1 00:00:01,233 --> 00:00:03,900 ♪ ♪ 2 00:00:05,866 --> 00:00:07,542 (creatures croaking) 3 00:00:07,566 --> 00:00:11,809 ♪ ♪ 4 00:00:11,833 --> 00:00:14,676 DAVID ATTENBOROUGH: 66 million years ago, 5 00:00:14,700 --> 00:00:18,409 {\an1}planet Earth was very different from today. 6 00:00:18,433 --> 00:00:22,100 ♪ ♪ 7 00:00:25,166 --> 00:00:27,909 {\an7}Some of our ancestors at the time 8 00:00:27,933 --> 00:00:31,276 {\an7}might have looked like this furry creature. 9 00:00:31,300 --> 00:00:32,676 ♪ ♪ 10 00:00:32,700 --> 00:00:34,600 (animal chittering) 11 00:00:40,833 --> 00:00:42,676 (dinosaur grunting) 12 00:00:42,700 --> 00:00:47,366 {\an1}The rulers of the land were giant reptiles. 13 00:00:48,800 --> 00:00:50,909 ♪ ♪ 14 00:00:50,933 --> 00:00:54,200 (animal chittering, dinosaur grunting) 15 00:00:57,066 --> 00:01:01,142 (footsteps thudding) 16 00:01:01,166 --> 00:01:02,766 ♪ ♪ 17 00:01:10,833 --> 00:01:12,442 Dinosaurs. 18 00:01:12,466 --> 00:01:16,976 {\an1}That's one of the most infamous, a carnivorous T. rex. 19 00:01:17,000 --> 00:01:20,976 And just behind are the bison of their time, 20 00:01:21,000 --> 00:01:25,042 {\an1}a common plant eater, Edmontosaurus. 21 00:01:25,066 --> 00:01:27,876 {\an1}But what happened to them all? 22 00:01:27,900 --> 00:01:32,042 {\an1}66 million years ago, an asteroid hit the Earth, 23 00:01:32,066 --> 00:01:35,209 {\an1}and scientists think that it was this collision 24 00:01:35,233 --> 00:01:38,433 {\an1}that wiped out the dinosaurs. 25 00:01:39,700 --> 00:01:43,342 {\an1}But no one has ever found the fossil of a dinosaur 26 00:01:43,366 --> 00:01:46,709 {\an1}that they know for certain died as a result of the impact. 27 00:01:46,733 --> 00:01:47,776 (dinosaur roaring) 28 00:01:47,800 --> 00:01:49,776 ♪ ♪ 29 00:01:49,800 --> 00:01:54,766 {\an1}However, a truly extraordinary dig site might change that. 30 00:01:57,366 --> 00:02:00,342 {\an1}Hell Creek Formation, North Dakota. 31 00:02:00,366 --> 00:02:03,476 ♪ ♪ 32 00:02:03,500 --> 00:02:07,533 {\an1}These sedimentary rocks are rich in dinosaur remains. 33 00:02:08,933 --> 00:02:11,876 (roaring) 34 00:02:11,900 --> 00:02:14,242 From triceratops... 35 00:02:14,266 --> 00:02:16,009 (growling) 36 00:02:16,033 --> 00:02:19,300 to T. rex. 37 00:02:20,666 --> 00:02:24,476 {\an1}Now, in a patch of land no bigger than two football fields, 38 00:02:24,500 --> 00:02:27,209 a long-buried secret is coming to light. 39 00:02:27,233 --> 00:02:29,776 ♪ ♪ 40 00:02:29,800 --> 00:02:33,276 {\an1}Because this place might hold evidence of one of the most 41 00:02:33,300 --> 00:02:37,409 {\an1}dramatic events in all the four- and-a-half-billion-year history 42 00:02:37,433 --> 00:02:38,876 of our planet. 43 00:02:38,900 --> 00:02:41,509 ♪ ♪ 44 00:02:41,533 --> 00:02:43,042 RILEY BLACK: Everything was fine 45 00:02:43,066 --> 00:02:46,442 {\an1}on Tuesday in the Cretaceous, and the next second, 46 00:02:46,466 --> 00:02:48,176 {\an1}the world just wasn't the same. 47 00:02:48,200 --> 00:02:51,509 STEVE BRUSATTE: Any time that an asteroid 48 00:02:51,533 --> 00:02:53,509 {\an1}the size of Mount Everest smashes into the Earth, 49 00:02:53,533 --> 00:02:55,909 that's not going to be a good day. 50 00:02:55,933 --> 00:02:57,676 EMILY BAMFORTH: It's actually pretty remarkable 51 00:02:57,700 --> 00:02:59,042 {\an1}that anything survived. 52 00:02:59,066 --> 00:03:01,276 ♪ ♪ 53 00:03:01,300 --> 00:03:03,009 ROBERT DEPALMA: Let me get down here between you. 54 00:03:03,033 --> 00:03:05,509 ATTENBOROUGH: For almost ten years, a team of scientists 55 00:03:05,533 --> 00:03:09,609 {\an1}has been trying to find out exactly what happened here. 56 00:03:09,633 --> 00:03:12,509 ♪ ♪ 57 00:03:12,533 --> 00:03:13,542 DEPALMA: You're at the edge 58 00:03:13,566 --> 00:03:14,809 {\an1}of your seat every moment 59 00:03:14,833 --> 00:03:17,376 {\an1}trying to dig this stuff up. 60 00:03:17,400 --> 00:03:19,909 ATTENBOROUGH: They call the site Tanis, 61 00:03:19,933 --> 00:03:22,176 {\an7}after an ancient Egyptian city, 62 00:03:22,200 --> 00:03:24,809 {\an7}and believe it could be a mass graveyard of creatures 63 00:03:24,833 --> 00:03:26,509 {\an8}which were killed 64 00:03:26,533 --> 00:03:29,676 {\an1}in the asteroid strike 66 million years ago. 65 00:03:29,700 --> 00:03:32,476 ♪ ♪ 66 00:03:32,500 --> 00:03:35,542 {\an1}This site might reveal the remarkable story 67 00:03:35,566 --> 00:03:37,876 not just of how the dinosaurs lived, 68 00:03:37,900 --> 00:03:40,776 but how they died. 69 00:03:40,800 --> 00:03:43,876 ♪ ♪ 70 00:03:43,900 --> 00:03:46,509 {\an1}The impact really was a worst-case scenario. 71 00:03:46,533 --> 00:03:48,476 DAVID UNWIN: It's almost beyond 72 00:03:48,500 --> 00:03:50,176 what we can imagine. 73 00:03:50,200 --> 00:03:52,476 ATTENBOROUGH: If the dig team is right, 74 00:03:52,500 --> 00:03:55,709 Tanis could be a place where the remains 75 00:03:55,733 --> 00:03:59,742 of a long-lost world are frozen in time. 76 00:03:59,766 --> 00:04:01,642 ♪ ♪ 77 00:04:01,666 --> 00:04:04,576 {\an1}A place that gives us, for the first time, 78 00:04:04,600 --> 00:04:06,809 {\an1}an unprecedented window... 79 00:04:06,833 --> 00:04:09,776 {\an7}(dinosaur screeching) 80 00:04:09,800 --> 00:04:12,209 {\an1}into the lives of the very last dinosaurs. 81 00:04:12,233 --> 00:04:16,709 ♪ ♪ 82 00:04:16,733 --> 00:04:20,509 {\an1}And a minute-by-minute picture of what happened 83 00:04:20,533 --> 00:04:23,942 {\an1}on the day the asteroid hit. 84 00:04:23,966 --> 00:04:25,609 ♪ ♪ 85 00:04:25,633 --> 00:04:29,342 {\an1}"Dinosaur Apocalypse: The New Evidence"... 86 00:04:29,366 --> 00:04:32,000 Right now on "NOVA." 87 00:04:33,733 --> 00:04:38,633 ♪ ♪ 88 00:04:56,066 --> 00:04:59,400 ♪ ♪ 89 00:05:01,500 --> 00:05:04,742 ATTENBOROUGH: This landscape is full of fossils 90 00:05:04,766 --> 00:05:07,342 {\an1}dating from the Late Cretaceous, 91 00:05:07,366 --> 00:05:11,042 {\an1}the period which began around 100 million years ago 92 00:05:11,066 --> 00:05:15,766 {\an1}and ended 66 million years ago, when the dinosaurs vanished. 93 00:05:17,466 --> 00:05:22,209 {\an1}Paleontologist Robert DePalma wants to find out more. 94 00:05:22,233 --> 00:05:24,709 ♪ ♪ 95 00:05:24,733 --> 00:05:27,442 {\an7}I think anybody who has ever liked dinosaurs in the past, 96 00:05:27,466 --> 00:05:30,842 {\an7}or still does, has thought at one point or another, 97 00:05:30,866 --> 00:05:32,109 {\an7}well, what happened to them? 98 00:05:32,133 --> 00:05:34,209 Why are they not here anymore? 99 00:05:34,233 --> 00:05:37,900 ♪ ♪ 100 00:05:48,266 --> 00:05:52,109 ♪ ♪ 101 00:05:52,133 --> 00:05:54,409 ATTENBOROUGH: At the end of the Late Cretaceous, 102 00:05:54,433 --> 00:05:57,209 {\an1}fossil evidence tells us Hell Creek 103 00:05:57,233 --> 00:05:59,242 {\an1}might have looked like this. 104 00:05:59,266 --> 00:06:01,709 (creature croaking) 105 00:06:01,733 --> 00:06:04,409 There were low-lying marshy flood plains, 106 00:06:04,433 --> 00:06:06,576 {\an7}intercut by river channels, 107 00:06:06,600 --> 00:06:10,976 {\an7}and covered with horsetails, ferns, and trees. 108 00:06:11,000 --> 00:06:15,300 {\an1}Back then it was warm and wet here all year round. 109 00:06:16,266 --> 00:06:17,742 {\an1}(creature bellowing in distance) 110 00:06:17,766 --> 00:06:21,376 ♪ ♪ 111 00:06:21,400 --> 00:06:25,042 STEVE BRUSATTE: If we go back to about 66 million years ago, 112 00:06:25,066 --> 00:06:27,876 {\an7}the Earth in some ways was very similar to today, 113 00:06:27,900 --> 00:06:30,242 {\an8}and in other ways it was an alien world. 114 00:06:30,266 --> 00:06:32,842 {\an1}The climate was very different, the temperature was different. 115 00:06:32,866 --> 00:06:35,609 There were no ice caps at the poles. 116 00:06:35,633 --> 00:06:38,109 ATTENBOROUGH: Hell Creek is one of the most famous 117 00:06:38,133 --> 00:06:41,742 {\an1}and well-studied areas for digging up dinosaurs. 118 00:06:41,766 --> 00:06:42,876 BRUSATTE: Hell Creek 119 00:06:42,900 --> 00:06:45,576 {\an1}is really the only place in the world, 120 00:06:45,600 --> 00:06:48,509 {\an1}at least right now, where we have a really good record 121 00:06:48,533 --> 00:06:51,009 {\an1}of the last surviving dinosaurs. 122 00:06:51,033 --> 00:06:53,676 BAMFORTH: Hell Creek records the very, very last 123 00:06:53,700 --> 00:06:56,176 {\an7}days of the dinosaurs, and it's, it's the best information 124 00:06:56,200 --> 00:07:00,542 {\an7}that we have in the world about that extinction event. 125 00:07:00,566 --> 00:07:03,742 ♪ ♪ 126 00:07:03,766 --> 00:07:07,309 ATTENBOROUGH: This dig site lies in the northeastern corner 127 00:07:07,333 --> 00:07:09,076 {\an1}of the Hell Creek Formation. 128 00:07:09,100 --> 00:07:11,409 {\an7}66 million years ago, 129 00:07:11,433 --> 00:07:14,009 {\an8}instead of today's dusty prairies, 130 00:07:14,033 --> 00:07:17,509 {\an8}there were sandy, silty riverbanks. 131 00:07:17,533 --> 00:07:20,776 {\an1}Instead of rocky cliffs, there were forests. 132 00:07:20,800 --> 00:07:23,042 ♪ ♪ 133 00:07:23,066 --> 00:07:27,276 And instead of the wildlife we know today... 134 00:07:27,300 --> 00:07:29,733 {\an1}(creatures bellowing) 135 00:07:31,466 --> 00:07:35,633 {\an1}Well, scientists are trying to find out what that was like. 136 00:07:37,333 --> 00:07:40,042 BAMFORTH: One of the great things about paleontology 137 00:07:40,066 --> 00:07:43,042 is also one of its most frustrating elements, 138 00:07:43,066 --> 00:07:45,609 and that is that you can never be sure. 139 00:07:45,633 --> 00:07:48,109 {\an1}Until somebody builds a time machine 140 00:07:48,133 --> 00:07:51,142 {\an1}and we can go back in time and actually observe dinosaurs 141 00:07:51,166 --> 00:07:52,676 in their natural environment, 142 00:07:52,700 --> 00:07:54,476 {\an1}we will never know for sure 143 00:07:54,500 --> 00:07:57,309 {\an1}whether our inferences are correct or not. 144 00:07:57,333 --> 00:08:00,809 {\an1}So it'll always be open to a bit of interpretation 145 00:08:00,833 --> 00:08:03,776 and uncertainty because fundamentally 146 00:08:03,800 --> 00:08:06,176 trying to pinpoint something that happened 147 00:08:06,200 --> 00:08:08,976 on a given day 66 million years ago 148 00:08:09,000 --> 00:08:11,042 {\an1}is really, really tough. 149 00:08:11,066 --> 00:08:13,376 BAMFORTH: And so a lot of paleontology 150 00:08:13,400 --> 00:08:15,076 {\an1}is putting forth theories 151 00:08:15,100 --> 00:08:18,242 {\an1}and then other paleontologists coming forward and saying, 152 00:08:18,266 --> 00:08:21,976 {\an1}"No, that doesn't make sense because here's another theory." 153 00:08:22,000 --> 00:08:25,642 ATTENBOROUGH: Every paleontologist can only hope 154 00:08:25,666 --> 00:08:29,076 {\an1}their site might uncover something new to debate. 155 00:08:29,100 --> 00:08:31,542 ♪ ♪ 156 00:08:31,566 --> 00:08:34,576 {\an1}A sand bank lying between a river and a forest 157 00:08:34,600 --> 00:08:38,209 {\an1}would one day become what Robert now calls Tanis. 158 00:08:38,233 --> 00:08:41,400 ♪ ♪ 159 00:08:43,200 --> 00:08:46,733 {\an1}The site had been explored by others in the past. 160 00:08:47,733 --> 00:08:50,242 (wind whipping) 161 00:08:50,266 --> 00:08:52,676 {\an1}But it wasn't until after Robert and his team 162 00:08:52,700 --> 00:08:55,742 {\an1}started digging here in 2012... 163 00:08:55,766 --> 00:08:57,876 DEPALMA: So somewhere from between 164 00:08:57,900 --> 00:08:59,576 {\an1}there and down here is where that came from, 165 00:08:59,600 --> 00:09:01,209 {\an1}it's coming from up above. Hey, look at this. 166 00:09:01,233 --> 00:09:02,842 {\an1}What? 167 00:09:02,866 --> 00:09:05,642 ATTENBOROUGH: That anyone would know how important this site could be... 168 00:09:05,666 --> 00:09:07,376 {\an1}DEPALMA: Here we've got this 169 00:09:07,400 --> 00:09:11,509 {\an1}freshwater environment of the Hell Creek formation, and this 170 00:09:11,533 --> 00:09:14,876 {\an7}shocking red, green colors coming from the shells 171 00:09:14,900 --> 00:09:16,709 {\an7}of ammonites, a marine organism, 172 00:09:16,733 --> 00:09:19,276 {\an7}kind of like a coiled snail in appearance. 173 00:09:19,300 --> 00:09:21,842 {\an7}So we've got this marine organism that's been thrown up 174 00:09:21,866 --> 00:09:24,509 {\an7}into this freshwater environment 175 00:09:24,533 --> 00:09:27,166 {\an1}and they do not belong here. 176 00:09:28,933 --> 00:09:30,976 ATTENBOROUGH: How they got there is a mystery, 177 00:09:31,000 --> 00:09:34,076 {\an1}but even more intriguing. 178 00:09:34,100 --> 00:09:36,642 DEPALMA: I'm just gonna go ahead and plane down some of this rock. 179 00:09:36,666 --> 00:09:39,809 ATTENBOROUGH: Sitting above the ammonite shells is something that 180 00:09:39,833 --> 00:09:44,876 {\an1}holds a crucial clue about the age of these rocks. 181 00:09:44,900 --> 00:09:46,742 {\an7}So this orange layer right here 182 00:09:46,766 --> 00:09:47,710 {\an8}is composed 183 00:09:47,734 --> 00:09:50,009 {\an7}100% of impact-related debris. 184 00:09:50,033 --> 00:09:52,242 {\an1}It is enriched in iridium. 185 00:09:52,266 --> 00:09:54,309 ATTENBOROUGH: Iridium is an element that's rare 186 00:09:54,333 --> 00:09:56,109 {\an1}in the Earth's crust, 187 00:09:56,133 --> 00:09:58,700 {\an1}but it's common in asteroids. 188 00:10:00,000 --> 00:10:04,433 {\an1}The layer it's in marks the K-Pg boundary. 189 00:10:05,666 --> 00:10:08,476 {\an1}The boundary is made up of dust and debris 190 00:10:08,500 --> 00:10:11,209 {\an1}from a huge asteroid impact. 191 00:10:11,233 --> 00:10:14,709 {\an8}It's been dated to 66 million years ago, 192 00:10:14,733 --> 00:10:18,009 {\an8}the time when dinosaurs disappeared. 193 00:10:18,033 --> 00:10:19,842 {\an7}Look at that. That's what you need? 194 00:10:19,866 --> 00:10:21,576 {\an7}Yeah, yeah, yeah, yeah, yeah, that's what we want. 195 00:10:21,600 --> 00:10:22,942 {\an1}Okay, so it's coming from this area here. 196 00:10:22,966 --> 00:10:24,509 {\an1}So somewhere within that region is where 197 00:10:24,533 --> 00:10:26,209 {\an1}these pieces are coming from. 198 00:10:26,233 --> 00:10:28,642 ATTENBOROUGH: And it has been found all over the world. 199 00:10:28,666 --> 00:10:31,476 SONIA TIKOO: In this layer, the concentration of iridium 200 00:10:31,500 --> 00:10:33,476 {\an7}is a hundred times higher than the baseline 201 00:10:33,500 --> 00:10:35,509 {\an8}for the rest of the Earth's crust. 202 00:10:35,533 --> 00:10:38,542 {\an1}So, perhaps the simplest answer to that is that 203 00:10:38,566 --> 00:10:40,109 {\an1}it came from outer space. 204 00:10:40,133 --> 00:10:42,176 SEAN GULICK: And so we have this 205 00:10:42,200 --> 00:10:43,476 {\an8}wonderful marker 206 00:10:43,500 --> 00:10:44,876 {\an7}that is the iridium layer, 207 00:10:44,900 --> 00:10:46,209 {\an8}that coincides 208 00:10:46,233 --> 00:10:47,509 {\an1}with the extinction event. 209 00:10:47,533 --> 00:10:49,742 {\an1}So this is one of those few cases where you can 210 00:10:49,766 --> 00:10:53,776 {\an1}really tie what is often a fuzzy thing and kind of 211 00:10:53,800 --> 00:10:55,509 bring it into focus because you have 212 00:10:55,533 --> 00:10:58,442 {\an1}this moment in time represented by that layer. 213 00:10:58,466 --> 00:11:01,142 ♪ ♪ 214 00:11:01,166 --> 00:11:03,842 ATTENBOROUGH: Having the K-Pg boundary here at Tanis 215 00:11:03,866 --> 00:11:08,466 {\an1}dates the site to around the time dinosaurs went extinct. 216 00:11:10,400 --> 00:11:12,209 No rattlesnakes. 217 00:11:12,233 --> 00:11:13,542 BRUSATTE: Once you see that layer, 218 00:11:13,566 --> 00:11:14,942 {\an1}once you identify it, 219 00:11:14,966 --> 00:11:18,376 {\an1}it really does stand out because it is a thin layer 220 00:11:18,400 --> 00:11:21,909 {\an1}of rock that caps one world, 221 00:11:21,933 --> 00:11:24,376 {\an1}the world of dinosaurs. 222 00:11:24,400 --> 00:11:27,776 {\an1}And it ushers in another world, a world where you never find 223 00:11:27,800 --> 00:11:31,709 {\an1}a single dinosaur bone or tooth or footprint again. 224 00:11:31,733 --> 00:11:34,709 ♪ ♪ 225 00:11:34,733 --> 00:11:38,376 ATTENBOROUGH: What makes this site even more exciting is 226 00:11:38,400 --> 00:11:40,942 the rock layer right beneath the boundary, 227 00:11:40,966 --> 00:11:45,076 {\an1}in which Robert and his team found the ammonites. 228 00:11:45,100 --> 00:11:46,876 The rock here is really not quite rocky, 229 00:11:46,900 --> 00:11:49,966 and it just falls apart in your hands. 230 00:11:51,733 --> 00:11:54,142 ATTENBOROUGH: This crumbly rock isn't unique, 231 00:11:54,166 --> 00:11:57,042 {\an1}especially in Hell Creek. 232 00:11:57,066 --> 00:11:59,842 {\an7}But it's rarely found in layers like this one. 233 00:11:59,866 --> 00:12:02,176 {\an8}♪ ♪ 234 00:12:02,200 --> 00:12:05,309 {\an7}Over four feet thick, this layer contains 235 00:12:05,333 --> 00:12:08,542 {\an7}several geological features which, to an expert, 236 00:12:08,566 --> 00:12:12,066 {\an8}signify that it was deposited very rapidly. 237 00:12:13,900 --> 00:12:16,176 {\an1}As in a storm or a flood, 238 00:12:16,200 --> 00:12:19,442 {\an1}burying anything within it in an instant. 239 00:12:19,466 --> 00:12:25,309 {\an1}(rocks tumbling, water gurgling) 240 00:12:25,333 --> 00:12:27,376 ATTENBOROUGH: Which could mean that 241 00:12:27,400 --> 00:12:30,642 {\an1}anything in this layer would have been quickly entombed, 242 00:12:30,666 --> 00:12:33,800 like the bodies in the volcanic ash of Pompeii. 243 00:12:37,700 --> 00:12:39,276 BAMFORTH: Generally speaking, 244 00:12:39,300 --> 00:12:41,376 the faster you get buried after you die, 245 00:12:41,400 --> 00:12:44,842 {\an1}or even if the burial is what actually kills the animal, 246 00:12:44,866 --> 00:12:48,309 {\an1}that's one of the best scenarios for fossilization. 247 00:12:48,333 --> 00:12:51,976 {\an1}(creature grunting in distance) 248 00:12:52,000 --> 00:12:55,709 ATTENBOROUGH: Robert knows from the geology that anything he finds 249 00:12:55,733 --> 00:12:58,609 {\an1}could be so well preserved that it could reveal 250 00:12:58,633 --> 00:13:01,576 {\an1}new evidence that will bring this time period 251 00:13:01,600 --> 00:13:05,376 {\an1}to life in a way no one has ever done before. 252 00:13:05,400 --> 00:13:08,842 BLACK: When you think about it for a second, 253 00:13:08,866 --> 00:13:11,009 {\an7}it's actually incredibly amazing 254 00:13:11,033 --> 00:13:12,709 {\an7}that we have any fossils at all, 255 00:13:12,733 --> 00:13:15,242 {\an1}much less a fossil record. 256 00:13:15,266 --> 00:13:16,976 {\an8}So 99.9% the animals 257 00:13:17,000 --> 00:13:18,076 {\an8}that we have 258 00:13:18,100 --> 00:13:20,076 {\an1}don't get preserved as fossils, 259 00:13:20,100 --> 00:13:22,976 {\an1}because you have scavengers and you have other animals 260 00:13:23,000 --> 00:13:26,476 {\an1}that tear away the skeleton as it's being deposited. 261 00:13:26,500 --> 00:13:29,209 To become a fossil, you need certain conditions 262 00:13:29,233 --> 00:13:30,676 for fossils to form. 263 00:13:30,700 --> 00:13:32,042 (dinosaurs grunting) 264 00:13:32,066 --> 00:13:34,866 {\an1}And so a lot of the fossil record is really missing. 265 00:13:36,533 --> 00:13:38,609 ATTENBOROUGH: So, for fossil hunters, 266 00:13:38,633 --> 00:13:41,409 this site is particularly interesting. 267 00:13:41,433 --> 00:13:44,776 {\an1}Such rapidly deposited sediment so close 268 00:13:44,800 --> 00:13:47,376 to the K-Pg boundary could be evidence 269 00:13:47,400 --> 00:13:49,942 {\an1}that what happened to the last dinosaurs here 270 00:13:49,966 --> 00:13:53,742 was as swift as it was destructive. 271 00:13:53,766 --> 00:13:56,809 {\an1}Yet the story of that devastating day 272 00:13:56,833 --> 00:13:59,300 {\an1}begins long before... 273 00:14:00,966 --> 00:14:05,276 {\an7}Millions of miles away and billions of years earlier. 274 00:14:05,300 --> 00:14:09,276 {\an8}♪ ♪ 275 00:14:09,300 --> 00:14:11,842 {\an8}Most scientists think it all started 276 00:14:11,866 --> 00:14:14,609 {\an8}in a ring of dust, rocks, and debris 277 00:14:14,633 --> 00:14:17,576 {\an7}known as the asteroid belt. 278 00:14:17,600 --> 00:14:20,666 {\an8}♪ ♪ 279 00:14:22,833 --> 00:14:26,809 {\an8}It's usually an uneventful place. 280 00:14:26,833 --> 00:14:30,676 {\an8}♪ ♪ 281 00:14:30,700 --> 00:14:35,476 {\an1}But sometimes, a rock can get bumped into a new orbit. 282 00:14:35,500 --> 00:14:38,733 ♪ ♪ 283 00:14:42,566 --> 00:14:46,742 {\an7}And diverted onto a collision course with planet Earth. 284 00:14:46,766 --> 00:14:49,900 {\an8}♪ ♪ 285 00:14:51,300 --> 00:14:53,309 TIKOO: Jupiter, in particular, is a big bully 286 00:14:53,333 --> 00:14:54,942 in our solar system, 287 00:14:54,966 --> 00:14:57,176 {\an1}because it's the largest planet, it has the most gravity. 288 00:14:57,200 --> 00:14:59,909 And it doesn't just take one orbital pass 289 00:14:59,933 --> 00:15:01,876 for an asteroid to be influenced. 290 00:15:01,900 --> 00:15:05,742 {\an1}This is a slow build-up over tens of millions of years, 291 00:15:05,766 --> 00:15:08,209 interacting with Jupiter over and over 292 00:15:08,233 --> 00:15:10,342 {\an1}and over in its orbit. 293 00:15:10,366 --> 00:15:13,242 {\an1}Another thing that can change asteroid orbits 294 00:15:13,266 --> 00:15:15,909 is collisions within the asteroid belt. 295 00:15:15,933 --> 00:15:18,276 {\an1}And what happens is, over time, 296 00:15:18,300 --> 00:15:20,809 the asteroid's orbit can be nudged until it 297 00:15:20,833 --> 00:15:24,642 becomes a near-Earth orbiting asteroid. 298 00:15:24,666 --> 00:15:27,676 {\an1}And it has to be pretty bad luck for both 299 00:15:27,700 --> 00:15:29,309 {\an1}the asteroid and the Earth 300 00:15:29,333 --> 00:15:31,476 to be in the same place at the same time. 301 00:15:31,500 --> 00:15:34,900 {\an1}But it does occasionally happen. 302 00:15:37,600 --> 00:15:39,976 ♪ ♪ 303 00:15:40,000 --> 00:15:41,909 ATTENBOROUGH: Robert and his team dig at this site 304 00:15:41,933 --> 00:15:43,942 {\an1}in North Dakota each summer, 305 00:15:43,966 --> 00:15:47,509 {\an1}the only time the weather allows them to do so. 306 00:15:47,533 --> 00:15:50,433 Come on down, check out this lens over here. 307 00:15:52,000 --> 00:15:54,209 {\an1}In order to understand how the impact 308 00:15:54,233 --> 00:15:56,242 {\an1}affected life on Earth, you really 309 00:15:56,266 --> 00:15:58,476 need to get a very clear picture of what 310 00:15:58,500 --> 00:16:00,776 {\an1}the world was like right before. 311 00:16:00,800 --> 00:16:03,142 That is a critical part of the story. 312 00:16:03,166 --> 00:16:05,509 ♪ ♪ 313 00:16:05,533 --> 00:16:08,709 ATTENBOROUGH: Paleontologist Dr. David Burnham 314 00:16:08,733 --> 00:16:12,942 {\an7}and Loren Gurche have been digging with Robert for years. 315 00:16:12,966 --> 00:16:15,776 ♪ ♪ 316 00:16:15,800 --> 00:16:18,276 {\an8}(chuckles) Oh, wow. 317 00:16:18,300 --> 00:16:20,276 {\an7}See, see the brown? Yeah. 318 00:16:20,300 --> 00:16:22,976 {\an7}That might be a tubercle right there. 319 00:16:23,000 --> 00:16:25,209 ATTENBOROUGH: And it seems today is their lucky day. 320 00:16:25,233 --> 00:16:28,342 {\an4}Oh, my God, look at that! Look at that! 321 00:16:28,366 --> 00:16:29,942 {\an1}Look, the scales are preserved. 322 00:16:29,966 --> 00:16:32,209 They're, like, doing a freaking dissection. 323 00:16:32,233 --> 00:16:35,409 {\an1}Oh, my God... Biology of Tanis. 324 00:16:35,433 --> 00:16:37,209 {\an1}Oh, the scale... look, look 325 00:16:37,233 --> 00:16:39,209 {\an1}the wrinkles continue down that way. 326 00:16:39,233 --> 00:16:41,809 BURNHAM: Mine's all nice and wet so far. 327 00:16:41,833 --> 00:16:43,776 {\an7}The scales are getting smaller in that direction. 328 00:16:43,800 --> 00:16:45,209 {\an7}How big are they there? 329 00:16:45,233 --> 00:16:46,576 {\an7}I got a, I got a one with the, 330 00:16:46,600 --> 00:16:48,242 {\an8}the projection over here. What? 331 00:16:48,266 --> 00:16:50,009 {\an3}Oh! Yeah. 332 00:16:50,033 --> 00:16:51,709 {\an1}DEPALMA: Yeah, there's the protuberance right there. 333 00:16:51,733 --> 00:16:52,976 BURNHAM: I've only seen that on one other specimen 334 00:16:53,000 --> 00:16:54,809 {\an8}in my life. Yeah. 335 00:16:54,833 --> 00:16:56,409 {\an1}This is the closest thing to getting to touch 336 00:16:56,433 --> 00:16:58,009 {\an1}a living, breathing dinosaur. It is. 337 00:16:58,033 --> 00:17:01,209 ATTENBOROUGH: They've found something extraordinary... 338 00:17:01,233 --> 00:17:03,009 Dinosaur skin. 339 00:17:03,033 --> 00:17:06,876 {\an1}And they've uncovered it right next to another fossil. 340 00:17:06,900 --> 00:17:08,442 {\an7}This is obviously horn. 341 00:17:08,466 --> 00:17:11,409 {\an1}The gnarliest horn I've ever seen. 342 00:17:11,433 --> 00:17:14,009 ATTENBOROUGH: Which helps them piece together 343 00:17:14,033 --> 00:17:15,976 {\an1}the creature they're from, 344 00:17:16,000 --> 00:17:17,742 a triceratops. 345 00:17:17,766 --> 00:17:20,176 DEPALMA: It is so exceedingly rare, 346 00:17:20,200 --> 00:17:21,576 {\an7}a piece of triceratops skin 347 00:17:21,600 --> 00:17:22,776 {\an7}in the Hell Creek formation. 348 00:17:22,800 --> 00:17:24,876 ♪ ♪ 349 00:17:24,900 --> 00:17:26,576 ATTENBOROUGH: The skin that they have found 350 00:17:26,600 --> 00:17:28,476 may look like an impression in the rock, 351 00:17:28,500 --> 00:17:30,709 {\an1}but this is skin that has been fossilized, 352 00:17:30,733 --> 00:17:34,142 {\an1}and over millions of years has turned to stone. 353 00:17:34,166 --> 00:17:36,976 ♪ ♪ 354 00:17:37,000 --> 00:17:39,276 Triceratops bones 355 00:17:39,300 --> 00:17:42,342 {\an1}are relatively common finds in Hell Creek, 356 00:17:42,366 --> 00:17:45,042 {\an7}but skin in such condition 357 00:17:45,066 --> 00:17:48,242 {\an7}as this is very rare indeed. 358 00:17:48,266 --> 00:17:51,009 The size and the patterning of the scales 359 00:17:51,033 --> 00:17:53,276 together with the age and location 360 00:17:53,300 --> 00:17:55,276 of the rocks where it was found, 361 00:17:55,300 --> 00:17:59,476 {\an1}strongly suggests that this is from a triceratops. 362 00:17:59,500 --> 00:18:02,942 {\an1}The presence of the horn where the skin was found 363 00:18:02,966 --> 00:18:04,576 supports this. 364 00:18:04,600 --> 00:18:08,742 {\an1}The brown color contains traces of organic material. 365 00:18:08,766 --> 00:18:11,576 So it might even be possible from this 366 00:18:11,600 --> 00:18:14,676 to work out which pigments were in it. 367 00:18:14,700 --> 00:18:19,076 {\an1}Finding and studying such well-preserved fossils as this 368 00:18:19,100 --> 00:18:22,976 {\an1}helps paleontologists build a much more detailed picture 369 00:18:23,000 --> 00:18:24,876 {\an1}of how these creatures lived. 370 00:18:24,900 --> 00:18:28,342 {\an1}Combining this information with insights 371 00:18:28,366 --> 00:18:31,342 {\an1}from scientists around the world makes it possible 372 00:18:31,366 --> 00:18:34,309 {\an1}to speculate about what life in the Late Cretaceous 373 00:18:34,333 --> 00:18:36,742 {\an1}might have been like. 374 00:18:36,766 --> 00:18:40,200 ♪ ♪ 375 00:18:42,433 --> 00:18:45,666 (dinosaur bellowing, footsteps crunching) 376 00:18:47,366 --> 00:18:50,342 We know from bones that adult triceratops 377 00:18:50,366 --> 00:18:52,676 {\an1}could reach 30 feet in length 378 00:18:52,700 --> 00:18:54,676 {\an1}and ten feet in height. 379 00:18:54,700 --> 00:18:56,909 (dinosaur grunting) ♪ ♪ 380 00:18:56,933 --> 00:18:58,909 Marks on the fossil also show us that 381 00:18:58,933 --> 00:19:01,309 {\an1}this one was badly scared. 382 00:19:01,333 --> 00:19:03,842 (dinosaur grunts) 383 00:19:03,866 --> 00:19:06,033 ♪ ♪ 384 00:19:10,933 --> 00:19:13,509 {\an1}Triceratops were plant eaters. 385 00:19:13,533 --> 00:19:15,542 (leaves rustling) 386 00:19:15,566 --> 00:19:18,276 (dinosaur grunting) 387 00:19:18,300 --> 00:19:21,909 {\an1}Other fossils tell us they had sharp beaks 388 00:19:21,933 --> 00:19:24,709 {\an1}and hundreds of teeth, which enabled them to 389 00:19:24,733 --> 00:19:28,109 {\an1}shred hundreds of pounds of tough vegetation. 390 00:19:28,133 --> 00:19:30,400 (dinosaur growls) 391 00:19:32,100 --> 00:19:35,742 Almost all adult triceratops fossils 392 00:19:35,766 --> 00:19:38,742 {\an1}ever found were on their own. 393 00:19:38,766 --> 00:19:41,909 {\an1}So it's possible that the adults were solitary, 394 00:19:41,933 --> 00:19:45,666 {\an1}a pattern observed in many modern-day animals. 395 00:19:49,666 --> 00:19:51,342 (dinosaur grunting) 396 00:19:51,366 --> 00:19:53,676 If you look at American bison, for example, 397 00:19:53,700 --> 00:19:55,709 {\an1}they herd through much of their youth and much 398 00:19:55,733 --> 00:19:58,342 {\an1}of their young adulthood, but especially old males 399 00:19:58,366 --> 00:20:00,009 {\an1}will be by themselves. 400 00:20:00,033 --> 00:20:01,942 So that's not to say that all the triceratops 401 00:20:01,966 --> 00:20:03,876 {\an1}you find by themselves are these old bulls, 402 00:20:03,900 --> 00:20:06,242 but there might be something similar at play. 403 00:20:06,266 --> 00:20:09,376 So they were probably territorial, 404 00:20:09,400 --> 00:20:11,376 {\an1}fighting rivals away. 405 00:20:11,400 --> 00:20:12,909 (both growling) 406 00:20:12,933 --> 00:20:14,942 {\an7}These were very large animals that probably 407 00:20:14,966 --> 00:20:18,076 {\an8}had very large territorial ranges. 408 00:20:18,100 --> 00:20:20,742 CAMERON MUSKELLEY: There actually is fossil evidence of 409 00:20:20,766 --> 00:20:23,709 {\an1}puncture wounds in the frills of these dinosaurs, 410 00:20:23,733 --> 00:20:25,642 {\an1}but they were probably using their horns 411 00:20:25,666 --> 00:20:29,142 {\an1}just like modern caribou, where they lock their horns together 412 00:20:29,166 --> 00:20:32,700 to compete for mates and other territorial places. 413 00:20:34,166 --> 00:20:38,676 ATTENBOROUGH: A solitary animal would perhaps mark its territory. 414 00:20:38,700 --> 00:20:41,933 ♪ ♪ 415 00:20:44,600 --> 00:20:46,276 (spraying) 416 00:20:46,300 --> 00:20:49,042 If you weigh more than an African elephant, 417 00:20:49,066 --> 00:20:51,609 {\an1}there's not much that can bother you. 418 00:20:51,633 --> 00:20:54,142 (animal chittering, dinosaur grunting) 419 00:20:54,166 --> 00:20:57,076 {\an1}Except perhaps a little mammal. 420 00:20:57,100 --> 00:21:00,766 ♪ ♪ 421 00:21:02,133 --> 00:21:04,200 {\an8}(dinosaur roaring) 422 00:21:05,666 --> 00:21:08,742 ♪ ♪ 423 00:21:08,766 --> 00:21:11,866 {\an1}(animals chittering, squeaking) 424 00:21:14,300 --> 00:21:17,676 ATTENBOROUGH: Robert found these jawbones 425 00:21:17,700 --> 00:21:20,576 {\an1}in the fossilized burrow. 426 00:21:20,600 --> 00:21:23,842 {\an1}The shape of this tiny bone and tooth 427 00:21:23,866 --> 00:21:27,109 {\an1}means it's most likely come from what's known as 428 00:21:27,133 --> 00:21:30,309 {\an1}a pediomyid, an early mammal... 429 00:21:30,333 --> 00:21:33,276 {\an1}and a type of marsupial. 430 00:21:33,300 --> 00:21:35,242 {\an1}The team also discovered 431 00:21:35,266 --> 00:21:37,842 fossilized nuts and seeds in the burrow, 432 00:21:37,866 --> 00:21:40,976 {\an1}so we have an idea of what it might have eaten. 433 00:21:41,000 --> 00:21:42,609 {\an1}(animal bellowing in distance) 434 00:21:42,633 --> 00:21:45,342 BRUSATTE: We think of mammals oftentimes 435 00:21:45,366 --> 00:21:47,933 {\an1}as the new kids on the block... 436 00:21:50,133 --> 00:21:52,176 {\an8}But what we often don't appreciate is that 437 00:21:52,200 --> 00:21:54,109 {\an7}mammals and dinosaurs, 438 00:21:54,133 --> 00:21:57,009 {\an1}their legacies go back to the same time. 439 00:21:57,033 --> 00:21:58,409 {\an1}ANUSUYA CHINSAMY-TURAN: Some of them, we think, 440 00:21:58,433 --> 00:21:59,776 {\an1}may have been opportunistic 441 00:21:59,800 --> 00:22:03,976 {\an8}because there's even evidence of a small mammal 442 00:22:04,000 --> 00:22:06,276 {\an7}that actually has the remains of 443 00:22:06,300 --> 00:22:09,033 a baby dinosaur within its belly. 444 00:22:09,833 --> 00:22:12,209 {\an1}(animals grunting in distance) 445 00:22:12,233 --> 00:22:14,609 ATTENBOROUGH: The team's finds are adding to our knowledge 446 00:22:14,633 --> 00:22:16,342 of the complex world 447 00:22:16,366 --> 00:22:19,109 at the very end of the Late Cretaceous. 448 00:22:19,133 --> 00:22:22,809 And it's not just the fossilized creatures. 449 00:22:22,833 --> 00:22:27,700 {\an1}If you walk on damp sand, you'll leave a trace behind. 450 00:22:31,666 --> 00:22:34,176 A footprint. 451 00:22:34,200 --> 00:22:38,276 The same was true 66 million years ago. 452 00:22:38,300 --> 00:22:40,442 {\an1}And very, very occasionally, 453 00:22:40,466 --> 00:22:42,933 {\an1}such traces were preserved. 454 00:22:45,200 --> 00:22:47,209 GURCHE: We wont to foil the backside. 455 00:22:47,233 --> 00:22:49,142 {\an5}Right. We'll just put the plaster right on. 456 00:22:49,166 --> 00:22:51,009 ATTENBOROUGH: The dig team has discovered 457 00:22:51,033 --> 00:22:53,042 {\an1}a number of footprints. 458 00:22:53,066 --> 00:22:54,576 DEPALMA: Yeah, let's see. 459 00:22:54,600 --> 00:22:57,200 Looks like a good print. Yeah. 460 00:22:59,900 --> 00:23:02,309 ATTENBOROUGH: Their shape gives them an idea 461 00:23:02,333 --> 00:23:04,442 {\an1}of what might have made them. 462 00:23:04,466 --> 00:23:07,566 {\an8}♪ ♪ 463 00:23:10,833 --> 00:23:13,542 {\an7}If the team is right, they were made by 464 00:23:13,566 --> 00:23:15,809 {\an7}a winged creature that might well have liked 465 00:23:15,833 --> 00:23:17,876 a small mammal... 466 00:23:17,900 --> 00:23:19,642 for lunch. 467 00:23:19,666 --> 00:23:22,900 (animal chittering, beak thudding) 468 00:23:25,000 --> 00:23:27,909 {\an8}(dinosaur grunting, animal chittering) 469 00:23:27,933 --> 00:23:32,400 {\an7}The footprints are long and narrow with four toe prints. 470 00:23:34,066 --> 00:23:36,276 {\an7}Two are slightly longer than the others. 471 00:23:36,300 --> 00:23:39,700 {\an8}And that suggests they were made by... 472 00:23:43,066 --> 00:23:45,476 A pterosaur. 473 00:23:45,500 --> 00:23:48,433 ♪ ♪ (pterosaur bellows) 474 00:23:51,966 --> 00:23:54,176 {\an1}Pterosaurs are not dinosaurs, 475 00:23:54,200 --> 00:23:57,242 {\an1}but flying reptiles on a different branch 476 00:23:57,266 --> 00:23:59,676 {\an1}of the evolutionary tree. 477 00:23:59,700 --> 00:24:02,876 ♪ ♪ 478 00:24:02,900 --> 00:24:04,776 UNWIN: There is nothing 479 00:24:04,800 --> 00:24:07,909 {\an7}like a flying reptile around today. 480 00:24:07,933 --> 00:24:10,109 {\an7}Pterosaurs got to enormous sizes. 481 00:24:10,133 --> 00:24:13,109 {\an1}A group of pterosaurs known as azhdarchids, 482 00:24:13,133 --> 00:24:16,442 {\an1}which include the pterosaur known as Quetzalcoatlus, 483 00:24:16,466 --> 00:24:19,309 {\an1}is a pterosaur that grew up to around 40 feet. 484 00:24:19,333 --> 00:24:21,676 {\an1}This was an animal that had a 40-foot-long wingspan. 485 00:24:21,700 --> 00:24:24,109 ♪ ♪ 486 00:24:24,133 --> 00:24:26,842 ATTENBOROUGH: Some evidence shows that some pterosaurs 487 00:24:26,866 --> 00:24:28,509 might have lived in large groups, 488 00:24:28,533 --> 00:24:29,942 {\an1}much as flamingos do today. 489 00:24:29,966 --> 00:24:33,676 {\an1}(pterosaurs bellowing) 490 00:24:33,700 --> 00:24:37,142 ATTENBOROUGH: Male pterosaurs usually had crests, 491 00:24:37,166 --> 00:24:38,742 {\an1}while females didn't. 492 00:24:38,766 --> 00:24:42,509 {\an1}So, crests may have been used in courtship displays. 493 00:24:42,533 --> 00:24:45,966 ♪ ♪ (beaks clattering) 494 00:24:51,033 --> 00:24:52,309 (pterosaur bellows) 495 00:24:52,333 --> 00:24:56,376 {\an1}And we have a clue about where females laid their eggs 496 00:24:56,400 --> 00:25:00,009 {\an1}because evidence suggests that at least one pterosaur 497 00:25:00,033 --> 00:25:04,776 {\an1}laid hers in the soft, sandy banks of the river at Tanis. 498 00:25:04,800 --> 00:25:08,133 ♪ ♪ 499 00:25:16,400 --> 00:25:19,476 ♪ ♪ 500 00:25:19,500 --> 00:25:20,976 UNWIN: The fossil record 501 00:25:21,000 --> 00:25:24,642 of pterosaur eggs is really small. 502 00:25:24,666 --> 00:25:29,676 {\an1}Um, so far we have a, a couple of eggs 503 00:25:29,700 --> 00:25:31,776 {\an1}from northeastern China, 504 00:25:31,800 --> 00:25:37,009 and we also have an extraordinary trove of eggs 505 00:25:37,033 --> 00:25:40,742 from western China, from Xinjiang Province. 506 00:25:40,766 --> 00:25:44,509 {\an1}The only other record of eggs is a single egg 507 00:25:44,533 --> 00:25:46,709 {\an1}that comes from Argentina. 508 00:25:46,733 --> 00:25:50,742 {\an1}So our record is very, very small indeed. 509 00:25:50,766 --> 00:25:53,509 ATTENBOROUGH: This is the fossilized egg of a pterosaur 510 00:25:53,533 --> 00:25:57,276 {\an1}that Robert and his team found in the crumbly layer, 511 00:25:57,300 --> 00:26:00,109 the only one ever discovered in North America. 512 00:26:00,133 --> 00:26:02,942 If you look at it with the naked eye, 513 00:26:02,966 --> 00:26:06,342 all you see is a jumble of lines. 514 00:26:06,366 --> 00:26:10,276 {\an1}But if you examine it with the latest technology, 515 00:26:10,300 --> 00:26:13,809 you can find out a wealth of information 516 00:26:13,833 --> 00:26:16,576 from the chemistry of the bones, 517 00:26:16,600 --> 00:26:18,476 {\an1}to the composition of the shell. 518 00:26:18,500 --> 00:26:19,976 {\an8}And that, in turn, 519 00:26:20,000 --> 00:26:21,609 {\an7}can tell us a lot about 520 00:26:21,633 --> 00:26:24,333 {\an7}how these incredible creatures lived. 521 00:26:26,900 --> 00:26:29,109 To investigate the pterosaur egg, 522 00:26:29,133 --> 00:26:31,076 {\an1}Robert has been given access 523 00:26:31,100 --> 00:26:34,642 to the Diamond Light Source synchrotron. 524 00:26:34,666 --> 00:26:37,409 {\an1}Situated in Oxfordshire, in the U.K., 525 00:26:37,433 --> 00:26:39,442 {\an1}it's a powerful research tool 526 00:26:39,466 --> 00:26:42,109 that acts like a giant microscope. 527 00:26:42,133 --> 00:26:45,142 ♪ ♪ 528 00:26:45,166 --> 00:26:48,009 ATTENBOROUGH: By accelerating electrons in this huge ring, 529 00:26:48,033 --> 00:26:50,909 the synchrotron creates beams of light 530 00:26:50,933 --> 00:26:55,309 billions of times brighter than the sun. 531 00:26:55,333 --> 00:26:58,276 ♪ ♪ 532 00:26:58,300 --> 00:27:03,109 {\an1}Robert and paleobiologist Dr. Victoria Egerton 533 00:27:03,133 --> 00:27:06,276 {\an1}now want to turn that beam onto the egg fossil 534 00:27:06,300 --> 00:27:09,742 {\an1}to discover more about its chemical makeup. 535 00:27:09,766 --> 00:27:12,109 ♪ ♪ 536 00:27:12,133 --> 00:27:13,776 We're pretty much lined up on the skeleton, 537 00:27:13,800 --> 00:27:15,342 but we might have to move the stage a little bit 538 00:27:15,366 --> 00:27:17,042 to get to the right part. Sure. 539 00:27:17,066 --> 00:27:19,676 ATTENBOROUGH: Each synchrotron scan 540 00:27:19,700 --> 00:27:21,609 {\an1}can take several hours. 541 00:27:21,633 --> 00:27:25,576 {\an1}Meanwhile, Robert can reveal the creature inside. 542 00:27:25,600 --> 00:27:27,976 Who made this wonderful thing? 543 00:27:28,000 --> 00:27:31,976 DEPALMA: I got replicas of the bones from inside that egg 544 00:27:32,000 --> 00:27:34,442 and I restored the remainder 545 00:27:34,466 --> 00:27:36,276 and put together what the skeleton 546 00:27:36,300 --> 00:27:38,276 would've looked like when it hatched. 547 00:27:38,300 --> 00:27:39,909 That's how big the creature would've been 548 00:27:39,933 --> 00:27:41,709 outside the egg, if it had hatched. 549 00:27:41,733 --> 00:27:44,276 {\an1}So this is the baby. 550 00:27:44,300 --> 00:27:46,342 {\an1}How big was it gonna grow? 551 00:27:46,366 --> 00:27:49,076 These very long neck vertebrae here 552 00:27:49,100 --> 00:27:51,309 are what really gave part of the story away to us, 553 00:27:51,333 --> 00:27:53,409 because those long bones 554 00:27:53,433 --> 00:27:56,176 {\an1}match very, very closely with the azhdarchoid pterosaurs. 555 00:27:56,200 --> 00:27:58,209 That is the giant pterosaurs. 556 00:27:58,233 --> 00:28:00,442 {\an1}Oh, they were the whoppers, weren't they? 557 00:28:00,466 --> 00:28:04,876 {\an4}I mean, what, 25 feet wingspan? Some of them. 558 00:28:04,900 --> 00:28:06,509 {\an8}This probably had a wingspan, 559 00:28:06,533 --> 00:28:08,242 {\an8}maybe 15 feet? 560 00:28:08,266 --> 00:28:09,909 {\an1}Well, it looks as though 561 00:28:09,933 --> 00:28:11,409 {\an1}it could take off, really. 562 00:28:11,433 --> 00:28:13,076 It's easy to picture something like that 563 00:28:13,100 --> 00:28:14,742 just hatching out of the egg and fluttering 564 00:28:14,766 --> 00:28:17,000 out almost like a little bat. 565 00:28:19,466 --> 00:28:20,876 DAVID MARTILL: A lot of birds are 566 00:28:20,900 --> 00:28:22,109 {\an7}utterly dependent on the parents 567 00:28:22,133 --> 00:28:24,242 {\an8}bringing them food for a long time. 568 00:28:24,266 --> 00:28:26,042 {\an7}But there are precocious birds, 569 00:28:26,066 --> 00:28:28,509 {\an8}and there are some that simply stand up 570 00:28:28,533 --> 00:28:30,376 after a few minutes 571 00:28:30,400 --> 00:28:32,176 and start foraging for food themselves. 572 00:28:32,200 --> 00:28:34,809 {\an1}Well, pterosaurs might have taken that a stage further, 573 00:28:34,833 --> 00:28:36,542 {\an1}and they simply flew away. 574 00:28:36,566 --> 00:28:38,142 ♪ ♪ 575 00:28:38,166 --> 00:28:39,609 ATTENBOROUGH: They've scanned the egg 576 00:28:39,633 --> 00:28:42,333 {\an1}here and in America... 577 00:28:43,700 --> 00:28:46,809 {\an1}Victoria has the results. 578 00:28:46,833 --> 00:28:48,842 ♪ ♪ 579 00:28:48,866 --> 00:28:52,209 {\an1}So what have you learned from the synchrotron image? 580 00:28:52,233 --> 00:28:54,609 What we have here is a chemical map 581 00:28:54,633 --> 00:28:58,576 of calcium directly within the bones of this animal. 582 00:28:58,600 --> 00:29:02,642 {\an8}That tells us that these bones were already hardened. 583 00:29:02,666 --> 00:29:04,476 So it might be ready to fly 584 00:29:04,500 --> 00:29:06,942 not long after it hatches. 585 00:29:06,966 --> 00:29:08,409 {\an1}Can you see any sign of the shell 586 00:29:08,433 --> 00:29:11,409 {\an4}and what sort of shell was it? We can. 587 00:29:11,433 --> 00:29:12,909 What I can show you... 588 00:29:12,933 --> 00:29:14,209 {\an1}Ah. 589 00:29:14,233 --> 00:29:16,376 {\an7}We can see the rim of the egg 590 00:29:16,400 --> 00:29:18,542 {\an8}in sulphur. 591 00:29:18,566 --> 00:29:19,709 {\an1}Does that tell you whether it was 592 00:29:19,733 --> 00:29:22,176 {\an1}a hard shell or a soft shell? 593 00:29:22,200 --> 00:29:23,776 We have been looking at this. 594 00:29:23,800 --> 00:29:26,676 {\an8}We can see folding occurring 595 00:29:26,700 --> 00:29:28,909 and this unusual undulation. 596 00:29:28,933 --> 00:29:31,742 If it were a hard egg, we would expect 597 00:29:31,766 --> 00:29:33,676 splintered bits and broken bits, 598 00:29:33,700 --> 00:29:35,742 just like a chicken egg. 599 00:29:35,766 --> 00:29:37,609 This helped to tell us that it was soft. 600 00:29:37,633 --> 00:29:39,809 {\an1}So it was perhaps like a turtle? 601 00:29:39,833 --> 00:29:41,142 Absolutely. 602 00:29:41,166 --> 00:29:43,809 {\an1}That's not the case, is it, with dinosaurs? 603 00:29:43,833 --> 00:29:46,742 {\an4}Many dinosaurs laid hard-shelled eggs. Yes. 604 00:29:46,766 --> 00:29:48,276 {\an1}So this is a new discovery about 605 00:29:48,300 --> 00:29:49,742 {\an1}azhdarchoid pterosaurs? 606 00:29:49,766 --> 00:29:51,176 Absolutely. 607 00:29:51,200 --> 00:29:53,442 This is something that we are confirming 608 00:29:53,466 --> 00:29:55,842 for the first time. Huh. 609 00:29:55,866 --> 00:29:58,442 {\an1}Some flying pterosaurs had eggs like turtles. 610 00:29:58,466 --> 00:29:59,476 {\an3}Yes. 611 00:29:59,500 --> 00:30:02,076 Much more reptilian-like than bird-like. 612 00:30:02,100 --> 00:30:04,909 And that can potentially tell us more about 613 00:30:04,933 --> 00:30:07,909 the environment in which these eggs were laid. 614 00:30:07,933 --> 00:30:10,942 {\an1}How interesting, yeah. 615 00:30:10,966 --> 00:30:14,133 ♪ ♪ 616 00:30:16,200 --> 00:30:19,142 {\an1}Creatures that lay soft eggs 617 00:30:19,166 --> 00:30:22,376 tend to bury them in order to protect them. 618 00:30:22,400 --> 00:30:25,442 ♪ ♪ 619 00:30:25,466 --> 00:30:27,142 {\an1}(pterosaur bellowing) 620 00:30:27,166 --> 00:30:29,976 So female pterosaurs probably looked 621 00:30:30,000 --> 00:30:32,976 for places like this to lay their eggs. 622 00:30:33,000 --> 00:30:36,042 {\an1}Because the sandy soil here 623 00:30:36,066 --> 00:30:37,909 is just soft enough 624 00:30:37,933 --> 00:30:40,876 for the hatchling to dig itself out. 625 00:30:40,900 --> 00:30:43,766 ♪ ♪ 626 00:30:45,933 --> 00:30:48,509 {\an8}Now, the pterosaur just has to make sure 627 00:30:48,533 --> 00:30:50,333 {\an8}that the hole... 628 00:30:51,933 --> 00:30:53,276 {\an8}is perfect. 629 00:30:53,300 --> 00:30:55,609 (animal chittering) 630 00:30:55,633 --> 00:30:58,176 ♪ ♪ 631 00:30:58,200 --> 00:31:00,509 (pterosaur bellows) 632 00:31:00,533 --> 00:31:05,276 ♪ ♪ 633 00:31:05,300 --> 00:31:06,110 (pterosaur grunting) 634 00:31:06,134 --> 00:31:09,209 {\an8}♪ ♪ 635 00:31:09,233 --> 00:31:10,509 {\an8}(pterosaur grunts) 636 00:31:10,533 --> 00:31:13,276 {\an8}ATTENBOROUGH: Success. 637 00:31:13,300 --> 00:31:15,676 {\an7}But it's not over yet. 638 00:31:15,700 --> 00:31:18,809 {\an7}Pterosaurs had two ovaries (pterosaur grunts) 639 00:31:18,833 --> 00:31:22,242 and they laid their eggs in pairs. 640 00:31:22,266 --> 00:31:24,776 (pterosaur bellows) 641 00:31:24,800 --> 00:31:28,642 ♪ ♪ 642 00:31:28,666 --> 00:31:30,342 UNWIN: So clearly, 643 00:31:30,366 --> 00:31:32,609 {\an8}this method, this way of reproducing 644 00:31:32,633 --> 00:31:36,042 {\an8}for pterosaurs was incredibly successful. 645 00:31:36,066 --> 00:31:38,209 {\an1}What it kind of says is, 646 00:31:38,233 --> 00:31:39,776 {\an1}"Hey, everything's normal" 647 00:31:39,800 --> 00:31:43,842 until the moment when the impact happens 648 00:31:43,866 --> 00:31:46,376 and it all goes horribly wrong, basically. 649 00:31:46,400 --> 00:31:49,342 ♪ ♪ 650 00:31:49,366 --> 00:31:51,742 ATTENBOROUGH: Here on the sand bank, 651 00:31:51,766 --> 00:31:55,442 {\an7}sandwiched between the river and these glorious trees, 652 00:31:55,466 --> 00:31:58,776 {\an7}life at Tanis seemed to be thriving. 653 00:31:58,800 --> 00:32:00,976 {\an8}(gasps) Whoops. 654 00:32:01,000 --> 00:32:03,109 Never a dull moment. 655 00:32:03,133 --> 00:32:05,766 But all that was about to change. 656 00:32:06,666 --> 00:32:09,966 ♪ ♪ 657 00:32:12,666 --> 00:32:16,876 Deep in space, a countdown clock is ticking. 658 00:32:16,900 --> 00:32:20,576 ♪ ♪ 659 00:32:20,600 --> 00:32:23,109 {\an1}The asteroid's journey would take it through 660 00:32:23,133 --> 00:32:26,476 the orbit of our neighboring planet, Mars. 661 00:32:26,500 --> 00:32:29,742 ♪ ♪ 662 00:32:29,766 --> 00:32:33,242 {\an1}Had the two collided, a catastrophe on Earth 663 00:32:33,266 --> 00:32:35,409 {\an1}would have been avoided. 664 00:32:35,433 --> 00:32:38,609 ♪ ♪ 665 00:32:38,633 --> 00:32:40,509 But it didn't happen 666 00:32:40,533 --> 00:32:43,876 and the fate of life on Earth was sealed. 667 00:32:43,900 --> 00:32:47,833 ♪ ♪ 668 00:32:52,366 --> 00:32:55,176 {\an1}New evidence is helping to build a vivid picture 669 00:32:55,200 --> 00:32:57,042 {\an1}of Late Cretaceous life, 670 00:32:57,066 --> 00:33:01,009 here in this corner of North Dakota. 671 00:33:01,033 --> 00:33:02,876 And the team have found some more 672 00:33:02,900 --> 00:33:04,876 {\an1}well-preserved footprints. 673 00:33:04,900 --> 00:33:07,042 ♪ ♪ 674 00:33:07,066 --> 00:33:09,276 BURNHAM: So these are animals that were actually 675 00:33:09,300 --> 00:33:10,809 {\an1}walking in the water? 676 00:33:10,833 --> 00:33:12,576 {\an1}DEPALMA: These guys would've been essentially on 677 00:33:12,600 --> 00:33:14,609 {\an1}a mushy riverbank going down to drink 678 00:33:14,633 --> 00:33:15,842 {\an1}at some point, you know, 679 00:33:15,866 --> 00:33:18,142 {\an7}animals tend to congregate around the rivers. 680 00:33:18,166 --> 00:33:21,800 {\an8}ATTENBOROUGH: This footprint is about a foot long. 681 00:33:24,100 --> 00:33:25,642 So I think this is from a type of dinosaur that 682 00:33:25,666 --> 00:33:27,042 {\an1}we call a duck-billed dinosaur. 683 00:33:27,066 --> 00:33:30,742 {\an1}And they would've been very common in the Cretaceous. 684 00:33:30,766 --> 00:33:32,809 {\an1}They ate the plants in the area 685 00:33:32,833 --> 00:33:35,509 and they got very large, 30 feet long. 686 00:33:35,533 --> 00:33:38,709 ATTENBOROUGH: And there are more. 687 00:33:38,733 --> 00:33:42,142 {\an1}This track, you see all the toes are very well preserved. 688 00:33:42,166 --> 00:33:45,609 You even see a nail print at the tips of the toes. 689 00:33:45,633 --> 00:33:48,009 So the little toenails dug into the mud. 690 00:33:48,033 --> 00:33:50,600 I love this one. 691 00:33:51,966 --> 00:33:55,166 {\an8}ATTENBOROUGH: This is the team's prize footprint. 692 00:33:57,100 --> 00:33:59,976 {\an8}It has three toes, 693 00:34:00,000 --> 00:34:03,442 {\an8}and it's longer than it is wide. 694 00:34:03,466 --> 00:34:05,109 {\an8}So it's very likely to be 695 00:34:05,133 --> 00:34:07,642 {\an8}a carnivorous dinosaur. 696 00:34:07,666 --> 00:34:10,042 {\an8}It's so well preserved 697 00:34:10,066 --> 00:34:12,309 {\an8}that you can see the mark left by 698 00:34:12,333 --> 00:34:14,642 {\an1}its sharp claw there. 699 00:34:14,666 --> 00:34:16,509 {\an1}Hell Creek is well known 700 00:34:16,533 --> 00:34:18,942 for one carnivore in particular, 701 00:34:18,966 --> 00:34:21,242 {\an8}T. rex. 702 00:34:21,266 --> 00:34:25,642 {\an7}This footprint is too small for an adult T. rex, 703 00:34:25,666 --> 00:34:29,676 {\an1}but it's possible that it was made by a young one. 704 00:34:29,700 --> 00:34:31,642 ♪ ♪ 705 00:34:31,666 --> 00:34:33,633 {\an8}(dinosaur growls) 706 00:34:37,100 --> 00:34:39,776 (growls) 707 00:34:39,800 --> 00:34:42,009 {\an1}Robert also found this, 708 00:34:42,033 --> 00:34:44,676 {\an1}the crown of a tooth. 709 00:34:44,700 --> 00:34:48,276 {\an1}Its shape and its serrated edge 710 00:34:48,300 --> 00:34:52,642 {\an1}are indications that it comes from an adult T. rex. 711 00:34:52,666 --> 00:34:54,509 (animal chittering) 712 00:34:54,533 --> 00:34:57,233 (dinosaur growls) 713 00:35:00,566 --> 00:35:02,000 ♪ ♪ 714 00:35:09,400 --> 00:35:13,176 ♪ ♪ 715 00:35:13,200 --> 00:35:16,442 ATTENBOROUGH: Bite marks found on T. rex bones 716 00:35:16,466 --> 00:35:19,500 how that they may have eaten each other. 717 00:35:21,166 --> 00:35:23,742 {\an1}And a youngster would make an easy catch. 718 00:35:23,766 --> 00:35:28,309 ♪ ♪ 719 00:35:28,333 --> 00:35:29,866 (roars, snaps jaw) 720 00:35:31,500 --> 00:35:34,676 ♪ ♪ 721 00:35:34,700 --> 00:35:37,009 ATTENBOROUGH: But not this time. 722 00:35:37,033 --> 00:35:40,366 ♪ ♪ 723 00:35:42,533 --> 00:35:45,142 Very few footprints are preserved 724 00:35:45,166 --> 00:35:47,409 {\an1}as fossils in Hell Creek. 725 00:35:47,433 --> 00:35:50,809 {\an7}So if you find several in one place, as Robert has done, 726 00:35:50,833 --> 00:35:53,309 {\an8}it's a reasonable assumption that 727 00:35:53,333 --> 00:35:56,200 {\an8}there would've been many more nearby. 728 00:35:57,433 --> 00:35:59,609 MARTILL: When one dinosaur leaves a track, 729 00:35:59,633 --> 00:36:02,609 {\an1}the next one that comes along obliterates that track. 730 00:36:02,633 --> 00:36:04,742 {\an1}And eventually you end up with a ploughed field effect. 731 00:36:04,766 --> 00:36:07,309 If we think about the actual extent 732 00:36:07,333 --> 00:36:11,009 of the rock in which we're making our excavations, 733 00:36:11,033 --> 00:36:15,042 {\an1}our excavations are tiny, tiny samples. 734 00:36:15,066 --> 00:36:18,276 {\an1}So it's entirely possible there are more out there. 735 00:36:18,300 --> 00:36:21,209 ♪ ♪ 736 00:36:21,233 --> 00:36:23,109 ATTENBOROUGH: And that supports the idea... 737 00:36:23,133 --> 00:36:26,942 (dinosaur squawks) ♪ ♪ 738 00:36:26,966 --> 00:36:29,576 {\an1}...that dinosaurs and pterosaurs were thriving 739 00:36:29,600 --> 00:36:33,009 {\an1}at Hell Creek shortly before the impact. 740 00:36:33,033 --> 00:36:36,142 {\an1}(dinosaurs growl, squawk) 741 00:36:36,166 --> 00:36:38,609 {\an1}And if they were thriving... 742 00:36:38,633 --> 00:36:41,609 (pterosaur bellows) 743 00:36:41,633 --> 00:36:43,942 ATTENBOROUGH: They must have been reproducing. 744 00:36:43,966 --> 00:36:46,609 ♪ ♪ 745 00:36:46,633 --> 00:36:50,000 (snorts, growls) 746 00:36:52,500 --> 00:36:55,409 {\an8}ATTENBOROUGH: No one has ever found a T. rex's nest, 747 00:36:55,433 --> 00:36:59,509 {\an1}but fossils from similar dinosaurs showed that 748 00:36:59,533 --> 00:37:02,076 they may have laid around 20 eggs 749 00:37:02,100 --> 00:37:05,242 in a circular nest. 750 00:37:05,266 --> 00:37:10,009 ♪ ♪ 751 00:37:10,033 --> 00:37:12,376 {\an8}ATTENBOROUGH: It's possible that like crocodiles, 752 00:37:12,400 --> 00:37:16,109 {\an7}they partially covered their eggs with vegetation 753 00:37:16,133 --> 00:37:17,709 to keep them warm. 754 00:37:17,733 --> 00:37:20,000 (dinosaur snorts) 755 00:37:23,266 --> 00:37:25,842 ATTENBOROUGH: Looking after eggs must've been a tricky business 756 00:37:25,866 --> 00:37:28,233 {\an1}when you weigh seven tons. 757 00:37:29,433 --> 00:37:33,166 ♪ ♪ 758 00:37:33,700 --> 00:37:35,966 (dinosaur grunts) 759 00:37:39,900 --> 00:37:44,233 ♪ ♪ 760 00:37:45,933 --> 00:37:48,242 ATTENBOROUGH: As the team's dig continues, 761 00:37:48,266 --> 00:37:52,833 {\an1}a vision of the prehistoric world here is emerging. 762 00:37:54,166 --> 00:37:57,242 It seems the sand bank was full of life. 763 00:37:57,266 --> 00:37:59,809 T. rex, triceratops, 764 00:37:59,833 --> 00:38:01,609 {\an7}little mammals alongside 765 00:38:01,633 --> 00:38:02,676 {\an7}the footprints of other 766 00:38:02,700 --> 00:38:04,609 {\an7}dinosaurs and pterosaurs, 767 00:38:04,633 --> 00:38:07,342 {\an7}all in a very small area. 768 00:38:07,366 --> 00:38:09,009 {\an8}♪ ♪ 769 00:38:09,033 --> 00:38:11,076 (blows) You see the scales? 770 00:38:11,100 --> 00:38:12,742 {\an1}GURCHE: I do, oh, my God. 771 00:38:12,766 --> 00:38:15,909 {\an8}That excites me just looking at it. (chuckles) 772 00:38:15,933 --> 00:38:17,842 {\an8}ATTENBOROUGH: In 2019, 773 00:38:17,866 --> 00:38:21,942 {\an7}Robert finds something truly remarkable. 774 00:38:21,966 --> 00:38:24,476 {\an8}♪ ♪ 775 00:38:24,500 --> 00:38:26,242 {\an8}DEPALMA: See the cracks already forming? 776 00:38:26,266 --> 00:38:27,842 {\an8}Look at that. 777 00:38:27,866 --> 00:38:29,609 {\an7}So we're gonna have to really monitor that before we glue it. 778 00:38:29,633 --> 00:38:31,776 {\an8}'Cause this is getting vulnerable now. 779 00:38:31,800 --> 00:38:33,742 {\an8}♪ ♪ 780 00:38:33,766 --> 00:38:36,676 {\an8}ATTENBOROUGH: An almost complete creature. 781 00:38:36,700 --> 00:38:38,676 {\an1}After 66 million years, 782 00:38:38,700 --> 00:38:41,633 {\an1}finding anything intact is extremely rare. 783 00:38:43,366 --> 00:38:45,209 (speaking indistinctly) Get the consolidant, 784 00:38:45,233 --> 00:38:48,766 and to get this block out, we're freezing it. 785 00:38:52,866 --> 00:38:54,809 ATTENBOROUGH: To keep the fossil in one piece 786 00:38:54,833 --> 00:38:57,342 {\an1}as they remove it from the crumbly layer, 787 00:38:57,366 --> 00:39:01,533 {\an1}the team decides to use a potentially tricky technique. 788 00:39:04,766 --> 00:39:08,076 {\an1}They've covered the fossil in plaster to protect it. 789 00:39:08,100 --> 00:39:09,576 {\an8}Steady. 790 00:39:09,600 --> 00:39:11,542 {\an8}ATTENBOROUGH: Freeing it means they have to flash freeze 791 00:39:11,566 --> 00:39:14,100 {\an8}the crumbly rock surrounding it... 792 00:39:16,900 --> 00:39:18,409 {\an1}...using liquid nitrogen, 793 00:39:18,433 --> 00:39:22,600 {\an1}at around minus-300 degrees Fahrenheit. 794 00:39:26,733 --> 00:39:28,433 DEPALMA: Watch your footing. 795 00:39:29,500 --> 00:39:31,576 {\an8}Loren, I'm worried about brittleness here. 796 00:39:31,600 --> 00:39:33,409 {\an8}Get that hammer. 797 00:39:33,433 --> 00:39:35,076 {\an8}Give this a couple whacks with the hammer. 798 00:39:35,100 --> 00:39:36,709 {\an8}(hammer tapping) 799 00:39:36,733 --> 00:39:38,942 {\an8}Okay... move over five centimeters. 800 00:39:38,966 --> 00:39:40,633 {\an9}Good. 801 00:39:42,900 --> 00:39:44,809 {\an7}It's cracked loose. 802 00:39:44,833 --> 00:39:46,676 {\an7}Yep. Okay, it's loose. 803 00:39:46,700 --> 00:39:48,242 {\an7}So we have to get this out in one piece. 804 00:39:48,266 --> 00:39:50,109 {\an1}One... 805 00:39:50,133 --> 00:39:51,709 {\an1}two... 806 00:39:51,733 --> 00:39:52,866 {\an1}three. 807 00:39:54,033 --> 00:39:55,466 Yee-haw! 808 00:39:56,666 --> 00:39:59,776 {\an1}Total success. Total success. 809 00:39:59,800 --> 00:40:02,542 DEPALMA (voiceover): This is a technique used in archaeology 810 00:40:02,566 --> 00:40:04,642 {\an1}for digging up human remains. 811 00:40:04,666 --> 00:40:07,042 {\an1}We've got enough time to work with the fossil 812 00:40:07,066 --> 00:40:08,909 and not damage it. 813 00:40:08,933 --> 00:40:11,376 {\an1}And I couldn't be happier. 814 00:40:11,400 --> 00:40:13,476 ♪ ♪ 815 00:40:13,500 --> 00:40:16,409 ATTENBOROUGH: And the creature Robert and his team have found? 816 00:40:16,433 --> 00:40:18,309 A turtle. 817 00:40:18,333 --> 00:40:21,276 ♪ ♪ 818 00:40:21,300 --> 00:40:25,242 This is the fossil now it's been cleaned up. 819 00:40:25,266 --> 00:40:27,876 {\an1}It's lying on its side. 820 00:40:27,900 --> 00:40:31,976 {\an1}Here's the outline of its shell. 821 00:40:32,000 --> 00:40:35,042 {\an1}The shape of the shell and the sculpt edges here 822 00:40:35,066 --> 00:40:38,476 {\an1}tell us that this will was a baenid turtle. 823 00:40:38,500 --> 00:40:41,976 ♪ ♪ 824 00:40:42,000 --> 00:40:45,642 {\an1}This baenid turtle would have looked very similar 825 00:40:45,666 --> 00:40:48,076 {\an1}to modern Cooter turtles 826 00:40:48,100 --> 00:40:51,700 {\an1}and lived in the same sort of freshwater environments. 827 00:40:52,900 --> 00:40:55,009 (water splashes) 828 00:40:55,033 --> 00:40:57,076 ♪ ♪ 829 00:40:57,100 --> 00:40:59,576 BAMFORTH: The Late Cretaceous period is 830 00:40:59,600 --> 00:41:01,942 {\an1}kind of the heyday of turtles, 831 00:41:01,966 --> 00:41:04,509 {\an8}in at least northern North America. 832 00:41:04,533 --> 00:41:07,476 {\an7}There were at least 16 species 833 00:41:07,500 --> 00:41:09,409 {\an8}that were known from Saskatchewan. 834 00:41:09,433 --> 00:41:12,409 {\an1}And compare that to today, we only have three. 835 00:41:12,433 --> 00:41:16,176 {\an1}So back then, it was a much better time to be a turtle. 836 00:41:16,200 --> 00:41:19,842 ♪ ♪ 837 00:41:19,866 --> 00:41:23,209 ATTENBOROUGH: The turtle fossil Robert found is almost complete, 838 00:41:23,233 --> 00:41:26,376 so we can tell a lot about the way it died. 839 00:41:26,400 --> 00:41:28,842 {\an1}This is the underside, 840 00:41:28,866 --> 00:41:32,409 {\an1}and this brown material up here 841 00:41:32,433 --> 00:41:33,976 is fossilized wood. 842 00:41:34,000 --> 00:41:37,076 {\an1}It's the end of a stick that passes right through 843 00:41:37,100 --> 00:41:41,209 its body and comes out just here. 844 00:41:41,233 --> 00:41:43,542 {\an1}So the evidence points towards this turtle 845 00:41:43,566 --> 00:41:45,409 having been impaled. 846 00:41:45,433 --> 00:41:48,476 {\an1}Another well-preserved creature 847 00:41:48,500 --> 00:41:51,676 {\an1}amongst those found in the thick rock layer. 848 00:41:51,700 --> 00:41:55,400 ♪ ♪ 849 00:41:56,766 --> 00:41:58,976 DEPALMA: When I look at the animals and plants preserved 850 00:41:59,000 --> 00:42:02,009 {\an1}in the sediments of Tanis and the footprints beneath it, 851 00:42:02,033 --> 00:42:05,276 {\an8}I see a picture of a vibrant ecosystem, 852 00:42:05,300 --> 00:42:08,809 {\an7}many different dinosaurs, and a thriving, thriving place. 853 00:42:08,833 --> 00:42:12,376 {\an8}♪ ♪ 854 00:42:12,400 --> 00:42:16,609 {\an8}ATTENBOROUGH: Robert and his team have found so many fossils, 855 00:42:16,633 --> 00:42:18,876 {\an8}it looks as if even at the very end of 856 00:42:18,900 --> 00:42:23,109 {\an7}the Late Cretaceous, this area could have been flourishing. 857 00:42:23,133 --> 00:42:25,276 {\an8}(all bellowing) 858 00:42:25,300 --> 00:42:27,442 {\an8}ATTENBOROUGH: Full of dinosaurs and reptiles 859 00:42:27,466 --> 00:42:28,942 {\an7}that had dominated the planet 860 00:42:28,966 --> 00:42:32,809 {\an7}for more than 150 million years. 861 00:42:32,833 --> 00:42:36,642 {\an8}♪ ♪ 862 00:42:36,666 --> 00:42:40,076 {\an1}It's impossible to know how much longer the dinosaurs' reign 863 00:42:40,100 --> 00:42:41,833 {\an1}would have continued... 864 00:42:44,266 --> 00:42:46,242 (pterosaur bellows) 865 00:42:46,266 --> 00:42:48,476 {\an1}Because what happened next 866 00:42:48,500 --> 00:42:52,266 {\an1}would bring this to an end. 867 00:42:55,100 --> 00:42:58,233 ♪ ♪ 868 00:43:06,033 --> 00:43:09,600 ♪ ♪ 869 00:43:15,233 --> 00:43:18,376 {\an1}The asteroid hit the sea in an area that is now 870 00:43:18,400 --> 00:43:20,709 {\an1}the Yucatan Peninsula in Mexico. 871 00:43:20,733 --> 00:43:23,076 ♪ ♪ 872 00:43:23,100 --> 00:43:25,776 It's called the Chicxulub asteroid 873 00:43:25,800 --> 00:43:28,709 {\an1}after the town nearest to the center of its crater. 874 00:43:28,733 --> 00:43:32,433 ♪ ♪ 875 00:43:34,366 --> 00:43:36,809 Anything living within 900 miles 876 00:43:36,833 --> 00:43:39,676 {\an1}of the hit is destroyed by the blast. 877 00:43:39,700 --> 00:43:41,966 (rumbling) 878 00:43:45,166 --> 00:43:48,309 {\an1}But what effect does the impact have on Tanis, 879 00:43:48,333 --> 00:43:51,400 {\an1}nearly 2,000 miles away? 880 00:43:52,933 --> 00:43:56,042 {\an1}Is it possible to link the creatures Robert and the team 881 00:43:56,066 --> 00:43:57,576 have found so far 882 00:43:57,600 --> 00:44:00,476 {\an7}with the day of the impact? 883 00:44:00,500 --> 00:44:02,876 {\an8}BRUSATTE: When we date rocks from the Cretaceous, 884 00:44:02,900 --> 00:44:06,142 {\an7}we can say the end Cretaceous was 66 million years ago, 885 00:44:06,166 --> 00:44:09,076 {\an8}plus or minus a few tens of thousands of years. 886 00:44:09,100 --> 00:44:11,076 {\an7}That is a huge achievement of modern science. 887 00:44:11,100 --> 00:44:13,742 {\an7}However, when it comes to the asteroid, 888 00:44:13,766 --> 00:44:17,276 {\an8}that asteroid hit the Earth one day. 889 00:44:17,300 --> 00:44:18,442 (chuckles) 890 00:44:18,466 --> 00:44:20,409 And really it hit the Earth at one instant. 891 00:44:20,433 --> 00:44:23,642 {\an1}And so to date fossils in the rock and to try 892 00:44:23,666 --> 00:44:26,642 {\an1}to tie them to one instant in geological time 893 00:44:26,666 --> 00:44:28,709 that happened 66 million years ago, 894 00:44:28,733 --> 00:44:32,742 {\an1}it's just outside of the scope of the chemical methods 895 00:44:32,766 --> 00:44:36,276 {\an1}that we have to date rocks, so other evidence is needed 896 00:44:36,300 --> 00:44:40,276 {\an1}to make a plausible scenario or a plausible story 897 00:44:40,300 --> 00:44:43,176 {\an1}if somebody were to find a fossil and wanted to argue 898 00:44:43,200 --> 00:44:46,042 {\an1}that that fossil came from the very end of the Cretaceous, 899 00:44:46,066 --> 00:44:48,109 {\an1}killed by the asteroid. 900 00:44:48,133 --> 00:44:50,309 ♪ ♪ 901 00:44:50,333 --> 00:44:52,642 ATTENBOROUGH: To tie the site to the day 902 00:44:52,666 --> 00:44:55,042 the asteroid hit is a challenge. 903 00:44:55,066 --> 00:44:57,742 But Robert and his team are following 904 00:44:57,766 --> 00:45:01,009 {\an1}a compelling trail of clues, 905 00:45:01,033 --> 00:45:03,709 {\an7}the first of which lies in a jumble of fossils 906 00:45:03,733 --> 00:45:07,009 {\an7}known as a mass death assemblage. 907 00:45:07,033 --> 00:45:08,209 {\an8}DEPALMA: We've got some wood, 908 00:45:08,233 --> 00:45:09,609 {\an7}and pressed up against this 909 00:45:09,633 --> 00:45:11,376 {\an8}and all intertangled 910 00:45:11,400 --> 00:45:13,400 {\an7}we've got the carcasses of fish. 911 00:45:16,266 --> 00:45:18,009 {\an8}That's a beautifully preserved tail, 912 00:45:18,033 --> 00:45:21,109 {\an7}so that fish is gonna be absolutely gorgeous. 913 00:45:21,133 --> 00:45:23,276 {\an8}♪ ♪ 914 00:45:23,300 --> 00:45:25,842 {\an8}ATTENBOROUGH: Some of the evidence he's found so far 915 00:45:25,866 --> 00:45:28,676 {\an8}has been inside the fishes themselves. 916 00:45:28,700 --> 00:45:31,609 {\an8}♪ ♪ 917 00:45:31,633 --> 00:45:33,609 {\an8}DEPALMA: In more ways than one, it literally is an 918 00:45:33,633 --> 00:45:35,042 {\an7}operation of a Cretaceous fish, 919 00:45:35,066 --> 00:45:38,309 {\an8}so we're performing surgery on this thing. 920 00:45:38,333 --> 00:45:42,809 {\an8}ATTENBOROUGH: Robert wants to look inside this fish's skull. 921 00:45:42,833 --> 00:45:45,876 {\an8}DEPALMA: And very carefully we want to separate this 922 00:45:45,900 --> 00:45:48,942 {\an7}from the rest of the fish. 923 00:45:48,966 --> 00:45:50,542 {\an8}Okay... 924 00:45:50,566 --> 00:45:53,342 {\an8}♪ ♪ 925 00:45:53,366 --> 00:45:55,576 {\an8}Here we go. 926 00:45:55,600 --> 00:45:57,976 {\an8}Opening up the fish. 927 00:45:58,000 --> 00:46:00,566 {\an8}Got a nice ant that made a home in there. 928 00:46:01,733 --> 00:46:03,409 {\an7}And beautiful, look at that. 929 00:46:03,433 --> 00:46:04,809 {\an8}Okay, here we have 930 00:46:04,833 --> 00:46:06,442 {\an1}the gill bars of the fish. 931 00:46:06,466 --> 00:46:09,076 {\an1}Those are the bars that hold the filaments of the gills. 932 00:46:09,100 --> 00:46:11,209 {\an1}Between the gill bars, 933 00:46:11,233 --> 00:46:14,042 {\an1}all of these clusters of round objects. 934 00:46:14,066 --> 00:46:16,409 ATTENBOROUGH: Tiny round balls of clay. 935 00:46:16,433 --> 00:46:18,109 But, what are they? 936 00:46:18,133 --> 00:46:22,042 ♪ ♪ 937 00:46:22,066 --> 00:46:24,876 ATTENBOROUGH: After a large asteroid impact, 938 00:46:24,900 --> 00:46:28,309 {\an1}a mix of vaporized and molten rock is propelled 939 00:46:28,333 --> 00:46:32,476 {\an1}into the stratosphere, some of it into space. 940 00:46:32,500 --> 00:46:34,742 {\an1}There, much of it cools, 941 00:46:34,766 --> 00:46:39,476 solidifying into tiny glass droplets. 942 00:46:39,500 --> 00:46:41,176 Some of it is high enough velocity, 943 00:46:41,200 --> 00:46:44,242 {\an1}they can actually leave the Earth's gravitational field. 944 00:46:44,266 --> 00:46:46,109 {\an1}So it's almost certain 945 00:46:46,133 --> 00:46:49,176 {\an7}that some of the material ejected from Chicxulub 946 00:46:49,200 --> 00:46:51,076 {\an7}would have ended up on, on the moon, 947 00:46:51,100 --> 00:46:52,976 {\an8}which is kind of 948 00:46:53,000 --> 00:46:54,376 an exciting thing to think about. 949 00:46:54,400 --> 00:46:56,642 ♪ ♪ 950 00:46:56,666 --> 00:47:01,042 ATTENBOROUGH: But most of the droplets, known as ejecta spherules, 951 00:47:01,066 --> 00:47:06,066 {\an1}would have been pulled back to Earth by gravity. 952 00:47:07,200 --> 00:47:09,042 {\an1}Then, over millions of years, 953 00:47:09,066 --> 00:47:11,842 {\an7}pressure and chemical reactions in the ground 954 00:47:11,866 --> 00:47:15,342 {\an7}would turn most of them to clay. 955 00:47:15,366 --> 00:47:18,166 {\an1}They'd look something like this. 956 00:47:20,033 --> 00:47:22,576 {\an1}So, finding spherules in the gills of a fish, 957 00:47:22,600 --> 00:47:25,309 {\an1}as Robert has done at Tanis, 958 00:47:25,333 --> 00:47:28,076 suggests the fish sucked them in 959 00:47:28,100 --> 00:47:30,342 while the spherules were still forming. 960 00:47:30,366 --> 00:47:32,742 So these creatures could have died 961 00:47:32,766 --> 00:47:35,942 at the time of an asteroid impact. 962 00:47:35,966 --> 00:47:38,709 (pattering) 963 00:47:38,733 --> 00:47:40,742 GULICK: Those have to have come 964 00:47:40,766 --> 00:47:42,076 {\an1}from the impact event. 965 00:47:42,100 --> 00:47:44,109 You can't make spherules in other ways; 966 00:47:44,133 --> 00:47:47,576 {\an1}they're a vapor plume condensate feature. 967 00:47:47,600 --> 00:47:49,242 {\an7}That shows that these were fish 968 00:47:49,266 --> 00:47:51,509 {\an8}that were alive before the impact. 969 00:47:51,533 --> 00:47:54,076 {\an8}Those spherules arrived in the next 970 00:47:54,100 --> 00:47:55,942 {\an1}20 minutes to perhaps hour. 971 00:47:55,966 --> 00:47:58,742 {\an1}Those fish swallowed them and surely died soon afterwards. 972 00:47:58,766 --> 00:48:01,442 {\an1}So that's an absolutely amazing discovery. 973 00:48:01,466 --> 00:48:03,642 {\an7}The fact that there's spherules in the gills of the fish 974 00:48:03,666 --> 00:48:06,876 {\an7}at the Tanis site really brings them as close 975 00:48:06,900 --> 00:48:08,976 {\an7}as really you can possibly get 976 00:48:09,000 --> 00:48:11,009 to impact. 977 00:48:11,033 --> 00:48:13,142 ATTENBOROUGH: These ejecta spherules 978 00:48:13,166 --> 00:48:16,442 could be evidence of what Robert suspects... 979 00:48:16,466 --> 00:48:21,433 {\an1}that creatures here died on the day of the asteroid strike. 980 00:48:23,300 --> 00:48:26,142 Once the team begins to look for ejecta spherules, 981 00:48:26,166 --> 00:48:28,309 {\an1}they find more and more, 982 00:48:28,333 --> 00:48:30,842 {\an1}and realize the thick crumbly layer of rock 983 00:48:30,866 --> 00:48:33,300 {\an1}at Tanis is full of them. 984 00:48:36,000 --> 00:48:37,609 {\an8}DEPALMA: I mean, this stuff is... 985 00:48:37,633 --> 00:48:38,742 {\an7}oh my God, look at that one. 986 00:48:38,766 --> 00:48:42,242 {\an7}These things are just gorgeous. 987 00:48:42,266 --> 00:48:43,442 {\an8}(voiceover): Ejecta spherules like this 988 00:48:43,466 --> 00:48:44,876 {\an7}give us a fingerprint 989 00:48:44,900 --> 00:48:47,042 {\an7}of where they came from. 990 00:48:47,066 --> 00:48:48,509 {\an8}ATTENBOROUGH: If these spherules were connected 991 00:48:48,533 --> 00:48:51,509 {\an7}to the Chicxulub impact, then the whole 992 00:48:51,533 --> 00:48:53,576 crumbly layer could be full of evidence 993 00:48:53,600 --> 00:48:57,066 of what happened on the day the asteroid hit. 994 00:48:58,300 --> 00:48:59,676 {\an1}That's a good one. 995 00:48:59,700 --> 00:49:02,342 Oh, is that a droplet right there? 996 00:49:02,366 --> 00:49:04,076 ATTENBOROUGH: But to do the best analysis, 997 00:49:04,100 --> 00:49:08,609 {\an7}they need to find a spherule that hasn't turned to clay. 998 00:49:08,633 --> 00:49:11,476 DEPALMA: Oh, my God, that's a beautiful droplet. 999 00:49:11,500 --> 00:49:13,309 {\an3}Okay. 1000 00:49:13,333 --> 00:49:15,109 ATTENBOROUGH: The small pieces of orange material 1001 00:49:15,133 --> 00:49:19,476 {\an1}that Robert and Loren are digging up may be able to help. 1002 00:49:19,500 --> 00:49:21,676 They're amber. 1003 00:49:21,700 --> 00:49:23,709 ♪ ♪ 1004 00:49:23,733 --> 00:49:25,909 DEPALMA: If there was anything flying through the air at that time, 1005 00:49:25,933 --> 00:49:29,009 this is where it's gonna get caught. 1006 00:49:29,033 --> 00:49:31,809 ATTENBOROUGH: The amber they're collecting was once sticky resin 1007 00:49:31,833 --> 00:49:34,809 oozing out of a Late Cretaceous tree trunk. 1008 00:49:34,833 --> 00:49:36,642 ♪ ♪ 1009 00:49:36,666 --> 00:49:38,776 {\an7}It's a way for the tree to protect itself, 1010 00:49:38,800 --> 00:49:41,309 {\an1}like a scab forming on a cut. 1011 00:49:41,333 --> 00:49:43,609 ♪ ♪ 1012 00:49:43,633 --> 00:49:46,276 (thunder crashes) 1013 00:49:46,300 --> 00:49:48,342 {\an1}(spherules pattering) 1014 00:49:48,366 --> 00:49:51,309 ♪ ♪ 1015 00:49:51,333 --> 00:49:54,676 {\an1}Anything covered by the resin would be frozen 1016 00:49:54,700 --> 00:49:56,142 {\an7}in an amber time capsule. 1017 00:49:56,166 --> 00:49:59,300 {\an8}♪ ♪ 1018 00:50:03,500 --> 00:50:05,476 ATTENBOROUGH: A well-preserved spherule 1019 00:50:05,500 --> 00:50:08,076 can be analyzed to see if it came 1020 00:50:08,100 --> 00:50:10,742 {\an1}from the asteroid impact. 1021 00:50:10,766 --> 00:50:14,142 {\an1}Loren has found something trapped in there. 1022 00:50:14,166 --> 00:50:15,742 GURCHE: So during this batch, 1023 00:50:15,766 --> 00:50:19,676 {\an7}we were incredibly lucky that we came across two 1024 00:50:19,700 --> 00:50:21,676 {\an7}completely unaltered spherules. 1025 00:50:21,700 --> 00:50:23,609 ♪ ♪ 1026 00:50:23,633 --> 00:50:26,509 ATTENBOROUGH: Could this spherule be the evidence to link 1027 00:50:26,533 --> 00:50:31,076 {\an1}the site directly with the Chicxulub impact? 1028 00:50:31,100 --> 00:50:32,676 {\an7}There are several lines of evidence that 1029 00:50:32,700 --> 00:50:35,609 {\an7}geologists would need in order 1030 00:50:35,633 --> 00:50:37,776 {\an8}to definitively say 1031 00:50:37,800 --> 00:50:40,342 {\an1}that this ejecta and this ejecta are from the same event. 1032 00:50:40,366 --> 00:50:42,476 FLORENTIN MAURASSE: The shape of the spherules, 1033 00:50:42,500 --> 00:50:44,776 {\an1}the size of the spherules, 1034 00:50:44,800 --> 00:50:46,476 {\an7}the color of the spherules, 1035 00:50:46,500 --> 00:50:50,942 {\an7}can be similar for material coming from different sources. 1036 00:50:50,966 --> 00:50:54,176 {\an1}Only the geochemical signature would tell you exactly 1037 00:50:54,200 --> 00:50:58,276 {\an1}what the origin of the parent material was. 1038 00:50:58,300 --> 00:51:00,742 GULICK: The ability to use 1039 00:51:00,766 --> 00:51:04,642 {\an1}trace minerals as a way to diagnose the provenance, 1040 00:51:04,666 --> 00:51:06,642 {\an1}the place from which the rocks, 1041 00:51:06,666 --> 00:51:09,309 {\an1}or the particles within the rocks, originally came, 1042 00:51:09,333 --> 00:51:11,476 {\an1}it is a whole field of geology. 1043 00:51:11,500 --> 00:51:15,309 {\an1}And it's a pretty mature science at this point. 1044 00:51:15,333 --> 00:51:18,676 ATTENBOROUGH: If it's a match, Tanis could be 1045 00:51:18,700 --> 00:51:20,842 {\an1}something incredibly rare. 1046 00:51:20,866 --> 00:51:22,809 TIKOO: If we can match 1047 00:51:22,833 --> 00:51:24,609 {\an7}spherules to the impact site 1048 00:51:24,633 --> 00:51:27,676 {\an8}geochemically and in terms of radiometric ages, 1049 00:51:27,700 --> 00:51:29,642 {\an7}that's pretty accurate. 1050 00:51:29,666 --> 00:51:31,509 {\an1}That's a smoking gun. 1051 00:51:31,533 --> 00:51:34,942 ATTENBOROUGH: Does the site Robert and his team have found 1052 00:51:34,966 --> 00:51:38,009 record the very last day of the Cretaceous, 1053 00:51:38,033 --> 00:51:41,076 full of fossilized creatures that were alive 1054 00:51:41,100 --> 00:51:44,642 at the moment the asteroid hit? 1055 00:51:44,666 --> 00:51:47,376 The potential for the Tanis site is, is huge. 1056 00:51:47,400 --> 00:51:48,776 ♪ ♪ 1057 00:51:48,800 --> 00:51:50,909 ATTENBOROUGH: And might Robert's team find 1058 00:51:50,933 --> 00:51:51,910 {\an1}something extraordinary? 1059 00:51:51,934 --> 00:51:53,809 {\an1}That's bone right next to that skin. 1060 00:51:53,833 --> 00:51:56,709 ATTENBOROUGH: A dinosaur that died 1061 00:51:56,733 --> 00:51:59,509 as a direct result of the asteroid impact. 1062 00:51:59,533 --> 00:52:01,876 ♪ ♪ 1063 00:52:01,900 --> 00:52:03,176 {\an7}The day that the asteroid hit 1064 00:52:03,200 --> 00:52:05,109 {\an8}would definitely be hell on Earth. 1065 00:52:05,133 --> 00:52:07,442 TIKOO: No matter where it is, 1066 00:52:07,466 --> 00:52:09,476 {\an1}you're in for a bunch of chaos. 1067 00:52:09,500 --> 00:52:12,033 ♪ ♪ 1068 00:52:34,033 --> 00:52:37,366 ♪ ♪ 1069 00:52:47,233 --> 00:52:50,566 ♪ ♪ 1070 00:53:02,100 --> 00:53:05,600 ♪ ♪ 1071 00:53:15,466 --> 00:53:18,966 ♪ ♪