really exciting and 478 00:35:36,367 --> 00:35:40,303 very rare is this clutch of eggs here which are very badly crushed. 479 00:35:40,571 --> 00:35:44,371 But we do have an embryo, and it is lying here. 480 00:35:44,509 --> 00:35:47,137 We can see the eye socket, the skull, 481 00:35:47,712 --> 00:35:51,671 the backbone in here, the pelvis, a hind leg. 482 00:35:52,717 --> 00:35:56,551 This embryo is about the size that we would expect for a Tyrannosaurus rex." 483 00:35:57,955 --> 00:36:00,947 "We can imagine this hatchling coming out of the egg 484 00:36:01,092 --> 00:36:05,529 and scurrying off into the underbrush or, possibly if there was parental care, 485 00:36:05,663 --> 00:36:07,995 it may have scurried off and joined its parents." 486 00:36:55,847 --> 00:36:59,681 Sixty-five million years ago the earth was ruled by the dinosaurs 487 00:36:59,784 --> 00:37:02,912 and the dinosaurs were ruled by Tyrannosaurus rex, 488 00:37:03,287 --> 00:37:05,847 a hunter fast enough, big enough, powerful 489 00:37:05,990 --> 00:37:08,720 enough to catch and consume any prey. 490 00:37:10,962 --> 00:37:14,796 But one paleontologist dares to suggest T. Rex was not a killer 491 00:37:14,932 --> 00:37:18,459 but a scavenger, a giant marauding vulture. 492 00:37:20,438 --> 00:37:23,134 "There is a controversy right now, um, 493 00:37:23,274 --> 00:37:27,643 of which I seem to be the, ah ha, to be one of and almost everyone else 494 00:37:27,778 --> 00:37:30,838 in paleontology seems to be at the other side of. 495 00:37:31,249 --> 00:37:35,743 And this has to do with Tyrannosaurus rex being a predator or a scavenger. 496 00:37:36,220 --> 00:37:40,020 A predator we have to remember is, is actually a hunter, 497 00:37:40,158 --> 00:37:44,151 and a scavenger is the kind of animal that only eats dead things." 498 00:37:45,163 --> 00:37:47,859 "We, we look down upon scavenging. 499 00:37:48,533 --> 00:37:53,664 Tyrannosaurus rex. We hate to think about Tyrannosaurus rex as a scavenger. 500 00:37:53,804 --> 00:37:55,863 We would rather think of it as a predator. 501 00:37:56,140 --> 00:37:58,335 It is named the tyrant lizard king. 502 00:37:58,476 --> 00:38:00,535 You cannot have a king that is a scavenger." 503 00:38:04,348 --> 00:38:09,615 "A hunter should have big eyes. It should have good eyesight. 504 00:38:09,754 --> 00:38:16,353 And if we look at the brain case or if we look at, at, at a, ah, T. Rex, 505 00:38:17,028 --> 00:38:19,258 the biggest lobe of the brain, the 506 00:38:19,397 --> 00:38:23,629 actual big openings in the brain are for the sense of smell. 507 00:38:23,734 --> 00:38:29,138 And, and because, because we, we can, 508 00:38:29,273 --> 00:38:32,174 we can actually carve out the area where the brain was, 509 00:38:32,310 --> 00:38:34,642 we can C AT scan it, we can do all sorts of things to it, 510 00:38:34,779 --> 00:38:38,112 we actually can make a model of what the brain would look like." 511 00:38:38,549 --> 00:38:43,714 "We see the optic lobe is right here. It is very small. 512 00:38:44,055 --> 00:38:48,185 And the olfactory lobe is this huge thing at the front end of the brain. 513 00:38:48,426 --> 00:38:49,688 This is huge. 514 00:38:49,894 --> 00:38:52,294 This is, this means that Tyrannosaurus 515 00:38:52,430 --> 00:38:58,665 had a very, very, very good sense of smell and not very good eyesight. 516 00:38:58,869 --> 00:39:01,064 This is contradictory to a hunter. 517 00:39:01,405 --> 00:39:04,033 This is what scavengers have." 518 00:39:16,287 --> 00:39:19,484 Horner's scavenger theory is disputed by Phil Currie, 519 00:39:19,657 --> 00:39:22,649 a stalwart defender of T. Rex, the hunter. 520 00:39:24,161 --> 00:39:27,927 "The skull of Tyrannosaurus is very narrow in the snout region, 521 00:39:28,065 --> 00:39:31,933 which allows the eyes to face forward, giving it stereoscopic vision. 522 00:39:32,270 --> 00:39:33,032 In addition to that, 523 00:39:33,170 --> 00:39:37,368 the ears themselves, um, are located in such a way that they should 524 00:39:37,508 --> 00:39:41,103 be able to pick up sounds in particular directions. 525 00:39:41,512 --> 00:39:45,278 Ah, the ears may not look, ah, very 526 00:39:45,416 --> 00:39:47,850 different from the other carnivorous dinosaurs externally, 527 00:39:47,985 --> 00:39:50,977 but internally there are a lot of changes that have taken place." 528 00:39:51,355 --> 00:39:55,792 "This gives Tyrannosaurus rex a greater range of hearing capabilities, 529 00:39:55,926 --> 00:39:57,359 that is, the frequencies that it could 530 00:39:57,495 --> 00:40:00,828 hear were lower than what most other dinosaurs could. 531 00:40:01,265 --> 00:40:04,928 Since Tyrannosaurus was probably hunting other dinosaurs which were 532 00:40:05,069 --> 00:40:07,629 animals that probably made low sounds, 533 00:40:07,938 --> 00:40:09,735 the changes in the ear would allow it 534 00:40:09,874 --> 00:40:12,468 to hear those animals better and to hunt them down." 535 00:40:33,631 --> 00:40:37,795 "The size of the Tyrannosaur is advantageous for a scavenger. 536 00:40:38,102 --> 00:40:41,401 The bigger you are, the better chance you have of chasing away another 537 00:40:41,539 --> 00:40:44,030 animal that may have made a kill. 538 00:40:44,408 --> 00:40:47,605 Even the short little arms are, T. Rex does not have anything for grabbing. 539 00:40:47,745 --> 00:40:48,803 And we are bipedal. 540 00:40:48,946 --> 00:40:52,438 We know that if we are going to go out and catch a chicken, we want, 541 00:40:52,583 --> 00:40:55,143 we do not want to have our hands tied behind us. 542 00:40:55,786 --> 00:41:01,156 All of the features that we see all suggest that Tyrannosaurus and the 543 00:41:01,292 --> 00:41:04,819 Tyrannosaurs in general, were scavengers." 544 00:41:39,630 --> 00:41:41,325 "When I look in the jaws of Tyrannosaurus rex, 545 00:41:41,465 --> 00:41:44,093 I have little doubt about its predatory capabilities. 546 00:41:44,402 --> 00:41:47,803 These are jaws that are meant to do some pretty nasty work. 547 00:41:48,305 --> 00:41:49,567 Like other carnivorous animals, 548 00:41:49,740 --> 00:41:53,403 Tyrannosaurus rex has teeth that are curved backwards 549 00:41:53,744 --> 00:41:55,905 and at the same time the tips of the 550 00:41:56,046 --> 00:41:59,174 teeth, in fact, curve towards the center of the mouth as well. 551 00:41:59,817 --> 00:42:03,776 What this means is that these teeth are specialized in such a way 552 00:42:03,921 --> 00:42:06,981 that if the prey is in the mouth and is struggling, 553 00:42:07,124 --> 00:42:11,288 ah, the only way for it to escape really is to go back further into the throat." 554 00:42:19,870 --> 00:42:24,000 "Because Tyrannosaur teeth are so tall, they have to have a very deep root. 555 00:42:24,275 --> 00:42:27,938 And this give them, ah, the strength so that the tooth is unlikely to break 556 00:42:28,078 --> 00:42:30,672 and also has the strength to puncture right through bone. 557 00:42:31,215 --> 00:42:34,673 And, ah, this is the reason the Tyrannosaurjaws are so deep. 558 00:42:35,219 --> 00:42:39,519 Um, almost two-thirds the length of the tooth is, in fact, root." 559 00:42:39,723 --> 00:42:43,853 There are these very fine serrations that run down the front of the tooth 560 00:42:43,994 --> 00:42:45,256 and the back of the tooth. 561 00:42:45,396 --> 00:42:48,888 These serrations function as little hooks, 562 00:42:49,033 --> 00:42:52,025 and as the tooth is driven through the meat, 563 00:42:52,169 --> 00:42:56,902 the hooks hook the fibers of meat and take it between the serrations. 564 00:42:57,041 --> 00:43:01,375 And between the serrations you have razor-sharp edges that cut those fibers. 565 00:43:02,913 --> 00:43:04,881 Now, if we shift to the inside of the jaw, 566 00:43:05,015 --> 00:43:08,917 we can see that there are some very powerful muscle attachments here 567 00:43:09,053 --> 00:43:11,920 going from the top down through this region. 568 00:43:12,056 --> 00:43:15,719 And this gives a muscle mass that fills in this whole area. 569 00:43:16,927 --> 00:43:21,364 These muscles allow the animal to close its jaws on very large animals 570 00:43:21,499 --> 00:43:24,491 and deliver a powerful bite very rapidly. 571 00:43:24,702 --> 00:43:25,999 And it would have no trouble at all 572 00:43:26,136 --> 00:43:29,663 cutting an animal such as myself in half in one, single bite. 573 00:43:33,611 --> 00:43:37,377 "We can say that Tyrannosaurus basically had a mouthful of steak knives. 574 00:43:37,815 --> 00:43:39,180 And if you have a mouthful of steak 575 00:43:39,316 --> 00:43:43,377 knives, obviously, you eat steak, which is meat. 576 00:43:43,854 --> 00:43:45,879 We know that Tyrannosaurs ate meat. 577 00:43:46,023 --> 00:43:50,119 We know that they ate dinosaurs because we have evidence. 578 00:43:50,461 --> 00:43:56,297 Yet this is a, a piece of a, a fibula, a shin bone from a duckbill dinosaur, 579 00:43:56,433 --> 00:44:01,871 and this shin bone actually has gauges, tooth marks from, from 580 00:44:02,006 --> 00:44:04,065 being bitten by a Tyrannosaur. 581 00:44:04,375 --> 00:44:06,935 And what is really interesting, it has a puncture mark in it. 582 00:44:07,378 --> 00:44:09,141 And in that puncture mark within 583 00:44:09,280 --> 00:44:13,273 the bone is actually the tip of a Tyrannosaur tooth. 584 00:44:13,784 --> 00:44:15,718 So this is absolute proof that 585 00:44:15,853 --> 00:44:19,311 Tyrannosaurs ate meat, that they ate other dinosaurs. 586 00:44:19,757 --> 00:44:25,059 But what it is not is evidence that the Tyrannosaur killed this particular animal." 587 00:44:28,532 --> 00:44:32,229 But Ken Carpenter's forensic examination of another duckbill 588 00:44:32,369 --> 00:44:35,930 provides more compelling evidence that T. Rex was a powerful, 589 00:44:36,073 --> 00:44:38,667 if not always successful, predator. 590 00:44:41,211 --> 00:44:44,806 "I have been involved in a bit of detective work with this skeleton, 591 00:44:45,115 --> 00:44:48,016 mostly centered around the damaged area, this part of the tail. 592 00:44:48,485 --> 00:44:51,852 If we look here, we will see that part of this, ah, spine is missing. 593 00:44:52,256 --> 00:44:54,816 And it turns out that there is a very nice groove here that 594 00:44:54,959 --> 00:44:57,519 if I were to take a Tyrannosaurus tooth, 595 00:44:57,795 --> 00:45:00,525 we find that it fits very well in that groove. 596 00:45:01,498 --> 00:45:06,197 Most likely then that this part of the vertebrae was bitten off by a 597 00:45:06,337 --> 00:45:09,272 Tyrannosaurus rex that was attacking from the right rear. 598 00:45:09,406 --> 00:45:13,775 Now interestingly, we have regrowth of bone around this spine as well 599 00:45:13,911 --> 00:45:17,210 as around some of the tooth puncture marks on these adjacent ones, 600 00:45:17,348 --> 00:45:19,873 indicating that this animal survived the attack. 601 00:45:20,217 --> 00:45:22,845 And the only animal that was big enough living at this time 602 00:45:22,987 --> 00:45:26,150 with jaws powerful enough to have sheared through this bone 603 00:45:26,290 --> 00:45:28,053 would have been a Tyrannosaurus rex. 604 00:45:28,292 --> 00:45:32,023 And I think it shows conclusively that Tyrannosaurus rex was a predator 605 00:45:32,162 --> 00:45:34,289 and not a scavenger, as some have thought." 606 00:46:42,900 --> 00:46:46,097 For the past century, the Badlands of North America have 607 00:46:46,236 --> 00:46:50,434 gradually yielded the first clues to a great prehistoric puzzle, 608 00:46:50,874 --> 00:46:53,365 evidence of how T. Rex lived. 609 00:46:53,944 --> 00:46:55,673 Many scientists are now convinced 610 00:46:55,746 --> 00:46:58,544 they have also uncovered the reason it died. 611 00:46:59,883 --> 00:47:04,445 A narrow band of sediment marks the end of the Age of Dinosaurs 612 00:47:04,722 --> 00:47:07,247 and the beginning of the rise of mammals, 613 00:47:07,658 --> 00:47:11,253 the boundary between two geological epochs. 614 00:47:12,096 --> 00:47:13,654 "Cretaceous-Tertiary boundary, 615 00:47:13,797 --> 00:47:18,291 ah, is well defined in this outcrop right here where we have been digging. 616 00:47:18,702 --> 00:47:24,334 Well, the actual boundary is known from a very narrow band of clay 617 00:47:24,475 --> 00:47:27,638 that was laid down sixty-five million years ago. 618 00:47:27,978 --> 00:47:31,641 We can, ah, recognize it on a global scale. 619 00:47:32,049 --> 00:47:33,846 And it tells us that something very 620 00:47:33,984 --> 00:47:37,215 specific happened at that time, in geological time." 621 00:47:39,389 --> 00:47:43,223 There was a rare mineral called iridium, found in the clay. 622 00:47:43,494 --> 00:47:46,986 It was carried here by an asteroid that smashed into the planet. 623 00:47:47,531 --> 00:47:51,695 But did that actually cause the extinction of the dinosaurs? 624 00:47:51,969 --> 00:47:55,166 Certainly it seems to have had devastating effects. 625 00:47:55,839 --> 00:47:57,966 "The fossil plants below the boundary 626 00:47:58,108 --> 00:48:02,636 tell us that there were lush forests existing in this region and, 627 00:48:02,780 --> 00:48:04,077 and throughout the prairie regions 628 00:48:04,214 --> 00:48:07,615 that we know, as we know them today before the boundary. 629 00:48:07,818 --> 00:48:10,446 And right before the boundary in some sediments that, 630 00:48:10,654 --> 00:48:14,954 that I have studied, we have a very typical cypress swamp, 631 00:48:15,092 --> 00:48:16,389 such as the bald cypress swamp that 632 00:48:16,527 --> 00:48:19,223 you would find down in southern parts of the United States. 633 00:48:19,363 --> 00:48:21,797 And above the boundary there are no cypress trees. 634 00:48:21,932 --> 00:48:25,060 There is nothing in the, in those remains above the boundary that 635 00:48:25,202 --> 00:48:27,693 tell us the cypress swamps was around. 636 00:48:27,838 --> 00:48:28,930 It was gone. 637 00:48:29,273 --> 00:48:32,765 So something happened at that boundary that was very dramatic. 638 00:48:32,910 --> 00:48:34,468 It leveled the forest. 639 00:48:34,678 --> 00:48:40,014 The standing vegetation was, was literally clear-cut in a sense." 640 00:48:44,254 --> 00:48:47,280 Did this single catastrophe kill T. Rex? 641 00:48:47,858 --> 00:48:51,259 There are no fossils in the sediments immediately below the boundary, 642 00:48:51,395 --> 00:48:52,657 leading many to argue that the 643 00:48:52,796 --> 00:48:56,664 dinosaurs were extinct long before the asteroid impact. 644 00:48:57,034 --> 00:49:00,299 But a newly-discovered footprint from New Mexico seems to indicate 645 00:49:00,437 --> 00:49:02,803 that the dinosaurs were still there. 646 00:49:03,407 --> 00:49:07,468 "This is the, ah, layer with the, ah, youngest, ah, known dinosaur tracks. 647 00:49:07,644 --> 00:49:12,741 They are only thirty-seven centimeters or so below this, ah, iridium layer. 648 00:49:13,083 --> 00:49:16,712 That could be as little as, ah, a thousand years or less. 649 00:49:16,854 --> 00:49:19,721 And what it indicates is that the dinosaurs in this region that made 650 00:49:19,857 --> 00:49:24,351 their footprints on this surface lived up until the very last minute. 651 00:49:24,661 --> 00:49:28,654 They were not dying off slowly for hundreds of thousands or millions 652 00:49:28,799 --> 00:49:30,824 of years before the K-T event. 653 00:49:30,968 --> 00:49:34,426 They survived until the eleventh hour, if you like." 654 00:49:36,573 --> 00:49:39,872 If Tyrannosaurus rex was around until the last moment, 655 00:49:40,177 --> 00:49:41,644 then it was witness to one of the most 656 00:49:41,712 --> 00:49:44,704 devastating events the world has ever seen, 657 00:49:45,115 --> 00:49:46,980 an environmental holocaust that not 658 00:49:47,117 --> 00:49:51,315 even the strongest of all the dinosaurs could survive. 659 00:50:00,364 --> 00:50:03,458 The Badlands have surrendered a few of their secrets. 660 00:50:03,901 --> 00:50:06,028 But many questions remain. 661 00:50:06,770 --> 00:50:11,673 Hidden somewhere in these canyons are more clues to the ferocious life 662 00:50:11,808 --> 00:50:14,208 and mysterious death of the most 663 00:50:14,344 --> 00:50:16,312 powerful creature that ever walked the earth.