WEBVTT FILE 1 00:00:07.800 --> 00:00:10.880 66 million years ago, 2 00:00:10.880 --> 00:00:14.120 Planet Earth was very different from today. 3 00:00:19.880 --> 00:00:24.040 Back then, one of our closest ancestors might have looked 4 00:00:24.040 --> 00:00:27.480 something like this little furry creature. 5 00:00:35.760 --> 00:00:37.400 RUMBLING GROWL 6 00:00:39.600 --> 00:00:43.600 The rulers of the land were giant reptiles. 7 00:01:05.880 --> 00:01:07.720 Dinosaurs. 8 00:01:07.720 --> 00:01:09.360 That's one of the most infamous, 9 00:01:09.360 --> 00:01:13.240 a carnivorous T-rex. 10 00:01:13.240 --> 00:01:16.200 And just behind are the bison of their time, 11 00:01:16.200 --> 00:01:19.960 a common plant-eater, Edmontosaurus. 12 00:01:19.960 --> 00:01:21.880 But what happened to them all? 13 00:01:23.640 --> 00:01:25.680 66 million years ago, 14 00:01:25.680 --> 00:01:28.000 an asteroid hit the Earth, 15 00:01:28.000 --> 00:01:31.200 and scientists think that it was this collision 16 00:01:31.200 --> 00:01:34.320 that wiped out the dinosaurs. 17 00:01:34.320 --> 00:01:37.880 But no-one has ever found direct evidence of that. 18 00:01:37.880 --> 00:01:42.200 In fact, no-one has ever found the fossil of a dinosaur 19 00:01:42.200 --> 00:01:45.240 that died within a thousand years of the impact. 20 00:01:48.160 --> 00:01:54.000 However, a remarkable dig site promises to change that. 21 00:01:55.800 --> 00:01:58.600 It's in the Hell Creek formation 22 00:01:58.600 --> 00:02:01.000 in the American Midwest. 23 00:02:02.520 --> 00:02:07.840 These badlands are rich in prehistoric remains... 24 00:02:07.840 --> 00:02:10.400 ROARS 25 00:02:07.840 --> 00:02:10.400 ..from triceratops... 26 00:02:13.520 --> 00:02:16.320 SQUAWKS 27 00:02:13.520 --> 00:02:16.320 ..to pterosaurs. 28 00:02:17.760 --> 00:02:20.160 And here, one patch of land 29 00:02:20.160 --> 00:02:22.600 about the size of a football pitch 30 00:02:22.600 --> 00:02:26.680 is yielding a collection of astonishing fossils. 31 00:02:29.000 --> 00:02:32.280 The precise location is a closely guarded secret, 32 00:02:32.280 --> 00:02:35.480 because this place may hold evidence... 33 00:02:37.600 --> 00:02:40.120 ..of one of the most dramatic events 34 00:02:40.120 --> 00:02:43.200 in all the four-and-a-half- billion-year history 35 00:02:43.200 --> 00:02:44.600 of our planet. 36 00:02:48.640 --> 00:02:51.040 Right, let me get down here between you. 37 00:02:51.040 --> 00:02:54.640 For ten years, a palaeontologist and his team 38 00:02:54.640 --> 00:02:57.800 have been trying to find out exactly what happened here. 39 00:02:57.800 --> 00:03:00.280 You're at the edge of your seat every moment, 40 00:03:00.280 --> 00:03:01.880 trying to dig this stuff up. 41 00:03:01.880 --> 00:03:03.840 It's like trying to defuse a nuclear weapon 42 00:03:03.840 --> 00:03:06.000 while you're in a rainstorm. 43 00:03:06.000 --> 00:03:08.360 He's named the site Tanis, 44 00:03:08.360 --> 00:03:10.800 and believes it could be a mass graveyard 45 00:03:10.800 --> 00:03:12.320 of creatures that were killed 46 00:03:12.320 --> 00:03:15.000 in the catastrophic asteroid strike. 47 00:03:19.960 --> 00:03:25.160 A site that could reveal not only how the last dinosaurs lived, 48 00:03:25.160 --> 00:03:26.720 but how they died. 49 00:03:28.440 --> 00:03:32.400 If the dig team is right, Tanis could be a place 50 00:03:32.400 --> 00:03:35.560 where the remains of a long-lost world 51 00:03:35.560 --> 00:03:37.480 are frozen in time. 52 00:03:39.400 --> 00:03:42.200 A place that gives us, for the first time, 53 00:03:42.200 --> 00:03:44.520 an unprecedented window... 54 00:03:44.520 --> 00:03:45.720 SHRIEKS 55 00:03:47.520 --> 00:03:51.000 ..into the lives of the very last dinosaurs... 56 00:03:55.440 --> 00:03:58.200 ..and a minute-by-minute picture of what happened 57 00:03:58.200 --> 00:04:00.880 on the day the asteroid hit. 58 00:04:20.600 --> 00:04:23.960 This landscape is full of fossils 59 00:04:23.960 --> 00:04:26.320 dating from the Late Cretaceous, 60 00:04:26.320 --> 00:04:29.720 the period which began around 100 million years ago 61 00:04:29.720 --> 00:04:33.320 and ended 66 million years ago, 62 00:04:33.320 --> 00:04:35.120 when the dinosaurs vanished. 63 00:04:36.800 --> 00:04:41.280 Palaeontologist Robert DePalma wants to find out more. 64 00:04:41.280 --> 00:04:44.680 I think anybody who's ever liked dinosaurs 65 00:04:44.680 --> 00:04:46.600 in the past, or still does, 66 00:04:46.600 --> 00:04:48.360 has thought at one point or another, 67 00:04:48.360 --> 00:04:49.680 "Well, what happened to them? 68 00:04:49.680 --> 00:04:52.400 "Why are they not here any more?" 69 00:04:52.400 --> 00:04:54.240 So many different theories are out there, 70 00:04:54.240 --> 00:04:57.840 and nobody has a tight answer to that question. 71 00:05:02.120 --> 00:05:04.200 Judging from fossil evidence, 72 00:05:04.200 --> 00:05:08.000 this is what Hell Creek looked like in the Late Cretaceous. 73 00:05:13.880 --> 00:05:16.520 There were low-lying, marshy flood plains, 74 00:05:16.520 --> 00:05:20.520 intercut by river channels and covered with horsetails, 75 00:05:20.520 --> 00:05:22.920 ferns and trees. 76 00:05:22.920 --> 00:05:27.280 Back then, it was warm and wet here all year round. 77 00:05:30.560 --> 00:05:33.720 Tanis lies in the north-eastern corner 78 00:05:33.720 --> 00:05:36.160 of the Hell Creek formation. 79 00:05:37.800 --> 00:05:40.360 Instead of today's dusty prairies, 80 00:05:40.360 --> 00:05:42.120 there were sandy river banks. 81 00:05:45.080 --> 00:05:48.640 Instead of rocky cliffs, there were forests. 82 00:05:50.480 --> 00:05:52.840 And instead of the life we know today... 83 00:05:52.840 --> 00:05:55.960 DEEP RUMBLING CALLS 84 00:05:55.960 --> 00:05:58.600 TRILLING 85 00:05:58.600 --> 00:06:01.200 ..well, Robert is hoping to find out more 86 00:06:01.200 --> 00:06:02.920 about what that was like. 87 00:06:04.040 --> 00:06:05.640 COOING 88 00:06:08.600 --> 00:06:12.680 A sandbank lying between a river and a forest 89 00:06:12.680 --> 00:06:16.360 would one day become what Robert now calls Tanis. 90 00:06:19.480 --> 00:06:24.840 He and his team have been digging here since 2012. 91 00:06:24.840 --> 00:06:26.360 So somewhere from between there 92 00:06:26.360 --> 00:06:28.040 and down here is where that came from. 93 00:06:28.040 --> 00:06:29.800 It's come from up above. Hey, look at this. 94 00:06:29.800 --> 00:06:31.200 What? Look. 95 00:06:31.200 --> 00:06:32.720 Oh, yeah, yeah, yeah. OK. 96 00:06:32.720 --> 00:06:36.240 And what they found is unexpected. 97 00:06:36.240 --> 00:06:39.280 Here we've got this freshwater environment 98 00:06:39.280 --> 00:06:40.600 of the Hell Creek formation, 99 00:06:40.600 --> 00:06:44.520 and these shocking red, green colours 100 00:06:44.520 --> 00:06:47.200 coming from the shells of ammonites, a marine organism, 101 00:06:47.200 --> 00:06:49.800 kind of like a coiled snail in appearance. 102 00:06:49.800 --> 00:06:52.480 So we've got this marine organism that's been thrown up 103 00:06:52.480 --> 00:06:55.000 into this freshwater environment, 104 00:06:55.000 --> 00:06:56.920 and they do not belong here. 105 00:06:57.960 --> 00:07:00.440 How they got here is a mystery. 106 00:07:00.440 --> 00:07:01.480 OK... 107 00:07:01.480 --> 00:07:03.600 And there's more. 108 00:07:03.600 --> 00:07:07.120 I'm just going to go ahead and plane down some of this rock. 109 00:07:07.120 --> 00:07:09.320 Sitting just above the ammonites 110 00:07:09.320 --> 00:07:12.040 is something that many dinosaur hunters 111 00:07:12.040 --> 00:07:14.080 are desperate to find. 112 00:07:14.080 --> 00:07:19.120 So this orange layer right here is composed 100% 113 00:07:19.120 --> 00:07:23.280 of impact-related debris that is enriched in iridium. 114 00:07:23.280 --> 00:07:27.080 Iridium is an element that's rare in the Earth's crust, 115 00:07:27.080 --> 00:07:30.200 but it's common in asteroids. 116 00:07:30.200 --> 00:07:34.800 The layer it's in is called the K-Pg boundary. 117 00:07:35.920 --> 00:07:37.200 Dear Momma... 118 00:07:38.560 --> 00:07:40.640 Oh, dear. Really? Yeah. 119 00:07:40.640 --> 00:07:45.200 It's made up of dust and debris from a huge asteroid impact. 120 00:07:47.360 --> 00:07:48.800 Look at that. That's amazing. 121 00:07:48.800 --> 00:07:50.880 Yeah, yeah, yeah, yeah, yeah. That's what we want. 122 00:07:50.880 --> 00:07:52.560 OK. So it's coming from this area here. 123 00:07:52.560 --> 00:07:55.480 So somewhere within that region is where these pieces are coming from. 124 00:07:55.480 --> 00:07:58.320 The boundary separates the age of the dinosaurs 125 00:07:58.320 --> 00:08:00.280 from the age of mammals, 126 00:08:00.280 --> 00:08:03.120 so the rocks here come from about the time 127 00:08:03.120 --> 00:08:05.560 that the dinosaurs became extinct. 128 00:08:05.560 --> 00:08:07.520 No rattlesnakes. 129 00:08:07.520 --> 00:08:10.360 What makes the site even more exciting 130 00:08:10.360 --> 00:08:13.360 is the rock layer right beneath the boundary 131 00:08:13.360 --> 00:08:15.160 where Robert found the ammonites. 132 00:08:15.160 --> 00:08:17.840 The rock here is really not quite rocky, 133 00:08:17.840 --> 00:08:20.480 as you would expect dinosaur bones and things to be encased - 134 00:08:20.480 --> 00:08:23.000 you expect really, really hard rocks and jackhammers 135 00:08:23.000 --> 00:08:25.640 and things like this, but it's very, very crumbly 136 00:08:25.640 --> 00:08:29.280 and it just falls apart in your hands. 137 00:08:29.280 --> 00:08:31.760 As well as being crumbly throughout, 138 00:08:31.760 --> 00:08:35.480 this layer of rock is also around a metre thick, 139 00:08:35.480 --> 00:08:38.760 which, along with other unusual features, makes 140 00:08:38.760 --> 00:08:43.880 Robert think that something very strange must have happened here. 141 00:08:47.280 --> 00:08:50.400 Maybe a flood or a mud flow, 142 00:08:50.400 --> 00:08:53.880 burying anything within it in an instant. 143 00:08:53.880 --> 00:08:57.160 Oh, there's a beautiful... Look at that one - beautiful. 144 00:08:57.160 --> 00:09:00.240 This could mean that anything he finds in this layer 145 00:09:00.240 --> 00:09:02.960 would have been quickly entombed, 146 00:09:02.960 --> 00:09:07.000 like the bodies in the volcanic ash of Pompeii. 147 00:09:10.400 --> 00:09:12.840 Robert knows from the geology 148 00:09:12.840 --> 00:09:17.400 that anything he finds at Tanis will be tantalisingly close 149 00:09:17.400 --> 00:09:20.640 to the end of the age of the dinosaurs 150 00:09:20.640 --> 00:09:22.880 and could be so well preserved 151 00:09:22.880 --> 00:09:24.880 that it could reveal new evidence 152 00:09:24.880 --> 00:09:27.800 that will bring this time period to life 153 00:09:27.800 --> 00:09:31.160 in a way no-one has ever done before. 154 00:09:34.840 --> 00:09:37.800 Robert digs at Tanis each summer, 155 00:09:37.800 --> 00:09:41.880 the only time the weather allows him to do so. 156 00:09:41.880 --> 00:09:45.400 Come on down, check out this lens over here. 157 00:09:45.400 --> 00:09:49.240 In order to understand how the impact affected life on Earth, 158 00:09:49.240 --> 00:09:52.240 you really need to get a very clear picture 159 00:09:52.240 --> 00:09:54.800 of what the world was like right before. 160 00:09:54.800 --> 00:09:57.440 That is a critical part of the story. 161 00:09:59.440 --> 00:10:02.680 Palaeontologists Dr David Burnham 162 00:10:02.680 --> 00:10:07.200 and Loren Gurche have been digging with Robert for years. 163 00:10:09.720 --> 00:10:12.240 Oh, wow! 164 00:10:12.240 --> 00:10:14.400 See...see the brown? Yep. 165 00:10:14.400 --> 00:10:16.000 That might be a tubercle right there. 166 00:10:16.000 --> 00:10:19.480 And it seems today is their lucky day. 167 00:10:19.480 --> 00:10:22.320 Oh, my God! Look at that! Look at that. 168 00:10:22.320 --> 00:10:23.760 Look, the scales are preserved! 169 00:10:23.760 --> 00:10:26.240 Holy crap! Like doing a freaking dissection. 170 00:10:26.240 --> 00:10:29.400 Oh, my God. Biology of Tanis. 171 00:10:29.400 --> 00:10:30.720 Oh, the scale... 172 00:10:30.720 --> 00:10:33.480 Look, look - the wrinkles continue down that way. 173 00:10:33.480 --> 00:10:35.280 Mine's all nice and wet so far. 174 00:10:35.280 --> 00:10:37.600 The scales are getting smaller in that direction. 175 00:10:37.600 --> 00:10:38.680 How big are they there? 176 00:10:38.680 --> 00:10:41.400 I got a...I got one with the projection over here. 177 00:10:41.400 --> 00:10:42.640 What? Oh! 178 00:10:42.640 --> 00:10:43.760 Yeah. Oh. 179 00:10:43.760 --> 00:10:45.640 Yeah, there's the protuberance right there. 180 00:10:45.640 --> 00:10:48.840 I've only seen that on one other specimen, in life. Yep. 181 00:10:48.840 --> 00:10:50.760 This is the closest thing to getting to touch 182 00:10:50.760 --> 00:10:52.160 a living, breathing dinosaur. 183 00:10:52.160 --> 00:10:53.600 It is. 184 00:10:53.600 --> 00:10:56.040 They found something extraordinary. 185 00:10:57.200 --> 00:10:59.720 It is so exceedingly rare - 186 00:10:59.720 --> 00:11:02.360 a piece of triceratops skin in the Hell Creek formation. 187 00:11:05.320 --> 00:11:07.480 It may look like an impression in the rock, 188 00:11:07.480 --> 00:11:11.760 but this is skin that has been fossilised 189 00:11:11.760 --> 00:11:15.240 and, over millions of years, has turned to stone. 190 00:11:16.560 --> 00:11:21.920 Triceratops bones are relatively common finds in Hell Creek, 191 00:11:21.920 --> 00:11:27.840 but skin in such condition as this is very rare indeed. 192 00:11:27.840 --> 00:11:31.560 The size and the patterning of the scales, 193 00:11:31.560 --> 00:11:34.160 together with the age and location of the rocks 194 00:11:34.160 --> 00:11:37.640 where it was found, strongly suggests 195 00:11:37.640 --> 00:11:40.760 that this is from a triceratops. 196 00:11:40.760 --> 00:11:45.080 The brown colour contains traces of organic material. 197 00:11:45.080 --> 00:11:48.080 So it might even be possible from this 198 00:11:48.080 --> 00:11:50.960 to work out which pigments were in it. 199 00:11:50.960 --> 00:11:53.120 Finding and studying 200 00:11:53.120 --> 00:11:55.520 such well-preserved fossils as this 201 00:11:55.520 --> 00:11:57.440 helps palaeontologists build 202 00:11:57.440 --> 00:12:01.280 a much more detailed picture of how these creatures lived. 203 00:12:03.280 --> 00:12:05.040 Combining this information 204 00:12:05.040 --> 00:12:07.960 with insights from scientists around the world 205 00:12:07.960 --> 00:12:10.000 makes it possible to speculate 206 00:12:10.000 --> 00:12:12.080 about what life in the Late Cretaceous 207 00:12:12.080 --> 00:12:14.080 might have been like. 208 00:12:22.520 --> 00:12:23.960 We know from bones 209 00:12:23.960 --> 00:12:27.720 that adult triceratops could reach nine metres in length 210 00:12:27.720 --> 00:12:29.640 and three metres in height. 211 00:12:29.640 --> 00:12:32.120 RUMBLING 212 00:12:33.960 --> 00:12:36.080 Marks on the fossil also show us 213 00:12:36.080 --> 00:12:38.680 that this one was badly scarred. 214 00:12:46.600 --> 00:12:49.080 RUMBLING GROWL 215 00:12:49.080 --> 00:12:51.560 Triceratops were plant-eaters. 216 00:12:55.680 --> 00:12:58.680 Other fossils tell us that they had sharp beaks 217 00:12:58.680 --> 00:13:02.680 and hundreds of teeth that enabled them to shred tough plants 218 00:13:02.680 --> 00:13:04.560 such as these cycads. 219 00:13:13.000 --> 00:13:14.400 DISTANT TRUMPETING 220 00:13:14.400 --> 00:13:17.400 Almost all adult triceratops fossils, 221 00:13:17.400 --> 00:13:20.640 including Robert's, have been found on their own. 222 00:13:22.240 --> 00:13:25.200 So it's possible that the adults were solitary, 223 00:13:25.200 --> 00:13:27.760 like modern-day male rhinos. 224 00:13:29.920 --> 00:13:32.160 So they were probably territorial, 225 00:13:32.160 --> 00:13:34.400 chasing rivals away. 226 00:13:40.640 --> 00:13:43.280 And perhaps marking their territories. 227 00:13:48.720 --> 00:13:51.040 If you weigh more than an African elephant, 228 00:13:51.040 --> 00:13:53.120 there's not much that can bother you... 229 00:13:54.240 --> 00:13:55.720 SQUEAKING 230 00:13:57.720 --> 00:14:00.800 ..except perhaps a little mammal. 231 00:14:03.280 --> 00:14:07.560 GROWLS 232 00:14:17.320 --> 00:14:20.200 Robert found these jawbones 233 00:14:20.200 --> 00:14:23.600 in the fossilised burrow at Tanis. 234 00:14:23.600 --> 00:14:26.840 The shape of this tiny bone and tooth 235 00:14:26.840 --> 00:14:30.160 means it's most likely come from what's known 236 00:14:30.160 --> 00:14:33.240 as a pediomyid, an early mammal 237 00:14:33.240 --> 00:14:36.240 and a type of marsupial. 238 00:14:39.640 --> 00:14:42.960 Robert also discovered fossilised nuts and seeds 239 00:14:42.960 --> 00:14:44.240 in the burrow. 240 00:14:45.560 --> 00:14:48.600 So we have an idea about what it might have eaten. 241 00:14:48.600 --> 00:14:50.240 DISTANT TRUMPETING 242 00:14:56.320 --> 00:14:58.240 Robert's finds are adding 243 00:14:58.240 --> 00:15:00.720 to our knowledge of the complex world 244 00:15:00.720 --> 00:15:03.840 at the very end of the Late Cretaceous. 245 00:15:03.840 --> 00:15:07.280 And it's not just the fossilised creatures. 246 00:15:07.280 --> 00:15:09.920 If you walk on damp sand, 247 00:15:09.920 --> 00:15:11.960 you'll leave a trace behind. 248 00:15:16.240 --> 00:15:17.280 A footprint. 249 00:15:18.680 --> 00:15:23.040 The same was true 66 million years ago. 250 00:15:23.040 --> 00:15:27.520 And very, very occasionally, such traces were preserved. 251 00:15:27.520 --> 00:15:31.120 And that's exactly what happened here at Tanis. 252 00:15:33.280 --> 00:15:35.640 You know, we won't foil a backside. 253 00:15:35.640 --> 00:15:37.720 Right, we'll just put... Put plaster right on. 254 00:15:37.720 --> 00:15:38.880 That way you've got... 255 00:15:38.880 --> 00:15:41.400 Robert has discovered a number of footprints. 256 00:15:41.400 --> 00:15:43.320 Yeah. Let's see. 257 00:15:43.320 --> 00:15:45.640 Looks like a good print. Yeah. 258 00:15:50.080 --> 00:15:52.680 Their shape gives him a clue 259 00:15:52.680 --> 00:15:55.280 as to what might have made them. 260 00:16:00.280 --> 00:16:01.600 If he's right, 261 00:16:01.600 --> 00:16:04.040 they were made by a winged creature, 262 00:16:04.040 --> 00:16:07.080 that might well have liked a small mammal... 263 00:16:09.880 --> 00:16:11.080 ..for lunch. 264 00:16:18.160 --> 00:16:20.640 The footprints are long and narrow 265 00:16:20.640 --> 00:16:22.200 with four toe prints. 266 00:16:23.600 --> 00:16:26.800 Two are slightly longer than the others, 267 00:16:26.800 --> 00:16:29.760 and that suggests they were made by... 268 00:16:32.400 --> 00:16:33.800 ..a pterosaur. 269 00:16:33.800 --> 00:16:35.320 SQUAWKS 270 00:16:43.040 --> 00:16:47.200 Pterosaurs are not dinosaurs, but flying reptiles 271 00:16:47.200 --> 00:16:50.240 on a different branch of the evolutionary tree. 272 00:16:57.560 --> 00:16:59.160 SCREECHING 273 00:17:04.560 --> 00:17:07.200 Male pterosaurs usually had crests, 274 00:17:07.200 --> 00:17:09.000 while females didn't. 275 00:17:09.000 --> 00:17:12.600 So crests may have been used in courtship displays. 276 00:17:18.920 --> 00:17:20.360 SHRIEKS 277 00:17:22.160 --> 00:17:26.200 And we have an indication of where females laid their eggs, 278 00:17:26.200 --> 00:17:30.120 because evidence suggests one pterosaur laid hers 279 00:17:30.120 --> 00:17:33.840 in the soft, sandy banks of the river at Tanis. 280 00:17:49.080 --> 00:17:52.040 And this is a fossilised egg 281 00:17:52.040 --> 00:17:54.960 of a pterosaur that Robert found there. 282 00:17:56.400 --> 00:17:59.760 The only one ever discovered in North America. 283 00:17:59.760 --> 00:18:02.160 If you look at it with the naked eye, 284 00:18:02.160 --> 00:18:06.200 all you see is a jumble of lines. 285 00:18:06.200 --> 00:18:09.200 But if you examine it with the latest technology, 286 00:18:09.200 --> 00:18:13.280 you can find out a wealth of information, 287 00:18:13.280 --> 00:18:15.480 from the chemistry of the bones 288 00:18:15.480 --> 00:18:17.480 to the composition of the shell. 289 00:18:17.480 --> 00:18:20.360 And that, in turn, can tell us a lot about 290 00:18:20.360 --> 00:18:23.200 how these incredible creatures lived. 291 00:18:29.200 --> 00:18:31.160 Robert has been given access 292 00:18:31.160 --> 00:18:35.200 to the Diamond Light Source synchrotron in Oxfordshire. 293 00:18:36.920 --> 00:18:39.080 It's a very powerful research tool 294 00:18:39.080 --> 00:18:41.160 that acts like a giant microscope. 295 00:18:44.280 --> 00:18:47.960 By accelerating electrons in this huge ring, 296 00:18:47.960 --> 00:18:50.040 the synchrotron creates beams of light 297 00:18:50.040 --> 00:18:52.560 many times brighter than the sun. 298 00:18:59.160 --> 00:19:03.440 Robert and paleobiologist Dr Victoria Egerton 299 00:19:03.440 --> 00:19:06.480 now want to turn that beam onto the egg fossil 300 00:19:06.480 --> 00:19:09.920 to discover more about its chemical make-up. 301 00:19:09.920 --> 00:19:12.560 We're pretty much lined up on the skeleton, 302 00:19:12.560 --> 00:19:14.440 but we might have to move the stage a little bit 303 00:19:14.440 --> 00:19:17.320 to get to the right part. Sure. 304 00:19:17.320 --> 00:19:22.400 Meanwhile, Robert can reveal the creature inside. 305 00:19:22.400 --> 00:19:24.520 And this? 306 00:19:24.520 --> 00:19:27.760 Who made this wonderful thing? 307 00:19:27.760 --> 00:19:31.080 I got replicas of the bones from inside that egg 308 00:19:31.080 --> 00:19:33.520 and I restored the remainder 309 00:19:33.520 --> 00:19:34.560 and put together 310 00:19:34.560 --> 00:19:36.920 what the skeleton would've looked like when it hatched. 311 00:19:36.920 --> 00:19:39.000 That's how big the creature would've been 312 00:19:39.000 --> 00:19:40.440 outside the egg, if it had hatched. 313 00:19:40.440 --> 00:19:45.440 So this is the baby. How big was it going to grow? 314 00:19:45.440 --> 00:19:48.160 These very long neck vertebrae here 315 00:19:48.160 --> 00:19:51.320 are what really gave part of the story away to us, 316 00:19:51.320 --> 00:19:53.840 because those long bones match very, very closely 317 00:19:53.840 --> 00:19:55.480 with the azhdarchid pterosaurs. 318 00:19:55.480 --> 00:19:57.160 That is the giant pterosaurs. 319 00:19:57.160 --> 00:19:59.280 Oh, they were the whoppers, weren't they? 320 00:19:59.280 --> 00:20:02.360 I mean, what, 25 feet? 321 00:20:02.360 --> 00:20:03.880 Wingspan? Some of them. 322 00:20:03.880 --> 00:20:08.240 This probably had a wingspan, maybe 15 feet, five metres. 323 00:20:08.240 --> 00:20:11.000 Well, it looks as though it could take off, really. 324 00:20:11.000 --> 00:20:13.000 It's easy to picture something like that 325 00:20:13.000 --> 00:20:15.160 just hatching out of the egg and fluttering out, 326 00:20:15.160 --> 00:20:17.000 almost like a little bat. 327 00:20:21.880 --> 00:20:26.360 They've scanned the egg, here and in America. 328 00:20:28.120 --> 00:20:30.640 Victoria has the results. 329 00:20:32.480 --> 00:20:35.720 So what have you learned from the synchrotron image? 330 00:20:35.720 --> 00:20:38.120 What we have here is a chemical map 331 00:20:38.120 --> 00:20:41.960 of calcium directly within the bones of this animal. 332 00:20:41.960 --> 00:20:46.080 That tells us that these bones were already hardened. 333 00:20:46.080 --> 00:20:49.880 So it might be ready to fly not long after it hatches. 334 00:20:49.880 --> 00:20:52.440 OK. Can you see any sign of the shell, 335 00:20:52.440 --> 00:20:53.840 and what sort of shell was it? 336 00:20:53.840 --> 00:20:57.120 We can. What I can show you... 337 00:20:57.120 --> 00:20:58.520 Ah! 338 00:20:58.520 --> 00:21:01.600 ..is we can see the rim of the egg in sulphur. 339 00:21:01.600 --> 00:21:06.560 Does that tell you whether it was a hard shell or a soft shell? 340 00:21:06.560 --> 00:21:08.160 We have been looking at this. 341 00:21:08.160 --> 00:21:13.360 We can see folding occurring, and this unusual undulation. 342 00:21:13.360 --> 00:21:15.160 If it were a hard egg, 343 00:21:15.160 --> 00:21:18.080 we would expect splintered bits and broken bits, 344 00:21:18.080 --> 00:21:20.200 just like a chicken egg. 345 00:21:20.200 --> 00:21:22.000 This helped to tell us that it was soft. 346 00:21:22.000 --> 00:21:24.200 So it was perhaps like a turtle? 347 00:21:24.200 --> 00:21:25.520 Absolutely. 348 00:21:25.520 --> 00:21:28.040 That's not the case, is it, with dinosaurs? 349 00:21:28.040 --> 00:21:31.120 Many dinosaurs laid hard-shelled eggs. Yes. 350 00:21:31.120 --> 00:21:34.400 So this is a new discovery about azhdarchid pterosaurs? 351 00:21:34.400 --> 00:21:36.760 Absolutely. This is something 352 00:21:36.760 --> 00:21:39.000 that we are confirming for the first time. 353 00:21:39.000 --> 00:21:40.360 Huh! 354 00:21:40.360 --> 00:21:43.640 That flying pterosaurs had eggs like turtles. 355 00:21:43.640 --> 00:21:44.720 Yes. 356 00:21:44.720 --> 00:21:47.360 Much more reptilianlike than birdlike. 357 00:21:47.360 --> 00:21:49.720 And that can potentially tell us more 358 00:21:49.720 --> 00:21:53.120 about the environment in which these eggs were laid. 359 00:21:53.120 --> 00:21:54.920 How interesting. Yeah. 360 00:22:03.240 --> 00:22:07.160 Creatures that lay soft eggs tend to bury them 361 00:22:07.160 --> 00:22:08.800 in order to protect them. 362 00:22:10.640 --> 00:22:12.440 SQUAWKS 363 00:22:14.480 --> 00:22:17.040 So female pterosaurs probably looked for 364 00:22:17.040 --> 00:22:20.280 places like Tanis to lay their eggs... 365 00:22:22.960 --> 00:22:27.000 ..because the sandy soil here is just soft enough 366 00:22:27.000 --> 00:22:30.200 for the hatchling to dig itself out. 367 00:22:30.200 --> 00:22:31.960 SNIFFING 368 00:22:31.960 --> 00:22:35.480 Now the pterosaur just has to make sure 369 00:22:35.480 --> 00:22:37.040 that the hole... 370 00:22:38.560 --> 00:22:40.040 ..is perfect. 371 00:22:44.520 --> 00:22:45.880 SQUAWKS 372 00:22:50.280 --> 00:22:52.320 WARBLING 373 00:22:56.640 --> 00:22:58.200 Success! 374 00:22:59.680 --> 00:23:02.080 But it's not over yet. 375 00:23:02.080 --> 00:23:05.520 Pterosaurs had two ovaries, 376 00:23:05.520 --> 00:23:08.240 and they laid their eggs in pairs. 377 00:23:18.000 --> 00:23:20.040 Here on the sandbank, 378 00:23:20.040 --> 00:23:24.240 sandwiched between the river and these glorious trees, 379 00:23:24.240 --> 00:23:27.240 life at Tanis seemed to be thriving. 380 00:23:27.240 --> 00:23:29.240 GASPS 381 00:23:27.240 --> 00:23:29.240 Whoops! 382 00:23:29.240 --> 00:23:31.160 Never a dull moment. 383 00:23:31.160 --> 00:23:34.200 But all that was about to change. 384 00:23:41.520 --> 00:23:44.840 The chain of events that led to the extinction of the dinosaurs 385 00:23:44.840 --> 00:23:49.960 began in the distant past, deep in space. 386 00:23:54.400 --> 00:23:58.520 Most scientists think it all started in a ring of dust, 387 00:23:58.520 --> 00:24:02.280 rocks, and debris known as the asteroid belt. 388 00:24:05.520 --> 00:24:08.000 It's usually an uneventful place. 389 00:24:11.920 --> 00:24:15.080 But it's thought that many, many millions of years ago, 390 00:24:15.080 --> 00:24:18.240 a rock was bumped into a new orbit... 391 00:24:22.760 --> 00:24:26.720 ..and diverted onto a collision course with Planet Earth. 392 00:24:39.400 --> 00:24:42.200 Robert is building a vivid picture 393 00:24:42.200 --> 00:24:44.440 of Late Cretaceous life at Tanis. 394 00:24:47.120 --> 00:24:50.840 And the team have found some more well-preserved footprints. 395 00:24:52.160 --> 00:24:55.520 So these are animals that were actually walking in the water? 396 00:24:55.520 --> 00:24:57.560 These guys would've been essentially on 397 00:24:57.560 --> 00:24:59.080 a mushy river bank going down 398 00:24:59.080 --> 00:25:00.800 to drink at some point. 399 00:25:00.800 --> 00:25:03.960 You know, animals tend to congregate around the rivers. 400 00:25:03.960 --> 00:25:06.680 This print is 30 centimetres long. 401 00:25:07.880 --> 00:25:10.240 So I think this is from a type of dinosaur 402 00:25:10.240 --> 00:25:12.160 that we call a duck-billed dinosaur. 403 00:25:12.160 --> 00:25:15.800 And they would've been very common in the Cretaceous. 404 00:25:15.800 --> 00:25:18.120 They ate the plants in the area 405 00:25:18.120 --> 00:25:20.640 and they got very large - 30 feet long. 406 00:25:22.280 --> 00:25:23.840 And there are more. 407 00:25:23.840 --> 00:25:27.600 This track, you see all the toes are very well preserved. 408 00:25:27.600 --> 00:25:30.680 You even see a nail print at the tips of the toes. 409 00:25:30.680 --> 00:25:33.000 So the little toenails dug into the mud. 410 00:25:33.000 --> 00:25:34.240 I love this one. 411 00:25:38.960 --> 00:25:42.120 This is Robert's prized footprint. 412 00:25:42.120 --> 00:25:45.040 It has three toes, 413 00:25:45.040 --> 00:25:48.560 and it's longer than it is wide. 414 00:25:48.560 --> 00:25:53.160 So it's very likely to be a carnivorous dinosaur. 415 00:25:53.160 --> 00:25:55.680 It's so well preserved that you can see 416 00:25:55.680 --> 00:25:59.240 the mark left by its sharp claw there. 417 00:26:00.480 --> 00:26:02.040 Hell Creek is well known 418 00:26:02.040 --> 00:26:05.960 for one carnivore in particular - T-rex. 419 00:26:07.040 --> 00:26:11.480 This footprint is too small for an adult T-rex, 420 00:26:11.480 --> 00:26:15.480 but it's possible that it was made by a young one. 421 00:26:25.560 --> 00:26:29.320 Robert also found this at Tanis - 422 00:26:29.320 --> 00:26:31.800 the crown of a tooth. 423 00:26:31.800 --> 00:26:35.800 Its shape and its serrated edge 424 00:26:35.800 --> 00:26:38.200 are indications that it comes 425 00:26:38.200 --> 00:26:39.960 from an adult T-rex. 426 00:26:44.400 --> 00:26:46.400 RUMBLING GROWL 427 00:26:53.240 --> 00:26:58.360 DEEP RUMBLING GROWL 428 00:27:01.720 --> 00:27:03.760 GROWLS 429 00:27:05.360 --> 00:27:08.000 Bite marks found on T-rex bones 430 00:27:08.000 --> 00:27:11.000 show that they ate other T-rexes. 431 00:27:12.640 --> 00:27:15.320 And a youngster would make an easy catch. 432 00:27:15.320 --> 00:27:17.360 SNEEZES 433 00:27:20.840 --> 00:27:22.680 But not this time. 434 00:27:32.040 --> 00:27:35.320 Very few footprints are preserved as fossils 435 00:27:35.320 --> 00:27:37.200 in Hell Creek. 436 00:27:37.200 --> 00:27:39.520 So if you find several in one place, 437 00:27:39.520 --> 00:27:41.160 as Robert has done, 438 00:27:41.160 --> 00:27:42.720 it's a reasonable assumption 439 00:27:42.720 --> 00:27:46.120 that there would've been many more nearby. 440 00:27:49.440 --> 00:27:52.160 And that supports the idea 441 00:27:52.160 --> 00:27:56.880 that dinosaurs and pterosaurs were thriving at Tanis 442 00:27:56.880 --> 00:27:58.960 shortly before the impact. 443 00:27:58.960 --> 00:28:01.320 GROWLING 444 00:28:06.480 --> 00:28:08.040 And if they were thriving... 445 00:28:08.040 --> 00:28:09.360 SQUAWKING 446 00:28:10.760 --> 00:28:14.440 ..they must have been reproducing. 447 00:28:21.080 --> 00:28:24.080 Fossils from dinosaurs similar to T-rex 448 00:28:24.080 --> 00:28:27.280 show they may have laid around 20 eggs 449 00:28:27.280 --> 00:28:29.280 in a circular nest. 450 00:28:34.840 --> 00:28:37.280 It's possible that, like crocodiles, 451 00:28:37.280 --> 00:28:40.680 they partly covered their eggs to keep them warm. 452 00:28:42.120 --> 00:28:43.720 SNEEZES 453 00:28:56.240 --> 00:28:59.360 For one T-rex, a misfortune. 454 00:29:06.360 --> 00:29:09.080 But for all dinosaurs... 455 00:29:09.080 --> 00:29:10.280 ROARS 456 00:29:10.280 --> 00:29:13.320 ..a disaster was looming. 457 00:29:26.320 --> 00:29:30.720 Deep in space, the asteroid was approaching. 458 00:29:35.440 --> 00:29:37.440 Its journey would take it through the orbit 459 00:29:37.440 --> 00:29:40.240 of our neighbouring planet, Mars. 460 00:29:45.880 --> 00:29:47.720 Had the two collided, 461 00:29:47.720 --> 00:29:50.800 a catastrophe on Earth would've been avoided. 462 00:29:59.640 --> 00:30:01.560 But it was not to be... 463 00:30:03.120 --> 00:30:05.800 ..and Earth's fate was sealed. 464 00:30:19.560 --> 00:30:21.560 As Robert's dig continues, 465 00:30:21.560 --> 00:30:23.640 his vision of what happened at Tanis 466 00:30:23.640 --> 00:30:26.480 is finally starting to come together. 467 00:30:28.480 --> 00:30:31.320 It seems the sandbank was full of life. 468 00:30:31.320 --> 00:30:33.840 T-rex, triceratops, 469 00:30:33.840 --> 00:30:35.080 little mammals, 470 00:30:35.080 --> 00:30:39.000 alongside the footprints of other dinosaurs and pterosaurs, 471 00:30:39.000 --> 00:30:41.040 all in a very small area. 472 00:30:42.840 --> 00:30:44.800 BLOWS 473 00:30:42.840 --> 00:30:44.800 You see the scales? 474 00:30:44.800 --> 00:30:46.840 I do. Oh, my God. 475 00:30:46.840 --> 00:30:49.080 That excites me just looking at it! 476 00:30:50.960 --> 00:30:54.560 Then Robert finds something truly remarkable. 477 00:30:57.880 --> 00:31:00.600 See the cracks already forming? Look at that. 478 00:31:00.600 --> 00:31:03.520 So we're going to have to really monitor that before we glue it. 479 00:31:03.520 --> 00:31:05.880 Cos this is getting vulnerable now. 480 00:31:05.880 --> 00:31:08.320 An almost complete creature. 481 00:31:11.440 --> 00:31:13.800 To get this block out, we're freezing it. 482 00:31:20.440 --> 00:31:23.360 Robert is about to attempt something tricky. 483 00:31:25.200 --> 00:31:27.760 Steady... Let's go. 484 00:31:29.640 --> 00:31:32.640 To get the fossil out in one piece, they're trying 485 00:31:32.640 --> 00:31:35.120 to freeze it using liquid nitrogen 486 00:31:35.120 --> 00:31:38.280 at almost 200 degrees below zero. 487 00:31:44.080 --> 00:31:45.440 Watch your footing. 488 00:31:46.720 --> 00:31:48.880 Loren, I'm worried about brittleness here. 489 00:31:48.880 --> 00:31:52.200 Get that hammer. Give this a couple whacks with the hammer. 490 00:31:53.840 --> 00:31:56.800 OK. Move over five centimetres. Good. 491 00:32:00.000 --> 00:32:03.600 It's cracked loose. Yep. OK. It's loose. 492 00:32:03.600 --> 00:32:06.120 So we have to get this out in one piece. 493 00:32:06.120 --> 00:32:09.160 One, two, three. 494 00:32:10.760 --> 00:32:12.480 Yeehaw! 495 00:32:13.680 --> 00:32:15.640 Total success. Total success. 496 00:32:17.120 --> 00:32:19.800 This is a technique used in archaeology 497 00:32:19.800 --> 00:32:22.240 for digging up human remains. 498 00:32:22.240 --> 00:32:24.400 We've got enough time to work with the fossil 499 00:32:24.400 --> 00:32:26.120 and not damage it. 500 00:32:26.120 --> 00:32:28.600 And I couldn't be happier. 501 00:32:31.360 --> 00:32:33.640 And the creature Robert found? 502 00:32:35.120 --> 00:32:36.480 A turtle. 503 00:32:38.560 --> 00:32:42.440 This is the fossil now it's been cleaned up. 504 00:32:42.440 --> 00:32:45.080 It's lying on its side. 505 00:32:45.080 --> 00:32:47.960 Here's the outline of its shell. 506 00:32:49.280 --> 00:32:53.000 The shape of the shell and the scalloped edges here 507 00:32:53.000 --> 00:32:55.720 tell us that this was a baenid turtle. 508 00:32:59.240 --> 00:33:02.520 Robert's baenid turtle looks very similar 509 00:33:02.520 --> 00:33:04.320 to modern cooter turtles 510 00:33:04.320 --> 00:33:07.720 and lived in the same sort of freshwater environment. 511 00:33:14.760 --> 00:33:17.920 For a turtle, Tanis would've been ideal. 512 00:33:21.800 --> 00:33:24.520 Warm, shallow water. 513 00:33:26.760 --> 00:33:28.080 Plenty to eat. 514 00:33:32.880 --> 00:33:35.800 And lots of safe places in which to warm up 515 00:33:35.800 --> 00:33:37.960 in the Late Cretaceous sunshine. 516 00:33:42.720 --> 00:33:46.320 The turtle fossil Robert found is almost complete. 517 00:33:46.320 --> 00:33:49.200 This is the underside, 518 00:33:49.200 --> 00:33:54.280 and this brown material up here is fossilised wood. 519 00:33:54.280 --> 00:33:58.000 It's the end of a stick that passes right through its body 520 00:33:58.000 --> 00:34:01.200 and comes out just here. 521 00:34:01.200 --> 00:34:03.000 So the evidence points towards 522 00:34:03.000 --> 00:34:05.280 this turtle having been impaled. 523 00:34:08.000 --> 00:34:11.120 A violent end to one of the many creatures found 524 00:34:11.120 --> 00:34:14.400 in the crumbly rock layer at Tanis. 525 00:34:15.440 --> 00:34:17.080 When I look at the animals 526 00:34:17.080 --> 00:34:19.720 and plants preserved in the sediments of Tanis 527 00:34:19.720 --> 00:34:21.440 and the footprints beneath it, 528 00:34:21.440 --> 00:34:24.080 I see a picture of a vibrant ecosystem, 529 00:34:24.080 --> 00:34:28.240 many different dinosaurs, and a thriving, thriving place. 530 00:34:31.560 --> 00:34:33.480 After ten years of digging, 531 00:34:33.480 --> 00:34:36.600 there is now enough evidence to piece together 532 00:34:36.600 --> 00:34:38.440 much of the story of Tanis 533 00:34:38.440 --> 00:34:41.080 and the creatures which lived here. 534 00:34:44.600 --> 00:34:48.200 Robert has found so many fossils, it looks as if, 535 00:34:48.200 --> 00:34:50.600 even at the very end of the Late Cretaceous, 536 00:34:50.600 --> 00:34:52.680 Tanis was bursting with life. 537 00:34:52.680 --> 00:34:54.600 VARIOUS ANIMAL CALLS 538 00:34:54.600 --> 00:34:58.440 Full of the giant reptiles that had dominated the planet 539 00:34:58.440 --> 00:35:01.520 for more than 150 million years. 540 00:35:06.400 --> 00:35:07.440 BARKING 541 00:35:07.440 --> 00:35:10.640 It's impossible to know how much longer 542 00:35:10.640 --> 00:35:12.280 their reign would've continued... 543 00:35:14.320 --> 00:35:15.760 SQUAWKS 544 00:35:15.760 --> 00:35:20.240 ..because all this was about to end. 545 00:35:41.480 --> 00:35:43.400 The asteroid hit... 546 00:35:47.080 --> 00:35:51.280 ..in what is now the Yucatan peninsula in Mexico. 547 00:35:54.120 --> 00:35:56.800 It's called the Chicxulub asteroid 548 00:35:56.800 --> 00:35:59.720 after the town nearest to the centre of its crater. 549 00:36:02.840 --> 00:36:04.520 ROARING 550 00:36:10.920 --> 00:36:12.760 ROARS 551 00:36:17.920 --> 00:36:22.160 Any living thing within 900 miles of the impact... 552 00:36:24.280 --> 00:36:27.120 ..was destroyed by the blast. 553 00:36:32.000 --> 00:36:34.840 But what effect did the impact have on Tanis, 554 00:36:34.840 --> 00:36:37.360 nearly 2,000 miles away? 555 00:36:47.080 --> 00:36:48.640 To find out, 556 00:36:48.640 --> 00:36:52.720 Robert is looking for clues that might link Tanis 557 00:36:52.720 --> 00:36:55.920 to the actual day the asteroid hit. 558 00:36:57.040 --> 00:36:58.480 BLOWS 559 00:37:01.920 --> 00:37:03.320 We've got some wood, 560 00:37:03.320 --> 00:37:06.320 and pressed up against this and all intertangled, 561 00:37:06.320 --> 00:37:08.200 we've got the carcasses of fish. 562 00:37:08.200 --> 00:37:09.520 OK. 563 00:37:10.760 --> 00:37:12.720 That's a beautifully preserved tail, 564 00:37:12.720 --> 00:37:15.640 so that fish is going to be absolutely gorgeous. 565 00:37:15.640 --> 00:37:18.200 So part of the detail work that we're doing right now 566 00:37:18.200 --> 00:37:19.840 is going in and checking out 567 00:37:19.840 --> 00:37:23.600 all the individual elements in this mass death layer. 568 00:37:23.600 --> 00:37:26.840 Some of the evidence he's found so far 569 00:37:26.840 --> 00:37:30.400 has been hidden inside the fish themselves. 570 00:37:33.480 --> 00:37:36.640 In more ways than one, it literally is an operation of a Cretaceous 571 00:37:36.640 --> 00:37:39.640 fish, so we're performing surgery on this thing. 572 00:37:39.640 --> 00:37:42.680 Robert needs to open this fish's skull. 573 00:37:44.400 --> 00:37:47.720 And very carefully, we want to separate this 574 00:37:47.720 --> 00:37:49.200 from the rest of the fish. 575 00:37:50.440 --> 00:37:51.760 OK. 576 00:37:55.320 --> 00:37:57.640 Here we go. 577 00:37:57.640 --> 00:37:59.880 Opening up the fish. 578 00:37:59.880 --> 00:38:02.080 Got a nice ant that made a home in there. 579 00:38:03.200 --> 00:38:04.880 And beautiful, look at that. 580 00:38:04.880 --> 00:38:07.920 OK, here we have the gill bars of the fish. 581 00:38:07.920 --> 00:38:10.560 Those are the bars that hold the filaments of the gills. 582 00:38:11.760 --> 00:38:13.480 And between the gill bars, 583 00:38:13.480 --> 00:38:15.560 all of these clusters of round objects, 584 00:38:15.560 --> 00:38:17.360 those are the ejecta spherules. 585 00:38:18.400 --> 00:38:22.840 Ejecta spherules are tiny balls that were once molten rock. 586 00:38:22.840 --> 00:38:25.440 They could be evidence of what Robert suspects - 587 00:38:25.440 --> 00:38:27.040 that creatures here died 588 00:38:27.040 --> 00:38:29.760 on the day of the asteroid strike. 589 00:38:30.960 --> 00:38:33.880 Those ejecta spherules last saw the light of day 590 00:38:33.880 --> 00:38:36.880 when they were flying through the air 66 billion years ago. 591 00:38:47.400 --> 00:38:51.000 After a large asteroid impact, 592 00:38:51.000 --> 00:38:53.760 a mix of vaporised and molten rock 593 00:38:53.760 --> 00:38:55.880 is propelled into space. 594 00:38:58.840 --> 00:39:00.400 There, it cools, 595 00:39:00.400 --> 00:39:03.600 solidifying into tiny glass droplets. 596 00:39:05.160 --> 00:39:08.280 Some carry on deeper into space. 597 00:39:10.440 --> 00:39:13.760 But most are pulled back to Earth by gravity. 598 00:39:21.280 --> 00:39:24.120 After a major asteroid hit, 599 00:39:24.120 --> 00:39:28.840 trillions of ejecta spherules would fall from the sky. 600 00:39:28.840 --> 00:39:31.040 Then, over millions of years, 601 00:39:31.040 --> 00:39:34.040 pressure and chemical reactions in the ground 602 00:39:34.040 --> 00:39:37.200 would turn most of them to clay. 603 00:39:37.200 --> 00:39:39.760 They'd look something like this. 604 00:39:40.840 --> 00:39:44.960 So finding spherules in the gills of a fish, 605 00:39:44.960 --> 00:39:47.280 as Robert has done at Tanis, 606 00:39:47.280 --> 00:39:49.680 suggests the fish sucked them in 607 00:39:49.680 --> 00:39:52.480 while the spherules were still falling. 608 00:39:52.480 --> 00:39:54.280 So these creatures could have died 609 00:39:54.280 --> 00:39:57.160 at the time of an asteroid impact. 610 00:40:02.560 --> 00:40:05.960 Once Robert begins to look for ejecta spherules, 611 00:40:05.960 --> 00:40:07.640 he finds more and more, 612 00:40:07.640 --> 00:40:12.040 and realises the thick, crumbly layer of rock at Tanis 613 00:40:12.040 --> 00:40:13.440 is full of them. 614 00:40:16.760 --> 00:40:19.000 I mean, this stuff is go... Oh, my God, look at that one. 615 00:40:19.000 --> 00:40:20.960 These things are just gorgeous. 616 00:40:22.440 --> 00:40:23.840 Ejecta spherules like this 617 00:40:23.840 --> 00:40:26.440 give us a fingerprint of where they came from. 618 00:40:28.080 --> 00:40:30.120 If these spherules were connected 619 00:40:30.120 --> 00:40:31.880 to the Chicxulub impact, 620 00:40:31.880 --> 00:40:35.000 then the whole crumbly layer could be full of evidence 621 00:40:35.000 --> 00:40:38.680 of what happened on the day the asteroid hit. 622 00:40:38.680 --> 00:40:39.960 That's a good one. 623 00:40:39.960 --> 00:40:42.360 Oh, is that a droplet right there? 624 00:40:42.360 --> 00:40:44.320 To see if that's the case, 625 00:40:44.320 --> 00:40:47.960 Robert needs to find a spherule that hasn't turned to clay. 626 00:40:47.960 --> 00:40:51.760 Oh, my God, that's a beautiful droplet. 627 00:40:51.760 --> 00:40:53.680 OK. 628 00:40:53.680 --> 00:40:56.800 The small pieces of orange material 629 00:40:56.800 --> 00:40:58.640 that Robert and Loren are digging up 630 00:40:58.640 --> 00:41:00.800 may be able to help. 631 00:41:00.800 --> 00:41:03.840 They're amber. 632 00:41:03.840 --> 00:41:06.320 If there was anything flying through the air at that time, 633 00:41:06.320 --> 00:41:08.160 this is where it's going to get caught. 634 00:41:10.480 --> 00:41:13.800 The amber they're collecting was once sticky resin 635 00:41:13.800 --> 00:41:16.920 oozing out of a Late Cretaceous tree trunk. 636 00:41:18.720 --> 00:41:21.120 It's a way for the tree to protect itself, 637 00:41:21.120 --> 00:41:23.920 like a scab forming on a cut. 638 00:41:32.120 --> 00:41:34.960 Anything covered by the resin would be frozen 639 00:41:34.960 --> 00:41:37.000 in an amber time capsule. 640 00:41:43.480 --> 00:41:45.840 If they find a spherule preserved in amber, 641 00:41:45.840 --> 00:41:48.400 it could be analysed 642 00:41:48.400 --> 00:41:51.560 to see if it comes from the Chicxulub asteroid impact. 643 00:41:54.640 --> 00:41:56.080 So during this batch, 644 00:41:56.080 --> 00:41:59.640 we were incredibly lucky that we came across 645 00:41:59.640 --> 00:42:02.080 two completely unaltered spherules. 646 00:42:03.560 --> 00:42:06.960 This spherule could be something amazing. 647 00:42:06.960 --> 00:42:11.600 Evidence preserved well enough to analyse for chemical clues. 648 00:42:14.480 --> 00:42:15.880 If so, 649 00:42:15.880 --> 00:42:20.440 it could link Tanis directly with the Chicxulub impact 650 00:42:20.440 --> 00:42:22.920 and the last day of the dinosaurs. 651 00:42:30.520 --> 00:42:33.160 To investigate, Robert is joined 652 00:42:33.160 --> 00:42:35.240 at the Diamond Light Source 653 00:42:35.240 --> 00:42:38.120 by Professor of Natural History Phil Manning, 654 00:42:38.120 --> 00:42:40.440 of the University of Manchester. 655 00:42:40.440 --> 00:42:42.920 They've already run initial tests 656 00:42:42.920 --> 00:42:44.920 on the spherules in America. 657 00:42:44.920 --> 00:42:46.800 What have you found out so far? 658 00:42:46.800 --> 00:42:50.560 These little glass spherules, these globs 659 00:42:50.560 --> 00:42:52.520 of molten material from the impact site 660 00:42:52.520 --> 00:42:55.960 have a chemical signal that ties it with where they came from. 661 00:42:55.960 --> 00:42:57.480 Cos when an asteroid hits, 662 00:42:57.480 --> 00:42:59.680 it melts the ground that it hits, 663 00:42:59.680 --> 00:43:01.920 but also that glass has 664 00:43:01.920 --> 00:43:04.520 a little bit of contamination from the asteroid itself. 665 00:43:04.520 --> 00:43:07.920 And that gives you a unique geochemical fingerprint. 666 00:43:07.920 --> 00:43:09.440 We can see once we've scanned it, 667 00:43:09.440 --> 00:43:12.280 and looking at spherules from other sites in North Dakota, 668 00:43:12.280 --> 00:43:13.960 we can get a baseline 669 00:43:13.960 --> 00:43:18.200 for what the ejecta should look like when it's related to 670 00:43:18.200 --> 00:43:19.880 the Chicxulub crater. 671 00:43:19.880 --> 00:43:21.440 And you can see each element here 672 00:43:21.440 --> 00:43:23.480 and the ratios of those elements. 673 00:43:23.480 --> 00:43:26.720 And when we look at Tanis, it's a match. 674 00:43:26.720 --> 00:43:29.480 I mean, it perfectly overlays. 675 00:43:29.480 --> 00:43:32.480 So I think this is powerful evidence 676 00:43:32.480 --> 00:43:36.080 supporting that Tanis and Chicxulub are linked. 677 00:43:36.080 --> 00:43:38.120 And what do these findings mean 678 00:43:38.120 --> 00:43:41.040 for the rest of the fossils that you're finding in Tanis? 679 00:43:41.040 --> 00:43:44.080 This data is key for the entire site, 680 00:43:44.080 --> 00:43:46.360 because once you have that link 681 00:43:46.360 --> 00:43:49.120 and you know what impact affected Tanis, 682 00:43:49.120 --> 00:43:52.760 then you essentially know that every object in that site, 683 00:43:52.760 --> 00:43:55.640 all the animals and the plants and everything buried 684 00:43:55.640 --> 00:43:57.000 in those sediments, 685 00:43:57.000 --> 00:43:59.640 are linked to the last day of the Cretaceous. 686 00:44:01.560 --> 00:44:04.480 And the synchrotron here in the UK 687 00:44:04.480 --> 00:44:07.040 reveals something even more remarkable. 688 00:44:09.440 --> 00:44:14.000 So this is showing a beautiful synchrotron scan 689 00:44:14.000 --> 00:44:16.400 of the half of one spherule. 690 00:44:16.400 --> 00:44:19.240 The glass is a good geochemical fingerprint, 691 00:44:19.240 --> 00:44:22.920 and we've got calcium, some iron, 692 00:44:22.920 --> 00:44:24.960 we've got strontium, 693 00:44:24.960 --> 00:44:26.760 but when we look at the entire thing, 694 00:44:26.760 --> 00:44:29.720 we see something quite unexpected. 695 00:44:29.720 --> 00:44:31.880 That's your entire spherule. 696 00:44:31.880 --> 00:44:33.280 What's this? 697 00:44:33.280 --> 00:44:36.280 In this, we've got a little bit of a nugget. 698 00:44:36.280 --> 00:44:38.520 There was a little particle right there. 699 00:44:38.520 --> 00:44:39.760 So we scan it. 700 00:44:39.760 --> 00:44:42.240 And that's a lot of iron in there. 701 00:44:42.240 --> 00:44:45.080 Over here, we've got chromium, a big peak in chromium. 702 00:44:45.080 --> 00:44:48.160 Over here, we've got a big peak in nickel. 703 00:44:48.160 --> 00:44:50.960 And the abundances of iron, nickel and chromium, 704 00:44:50.960 --> 00:44:52.400 all together, 705 00:44:52.400 --> 00:44:55.120 that matches what you expect to see in a meteoric body. 706 00:44:55.120 --> 00:44:58.120 That does not match what you would normally have down here. 707 00:44:58.120 --> 00:45:01.720 So this is extraterrestrial material? 708 00:45:01.720 --> 00:45:03.960 If you were to sort of grind up 709 00:45:03.960 --> 00:45:09.320 and stuff into a spherule a piece of meteorite, 710 00:45:09.320 --> 00:45:11.200 that's what it's going to look like. 711 00:45:11.200 --> 00:45:14.560 This could be a piece of the Chicxulub asteroid. 712 00:45:14.560 --> 00:45:16.760 A piece of the bullet that killed the dinosaurs. 713 00:45:16.760 --> 00:45:18.160 No! 714 00:45:24.720 --> 00:45:26.320 Robert could have found 715 00:45:26.320 --> 00:45:29.680 a fragment of the asteroid itself in Tanis, 716 00:45:29.680 --> 00:45:35.440 physical evidence linking this site to the Chicxulub impact. 717 00:45:35.440 --> 00:45:38.680 But Tanis is almost 2,000 miles away 718 00:45:38.680 --> 00:45:40.600 from where the asteroid hit. 719 00:45:40.600 --> 00:45:44.400 So exactly how did it cause the creatures' deaths? 720 00:45:48.080 --> 00:45:50.200 To answer that question, 721 00:45:50.200 --> 00:45:53.880 Robert is searching in the mass death layer. 722 00:45:56.520 --> 00:46:00.280 Right here, we've got this intertangled mass of fish. 723 00:46:00.280 --> 00:46:02.800 There's one fish here, another sturgeon goes this way, 724 00:46:02.800 --> 00:46:04.800 underneath the body of a paddlefish. 725 00:46:04.800 --> 00:46:06.680 There's another sturgeon that goes this way, 726 00:46:06.680 --> 00:46:10.240 underneath this log, and continues out the other side. 727 00:46:10.240 --> 00:46:12.400 And his head hit that log 728 00:46:12.400 --> 00:46:15.760 and has deflected downward at a 90-degree angle. 729 00:46:17.760 --> 00:46:22.840 Robert uncovered a tangled mass of fossilised creatures and logs 730 00:46:22.840 --> 00:46:25.040 surrounded by spherules 731 00:46:25.040 --> 00:46:29.480 and crushed together in what's known as a logjam. 732 00:46:29.480 --> 00:46:32.280 He has a theory that the creatures were swept 733 00:46:32.280 --> 00:46:35.760 to their death in some kind of turbulent surge of water 734 00:46:35.760 --> 00:46:38.120 and quickly entombed in sediment, 735 00:46:38.120 --> 00:46:40.960 which is why they're so well preserved. 736 00:46:40.960 --> 00:46:43.720 But what could have caused the wave? 737 00:46:47.560 --> 00:46:50.200 One theory is a tsunami. 738 00:46:54.360 --> 00:46:56.880 The asteroid hit at sea. 739 00:46:56.880 --> 00:46:58.440 Recent studies show 740 00:46:58.440 --> 00:47:02.480 it may have caused a wave almost a mile high. 741 00:47:15.400 --> 00:47:18.280 The height of the wave would've gradually reduced 742 00:47:18.280 --> 00:47:20.520 as it spread across the oceans. 743 00:47:22.000 --> 00:47:23.480 In the Late Cretaceous, 744 00:47:23.480 --> 00:47:26.600 North America was divided by a narrow sea 745 00:47:26.600 --> 00:47:29.840 that's been called the Western Interior Seaway. 746 00:47:29.840 --> 00:47:32.640 The tsunami could have travelled up this, 747 00:47:32.640 --> 00:47:34.240 towards Tanis. 748 00:47:37.680 --> 00:47:40.440 But there's a big question about the tsunami idea. 749 00:47:42.040 --> 00:47:44.000 The timing. 750 00:47:44.000 --> 00:47:46.920 Oh, which fish is that? 751 00:47:46.920 --> 00:47:50.040 That's a new... It's a new contact. New one. Yeah. 752 00:47:50.040 --> 00:47:52.920 If a tsunami killed the fish, 753 00:47:52.920 --> 00:47:54.960 it would have to have hit 754 00:47:54.960 --> 00:47:56.760 while ejecta spherules were falling... 755 00:47:58.080 --> 00:48:02.160 ..because spherules were found in the fish's gills. 756 00:48:03.880 --> 00:48:09.200 So how long after impact did the spherules arrive at Tanis? 757 00:48:09.200 --> 00:48:11.680 Pretend this ball of foil is a piece of ejecta 758 00:48:11.680 --> 00:48:14.840 coming out of the crater. It would then go on an arc path, 759 00:48:14.840 --> 00:48:16.840 ballistic trajectory, out of the crater 760 00:48:16.840 --> 00:48:19.400 and to wherever it lands - in this case, Tanis. 761 00:48:21.480 --> 00:48:24.000 If we know the distance between myself 762 00:48:24.000 --> 00:48:27.360 and the landing site, and if we know the size of that ball, 763 00:48:27.360 --> 00:48:30.560 we can accurately calculate how long it would take to get there. 764 00:48:34.560 --> 00:48:36.480 The result is surprising. 765 00:48:36.480 --> 00:48:38.960 Robert and his team calculated 766 00:48:38.960 --> 00:48:42.320 that these ejecta spherules landed at Tanis 767 00:48:42.320 --> 00:48:46.680 between 13 minutes and two hours after the impact. 768 00:48:49.280 --> 00:48:51.320 If a wave killed the fish, 769 00:48:51.320 --> 00:48:54.680 it must also have reached Tanis within two hours. 770 00:48:58.760 --> 00:49:01.040 Data from recent tsunamis show 771 00:49:01.040 --> 00:49:04.400 even a powerful one would take much longer than that 772 00:49:04.400 --> 00:49:08.200 to travel almost 2,000 miles from the impact site 773 00:49:08.200 --> 00:49:09.640 to Tanis. 774 00:49:10.640 --> 00:49:13.280 So if it wasn't a tsunami, 775 00:49:13.280 --> 00:49:16.040 what could have caused a surge of water at Tanis? 776 00:49:25.320 --> 00:49:29.320 Professor Stein Bondevik is an expert in tsunamis. 777 00:49:34.800 --> 00:49:37.720 The fjords in Norway are very special. 778 00:49:39.120 --> 00:49:43.120 We have tall mountains surrounding bodies of water. 779 00:49:43.120 --> 00:49:46.400 So the water is usually very calm. 780 00:49:46.400 --> 00:49:51.120 In 2011, something very strange happened. 781 00:49:51.120 --> 00:49:55.480 The water in the fjord began to move violently. 782 00:49:55.480 --> 00:50:00.080 The height of the water increased by one and a half metre, 783 00:50:00.080 --> 00:50:04.080 like a maelstrom with the turbulent water. 784 00:50:04.080 --> 00:50:06.800 Someone said that the fjord was boiling. 785 00:50:06.800 --> 00:50:08.400 THUNDER RUMBLES 786 00:50:08.400 --> 00:50:10.240 News started to roll in - 787 00:50:10.240 --> 00:50:14.520 there'd been an earthquake 5,000 miles away in Japan. 788 00:50:17.440 --> 00:50:20.240 A journalist from the local newspaper called me, 789 00:50:20.240 --> 00:50:23.160 and he said that people were observing waves 790 00:50:23.160 --> 00:50:24.560 here, in the fjords. 791 00:50:26.680 --> 00:50:29.160 I got a video clip of the waves. 792 00:50:29.160 --> 00:50:32.600 I saw immediately that they looked like a tsunami wave. 793 00:50:32.600 --> 00:50:34.440 So later in the afternoon, 794 00:50:34.440 --> 00:50:37.600 you can see that the fjord is perfectly calm. 795 00:50:39.240 --> 00:50:40.480 But at the beach here, 796 00:50:40.480 --> 00:50:43.600 you could see that the water is sloshing back and forth, 797 00:50:43.600 --> 00:50:46.560 and no-one had ever seen anything like it. 798 00:50:47.920 --> 00:50:51.120 And some people got very upset and afraid. 799 00:50:54.320 --> 00:50:59.560 A magnitude nine earthquake had devastated the northeast of Japan, 800 00:50:59.560 --> 00:51:01.560 around Fukushima. 801 00:51:04.440 --> 00:51:08.280 But how did that affect a fjord so far away? 802 00:51:10.920 --> 00:51:13.840 So no-one in Norway could feel the earthquake, 803 00:51:13.840 --> 00:51:17.400 but I could see that the times matched 804 00:51:17.400 --> 00:51:20.200 the arrival of the waves here, in the fjord. 805 00:51:23.920 --> 00:51:27.200 Eventually, Stein and his team realised 806 00:51:27.200 --> 00:51:31.960 that this might have something to do with seismic waves - 807 00:51:31.960 --> 00:51:35.120 shock waves that pass quickly through the Earth 808 00:51:35.120 --> 00:51:36.680 during an earthquake. 809 00:51:38.080 --> 00:51:41.560 So it took only 12 minutes before the first signal 810 00:51:41.560 --> 00:51:44.240 of the earthquake in Japan reached all the way here, 811 00:51:44.240 --> 00:51:45.600 to western Norway. 812 00:51:48.120 --> 00:51:49.920 So it was the seismic waves 813 00:51:49.920 --> 00:51:52.720 that caused the normally calm water in the fjord 814 00:51:52.720 --> 00:51:55.680 to slosh turbulently back and forth. 815 00:51:57.480 --> 00:52:02.440 Just thinking of that, scientifically, it's fantastic. 816 00:52:08.560 --> 00:52:12.360 Could something similar have happened in Tanis? 817 00:52:12.360 --> 00:52:15.680 A large weather front's coming through the northwest... 818 00:52:17.120 --> 00:52:19.000 Trying to find out 819 00:52:19.000 --> 00:52:22.240 is geophysicist professor Mark Richards, 820 00:52:22.240 --> 00:52:25.800 who's been studying the site at Tanis for several years. 821 00:52:26.920 --> 00:52:29.280 He's working with Robert to discover 822 00:52:29.280 --> 00:52:32.120 what could have caused a surge of water here. 823 00:52:39.240 --> 00:52:42.520 A tsunami can't get here in less than minimum 12 hours. 824 00:52:44.400 --> 00:52:48.240 But seismic waves travelling from the Yucatan impact site 825 00:52:48.240 --> 00:52:51.120 to North Dakota can arrive here fairly quickly. 826 00:52:53.400 --> 00:52:57.320 In the Late Cretaceous, the Western Interior Seaway 827 00:52:57.320 --> 00:53:01.440 that divided North America could have been connected to Tanis 828 00:53:01.440 --> 00:53:03.360 through a system of rivers. 829 00:53:08.600 --> 00:53:11.080 If you have a very large body of water, 830 00:53:11.080 --> 00:53:14.080 like the Western Interior Seaway, 831 00:53:14.080 --> 00:53:16.360 and you can shake it back and forth, 832 00:53:16.360 --> 00:53:19.600 you can generate a large water wave 833 00:53:19.600 --> 00:53:22.200 coming up this river at Tanis. 834 00:53:26.680 --> 00:53:30.400 So seismic waves from the impact could have caused 835 00:53:30.400 --> 00:53:33.320 surges of water in the Tanis river system. 836 00:53:34.400 --> 00:53:37.560 The seismic waves get here quickly enough, 837 00:53:37.560 --> 00:53:39.920 coming up the Tanis river, 838 00:53:39.920 --> 00:53:42.320 inundating this area, arriving at the same time 839 00:53:42.320 --> 00:53:45.000 these spherules are still falling out of the air. 840 00:53:47.840 --> 00:53:49.440 The mystery of the wave 841 00:53:49.440 --> 00:53:53.760 and the thick layer of crumbly rock has been solved. 842 00:53:53.760 --> 00:53:56.280 Seismic waves travelling through the Earth 843 00:53:56.280 --> 00:54:00.120 could have caused powerful surges of water at Tanis... 844 00:54:02.760 --> 00:54:05.240 ..possibly carrying mud and marine creatures, 845 00:54:05.240 --> 00:54:09.320 like ammonites, from the Western Interior Seaway... 846 00:54:12.160 --> 00:54:16.680 ..dumping them on the Tanis sandbank and burying everything 847 00:54:16.680 --> 00:54:19.600 at the same time as spherules fell. 848 00:54:28.000 --> 00:54:29.240 Over millions of years, 849 00:54:29.240 --> 00:54:33.440 the mud would turn into the layer of crumbly rock. 850 00:54:35.200 --> 00:54:37.280 And that's the beauty of Tanis. 851 00:54:37.280 --> 00:54:40.400 What you're seeing is a deposit 852 00:54:40.400 --> 00:54:44.760 that is literally recording the last, say, 853 00:54:44.760 --> 00:54:48.600 45 minutes to an hour and a half of the Cretaceous. 854 00:54:58.760 --> 00:55:01.960 If the extinction of the dinosaurs was a crime, 855 00:55:01.960 --> 00:55:06.240 the detective solving it would have plenty of evidence. 856 00:55:06.240 --> 00:55:08.160 They would see that the asteroid was 857 00:55:08.160 --> 00:55:10.760 in the right place at the right time. 858 00:55:10.760 --> 00:55:13.360 They would see that no dinosaurs survived 859 00:55:13.360 --> 00:55:14.800 after the hit. 860 00:55:15.800 --> 00:55:18.120 They would have a piece of the murder weapon - 861 00:55:18.120 --> 00:55:20.200 a fragment of the asteroid. 862 00:55:20.200 --> 00:55:24.160 But they would be missing one very important thing - 863 00:55:24.160 --> 00:55:25.720 a body. 864 00:55:30.280 --> 00:55:34.000 No-one has ever found the fossil of a dinosaur 865 00:55:34.000 --> 00:55:38.360 that was killed by the effects of the asteroid impact. 866 00:55:38.360 --> 00:55:41.960 But Robert did find part of a triceratops 867 00:55:41.960 --> 00:55:44.280 in the crumbly layer at Tanis. 868 00:55:44.280 --> 00:55:46.480 So could that be the remains 869 00:55:46.480 --> 00:55:49.360 of a dinosaur that died on that day? 870 00:55:49.360 --> 00:55:50.880 I'm still dubious about the horn. 871 00:55:50.880 --> 00:55:52.880 I kind of want to keep the horn in the jacket. 872 00:55:52.880 --> 00:55:54.120 I think if you took it off, 873 00:55:54.120 --> 00:55:55.760 at least take this section off, 874 00:55:55.760 --> 00:55:57.400 to see what's going on under here. 875 00:55:57.400 --> 00:55:58.560 Yeah? 876 00:55:58.560 --> 00:56:03.400 To find out, the team needs to establish cause of death, 877 00:56:03.400 --> 00:56:06.760 which can be difficult when you only have a piece of skin 878 00:56:06.760 --> 00:56:08.880 and a horn to go on. 879 00:56:11.000 --> 00:56:15.120 This is the horn after they've cleaned it up. 880 00:56:15.120 --> 00:56:19.600 The team is particularly interested in these lines here. 881 00:56:19.600 --> 00:56:22.200 And they found that the fractures go 882 00:56:22.200 --> 00:56:24.800 right through the horn. 883 00:56:24.800 --> 00:56:28.080 So rather than dying as a result of the impact, 884 00:56:28.080 --> 00:56:31.440 they wondered whether it had been killed in a fight. 885 00:56:37.160 --> 00:56:39.560 But when they looked at the fractures in more detail, 886 00:56:39.560 --> 00:56:42.440 they found signs of new bone growth here. 887 00:56:43.480 --> 00:56:46.880 An indication that the bone had started to heal. 888 00:56:46.880 --> 00:56:49.440 So it looked as though the triceratops survived 889 00:56:49.440 --> 00:56:51.880 the event that broke its horn. 890 00:56:56.520 --> 00:56:59.280 Could this triceratops have survived 891 00:56:59.280 --> 00:57:02.000 until the day of the impact? 892 00:57:02.000 --> 00:57:05.640 The team found evidence, including sagging in the skin, 893 00:57:05.640 --> 00:57:09.400 which suggested that there was decay underneath. 894 00:57:09.400 --> 00:57:11.800 That means its body had started to rot 895 00:57:11.800 --> 00:57:15.720 before it was entombed and preserved by the surge. 896 00:57:15.720 --> 00:57:20.760 So it seems that this dinosaur didn't die as a result 897 00:57:20.760 --> 00:57:22.720 of the asteroid impact. 898 00:57:24.400 --> 00:57:27.520 Perhaps, in the months before the impact, 899 00:57:27.520 --> 00:57:29.600 the broken horn put the triceratops 900 00:57:29.600 --> 00:57:32.040 at a disadvantage over its rivals. 901 00:57:33.880 --> 00:57:35.520 GRUNTS 902 00:57:47.760 --> 00:57:50.480 And that might have led to starvation. 903 00:58:01.920 --> 00:58:04.360 THUNDER CRACKS 904 00:58:08.840 --> 00:58:10.400 WIND WHOOSHES 905 00:58:12.600 --> 00:58:15.880 Robert has still not found direct evidence 906 00:58:15.880 --> 00:58:18.840 of a dinosaur that was killed by the asteroid. 907 00:58:20.040 --> 00:58:22.120 We've got all these bones in the ground right now. 908 00:58:22.120 --> 00:58:24.920 But the one thing that we would just dream 909 00:58:24.920 --> 00:58:26.880 of finding is that one dinosaur 910 00:58:26.880 --> 00:58:29.520 that died on the day of the impact. 911 00:58:33.400 --> 00:58:36.560 And the weather isn't helping his search. 912 00:58:42.920 --> 00:58:44.840 GROANS 913 00:58:54.440 --> 00:58:56.640 That therapod print is toasted. 914 00:58:56.640 --> 00:58:58.800 Yeah, it was in a low corner. 915 00:58:58.800 --> 00:59:01.840 Look, it's full mud. It's full of mud and water. 916 00:59:01.840 --> 00:59:04.000 The problem is it's wet, look. 917 00:59:04.000 --> 00:59:06.720 See... If we're not careful, we're going to lose the print. 918 00:59:08.040 --> 00:59:10.160 And that's the biggest theropod print we've got. 919 00:59:11.200 --> 00:59:13.800 I see some areas that could use glue right now, too. 920 00:59:16.320 --> 00:59:19.640 The team is racing to excavate the footprints, 921 00:59:19.640 --> 00:59:22.080 along with dozens of fish fossils 922 00:59:22.080 --> 00:59:26.800 tangled together in a logjam, before storms wash them away. 923 00:59:26.800 --> 00:59:28.160 THUNDER RUMBLES 924 00:59:28.160 --> 00:59:29.760 We're up against the clock here. 925 00:59:29.760 --> 00:59:31.600 This stuff that could be exposed right now 926 00:59:31.600 --> 00:59:33.440 is going to get ruined by the rain. 927 00:59:36.000 --> 00:59:38.600 But then, Robert comes across something 928 00:59:38.600 --> 00:59:40.280 that looks very unusual. 929 00:59:40.280 --> 00:59:42.040 That's going there. 930 00:59:43.640 --> 00:59:45.320 What is going on right there? 931 00:59:45.320 --> 00:59:47.680 Are we sure this isn't crocodilian? 932 00:59:47.680 --> 00:59:49.680 That's not crocodilian. No. 933 00:59:49.680 --> 00:59:52.280 Right, let me try this piece right here. 934 00:59:52.280 --> 00:59:54.920 I'll go in from the top and then twist up, 935 00:59:54.920 --> 00:59:56.520 and it separates right on that line. 936 00:59:56.520 --> 00:59:59.040 Oh, that's skin right there. 937 00:59:59.040 --> 01:00:01.520 That's actually scaly skin. Oh, my God. 938 01:00:01.520 --> 01:00:03.360 No, no, no, no, no. Look, look, look. 939 01:00:03.360 --> 01:00:05.320 Look at that pattern right there. 940 01:00:05.320 --> 01:00:08.080 Have you ever seen elongated scales like that before, Dave? 941 01:00:08.080 --> 01:00:10.320 That's insane. Scuttelates - in birds. 942 01:00:10.320 --> 01:00:12.080 Just careful. 943 01:00:12.080 --> 01:00:14.440 Oh, my God. It's changing again. 944 01:00:14.440 --> 01:00:15.960 It's changing again. Oh, my God. 945 01:00:17.240 --> 01:00:20.760 We're seeing it for the first time in 66 million years. 946 01:00:20.760 --> 01:00:22.720 I think we've got ourselves a dinosaur. 947 01:00:27.320 --> 01:00:29.000 A dinosaur fossil! 948 01:00:29.000 --> 01:00:32.120 And, unlike the triceratops, 949 01:00:32.120 --> 01:00:36.360 this is located in the logjam, the mass death layer, 950 01:00:36.360 --> 01:00:40.680 surrounded by the fish with spherules in their gills. 951 01:00:43.560 --> 01:00:46.440 This is the most incredible thing that we could possibly imagine here. 952 01:00:46.440 --> 01:00:48.080 The best-case scenario. 953 01:00:48.080 --> 01:00:51.160 We're excavating this mass death layer of fish 954 01:00:51.160 --> 01:00:54.040 from the surge sent up by the impact, 955 01:00:54.040 --> 01:00:56.120 and we've got dinosaur remains. 956 01:00:56.120 --> 01:00:59.400 The one thing that we would always want to find at this site, 957 01:00:59.400 --> 01:01:01.720 and here we've got it. 958 01:01:01.720 --> 01:01:05.440 This is unreal. I-I-I cannot process this in my brain. 959 01:01:05.440 --> 01:01:08.080 No, I am absolutely blown away by this. 960 01:01:08.080 --> 01:01:10.520 Just my heart is literally pumping out of my chest 961 01:01:10.520 --> 01:01:11.920 wondering what is behind there, 962 01:01:11.920 --> 01:01:14.120 just a couple of centimetres back in the outcrop. 963 01:01:14.120 --> 01:01:15.760 What is waiting for us back there? 964 01:01:17.480 --> 01:01:19.320 Get it out... 965 01:01:19.320 --> 01:01:20.920 This is... 966 01:01:20.920 --> 01:01:22.240 The team keeps digging. 967 01:01:22.240 --> 01:01:24.200 The scales get big again over on this side. 968 01:01:24.200 --> 01:01:25.760 So this could be a ribcage, 969 01:01:25.760 --> 01:01:27.920 it could be laying against ribs that are curved. 970 01:01:27.920 --> 01:01:29.480 There's something here. 971 01:01:29.480 --> 01:01:30.960 That's hard. A bit more bone. 972 01:01:30.960 --> 01:01:32.920 That's bone right next to the skin. 973 01:01:32.920 --> 01:01:34.960 Yeah, that's an articular surface right there, 974 01:01:34.960 --> 01:01:37.400 so this is either a hip or a shoulder element. 975 01:01:41.400 --> 01:01:44.560 After hours of painstaking work... 976 01:01:47.760 --> 01:01:50.160 And we can go from the thigh of the animal. 977 01:01:50.160 --> 01:01:51.800 There's the knee. 978 01:01:51.800 --> 01:01:54.520 And then you've got the little calf muscles 979 01:01:54.520 --> 01:01:56.400 of the dinosaur, they're bulging out, 980 01:01:56.400 --> 01:01:59.360 and you go down to the anklebones, 981 01:01:59.360 --> 01:02:02.160 and these are the toes of the feet. 982 01:02:02.160 --> 01:02:04.200 We have got nails at the tips of the toes. 983 01:02:04.200 --> 01:02:06.040 It's a beautifully preserved leg, 984 01:02:06.040 --> 01:02:07.880 all articulated, covered with skin. 985 01:02:09.000 --> 01:02:12.840 The complete leg of a dinosaur. 986 01:02:12.840 --> 01:02:14.880 In my wildest dreams, 987 01:02:14.880 --> 01:02:17.120 I never expected to find a dinosaur leg in this deposit. 988 01:02:17.120 --> 01:02:20.480 Yeah. I mean, and then it's got skin and tissue. 989 01:02:20.480 --> 01:02:22.960 It does look just like a drumstick. 990 01:02:22.960 --> 01:02:24.840 It looks like a Thanksgiving turkey, 991 01:02:24.840 --> 01:02:26.600 just laid out in the ground. 992 01:02:26.600 --> 01:02:30.480 And this weird scale pattern on the thigh of the animal, 993 01:02:30.480 --> 01:02:33.240 which we've never seen in a dinosaur before. 994 01:02:33.240 --> 01:02:36.000 Well, thescelosaurs don't have any form of defence, 995 01:02:36.000 --> 01:02:38.240 so they have to have camouflage or something. 996 01:02:38.240 --> 01:02:39.680 That's a good point. 997 01:02:39.680 --> 01:02:43.240 So this could have been some sort of a camouflage marking. Yeah. 998 01:02:43.240 --> 01:02:47.000 Robert thinks he has found the body in question - 999 01:02:47.000 --> 01:02:51.240 a dinosaur that might itself have witnessed 1000 01:02:51.240 --> 01:02:53.080 the cataclysmic impact. 1001 01:02:56.280 --> 01:02:58.560 Dinosaur fossils are not known 1002 01:02:58.560 --> 01:03:01.440 from the last years of the Cretaceous. 1003 01:03:01.440 --> 01:03:04.040 And it was unclear whether they were already extinct 1004 01:03:04.040 --> 01:03:05.920 or in decline or what was going on. 1005 01:03:05.920 --> 01:03:07.760 So they were just sort of absent. 1006 01:03:11.320 --> 01:03:12.760 And this answers that question. 1007 01:03:12.760 --> 01:03:15.360 Were dinosaurs still there then? 1008 01:03:15.360 --> 01:03:19.480 Well, yes - this one likely died in that surge. 1009 01:03:23.320 --> 01:03:27.920 For such big claims, Robert needs verification. 1010 01:03:30.240 --> 01:03:32.520 He's brought the dinosaur leg to London 1011 01:03:32.520 --> 01:03:35.200 to get a second opinion... 1012 01:03:35.200 --> 01:03:37.760 And then here are the pads of the toes. 1013 01:03:37.760 --> 01:03:40.400 We see all those beautiful scales lined up. 1014 01:03:40.400 --> 01:03:42.720 ..from Professor Paul Barrett, 1015 01:03:42.720 --> 01:03:45.960 an expert in ornithischian dinosaurs 1016 01:03:45.960 --> 01:03:48.840 from the Natural History Museum. 1017 01:03:48.840 --> 01:03:51.120 So what do you think this might be? 1018 01:03:51.120 --> 01:03:54.000 When we look at the leg, it has claws, 1019 01:03:54.000 --> 01:03:58.600 like the claws we see in small, agile, bipedal, running dinosaurs 1020 01:03:58.600 --> 01:04:01.000 that are plant-eaters. 1021 01:04:01.000 --> 01:04:03.000 We can rule out things like triceratops, 1022 01:04:03.000 --> 01:04:05.400 partly just because it's not big and stocky. 1023 01:04:05.400 --> 01:04:08.600 And the proportions of those legs are also different 1024 01:04:08.600 --> 01:04:10.880 from some of the other plant-eaters we see, 1025 01:04:10.880 --> 01:04:12.760 in that they have this rather long ankle 1026 01:04:12.760 --> 01:04:16.120 and shin, compared with its thighbone. 1027 01:04:16.120 --> 01:04:18.160 So as we narrow those possibilities down, 1028 01:04:18.160 --> 01:04:19.640 what we're left with, probably, 1029 01:04:19.640 --> 01:04:21.480 is an animal called a thescelosaur. 1030 01:04:21.480 --> 01:04:23.000 SQUEAKS 1031 01:04:30.440 --> 01:04:33.160 Thescelosaurs lived next to rivers 1032 01:04:33.160 --> 01:04:36.200 where there was plenty of rich vegetation to feed on. 1033 01:04:38.680 --> 01:04:40.960 They had leaf-shaped teeth, 1034 01:04:40.960 --> 01:04:43.000 common amongst herbivores, 1035 01:04:43.000 --> 01:04:45.080 and claws on their short front limbs - 1036 01:04:45.080 --> 01:04:47.240 excellent for digging. 1037 01:04:57.600 --> 01:04:58.960 SQUEAKS 1038 01:05:01.000 --> 01:05:02.880 CRUNCHING 1039 01:05:04.680 --> 01:05:07.880 But how did Robert's thescelosaur die? 1040 01:05:09.480 --> 01:05:12.400 Could it have been killed by another dinosaur? 1041 01:05:12.400 --> 01:05:14.120 It's a possibility. 1042 01:05:14.120 --> 01:05:16.200 This is a relatively agile animal. 1043 01:05:16.200 --> 01:05:18.360 And that turn of speed would've been 1044 01:05:18.360 --> 01:05:22.360 its primary defence against the large predators living alongside it. 1045 01:05:27.760 --> 01:05:31.640 So, to escape a hungry T-rex, 1046 01:05:31.640 --> 01:05:34.040 a thescelosaur's first line of defence... 1047 01:05:34.040 --> 01:05:35.360 BARKS 1048 01:05:35.360 --> 01:05:36.880 ..would've been to run. 1049 01:05:39.560 --> 01:05:43.800 But it may have had another defensive trick. 1050 01:05:47.600 --> 01:05:49.440 ROARS 1051 01:05:52.280 --> 01:05:53.840 Living next to rivers, 1052 01:05:53.840 --> 01:05:57.640 it's possible thescelosaurs were able to swim. 1053 01:06:11.040 --> 01:06:13.480 It doesn't seem to me like there is any evidence 1054 01:06:13.480 --> 01:06:15.160 that this animal was predated - 1055 01:06:15.160 --> 01:06:17.800 none of the obvious tooth marks 1056 01:06:17.800 --> 01:06:19.960 or leftover bits of carnivore teeth 1057 01:06:19.960 --> 01:06:22.040 to suggest it's been eaten. 1058 01:06:22.040 --> 01:06:24.600 So how do you think it died? 1059 01:06:24.600 --> 01:06:27.560 It didn't have any particularly nasty diseases when it died, 1060 01:06:27.560 --> 01:06:30.280 as we can see that the bones look OK. 1061 01:06:30.280 --> 01:06:32.240 So this is an animal that was probably living 1062 01:06:32.240 --> 01:06:35.480 and healthy at the time that this happened to it. 1063 01:06:35.480 --> 01:06:40.600 Could this be a victim of the meteor strike? 1064 01:06:40.600 --> 01:06:42.000 I think it's entirely possible. 1065 01:06:42.000 --> 01:06:44.200 This is actually a shoulder bone, 1066 01:06:44.200 --> 01:06:46.160 and this bone in a living animal 1067 01:06:46.160 --> 01:06:48.200 would actually be way over here. 1068 01:06:48.200 --> 01:06:50.000 And similarly, this little bone here 1069 01:06:50.000 --> 01:06:52.800 would've been from about maybe a third of the way 1070 01:06:52.800 --> 01:06:54.760 along the tail, maybe halfway down. 1071 01:06:54.760 --> 01:06:59.320 So somehow these two bones have been telescoped together. 1072 01:06:59.320 --> 01:07:01.760 So maybe this animal's been tumbled around. 1073 01:07:01.760 --> 01:07:04.400 We've ruled out a lot of other possible 1074 01:07:04.400 --> 01:07:06.360 causes of death for this animal. 1075 01:07:06.360 --> 01:07:09.320 So it could well be that this is an animal 1076 01:07:09.320 --> 01:07:11.080 that was there, being tumbled around 1077 01:07:11.080 --> 01:07:12.760 in its death throes, in that river, 1078 01:07:12.760 --> 01:07:14.520 as a result of the asteroid impact. 1079 01:07:15.880 --> 01:07:18.440 Well, it is exactly analogous 1080 01:07:18.440 --> 01:07:21.600 to those human bodies found in Pompeii. 1081 01:07:21.600 --> 01:07:24.840 It's very similar in terms of you get that quick entombment. 1082 01:07:24.840 --> 01:07:26.880 Yes. And it's almost as evocative. 1083 01:07:26.880 --> 01:07:29.160 That's absolutely true. 1084 01:07:29.160 --> 01:07:31.440 You've got literally the blink of an eye 1085 01:07:31.440 --> 01:07:33.320 at the end of the Cretaceous, 1086 01:07:33.320 --> 01:07:35.480 snapped up into history, and there it is, 1087 01:07:35.480 --> 01:07:38.920 ready to be dug up. Wow. 1088 01:07:35.480 --> 01:07:38.920 LAUGHS 1089 01:07:50.320 --> 01:07:52.600 After years of investigation, 1090 01:07:52.600 --> 01:07:54.880 Robert has found out a great deal 1091 01:07:54.880 --> 01:07:57.000 about the creatures which lived at Tanis, 1092 01:07:57.000 --> 01:08:01.600 and he knows that many of them were alive on that fateful day 1093 01:08:01.600 --> 01:08:04.680 when the asteroid devastated our planet. 1094 01:08:05.800 --> 01:08:08.000 But how exactly did they die? 1095 01:08:09.000 --> 01:08:12.840 Robert's finds now allow us to tell the story of that day 1096 01:08:12.840 --> 01:08:15.320 and finally answer that question. 1097 01:08:19.640 --> 01:08:22.600 One of the most important days in Earth's history 1098 01:08:22.600 --> 01:08:26.520 probably started much like any other late spring morning. 1099 01:08:31.640 --> 01:08:36.520 We know the season because Robert found fossils of young fish that 1100 01:08:36.520 --> 01:08:39.200 died at the size they reach at that time of year. 1101 01:08:39.200 --> 01:08:41.840 This agrees with evidence already found 1102 01:08:41.840 --> 01:08:43.880 by other scientists. 1103 01:08:46.320 --> 01:08:49.960 Perhaps this day, that would end with so much death, 1104 01:08:49.960 --> 01:08:52.560 began with something different. 1105 01:08:54.360 --> 01:08:55.960 A new life. 1106 01:08:58.040 --> 01:09:00.400 SQUEAKING 1107 01:09:06.200 --> 01:09:08.080 SQUAWKS 1108 01:09:19.440 --> 01:09:22.760 No-one can be certain of the exact timings of the day 1109 01:09:22.760 --> 01:09:25.880 when the asteroid collided with our planet. 1110 01:09:25.880 --> 01:09:30.240 But it's estimated that within just 40 minutes of the impact, 1111 01:09:30.240 --> 01:09:32.800 the consequences for the creatures of Tanis 1112 01:09:32.800 --> 01:09:34.360 would have been profound. 1113 01:09:38.480 --> 01:09:39.880 Based on Robert's finds 1114 01:09:39.880 --> 01:09:42.680 and the latest evidence from other scientists, 1115 01:09:42.680 --> 01:09:46.160 this is how the catastrophe might have unfolded. 1116 01:09:48.840 --> 01:09:52.360 The asteroid is around seven miles across, 1117 01:09:52.360 --> 01:09:54.240 bigger than Mount Everest... 1118 01:09:55.800 --> 01:10:00.280 ..and travelling at close to 45,000mph. 1119 01:10:04.080 --> 01:10:06.280 The impact causes an explosion 1120 01:10:06.280 --> 01:10:10.440 bigger than a billion Hiroshima atomic bombs. 1121 01:10:17.720 --> 01:10:20.600 At Tanis, almost 2,000 miles away... 1122 01:10:22.200 --> 01:10:24.320 ..it's completely silent. 1123 01:10:28.320 --> 01:10:30.240 But at the impact site... 1124 01:10:32.560 --> 01:10:34.480 ..the asteroid vaporises. 1125 01:10:36.360 --> 01:10:38.880 More than three trillion tonnes of rock 1126 01:10:38.880 --> 01:10:40.800 are ejected into space 1127 01:10:40.800 --> 01:10:43.440 in a blast of super-heated violence. 1128 01:10:48.240 --> 01:10:51.160 Winds higher than 600mph. 1129 01:10:52.640 --> 01:10:57.320 A colossal earthquake, followed by a ring of massive tsunamis. 1130 01:11:03.080 --> 01:11:05.440 RUMBLING 1131 01:11:05.440 --> 01:11:07.800 ANIMAL CALLS 1132 01:11:07.800 --> 01:11:09.800 All the while, the creatures at Tanis 1133 01:11:09.800 --> 01:11:11.680 go about their business... 1134 01:11:11.680 --> 01:11:13.800 CACOPHONY OF ANIMAL NOISES 1135 01:11:15.680 --> 01:11:18.120 ..just like any other day. 1136 01:11:18.120 --> 01:11:21.160 COOING 1137 01:11:21.160 --> 01:11:23.080 CLICKING 1138 01:11:23.080 --> 01:11:24.440 WARBLES 1139 01:11:29.600 --> 01:11:32.080 SNEEZES 1140 01:11:32.080 --> 01:11:33.520 THUNDER RUMBLES 1141 01:11:35.120 --> 01:11:36.160 SQUAWKS 1142 01:11:36.160 --> 01:11:38.880 The evidence suggests that baby pterosaurs 1143 01:11:38.880 --> 01:11:42.360 emerge from the egg ready to fend for themselves. 1144 01:11:45.000 --> 01:11:46.880 And that includes... 1145 01:11:49.480 --> 01:11:50.880 ..flying? 1146 01:11:52.360 --> 01:11:53.960 Well, almost. 1147 01:12:02.600 --> 01:12:06.840 Elsewhere, as the devastation spreads out across North America 1148 01:12:06.840 --> 01:12:08.160 towards Tanis... 1149 01:12:09.800 --> 01:12:12.920 ..dinosaurs and creatures of all shapes and sizes 1150 01:12:12.920 --> 01:12:15.360 are obliterated by the blast. 1151 01:12:26.800 --> 01:12:30.320 At Tanis, for a few more precious minutes, 1152 01:12:30.320 --> 01:12:32.040 life carries on as usual. 1153 01:12:34.120 --> 01:12:36.320 But the clock is ticking. 1154 01:12:43.480 --> 01:12:44.680 GRUNTING 1155 01:12:45.720 --> 01:12:48.560 DEEP BELLOWING 1156 01:12:49.840 --> 01:12:53.600 The blast from the impact never reaches Tanis, 1157 01:12:53.600 --> 01:12:56.120 but seismic shock waves do. 1158 01:13:00.840 --> 01:13:02.680 RUMBLING 1159 01:13:04.200 --> 01:13:06.280 CHIRPS 1160 01:13:09.200 --> 01:13:11.200 They are far more powerful 1161 01:13:11.200 --> 01:13:13.640 than any earthquake ever recorded. 1162 01:13:16.640 --> 01:13:20.720 DEEP BELLOWING 1163 01:13:20.720 --> 01:13:22.240 SHRIEKING 1164 01:13:22.240 --> 01:13:25.680 The thescelosaur might head for a place of safety... 1165 01:13:30.440 --> 01:13:32.800 ..but seismic waves are now slowly shaking 1166 01:13:32.800 --> 01:13:37.200 the whole region, causing water to slosh and churn. 1167 01:13:42.520 --> 01:13:45.600 At Tanis, strange currents in the river 1168 01:13:45.600 --> 01:13:48.240 give a hint of what is still to come. 1169 01:13:54.120 --> 01:13:55.760 THUNDER CRACKS 1170 01:13:57.240 --> 01:14:00.120 Next, it begins to rain. 1171 01:14:00.120 --> 01:14:02.240 PATTERING 1172 01:14:02.240 --> 01:14:05.480 Ejecta spherules are falling back to Earth. 1173 01:14:13.360 --> 01:14:16.280 As the spherules begin their fall... 1174 01:14:17.400 --> 01:14:20.720 ..friction heats them until they're red hot. 1175 01:14:27.160 --> 01:14:30.560 Then the heat transfers to the air. 1176 01:14:32.040 --> 01:14:34.320 Temperatures rise with every second. 1177 01:14:42.760 --> 01:14:46.080 As the heat builds, the creatures of Tanis 1178 01:14:46.080 --> 01:14:47.720 are fighting for their lives. 1179 01:14:49.480 --> 01:14:51.280 ROARS 1180 01:14:52.840 --> 01:14:55.320 And then, as seismic waves 1181 01:14:55.320 --> 01:14:58.120 continue to slowly rock the whole region... 1182 01:15:01.640 --> 01:15:04.960 ..a violent surge wave ten metres high 1183 01:15:04.960 --> 01:15:07.280 rushes up the Tanis river. 1184 01:15:26.200 --> 01:15:28.680 Surviving the turbulence of the surge 1185 01:15:28.680 --> 01:15:31.840 is a challenge even for the best swimmers. 1186 01:15:43.760 --> 01:15:47.600 Then, the powerful rocking of the river system 1187 01:15:47.600 --> 01:15:51.240 slowly begins to draw the water back the way it came. 1188 01:16:00.880 --> 01:16:02.640 Swimming may have saved 1189 01:16:02.640 --> 01:16:05.320 the thescelosaur in the past, 1190 01:16:05.320 --> 01:16:07.120 but not this time. 1191 01:16:12.720 --> 01:16:15.320 A large, robust animal like a T-rex 1192 01:16:15.320 --> 01:16:17.400 might have survived the surge. 1193 01:16:22.880 --> 01:16:25.240 As might a hard-shelled reptile. 1194 01:16:26.920 --> 01:16:29.760 But there is much more to come. 1195 01:16:29.760 --> 01:16:34.880 As billions of tonnes of superheated spherules continue to fall, 1196 01:16:34.880 --> 01:16:37.200 the atmosphere gets even hotter... 1197 01:16:39.640 --> 01:16:43.760 ..igniting dead leaves and sparking wildfires. 1198 01:16:50.080 --> 01:16:51.680 Earthquakes, 1199 01:16:51.680 --> 01:16:53.640 fire... 1200 01:16:55.760 --> 01:16:57.240 ..devastation. 1201 01:16:59.760 --> 01:17:01.800 Little would survive for long, 1202 01:17:01.800 --> 01:17:03.640 on land.. 1203 01:17:03.640 --> 01:17:05.880 ROARS 1204 01:17:08.280 --> 01:17:10.080 ..or in the air. 1205 01:17:13.080 --> 01:17:15.400 SHRIEKS 1206 01:17:16.520 --> 01:17:18.280 GRUNTS 1207 01:17:30.400 --> 01:17:34.280 As the air reaches the temperature of an industrial oven... 1208 01:17:37.240 --> 01:17:39.320 ..those that live deep underground 1209 01:17:39.320 --> 01:17:40.880 may have a better chance. 1210 01:17:48.840 --> 01:17:52.360 As the slow sloshing of the river system continues... 1211 01:17:55.280 --> 01:17:57.600 ..another powerful surge hits. 1212 01:18:18.480 --> 01:18:21.080 There is no escaping the destruction. 1213 01:18:24.240 --> 01:18:27.280 For many of the creatures of Tanis, 1214 01:18:27.280 --> 01:18:29.680 their stories end underwater. 1215 01:18:45.280 --> 01:18:49.520 In less than two hours, the world has changed forever. 1216 01:18:56.200 --> 01:18:58.960 The mud the surge waves leave behind 1217 01:18:58.960 --> 01:19:02.960 will gradually turn into the thick layer of crumbly rock 1218 01:19:02.960 --> 01:19:05.880 entombing the creatures which died here... 1219 01:19:08.760 --> 01:19:11.880 ..until 66 million years later, 1220 01:19:11.880 --> 01:19:14.200 when they're finally unearthed. 1221 01:19:23.600 --> 01:19:27.920 Robert's finds have helped us understand in remarkable detail 1222 01:19:27.920 --> 01:19:29.600 what happened at Tanis 1223 01:19:29.600 --> 01:19:33.120 in the minutes after the asteroid impact. 1224 01:19:33.120 --> 01:19:35.280 But what about the rest of the world? 1225 01:19:38.400 --> 01:19:41.240 The impact triggered catastrophic events 1226 01:19:41.240 --> 01:19:44.120 such as earthquakes all over the planet. 1227 01:19:45.760 --> 01:19:48.240 And as spherules continued to fall... 1228 01:19:51.280 --> 01:19:54.560 ..wildfires may have sprung up around the globe. 1229 01:19:57.320 --> 01:20:00.600 As that horrific day drew to a close, 1230 01:20:00.600 --> 01:20:04.400 many of the world's dinosaurs were already dead. 1231 01:20:09.960 --> 01:20:14.440 Research shows that the angle at which the asteroid hit 1232 01:20:14.440 --> 01:20:17.440 and the sulphur-rich rocks at the impact site 1233 01:20:17.440 --> 01:20:19.720 amplified the devastation. 1234 01:20:19.720 --> 01:20:21.680 Billions of tonnes of sulphur 1235 01:20:21.680 --> 01:20:23.960 were ejected into the atmosphere, 1236 01:20:23.960 --> 01:20:25.840 blocking the sunlight. 1237 01:20:27.960 --> 01:20:32.800 Without light, most plants died, and food became scarce. 1238 01:20:34.600 --> 01:20:37.280 As the weeks and months passed, 1239 01:20:37.280 --> 01:20:40.680 any dinosaur left alive would've died of hunger. 1240 01:20:43.520 --> 01:20:46.240 In the oceans, it was the same. 1241 01:20:46.240 --> 01:20:49.560 Nearly all of the world's plankton disappeared, 1242 01:20:49.560 --> 01:20:53.600 leading to the starvation of most marine creatures. 1243 01:20:55.200 --> 01:20:58.720 It's thought that the nuclear winter that followed 1244 01:20:58.720 --> 01:21:01.360 caused a global temperature drop 1245 01:21:01.360 --> 01:21:04.320 of at least 25 degrees centigrade. 1246 01:21:04.320 --> 01:21:08.320 The fossil record tells us that this huge change in climate 1247 01:21:08.320 --> 01:21:12.200 marked the disappearance of three quarters of all species, 1248 01:21:12.200 --> 01:21:14.040 including the dinosaurs. 1249 01:21:16.520 --> 01:21:21.080 The planet was in semi-darkness for around a decade, 1250 01:21:21.080 --> 01:21:24.280 as dust and soot slowly fell to Earth. 1251 01:21:26.080 --> 01:21:28.440 But then came something wonderful. 1252 01:21:30.320 --> 01:21:32.040 A new beginning. 1253 01:21:36.440 --> 01:21:39.160 Once the dust cleared from the atmosphere 1254 01:21:39.160 --> 01:21:40.840 and the sunlight returned... 1255 01:21:42.360 --> 01:21:46.000 ..plant life was gradually restored, 1256 01:21:46.000 --> 01:21:47.960 led by ferns, 1257 01:21:47.960 --> 01:21:52.160 the spores of which had lain dormant deep underground, 1258 01:21:52.160 --> 01:21:56.160 and the world began to turn green once more. 1259 01:21:58.360 --> 01:22:00.480 But what about the animals? 1260 01:22:03.160 --> 01:22:06.520 Back at Tanis, Robert has unearthed something 1261 01:22:06.520 --> 01:22:09.320 that could have helped save some of the creatures 1262 01:22:09.320 --> 01:22:11.920 from the devastating fires. 1263 01:22:11.920 --> 01:22:13.560 We saw a little thing poking out, 1264 01:22:13.560 --> 01:22:15.560 so we kind of followed it back. 1265 01:22:15.560 --> 01:22:17.600 And I'm so glad that we did, 1266 01:22:17.600 --> 01:22:19.920 because what we have here is a fossil burrow 1267 01:22:19.920 --> 01:22:22.680 from an animal 66 million years ago. 1268 01:22:24.280 --> 01:22:26.680 The only animals that would've been around back then 1269 01:22:26.680 --> 01:22:28.960 that would likely build a burrow like this 1270 01:22:28.960 --> 01:22:31.880 would be the small mammals, roughly ferret-sized, 1271 01:22:31.880 --> 01:22:34.440 and also some reptiles. 1272 01:22:34.440 --> 01:22:38.680 If it is from a mammal, this is sort of a window 1273 01:22:38.680 --> 01:22:41.560 into the lifestyle of some of our oldest ancestors out here. 1274 01:22:42.600 --> 01:22:44.640 This guy would've burrowed sideways, 1275 01:22:44.640 --> 01:22:46.080 right into the river bank. 1276 01:22:47.400 --> 01:22:49.480 We actually have some scratch marks on there 1277 01:22:49.480 --> 01:22:51.680 from the interior when they were digging it, 1278 01:22:51.680 --> 01:22:54.560 going back, and he would've lived back here 1279 01:22:54.560 --> 01:22:56.360 and sought shelter from the dinosaurs 1280 01:22:56.360 --> 01:22:58.640 cos they just did not want to get eaten. 1281 01:23:05.000 --> 01:23:07.280 Burrows are part of the reason 1282 01:23:07.280 --> 01:23:10.320 that mammals survived the great extinction. 1283 01:23:12.000 --> 01:23:13.880 During the nuclear winter, 1284 01:23:13.880 --> 01:23:16.080 a burrow would've provided warmth, 1285 01:23:16.080 --> 01:23:19.280 protection, and a place to store food. 1286 01:23:26.520 --> 01:23:29.880 Mammals that survived were resourceful omnivores, 1287 01:23:29.880 --> 01:23:33.680 and insects would've been a plentiful source of food. 1288 01:23:39.360 --> 01:23:43.120 And they had another advantage - their size. 1289 01:23:45.440 --> 01:23:49.240 If conditions are right, many animal species get larger 1290 01:23:49.240 --> 01:23:52.200 as they evolve over millions of years. 1291 01:23:52.200 --> 01:23:55.680 Take T-rex as an example. 1292 01:23:55.680 --> 01:23:58.960 This is a cast of the lower jaw 1293 01:23:58.960 --> 01:24:01.600 of a predecessor, called gorgosaurus, 1294 01:24:01.600 --> 01:24:04.360 which lived 72 million years ago. 1295 01:24:04.360 --> 01:24:10.280 Whereas this is the cast of the lower jaw of a T-rex, 1296 01:24:10.280 --> 01:24:12.880 which lived five million years later. 1297 01:24:12.880 --> 01:24:16.800 Look at the difference in size. 1298 01:24:16.800 --> 01:24:18.200 But the bigger the creature, 1299 01:24:18.200 --> 01:24:20.760 the more energy they need to stay alive. 1300 01:24:20.760 --> 01:24:24.600 So when catastrophe strikes and food is scarce, 1301 01:24:24.600 --> 01:24:26.960 the largest tend to die out, 1302 01:24:26.960 --> 01:24:29.920 whilst the smallest often survive. 1303 01:24:33.040 --> 01:24:34.960 That's one of the reasons 1304 01:24:34.960 --> 01:24:37.400 why many of the smaller mammals 1305 01:24:37.400 --> 01:24:40.200 lived through the great darkness. 1306 01:24:40.200 --> 01:24:42.240 And they weren't alone. 1307 01:24:44.760 --> 01:24:47.960 Robert's fossil turtle may have been unlucky, 1308 01:24:47.960 --> 01:24:49.680 but many others survived. 1309 01:24:53.400 --> 01:24:56.000 As did crocodiles, 1310 01:24:56.000 --> 01:24:57.800 snakes, 1311 01:24:57.800 --> 01:25:00.720 and many fish species. 1312 01:25:00.720 --> 01:25:03.480 And as for the dinosaurs, 1313 01:25:03.480 --> 01:25:05.960 did the impact really kill them all? 1314 01:25:05.960 --> 01:25:09.640 Well, this beautiful fossilised feather 1315 01:25:09.640 --> 01:25:11.680 isn't from a bird, 1316 01:25:11.680 --> 01:25:13.840 but from a predatory dinosaur. 1317 01:25:13.840 --> 01:25:15.560 So we have to be careful 1318 01:25:15.560 --> 01:25:18.800 when we say that dinosaurs are extinct, 1319 01:25:18.800 --> 01:25:22.880 because what we call birds originally evolved 1320 01:25:22.880 --> 01:25:25.920 from the smallest feathered dinosaurs. 1321 01:25:25.920 --> 01:25:28.160 So to be correct, we should say 1322 01:25:28.160 --> 01:25:32.120 all non-avian dinosaurs are extinct. 1323 01:25:34.920 --> 01:25:37.080 Robert's finds have given us 1324 01:25:37.080 --> 01:25:39.400 a better idea than ever before... 1325 01:25:41.000 --> 01:25:44.800 ..about what happened on the day that led to the extinction... 1326 01:25:46.840 --> 01:25:50.360 ..of the largest beasts ever to walk the Earth. 1327 01:25:53.760 --> 01:25:56.000 Dinosaurs were perhaps 1328 01:25:56.000 --> 01:25:59.440 some of nature's most extraordinary creatures, 1329 01:25:59.440 --> 01:26:03.520 dominating the planet for over 150 million years 1330 01:26:03.520 --> 01:26:05.480 before they became extinct. 1331 01:26:08.200 --> 01:26:11.040 But extinction comes in different forms, 1332 01:26:11.040 --> 01:26:13.320 and many of the amazing creatures 1333 01:26:13.320 --> 01:26:16.760 and plants alive today are also threatened. 1334 01:26:16.760 --> 01:26:19.760 It's possible that humanity is having 1335 01:26:19.760 --> 01:26:22.120 as big an impact on the world 1336 01:26:22.120 --> 01:26:26.880 as the asteroid that ended the age of the dinosaurs. 1337 01:26:26.880 --> 01:26:30.440 As human beings, we are unique in our ability 1338 01:26:30.440 --> 01:26:33.520 to learn from the distant past. 1339 01:26:33.520 --> 01:26:38.640 Now we must use that ability wisely and do our very best 1340 01:26:38.640 --> 01:26:41.040 to protect the millions of species 1341 01:26:41.040 --> 01:26:45.520 for whom, alongside us, this planet is home.