WEBVTT 00:00:00.000 --> 00:00:03.000 Shall I ask for a show of hands 00:00:03.000 --> 00:00:05.000 or a clapping 00:00:05.000 --> 00:00:08.000 of people in different generations? 00:00:08.000 --> 00:00:10.000 I'm interested in how many 00:00:10.000 --> 00:00:12.000 are three to 12 years old. 00:00:12.000 --> 00:00:16.000 (Laughter) 00:00:16.000 --> 00:00:19.000 None, huh? 00:00:19.000 --> 00:00:21.000 All right. 00:00:21.000 --> 00:00:23.000 I'm going to talk about dinosaurs. 00:00:23.000 --> 00:00:26.000 Do you remember dinosaurs when you were that age? 00:00:26.000 --> 00:00:31.000 (Applause) 00:00:33.000 --> 00:00:36.000 Dinosaurs are kind of funny, you know. NOTE Paragraph 00:00:36.000 --> 00:00:38.000 (Laughter) NOTE Paragraph 00:00:38.000 --> 00:00:40.000 We're going to kind of go in a different direction right now. 00:00:40.000 --> 00:00:43.000 I hope you all realize that. 00:00:43.000 --> 00:00:45.000 So I'll just give you my message up front: 00:00:45.000 --> 00:00:47.000 Try not to go extinct. 00:00:47.000 --> 00:00:49.000 (Laughter) 00:00:49.000 --> 00:00:51.000 That's it. NOTE Paragraph 00:00:51.000 --> 00:00:55.000 (Laughter) NOTE Paragraph 00:00:55.000 --> 00:00:57.000 People ask me a lot -- 00:00:57.000 --> 00:01:00.000 in fact, one of the most asked questions I get 00:01:00.000 --> 00:01:04.000 is, why do children like dinosaurs so much? 00:01:04.000 --> 00:01:06.000 What's the fascination? 00:01:06.000 --> 00:01:09.000 And I usually just say, 00:01:09.000 --> 00:01:11.000 "Well dinosaurs were big, 00:01:11.000 --> 00:01:14.000 different and gone." 00:01:14.000 --> 00:01:16.000 They're all gone. 00:01:16.000 --> 00:01:18.000 Well that's not true, 00:01:18.000 --> 00:01:20.000 but we'll get to the goose in a minute. 00:01:20.000 --> 00:01:23.000 So that's sort of the theme: 00:01:23.000 --> 00:01:27.000 big, different and gone. 00:01:27.000 --> 00:01:29.000 The title of my talk: 00:01:29.000 --> 00:01:31.000 Shape-shifting Dinosaurs: 00:01:31.000 --> 00:01:33.000 The Cause of a Premature Extinction. NOTE Paragraph 00:01:33.000 --> 00:01:36.000 Now I assume that we remember dinosaurs. 00:01:36.000 --> 00:01:39.000 And there's lots of different shapes. 00:01:39.000 --> 00:01:42.000 Lots of different kinds. 00:01:42.000 --> 00:01:44.000 A long time ago, 00:01:44.000 --> 00:01:46.000 back in the early 1900s, 00:01:46.000 --> 00:01:49.000 museums were out looking for dinosaurs. 00:01:49.000 --> 00:01:52.000 They went out and gathered them up. 00:01:52.000 --> 00:01:54.000 And this is an interesting story. 00:01:54.000 --> 00:01:57.000 Every museum wanted a little bigger or better one 00:01:57.000 --> 00:01:59.000 than anybody else had. 00:01:59.000 --> 00:02:02.000 So if the museum in Toronto went out 00:02:02.000 --> 00:02:05.000 and collected a Tyrannosaur, a big one, 00:02:05.000 --> 00:02:08.000 then the museum in Ottawa wanted a bigger one 00:02:08.000 --> 00:02:10.000 and a better one. 00:02:10.000 --> 00:02:12.000 And that happened for all museums. 00:02:12.000 --> 00:02:14.000 So everyone was out looking 00:02:14.000 --> 00:02:17.000 for all these bigger and better dinosaurs. 00:02:17.000 --> 00:02:21.000 And this was in the early 1900s. NOTE Paragraph 00:02:21.000 --> 00:02:24.000 By about 1970, 00:02:24.000 --> 00:02:26.000 some scientists were sitting around 00:02:26.000 --> 00:02:29.000 and they thought, "What in the world? 00:02:29.000 --> 00:02:31.000 Look at these dinosaurs. 00:02:31.000 --> 00:02:33.000 They're all big. 00:02:33.000 --> 00:02:36.000 Where are all the little ones?" 00:02:38.000 --> 00:02:40.000 And they thought about it 00:02:40.000 --> 00:02:42.000 and they even wrote papers about it: 00:02:42.000 --> 00:02:44.000 "Where are the little dinosaurs?" 00:02:44.000 --> 00:02:49.000 (Laughter) 00:02:52.000 --> 00:02:56.000 Well, go to a museum, you'll see, 00:02:56.000 --> 00:02:59.000 see how many baby dinosaurs there are. 00:02:59.000 --> 00:03:02.000 People assumed -- and this was actually a problem -- 00:03:02.000 --> 00:03:04.000 people assumed 00:03:04.000 --> 00:03:06.000 that if they had little dinosaurs, 00:03:06.000 --> 00:03:08.000 if they had juvenile dinosaurs, 00:03:08.000 --> 00:03:10.000 they'd be easy to identify. 00:03:10.000 --> 00:03:12.000 You'd have a big dinosaur 00:03:12.000 --> 00:03:15.000 and a littler dinosaur. 00:03:15.000 --> 00:03:18.000 But all they had were big dinosaurs. NOTE Paragraph 00:03:18.000 --> 00:03:21.000 And it comes down to a couple of things. 00:03:21.000 --> 00:03:25.000 First off, scientists have egos, 00:03:25.000 --> 00:03:29.000 and scientists like to name dinosaurs. 00:03:29.000 --> 00:03:31.000 They like to name anything. 00:03:31.000 --> 00:03:34.000 Everybody likes to have their own animal that they named. 00:03:34.000 --> 00:03:37.000 (Laughter) 00:03:37.000 --> 00:03:40.000 And so every time they found something that looked a little different, 00:03:40.000 --> 00:03:43.000 they named it something different. 00:03:43.000 --> 00:03:45.000 And what happened, of course, 00:03:45.000 --> 00:03:48.000 is we ended up with a whole bunch of different dinosaurs. NOTE Paragraph 00:03:50.000 --> 00:03:53.000 In 1975, 00:03:53.000 --> 00:03:56.000 a light went on in somebody's head. 00:03:56.000 --> 00:03:58.000 Dr. Peter Dodson 00:03:58.000 --> 00:04:00.000 at the University of Pennsylvania 00:04:00.000 --> 00:04:03.000 actually realized 00:04:03.000 --> 00:04:06.000 that dinosaurs grew 00:04:06.000 --> 00:04:08.000 kind of like birds do, 00:04:08.000 --> 00:04:10.000 which is different 00:04:10.000 --> 00:04:12.000 than the way reptiles grow. 00:04:12.000 --> 00:04:14.000 And in fact, 00:04:14.000 --> 00:04:17.000 he used the cassowary as an example. 00:04:17.000 --> 00:04:20.000 And it's kind of cool -- if you look at the cassowary, 00:04:20.000 --> 00:04:23.000 or any of the birds that have crests on their heads, 00:04:23.000 --> 00:04:25.000 they actually grow 00:04:25.000 --> 00:04:27.000 to about 80 percent adult size 00:04:27.000 --> 00:04:30.000 before the crest starts to grow. 00:04:30.000 --> 00:04:33.000 Now think about that. 00:04:33.000 --> 00:04:36.000 They're basically retaining their juvenile characteristics 00:04:36.000 --> 00:04:39.000 very late in what we call ontogeny. 00:04:39.000 --> 00:04:43.000 So allometric cranial ontogeny 00:04:43.000 --> 00:04:46.000 is relative skull growth. 00:04:46.000 --> 00:04:48.000 So you can see 00:04:48.000 --> 00:04:50.000 that if you actually found one 00:04:50.000 --> 00:04:53.000 that was 80 percent grown 00:04:53.000 --> 00:04:56.000 and you didn't know that it was going to grow up to a cassowary, 00:04:56.000 --> 00:04:59.000 you would think they were two different animals. NOTE Paragraph 00:05:00.000 --> 00:05:03.000 So this was a problem, 00:05:03.000 --> 00:05:06.000 and Peter Dodson pointed this out 00:05:06.000 --> 00:05:08.000 using some duck-billed dinosaurs 00:05:08.000 --> 00:05:10.000 then called Hypacrosaurus. 00:05:10.000 --> 00:05:12.000 And he showed 00:05:12.000 --> 00:05:15.000 that if you were to take a baby and an adult 00:05:15.000 --> 00:05:18.000 and make an average of what it should look like, 00:05:18.000 --> 00:05:21.000 if it grew in sort of a linear fashion, 00:05:21.000 --> 00:05:23.000 it would have a crest 00:05:23.000 --> 00:05:26.000 about half the size of the adult. 00:05:26.000 --> 00:05:28.000 But the actual sub-adult 00:05:28.000 --> 00:05:30.000 at 65 percent 00:05:30.000 --> 00:05:32.000 had no crest at all. 00:05:32.000 --> 00:05:34.000 So this was interesting. 00:05:34.000 --> 00:05:37.000 So this is where 00:05:37.000 --> 00:05:40.000 people went astray again. 00:05:40.000 --> 00:05:42.000 I mean, if they'd have just taken that, 00:05:42.000 --> 00:05:45.000 taken Peter Dodson's work, and gone on with that, 00:05:45.000 --> 00:05:47.000 then we would have a lot less dinosaurs 00:05:47.000 --> 00:05:49.000 than we have. 00:05:49.000 --> 00:05:51.000 But scientists have egos; 00:05:51.000 --> 00:05:54.000 they like to name things. 00:05:54.000 --> 00:05:57.000 And so they went on naming dinosaurs 00:05:57.000 --> 00:06:00.000 because they were different. NOTE Paragraph 00:06:00.000 --> 00:06:02.000 Now we have a way of actually testing 00:06:02.000 --> 00:06:05.000 to see whether a dinosaur, or any animal, 00:06:05.000 --> 00:06:08.000 is a young one or an older one. 00:06:08.000 --> 00:06:11.000 And that's by actually cutting into their bones. 00:06:11.000 --> 00:06:15.000 But cutting into the bones of a dinosaur 00:06:15.000 --> 00:06:18.000 is hard to do, as you can imagine, 00:06:18.000 --> 00:06:21.000 because in museums 00:06:21.000 --> 00:06:25.000 bones are precious. 00:06:25.000 --> 00:06:28.000 You go into a museum and they take really good care of them. 00:06:28.000 --> 00:06:31.000 They put them in foam, little containers. 00:06:31.000 --> 00:06:34.000 They're very well taken care of. 00:06:35.000 --> 00:06:37.000 They don't like it if you come in 00:06:37.000 --> 00:06:39.000 and want to saw them open and look inside. 00:06:39.000 --> 00:06:41.000 (Laughter) 00:06:41.000 --> 00:06:44.000 So they don't normally let you do that. 00:06:44.000 --> 00:06:47.000 But I have a museum 00:06:47.000 --> 00:06:49.000 and I collect dinosaurs 00:06:49.000 --> 00:06:51.000 and I can saw mine open. 00:06:51.000 --> 00:06:53.000 So that's what I do. NOTE Paragraph 00:06:53.000 --> 00:06:58.000 (Applause) NOTE Paragraph 00:06:58.000 --> 00:07:03.000 So if you cut open a little dinosaur, 00:07:03.000 --> 00:07:05.000 it's very spongy inside like A. 00:07:05.000 --> 00:07:07.000 And if you cut into an older dinosaur, 00:07:07.000 --> 00:07:09.000 it's very massive. 00:07:09.000 --> 00:07:11.000 You can tell it's mature bone. 00:07:11.000 --> 00:07:14.000 So it's real easy to tell them apart. 00:07:14.000 --> 00:07:16.000 So what I want to do 00:07:16.000 --> 00:07:18.000 is show you these. 00:07:18.000 --> 00:07:22.000 In North America in the Northern Plains of the United States 00:07:22.000 --> 00:07:26.000 and the Southern Plains of Alberta and Saskatchewan, 00:07:26.000 --> 00:07:29.000 there's this unit of rock called the Hell Creek Formation 00:07:29.000 --> 00:07:32.000 that produces the last dinosaurs that lived on Earth. 00:07:32.000 --> 00:07:34.000 And there are 12 of them 00:07:34.000 --> 00:07:36.000 that everyone recognizes -- 00:07:36.000 --> 00:07:38.000 I mean the 12 primary dinosaurs 00:07:38.000 --> 00:07:40.000 that went extinct. 00:07:40.000 --> 00:07:43.000 And so we will evaluate them. 00:07:43.000 --> 00:07:45.000 And that's sort of what I've been doing. 00:07:45.000 --> 00:07:48.000 So my students, my staff, 00:07:48.000 --> 00:07:51.000 we've been cutting them open. 00:07:51.000 --> 00:07:53.000 Now as you can imagine, 00:07:53.000 --> 00:07:55.000 cutting open a leg bone is one thing, 00:07:55.000 --> 00:07:58.000 but when you go to a museum 00:07:58.000 --> 00:08:00.000 and say, "You don't mind if I cut open 00:08:00.000 --> 00:08:03.000 your dinosaur's skull do you?" 00:08:03.000 --> 00:08:06.000 they say, "Go away." 00:08:06.000 --> 00:08:11.000 (Laughter) 00:08:11.000 --> 00:08:15.000 So here are 12 dinosaurs. 00:08:15.000 --> 00:08:18.000 And we want to look at these three first. NOTE Paragraph 00:08:18.000 --> 00:08:21.000 So these are dinosaurs that are called Pachycephalosaurs. 00:08:21.000 --> 00:08:23.000 And everybody knows 00:08:23.000 --> 00:08:25.000 that these three animals are related. 00:08:25.000 --> 00:08:27.000 And the assumption is 00:08:27.000 --> 00:08:29.000 is that they're related 00:08:29.000 --> 00:08:32.000 like cousins or whatever. 00:08:32.000 --> 00:08:34.000 But no one ever considered 00:08:34.000 --> 00:08:37.000 that they might be more closely related. 00:08:37.000 --> 00:08:39.000 In other words, 00:08:39.000 --> 00:08:42.000 people looked at them and they saw the differences. 00:08:42.000 --> 00:08:44.000 And you all know 00:08:44.000 --> 00:08:46.000 that if you are going to determine 00:08:46.000 --> 00:08:48.000 whether you're related to your brother or your sister, 00:08:48.000 --> 00:08:52.000 you can't do it by looking at differences. 00:08:52.000 --> 00:08:54.000 You can only determine relatedness 00:08:54.000 --> 00:08:56.000 by looking for similarities. NOTE Paragraph 00:08:56.000 --> 00:08:58.000 So people were looking at these 00:08:58.000 --> 00:09:00.000 and they were talking about how different they are. 00:09:00.000 --> 00:09:03.000 Pachycephalosaurus has a big, thick dome on its head, 00:09:03.000 --> 00:09:06.000 and it's got some little bumps on the back of its head, 00:09:06.000 --> 00:09:10.000 and it's got a bunch of gnarly things on the end of its nose. 00:09:10.000 --> 00:09:12.000 And then Stygimoloch, another dinosaur 00:09:12.000 --> 00:09:16.000 from the same age, lived at the same time, 00:09:16.000 --> 00:09:18.000 has spikes sticking out the back of its head. 00:09:18.000 --> 00:09:20.000 It's got a little, tiny dome, 00:09:20.000 --> 00:09:24.000 and it's got a bunch of gnarly stuff on its nose. 00:09:24.000 --> 00:09:26.000 And then there's this thing called Dracorex, 00:09:26.000 --> 00:09:28.000 Hogwart's Eye. 00:09:28.000 --> 00:09:31.000 Guess where that came from? Dragon. 00:09:31.000 --> 00:09:33.000 So here's a dinosaur 00:09:33.000 --> 00:09:36.000 that has spikes sticking out of its head, no dome 00:09:36.000 --> 00:09:39.000 and gnarly stuff on its nose. NOTE Paragraph 00:09:39.000 --> 00:09:42.000 Nobody noticed the gnarly stuff sort of looked alike. 00:09:42.000 --> 00:09:44.000 But they did look at these three 00:09:44.000 --> 00:09:46.000 and they said, "These are three different dinosaurs, 00:09:46.000 --> 00:09:49.000 and Dracorex is probably the most primitive of them. 00:09:49.000 --> 00:09:52.000 And the other one is more primitive than the other. 00:09:52.000 --> 00:09:55.000 It's unclear to me 00:09:55.000 --> 00:09:58.000 how they actually sorted these three of them out. 00:09:58.000 --> 00:10:00.000 But if you line them up, 00:10:00.000 --> 00:10:03.000 if you just take those three skulls and just line them up, 00:10:03.000 --> 00:10:05.000 they line up like this. 00:10:05.000 --> 00:10:07.000 Dracorex is the littlest one, 00:10:07.000 --> 00:10:09.000 Stygimoloch is the middle size one, 00:10:09.000 --> 00:10:12.000 Pachycephalosaurus is the largest one. 00:10:12.000 --> 00:10:14.000 And one would think, 00:10:14.000 --> 00:10:16.000 that should give me a clue. 00:10:16.000 --> 00:10:18.000 (Laughter) 00:10:18.000 --> 00:10:21.000 But it didn't give them a clue. 00:10:21.000 --> 00:10:24.000 Because, well we know why. 00:10:24.000 --> 00:10:27.000 Scientists like to name things. NOTE Paragraph 00:10:27.000 --> 00:10:29.000 So if we cut open 00:10:29.000 --> 00:10:31.000 Dracorex -- 00:10:31.000 --> 00:10:33.000 I cut open our Dracorex -- 00:10:33.000 --> 00:10:35.000 and look, it was spongy inside, 00:10:35.000 --> 00:10:37.000 really spongy inside. 00:10:37.000 --> 00:10:39.000 I mean, it is a juvenile 00:10:39.000 --> 00:10:41.000 and it's growing really fast. 00:10:41.000 --> 00:10:43.000 So it is going to get bigger. 00:10:43.000 --> 00:10:45.000 If you cut open Stygimoloch, 00:10:45.000 --> 00:10:47.000 it is doing the same thing. 00:10:47.000 --> 00:10:49.000 The dome, that little dome, 00:10:49.000 --> 00:10:51.000 is growing really fast. 00:10:51.000 --> 00:10:53.000 It's inflating very fast. 00:10:53.000 --> 00:10:56.000 What's interesting is the spike on the back of the Dracorex 00:10:56.000 --> 00:10:58.000 was growing very fast as well. 00:10:58.000 --> 00:11:00.000 The spikes on the back of the Stygimoloch 00:11:00.000 --> 00:11:02.000 are actually resorbing, 00:11:02.000 --> 00:11:04.000 which means they're getting smaller 00:11:04.000 --> 00:11:06.000 as that dome is getting bigger. 00:11:06.000 --> 00:11:09.000 And if we look at Pachycephalosaurus, 00:11:09.000 --> 00:11:12.000 Pachycephalosaurus has a solid dome 00:11:12.000 --> 00:11:15.000 and its little bumps on the back of its head 00:11:15.000 --> 00:11:17.000 were also resorbing. NOTE Paragraph 00:11:17.000 --> 00:11:19.000 So just with these three dinosaurs, 00:11:19.000 --> 00:11:21.000 you can easily -- as a scientist -- 00:11:21.000 --> 00:11:23.000 we can easily hypothesize 00:11:23.000 --> 00:11:25.000 that it is just a growth series 00:11:25.000 --> 00:11:28.000 of the same animal. 00:11:28.000 --> 00:11:31.000 Which of course means 00:11:31.000 --> 00:11:35.000 that Stygimoloch and Dracorex 00:11:35.000 --> 00:11:37.000 are extinct. 00:11:37.000 --> 00:11:42.000 (Laughter) 00:11:42.000 --> 00:11:44.000 Okay. 00:11:46.000 --> 00:11:49.000 Which of course means 00:11:49.000 --> 00:11:53.000 we have 10 primary dinosaurs to deal with. NOTE Paragraph 00:11:53.000 --> 00:11:55.000 So a colleague of mine at Berkley, 00:11:55.000 --> 00:11:58.000 he and I were looking at Triceratops. 00:11:58.000 --> 00:12:00.000 And before the year 2000 -- 00:12:00.000 --> 00:12:02.000 now remember, 00:12:02.000 --> 00:12:04.000 Triceratops was first found in the 1800s -- 00:12:04.000 --> 00:12:07.000 before 2000, no one had ever seen 00:12:07.000 --> 00:12:10.000 a juvenile Triceratops. 00:12:10.000 --> 00:12:13.000 There's a Triceratops in every museum in the world, 00:12:13.000 --> 00:12:17.000 but no one had ever collected a juvenile. 00:12:17.000 --> 00:12:19.000 And we know why, right? 00:12:19.000 --> 00:12:22.000 Because everybody wants to have a big one. 00:12:22.000 --> 00:12:24.000 So everyone had a big one. 00:12:24.000 --> 00:12:26.000 So we went out and collected a whole bunch of stuff 00:12:26.000 --> 00:12:28.000 and we found a whole bunch of little ones. 00:12:28.000 --> 00:12:32.000 They're everywhere. They're all over the place. 00:12:32.000 --> 00:12:34.000 So we have a whole bunch of them at our museum. 00:12:34.000 --> 00:12:39.000 (Laughter) 00:12:39.000 --> 00:12:41.000 And everybody says it's because I have a little museum. 00:12:41.000 --> 00:12:44.000 When you have a little museum, you have little dinosaurs. NOTE Paragraph 00:12:44.000 --> 00:12:47.000 (Laughter) NOTE Paragraph 00:12:47.000 --> 00:12:49.000 If you look at the Triceratops, 00:12:49.000 --> 00:12:51.000 you can see it's changing, it's shape-shifting. 00:12:51.000 --> 00:12:53.000 As the juveniles are growing up, 00:12:53.000 --> 00:12:55.000 their horns actually curve backwards. 00:12:55.000 --> 00:12:57.000 And then as they grow older, 00:12:57.000 --> 00:12:59.000 the horns grow forward. 00:12:59.000 --> 00:13:01.000 And that's pretty cool. 00:13:01.000 --> 00:13:03.000 If you look along the edge of the frill, 00:13:03.000 --> 00:13:06.000 they have these little triangular bones 00:13:06.000 --> 00:13:08.000 that actually grow big as triangles 00:13:08.000 --> 00:13:11.000 and then they flatten against the frill 00:13:11.000 --> 00:13:13.000 pretty much like the spikes do 00:13:13.000 --> 00:13:16.000 on the Pachycephalosaurs. 00:13:16.000 --> 00:13:20.000 And then, because the juveniles are in my collection, 00:13:20.000 --> 00:13:22.000 I cut them open 00:13:22.000 --> 00:13:24.000 and look inside. 00:13:24.000 --> 00:13:27.000 And the little one is really spongy. 00:13:27.000 --> 00:13:30.000 And the middle size one is really spongy. 00:13:30.000 --> 00:13:32.000 But what was interesting 00:13:32.000 --> 00:13:34.000 was the adult Triceratops was also spongy. 00:13:34.000 --> 00:13:37.000 And this is a skull that is two meters long. 00:13:37.000 --> 00:13:40.000 It's a big skull. NOTE Paragraph 00:13:40.000 --> 00:13:42.000 But there's another dinosaur 00:13:42.000 --> 00:13:45.000 that is found in this formation 00:13:45.000 --> 00:13:48.000 that looks like a Triceratops, except it's bigger, 00:13:48.000 --> 00:13:51.000 and it's called Torosaurus. 00:13:51.000 --> 00:13:54.000 And Torosaurus, when we cut into it, 00:13:54.000 --> 00:13:56.000 has mature bone. 00:13:56.000 --> 00:13:58.000 But it's got these big holes in its shield. 00:13:58.000 --> 00:14:01.000 And everybody says, "A Triceratops and a Torosaurus 00:14:01.000 --> 00:14:03.000 can't possibly be the same animal 00:14:03.000 --> 00:14:05.000 because one of them's bigger than the other one." 00:14:05.000 --> 00:14:10.000 (Laughter) 00:14:10.000 --> 00:14:12.000 "And it has holes in its frill." 00:14:12.000 --> 00:14:15.000 And I said, "Well do we have any juvenile Torosauruses?" 00:14:15.000 --> 00:14:18.000 And they said, "Well no, 00:14:18.000 --> 00:14:21.000 but it has holes in its frill." NOTE Paragraph 00:14:21.000 --> 00:14:24.000 So one of my graduate students, John Scannella, 00:14:24.000 --> 00:14:26.000 looked through our whole collection 00:14:26.000 --> 00:14:28.000 and he actually discovered 00:14:28.000 --> 00:14:30.000 that the hole starting to form 00:14:30.000 --> 00:14:32.000 in Triceratops 00:14:32.000 --> 00:14:35.000 and, of course it's open, in Torosaurus -- 00:14:35.000 --> 00:14:38.000 so he found the transitional ones 00:14:38.000 --> 00:14:40.000 between Triceratops and Torosaurus, 00:14:40.000 --> 00:14:42.000 which was pretty cool. 00:14:42.000 --> 00:14:44.000 So now we know 00:14:44.000 --> 00:14:46.000 that Torosaurus 00:14:46.000 --> 00:14:49.000 is actually a grownup Triceratops. 00:14:49.000 --> 00:14:51.000 Now when we name dinosaurs, 00:14:51.000 --> 00:14:53.000 when we name anything, 00:14:53.000 --> 00:14:55.000 the original name gets to stick 00:14:55.000 --> 00:14:59.000 and the second name is thrown out. 00:14:59.000 --> 00:15:02.000 So Torosaurus is extinct. 00:15:02.000 --> 00:15:05.000 Triceratops, if you've heard the news, 00:15:05.000 --> 00:15:07.000 a lot of the newscasters got it all wrong. 00:15:07.000 --> 00:15:10.000 They thought Torosaurus should be kept and Triceratops thrown out, 00:15:10.000 --> 00:15:12.000 but that's not going to happen. NOTE Paragraph 00:15:12.000 --> 00:15:17.000 (Laughter) NOTE Paragraph 00:15:18.000 --> 00:15:21.000 All right, so we can do this with a bunch of dinosaurs. 00:15:21.000 --> 00:15:23.000 I mean, here's Edmontosaurus 00:15:23.000 --> 00:15:25.000 and Anatotitan. 00:15:25.000 --> 00:15:28.000 Anatotitan: giant duck. 00:15:28.000 --> 00:15:30.000 It's a giant duck-bill dinosaur. 00:15:30.000 --> 00:15:32.000 Here's another one. 00:15:32.000 --> 00:15:34.000 So we look at the bone histology. 00:15:34.000 --> 00:15:37.000 The bone histology tells us 00:15:37.000 --> 00:15:39.000 that Edmontosaurus is a juvenile, 00:15:39.000 --> 00:15:41.000 or at least a sub-adult, 00:15:41.000 --> 00:15:44.000 and the other one is an adult 00:15:44.000 --> 00:15:47.000 and we have an ontogeny. 00:15:47.000 --> 00:15:50.000 And we get rid of Anatotitan. NOTE Paragraph 00:15:50.000 --> 00:15:53.000 So we can just keep doing this. 00:15:53.000 --> 00:15:55.000 And the last one 00:15:55.000 --> 00:15:57.000 is T. Rex. 00:15:57.000 --> 00:15:59.000 So there's these two dinosaurs, 00:15:59.000 --> 00:16:02.000 T. Rex and Nanotyrannus. 00:16:02.000 --> 00:16:04.000 (Laughter) 00:16:04.000 --> 00:16:07.000 Again, makes you wonder. 00:16:07.000 --> 00:16:10.000 (Laughter) 00:16:10.000 --> 00:16:12.000 But they had a good question. 00:16:12.000 --> 00:16:14.000 They were looking at them 00:16:14.000 --> 00:16:17.000 and they said, "One's got 17 teeth, and the biggest one's got 12 teeth. 00:16:17.000 --> 00:16:19.000 And that doesn't make any sense at all, 00:16:19.000 --> 00:16:21.000 because we don't know of any dinosaurs 00:16:21.000 --> 00:16:23.000 that gain teeth as they get older. 00:16:23.000 --> 00:16:25.000 So it must be true -- 00:16:25.000 --> 00:16:28.000 they must be different." 00:16:28.000 --> 00:16:30.000 So we cut into them. 00:16:30.000 --> 00:16:32.000 And sure enough, 00:16:32.000 --> 00:16:35.000 Nanotyrannus has juvenile bone 00:16:35.000 --> 00:16:38.000 and the bigger one has more mature bone. 00:16:38.000 --> 00:16:41.000 It looks like it could still get bigger. 00:16:41.000 --> 00:16:43.000 And at the Museum of the Rockies where we work, 00:16:43.000 --> 00:16:45.000 I have four T. Rexes, 00:16:45.000 --> 00:16:47.000 so I can cut a whole bunch of them. 00:16:47.000 --> 00:16:50.000 But I didn't have to cut any of them really, 00:16:50.000 --> 00:16:53.000 because I just lined up their jaws 00:16:53.000 --> 00:16:56.000 and it turned out the biggest one had 12 teeth 00:16:56.000 --> 00:16:58.000 and the next smallest one had 13 00:16:58.000 --> 00:17:00.000 and the next smallest had 14. 00:17:00.000 --> 00:17:02.000 And of course, Nano has 17. 00:17:02.000 --> 00:17:05.000 And we just went out and looked at other people's collections 00:17:05.000 --> 00:17:09.000 and we found one that has sort of 15 teeth. 00:17:09.000 --> 00:17:12.000 So again, real easy to say 00:17:12.000 --> 00:17:14.000 that Tyrannosaurus ontogeny 00:17:14.000 --> 00:17:17.000 included Nanotyrannus, 00:17:17.000 --> 00:17:22.000 and therefore we can take out another dinosaur. NOTE Paragraph 00:17:22.000 --> 00:17:24.000 (Laughter) NOTE Paragraph 00:17:24.000 --> 00:17:28.000 So when it comes down 00:17:28.000 --> 00:17:30.000 to our end cretaceous, 00:17:30.000 --> 00:17:33.000 we have seven left. 00:17:33.000 --> 00:17:36.000 And that's a good number. 00:17:36.000 --> 00:17:39.000 That's a good number to go extinct, I think. 00:17:39.000 --> 00:17:41.000 Now as you can imagine, 00:17:41.000 --> 00:17:44.000 this is not very popular with fourth-graders. 00:17:44.000 --> 00:17:46.000 Fourth-graders love their dinosaurs, 00:17:46.000 --> 00:17:49.000 they memorize them. 00:17:51.000 --> 00:17:54.000 And they're not happy with this. NOTE Paragraph 00:17:54.000 --> 00:17:56.000 (Laughter) NOTE Paragraph 00:17:56.000 --> 00:17:58.000 Thank you very much. NOTE Paragraph 00:17:58.000 --> 00:18:01.000 (Applause)