Smithsonian Science How Webinar: Explore How Dinosaurs Moved with Paleontologist Matthew Carrano
November 18, 2021
Maggy Benson:
My name is Maggy Benson. I'm a museum educator at the Smithsonian National Museum of Natural History. And my pronouns are she hers. In this week at the museum, we are celebrating all things fossils. And during today's program, you are going to be able to meet our Curator of Dinosauria and paleontologist Dr. Matthew Carrano to learn about dinosaurs and how they moved, and how he figures out how they did move. Before we meet Matt, we're just going to go over a couple of logistics about today's program. So today's webinar is a webinar, and so will you not be able to turn on your video or your microphone. But you can interact with us using the Q&A space like you are all doing right now. And there will also be polls that you can respond to during the program.
There are closed captions on this program. So just find the Zoom menu and click show subtitles to get those to show, or click the same button to turn them off. We also have ASL interpretation today that you should all be able to see. If you have any problem seeing either the closed captions or the ASL interpretation, please send us a message in the Q&A space, and one of our team members, one of our educators will help you. And thank you to all of our educators who are working behind the scenes, responding to your questions and making this program today possible. Now today's program is about dinosaur locomotion. We are going to explore how dinosaurs moved.
And the program has about four sections. First, we are going to meet our scientist, Dr. Matthew Carrano. Then he is going to help us understand a little bit more about how animals move. Then we're going to learn about how he studies movement, and then how dinosaurs moved and how scientists figure out how fast they could have moved. So throughout this program, after each one of those sections, we will pause to take your questions and we will monitor the Q&A space during today's program. Now we have a lot of people joining us today, and we usually receive hundreds if not thousands of questions. So we won't be able to get to every single one of them, but we will try our best to answer as many as we can. All right. So without any further ado, I am going to stop this share and welcome our scientist to the program. Hello, Matt. Thank you-
Matthew Carrano:
Thank you.
Maggy Benson:
... so much for joining us.
Matthew Carrano:
Hi, Maggy. Hi, everybody. Thank you for coming. It's exciting to be here.
Maggy Benson:
We are really excited to learn a little bit more about what you do as a paleontologist at the Smithsonian, and especially about your work in studying how dinosaurs moved.
Matthew Carrano:
Well, I'm excited talk to everybody. This is a topic I don't get to talk about very often. So it's fun for me. Hopefully it will be fun for all of you. Let's go ahead and share this.
Maggy Benson:
And we have a question. A couple people missed it. Where do we work? Matt and I work at the Smithsonian National Museum of Natural History which is located in Washington, D.C. But today we're both Zooming from our homes as we're working virtually.
Matthew Carrano:
Yes. I'm joining you from a picnic table in my bedroom office, hoping that we will all be able to welcome you back to the museum in the not too distant future. But for the time being here we are. And you can see me, but you can see me in the slide on the left here. This is a picture from about five years ago with several of my colleagues collecting a dinosaur skeleton in central Montana, something we also hope to get by act to doing in the future. There's a lot of them out there waiting. So we want to get back to the fun of finding, and excavating, and learning new things.
I'm now a paleontologist at the Smithsonian, but I started out like everybody else, as most of you as someone who just was interested in dinosaurs at some point. And I was a kid, I grew up in Connecticut, in a town called Branford. And in the second grade I read this book, National Geographic book on dinosaurs. And it was the most fascinating thing I'd ever seen. I got totally obsessed with dinosaurs at that age, and just kept trying to find books in the library that I could read. Anything I could get my hands on that would give me more information about dinosaurs.
And I was lucky enough that I grew up somewhere near a museum. I grew up near the Peabody Museum at Yale University, which has a nice dinosaur collection. And so I got out to go and see dinosaur skeletons, which was also an amazing experience for me. So I spent a lot of my childhood going back and forth between the museum and the library. This was the Neolithic period where there was no internet. So that was basically the only way to have an experience where you learned something about dinosaurs.
I don't have a favorite dinosaur, though after all this time you think I would. But it feels a little bit unfair to be a paleontologist with a favorite dinosaur. So I try to be treat them all equally. I have a special place, though, for Ceratosaurus just because it's an underdog dinosaur, it doesn't get all the press like a T. rex. It's on the left here and it's got this horn on its nose. And it was very exciting for me to come to work at Smithsonian because we have the original fossil of Ceratosaurus, which was a real treat to be able to work with. I found a lot of dinosaur fossils through the years. I've only found one dinosaur that I was able to help name. This animal on the right called Masiakasaurus. It's a Cretaceous dinosaur from Madagascar, and I named it.
Worked on it with a couple colleagues and we were able to realize it had this very, very bizarre set of teeth, and that it was very different from all other dinosaurs, which is the criterion for giving it a name. And I worked with Cathy Forster who is a paleontologist at George Washington University here in Washington, and Scott Sampson, who you may know from Dinosaur Train. Together we did a lot of work on this animal.
Maggy Benson:
Matt. I know-
Matthew Carrano:
Yeah. Go ahead, please.
Maggy Benson:
I was going to say, I know Masiakasaurus from Dinosaur Train. There's actually a character after this dinosaur, isn't there?
Matthew Carrano:
That's right. So my colleague decided that it deserved a little bit of spotlight time on the show so that was always fun to see, and actually was also a Jeopardy! Question once. So that was very exciting for us. A lot of times I get asked, how did you get to work at the Smithsonian, or just how did you get to actually be a paleontologist? And honestly, growing up and being a kid interested in dinosaurs, and maybe slightly obsessed with dinosaurs, I had very supportive parents and teachers.
I had good mentors, people who were able to help me learn about science, find resources, find opportunities to try science, and see if I really liked it. Obviously there's always good fortune, good luck along the way. And there's lots of hard work. I took a lot of science courses in school. A lot of science courses in college, spent six years getting a Ph.D. So there's that part of it too. But I knew I really wanted to do this, and I happened to be at the right place at the right time really, when the Smithsonian was looking for a curator of dinosaurs.
Maggy Benson:
All right. Let's take a couple of questions here. Mr. Gilmore's class wants to know, are dinosaurs descendants of birds and not lizards?
Matthew Carrano:
So birds are descendants of dinosaurs. You can think of birds as dinosaurs. I like to think of them that way, because then they're still around. And I would think of all of them as dinosaurs, lizards, other reptiles, think of them as cousins of one another. So they're all in the same animal group, like a family, but lizards and dinosaurs don't have a direct relationship. So lizards and dinosaurs went their own way many millions of years ago. They have unique qualities that the other group doesn't have. And so we know they've been distinct groups because of that for many millions of years.
Maggy Benson:
Okay. Now about you studying dinosaurs, what did you study after high school to become a paleontologist?
Matthew Carrano:
Well, the nice thing about paleontology is it has just a lot of different sub things you can do. So paleontologists use like incredible array of tools. The biggest ones, and the ones that I say are the most important to learn are geology and biology. So I studied a lot of both of those in college. But there are paleontologists who have a specialty in physics, or chemistry, or any mixing and matching of these things because there's just all sorts of really creative ways to try to get information out of fossils. And so really you want to have a good base understanding of geology and biology, but you can pick up lots of other kinds of science and use them in paleo as well.
Maggy Benson:
Okay. We'll take a couple more here. Miss Scardino Cuccinelli's class wants to know what my favorite dinosaur is. Which is an Ankylosaurus which is wild, and weird, and wonderful. And I love it. But for you, Matt, can tell us, what the Masiakasaurus ate to have such weird teeth? And that was-
Matthew Carrano:
Yeah. We have no idea. We looked at a bunch of different... We don't have any direct evidence of what the animal ate. We don't have anything preserved in the stomach area of the skeleton. It's a meat eater because we know that we can see that the teeth in the back are our typical meat eater teeth. They're curved and little serrations on them. It's the front teeth that are weird. And there are some animals today that have somewhat similar teeth where they stick forward.
And typically teeth like that are used for picking things up. So they're almost like having fingers. And so they pick stuff up with those teeth, and then they get it in the mouth and chew them. The only thing I can think of is these things are probably eating things that are small enough to be picked up and put in their mouths. So maybe little reptiles, or lizards, or frogs, or things. They're probably not eating a bigger animal, trying to bite chunks off of it because those teeth wouldn't work for that. But that's about as far as we got.
Maggy Benson:
All right. We'll do one more, and then we will move on. This is coupling two together from the Granbury Middle School, and let's see here, Greenier. What did you find interesting about dinosaurs as a kid? And how long have you been studying them?
Matthew Carrano:
As a kid I just remember thinking they were fantastic, amazing, amazing animals. That these things were possibly real. And going to the museum helped me, I think, appreciate that they were real. It wasn't like a picture of a dragon in a look or something. It was like a picture of a dragon, but then there's the skeleton of it. So that was just what was so amazing. And you always got to imagine stuff. Like the color, things we didn't know. So it was real, but there was this room to play around, and I really like that. And then I have been... So I got my Ph.D. In 1998. You're a paleontologist while you're trying to be one, but if you think about that as the start date, it's been 23 years, a long time. Doesn't feel like 23 years, but it's been 23 years since I officially became a paleontologist.
Maggy Benson:
And Matt, some of the first research that you did as a paleontologist was studying how dinosaurs may have moved.
Matthew Carrano:
Exactly.
Maggy Benson:
Which is the topic that we're going to be exploring today.
Matthew Carrano:
Yes. So-
Maggy Benson:
Where does that-
Matthew Carrano:
... let's get moving. So I'm going to talk about dinosaur locomotion, but I'm also going to talk about the broad ways that scientists think about problems like that. Like how do we understand how extinct animals move? And it gets into a very general idea, which is the idea of form and function. And form and function is something that we can use in the world today just like we could use it for extinct animals. And in a sense it's a little bit like thinking, how are living things engineered? What is the structure of the organism or the animal? And how does that allow it to do certain things, or maybe not do certain things? So I picked this antique image of different mammal skeletons which I thought it was sort of pretty. But it gives you a nice view of a big range of shapes and sizes, and therefore probably functions and lifestyles. Just by looking at the animals you can imagine just from the shape differences that they're doing different things.
If we're taking a scientific approach, we might want to pick a thing. Let's say we were interested in feeding, diet, that kind of function of an animal. Obviously you'd focus on the skull, the jaws, the teeth. Those are the most directly connected parts of the animal. If you wanted to think about things like breathing, or physiology, or stuff like that, you might look at the ribs, or what's inside them as a window into that. We're going to talk about locomotion, so the most important part of the animal is going to be the limbs, and maybe the hip and the shoulder, what we would call the girdles. And so I'm going to focus on that.
But the idea is really, we're thinking about what's the shape of things, and how does the shape relate to function. Now locomotion, I've used that word a bunch of times, it's basically anything having to do with the movement of the animal. You can think of a locomotive, it's the engine that moves the train, and that's what it does. So locomotion is a key thing. And obviously it's very important for animals in probably a bunch of different ways. And I'd be interested to see if you have some thoughts, like what movement is really going to do for an animal. Why bother? Why not be a tree?
Maggy Benson:
All right. So why would an animal move? So you can just think about this. We don't have a formal poll, but you can think about what are animals doing when they're moving? Why would they have to do this? Right. And I think we just have a gray box over your video again, Matt.
Matthew Carrano:
Oh, you know what it is? When I open a Zoom window, it covers it in the presentation. All right. I've now learned in the bug. Okay.
Maggy Benson:
Oh, there we go. Yes. We've been Zoom meetings for a very long time, but Zoom is always-
Matthew Carrano:
There's always something new that you could break.
Maggy Benson:
There really is. It's true. Okay. So we have run from predators. We have to survive, to eat. Are these some of the reasons why an animal needs to move?
Matthew Carrano:
These are top reasons why you want to move. You need to get food. Maybe you want to find your family or your herd. Maybe you want to find a mate. Somebody said predators. Yep. Other kinds of danger in your environment, you want to get away from. Maybe it's like a flood or a rainstorm. And some animals need to move.
Maggy Benson:
[crosstalk 00:17:51] shelter.
Matthew Carrano:
Yep. Shelter is important. Some animals need to move a lot. Maybe you live in a place where you have a dry season and a rainy season, and when it's the dry season, you got to go somewhere else. So migration is another one. Some animals might spend a month just moving from place to place. Let's look at this video here. So these are modern antelope, a black buck. This is something we can do in the modern world that we really, obviously, we can't do in the fossil world, which is we can really pay attention to the details of how animals move.
And as you look at this, just think about the things you might notice in this video. These animals are... I mean they look like they're having a pretty good time. I don't really know. But look how much time they spend in the air. They're just doing this enormous leap as they run. Look how far their legs go forward and back. And you can also see, let me start it again for you. Can also see how slender their legs are, how small their feet are. All of these little details of observation we can bring to try to understand what's going on with this animal when it's doing these things.
Now in living animals, helpful for us as paleontologists, some aspects of the skeleton are very closely tied to how animals move. So one example I'm going to give you in this slide is that the proportions of bones, and proportions of bones within the legs vary depending how the animal stands, or walks, or whether they climb or swim, et cetera. So on the left, these are an animal like ourselves. A human being or a bear. We stand with our heel on the ground. And so for example, if you look down here, you can see all of the foot touches the ground that we call that plantigrade.
Many, many animals however, more like dogs or cats, and they stand really just on their toes. The heel is up here. And a smaller amount of the foot touches the ground. We call that digitigrades. Stand on the digits. And then ungulates are the most extreme where they only stand on the toenail. And here's the heel way up here. Things like horses, zebras are good examples of that. And you can see in this animal the thigh bone is quite short. The foot is very, very long and slender. Whereas here the thigh bones quite long, and the foot is relatively short. All of these things we can put together and look then at how these animals move. We can look at individual bones. We could look at where the muscles are attaching all of that sort of stuff.
We could also tie together. Here's a rhino running, galloping really, and big animals still moves pretty fast. We could observe that animals will use, what we call different gates. Which is that they move their limbs in a different pattern, depending on whether they want to move fast, or slow, or accomplish different things with movement. And so on the top of this diagram you can see the rhino is frame by frame shown walking and running. Now we might look how the joints are used differently to accomplish, walk or run, or whether the limbs land in a certain pattern, and that might change. This is all the stuff we have access to in living animals. As scientists, we can capture this information now with a really sophisticated set of techniques. And I would just as a side note, most of which were not available to me when I worked on my Ph.D. 20 years ago. So it's really-
Maggy Benson:
Science is always changing.
Matthew Carrano:
It's always changing.
Maggy Benson:
A new tool is always coming.
Matthew Carrano:
It's very exciting. It is. So a technique that's actually been around for a while, you can see on the top left with the elephant, is to mark out how the limb is moving. So you get an animal to run in front of a camera. In this case, they actually painted dots on the elephant itself, and so that every frame they can digitize the position of every joint, and see what's going on at different speeds. You can see in this bottom left, there's a mole that is being filmed under an X-ray. So you can actually see the bones as they move. Hopefully it's in front of a grid of one centimeter squares, or one millimeter squares, whatever that is. And you can take that kind of information, and develop this incredible stuff. Like here's a chicken skeleton walking.
And what they've done is take X-rays of the animal walking, 3D scan the bones, and then map them onto those X-rays again. And you can get a 3D view as if the animal were invisible. The body part were invisible, and you just saw the skeleton. You get an incredible view of how that animal moves. And you could bring it all together. On the right is a bird, which on the bottom has been filmed in an X-ray, above that it's been filmed on what's called a force plate. So when the animal steps or presses down, it registers how much pressure is being given off by the limb. High speed camera work. You can look at the muscles. You can use essentially electrodes to see which muscles are being used. And you can get this very, very sophisticated view of what's going on inside this animal. If you're interested in locomotion, it's very, very exciting to be able to see it as much as we can see into living animals. But what about fossils?
Maggy Benson:
And Matt, I was just going to say, I have a big smile on my face because I'm reading the questions coming in from all of our students, and everyone is connecting the dots. And you're seeing what Matt is showing you about how scientist is studying movements and applying it to dinosaurs. We're getting some great questions connecting. If you study the bones to be able to study dinosaurs and other things. So we want to actually turn it back on you students, and ask you what can we study to learn about how dinosaurs moved? So Matt just shared a couple of things about how we study how animals move today, but what about those dinosaurs?
So you should have a poll that pops up on your screen in just a moment. And you can tell us what you think. Is it the size and shape of the bones? Is it the limb movements? Is it the footprints and trackways that dinosaurs leave behind? Is it living animals, or is it video footage of dinosaurs? So you can respond to as many as you think are correct. And we'll give you a moment to do that. (silence). All right. Well done. Everyone is still voting. We will give you about 10 more seconds. Great job. All right. We'll do a countdown now in 5, 4, 3, 2, 1, and we'll stop voting.
Matthew Carrano:
All right.
Maggy Benson:
All right. Well done everyone using the poll and responding, all of these great answers so we can all see them. Matt, I'm sure you can too, but I'll just say out loud that the top three responses were the size and the shape of bones, the limb movements, and footprints and trackways. Less responses, but still some, moving animals and video footage.
Matthew Carrano:
Yep. So if you think about living animals, then of course we can definitely use video footage and limb movement, but we don't have those four dinosaurs. So it's a limited use for that. And mostly we would look at living animals if we needed anything about live movement. And the two most important things for dinosaurs are really the things we can physically observe. So that is their skeletons, size and shape of bones, and their footprints and their trackways, which there are surprisingly lots and lots of dinosaur footprints out in the world. So it turns out to be a really valuable resource.
Maggy Benson:
All right. So we're going to pause here again and take some more of these questions because we have quite a few. Matt, while we're doing questions, I'm just going to stop your share so that folks can see you full screen here. All right. So this is a great way from Prasad that was connecting what you were sharing to dinosaurs. They want to know if dinosaurs were ungulates, the kinds of animals that walk on their toes.
Matthew Carrano:
Mm-hmm (affirmative). So interestingly, being an ungulate is pretty uncommon. We don't really have any examples of dinosaurs that are true ungulates, where they actually walk just on essentially the tip of their toes. We have a lot of dinosaurs that are what we call digitigrade, where they walk on the toes, but not the other kind. And even in mammals, it's very, very uncommon. There's mostly horses and there's a few extinct mammals that do it, but otherwise it seems to be a very, very specialized thing.
Maggy Benson:
All right. From Ms. Scardino Cuccinelli's class, how do you know what kind of dinosaur it is when you find their bones? And where do you get the bones?
Matthew Carrano:
When you find a fossil, so you have a couple of ways of interpreting it. We have an understanding of different groups of dinosaurs, and things about them that are unique. That's the most important thing. So you might say, if you like Ankylosaurus, Ankylosaurus have certain structures or shapes that only they have. So you look for that. Does it have it? That's a good clue that it might be an Ankylosaurus, and if it doesn't, it's a good clue it's not an Ankylosaurus. So either way, it's a pretty good thing to look for. But you also then want to compare it to things very specifically. So let's say, "Oh, I figured out it's a meat-eating dinosaur." Then I would maybe visit the museum and I'd say, "Okay." I'd look at it next to a T. rex, I'd look at it next to Allosaurus, does it look like one of these or does it look different?
And if I can't find anything it looks like, I might have something new. Finding dinosaurs is really, that's the trick, isn't it? There are places where we have a good handle that there are dinosaur fossils abundantly. And so you can go to these places and be pretty confident you'll find something. But it's a lot more fun to find something new. And so you tend to... You want to get your geology skills up and find the rocks of the right age, find rocks of the right type. You don't want to go looking in rocks that were lava, because there's not going to be any fossils there. You want to look in rocks that wear sediments, sedimentary rocks, lakes, ponds, rivers, that sort of thing.
And you want to go places where you can see rocks. So you don't want to go someplace where it's all covered in trees. You need to be able to have rocks exposed to the surface. And then you take a chance, you go out, and you walk around. Sometimes you walk around for a long time before you find something, and sometimes you don't find something and you try again. But a lot of time it's just being out there with your eyes looking for things.
Maggy Benson:
So this is a question tying together locomotion and diet. So Akash wants to know, does a locomotion of a dinosaur, how a dinosaur move, determine what kind of food they ate?
Matthew Carrano:
It's an interesting question. So I'll say, probably yes, but not always in ways that we can understand yet. I think one of the things we could say is that the general structure of a dinosaur certainly has a big influence on what it can eat, not just talking about teeth. So imagine, if you're a dinosaur like Stegosaurus, you're a big animal, but you're a very low to the ground. You don't have a terribly long neck or anything. You're not going to be able to eat things very high off the ground. So your range of food items is going to be limited, and that's going to constrain what you can and can't eat. Similarly, if you're a dinosaur with a huge long neck, the other way around, you might be eating things way up in the tree tops. If you could run, it means you could chase stuff. So there's going to be connections there. We can't always point to one animal and say, "Aha, this animal ate this food because of that." But speaking broadly it's probably true.
Maggy Benson:
All right. Well, we have a couple of questions that I think gets us into the next section of your presentation. Joy wants to know if there's certain living animals that make it especially useful to study dinosaurs. And Cassidy wants to know if you can tell how dinosaurs moved by their bones.
Matthew Carrano:
So yes, and yes, which I will be talking about. But I would say, the thing about dinosaurs is we have living dinosaurs so we can study birds and understand things about them. But birds have changed since they evolved from dinosaurs, so we need to try to understand what the differences are. And sometimes you can study an animal that isn't a close relative, but which has similar functions and that can still be pretty helpful. So there's a lot of options out there. I'm going to go through, shall we-
Maggy Benson:
Yeah, let's go.
Matthew Carrano:
... we start on the next topic? All right.
Maggy Benson:
Yeah.
Matthew Carrano:
So I'm going to reshare here.
Maggy Benson:
Wonderful questions, everyone. Keep them coming we're recording them and we'll get to as many as we can.
Matthew Carrano:
All right. So I'm going to just talk you through a little bit of what I did 20 years ago when I was working on my PhD, and I was interested in this topic. And I was interested very broadly, how are dinosaurs moving? How do they walk? I mean we don't have a lot of information on that. And I took the approach of looking at living animals and trying to understand what in their skeletons gave us some clues about how their limbs were moving. So I'm going to show you now a video of an elephant, and this elephant is just walking along. And what I want you to notice is, look at the leg and the thigh bone, and watch how much the thigh goes forward and back. And you can even walk around the room, because your walk is going to be very similar. Your thigh bone moves pretty far. You use your thigh a lot when you take a step. And so this-
Maggy Benson:
So you can do this even in your chair. If you pretend like you're walking in your chair, move your legs up and down, put your legs on top of your thighs between your knee and your hip, and just feel that movement. So that's similar to the-
Matthew Carrano:
And so there is-
Maggy Benson:
... elephant because we're both mammals.
Matthew Carrano:
So this big swing of the thigh bone is very typical of most mammals. And so it's very familiar to you because you're a mammal. But if you look at this chicken. Let's get that moving. The chicken doesn't do this. The thigh bone of a chicken doesn't move very much. And birds are very typical in this way, they walk almost like they're crouching all the time, and they move mostly their knee and their ankle. So it's very, very distinctive, very different. And so what you would see here is that there's not as much movement at all up here compared to what you see in the mammal. So then the question becomes, is this something that we can see in the skeleton?
Well, if we were to look at a bird. These are animals that weigh similar amounts, so the sizes are going to be somewhat comparable. So let's look at an ostrich which is a pretty heavy bird. And the thigh bone is very short, and robust. And it's because it's mostly held horizontally and the forces on it are trying to twist it. And so being robust is good to put up with that. But your thigh bone and the thigh bone of most mammal is a pretty slender bone. It tends to be held upright and it tends to bend a little bit, but not twist. And so it doesn't need to be as bulky. And if we were to take a dinosaur of a similar size and put thigh bone next to those, I think you'll see, it's not that similar to the bird, but it's proportioned more like a mammal thigh bone.
And so my inference from that was that these dinosaurs had bones built to walk in the manner of a mammal, where they were using their thighbone a lot. And not the way birds walk today, that birds had evolved that later, probably close to the time they actually evolved to be birds, but that dinosaurs weren't walking in crouches the way modern birds are walking.
Maggy Benson:
So you discovered that these dinosaurs are moving more like mammals and like us move today, by swinging that leg, rather than that crouch that bird was walking in. And we want to ask you students to make a prediction, to tell us about what kind of evidence helped Matt make that discovery. So you should have another poll that will pop up on your screen, and you have three options here. Is it the shape of the bones? Is it the proportions of those bones? You can see here, a couple different bones are lined up. Or is it the placement of their muscles? I'll give you a minute here. While you're thinking about this, I've been watching the Q&A there's a lot of questions about where the dinosaurs went, and that was an asteroid about 66 million years ago. So those who have made that prediction are correct.
Matthew Carrano:
This poll is neck and neck. It's very exciting.
Maggy Benson:
It is very exciting. We'll give you five more seconds. 5, 4, 3, 2, 1.
Matthew Carrano:
Wow.
Maggy Benson:
Look at that. We have pretty much all respond, 59%, 55%, 51% for each of these three responses. Most people think shape of the bones, and least amount of people placement and muscles. But they're all neck and neck.
Matthew Carrano:
Yeah. So the most important thing in terms of figuring out this answer was the proportions, which I guess you could think of as a shape in a way. Other things like muscle placement, and is the end of the bone round or whatever? Give us important details about movement, but haven't necessarily shown us the style of walking specifically.
Maggy Benson:
And so we have a good follow-up question here from Prasad. Does that mean dinosaurs are mammals?
Matthew Carrano:
It's a good question. No, it doesn't. And I think it's a good question because when you're talking about something like walking, or flying, or a function that's a pretty big function. Lots of organisms will do it, and they figure out how to do it independently. And so dinosaurs and mammals have come to the same style of walking independently from one another. They're not closely related. And probably what it means is that if you're a pretty, pretty big animal, and you're walking around on land, and you got gravity and all these other problems, there's not that many solutions to the, how do I walk question.
So even for birds, the biggest birds in an ostrich, it's not that big. So I think maybe it would be difficult to walk like a bird if you weighed three or four tons. You may not have any other real way of doing it. So sometimes that's an interesting observation because it gives you a clue that there are rules about stuff out there and you see different groups animals solve a problem in the same way, even though they're not closely related, sometimes it tells us, "Oh, there's some ways to do this, and there's just some ways that you can't do this, and animals are constrained sometimes."
Maggy Benson:
Great question. All right. You had something... Yeah. Let's keep thinking about what-
Matthew Carrano:
So I want-
Maggy Benson:
... that can tell us.
Matthew Carrano:
Yeah. And I wanted to go back to this old diagram here. And so let's just take a first look at these individual mammals. And I'm going to give you some basic types of locomotion, and some clues about what's a good adaptation for that. And see if you can pick out which animals might do which. So let's start with a pretty big category here, swimming. Things I'll suggest, but which you probably can imagine is if you're going to be adapted for swimming, you probably want to have flippers, or paddles, or something like that. It can be really helpful to have a nice big, flexible tail. So look at those skeletons, and any of those strike you as, maybe, a pretty good at swimming.
Maggy Benson:
Right. So you could just think about this. We're not going to do a poll, but just look at which one of those animals might be adapted to swim.
Matthew Carrano:
Yeah. [crosstalk 00:39:22].
Maggy Benson:
We are getting responses in the Q&A that suggest number one.
Matthew Carrano:
Yeah. And let's take out another one, running. Now you might think back to the antelope. Long, slender limbs, pretty small feet, stands on its toes. Those are all great adaptations for running. So any of these animals look like they might be pretty good at that?
Maggy Benson:
6, 7, 3, 2, 2, 5, 3, 4, 2, 3.
Matthew Carrano:
So two and three are probably the most well adapted for running. And keep in mind when you think about running, swimming, a lot of animals can do these things. So it's not that you can't swim and you can't run. What we're looking at are things where you're particularly good at it. Here's an unusual one. Digging. Some animals are quite specialized at this. And typically you will have big hands, almost shovel like hands, big claws on the hands, strong arms. So the arm bones will be pretty thick. Any of these things [crosstalk 00:40:39].
Maggy Benson:
So far we're having five. Yeah.
Matthew Carrano:
I see five with an exclamation point from Simon. That's a hard yes on five. Everybody loves that. Yep. Five is definitely a digger and there's-
Maggy Benson:
Lots of six too.
Matthew Carrano:
... actually one other one in here. Six. Sorry. The five was interesting. We'll get to five in a minute. So five is an animal that you would think is a digger. It's a little bit of a trick question. I apologize. Here's a mole. Number four is a mole, number six is an anteater. And these are both animals that dig. You see the big claws of the anteater. So what's going on with five here's what's going on with five. This is a sloth. And sloths have big claws, just like you would imagine in diggers. And in fact, they them on the back feet too. They have pretty sizable arms. The key here is that the arms are super skinny.
So unlike the anteater and the mole, they're not super strong arms, but they're long arms. Because if you think about what a sloth is doing, when it's climbing, essentially the arms are how it's walking from branch to branch. So the longer the arms are the more reach it gets. And so that's a typical thing of a climbing animal. Lot of primates have long, long arms, and they also then have feet that can grab things, because they want to grab both with the hands and the feet. So the sloth has a lot in common with the diggers, but it's actually gone in a different direction a little bit for this really, really specialized way of climbing.
Maggy Benson:
Yeah. And we have some observations that seven might be a climber too, but we also have-
Matthew Carrano:
Go ahead.
Maggy Benson:
But you tell us about that. Can you also tell us what each animal is? We have a couple of those.
Matthew Carrano:
Yes. So number one is a sea cow. I don't know if it's a dugong or manatee, one of the two. Number two is a sheep. Number three is a pig. Number four is a mole. Five is a sloth. Six is an anteater. And seven is a rodent. I don't know what kind. It looks a little bit squirrely. So seven I didn't label. Rodents are interesting, they are most run, scamper around a lot, and they're small so they can do a lot just because they're small. It's not hard when you're little to climb, jump, swim, et cetera. They tend not to have to bother to have these specializations that a really big animal might need. A little animal doesn't need your wrap its arm around a tree trunk because it can't. So it's small and it uses its claws. And so when you look at them, they don't look that specialized. They're all purpose animals. So I think of them as a very... A good general design.
Maggy Benson:
Okay. So what about dinosaurs? And while we move over to dinosaurs, we have gotten still lots of questions about people knowing what dinosaurs are, mammal, reptile, bird. So if you can clarify that, and [crosstalk 00:43:35].
Matthew Carrano:
So if you think about all of the big land-living animals we have. Mammals, we have things like crocodiles, lizards and snakes, turtles, and birds. Each of those is a group of animals, and they all have a common ancestor 350 million years ago. And since that time they've been evolving in separate lineages and they've acquired unique qualities that distinguish them from the others. So mammals are their own lineage, and then reptiles are a lineage. And then inside of reptiles, we have a whole bunch of separate groups. Turtles are one group, lizards and snakes are other group. And then there's a group that has crocodiles and birds and dinosaurs. Inside that group, birds and dinosaurs go together. So every time you look at a dinosaur, look at an alligator, and you think, "Oh, this thing looks prehistoric."
Its closest relative in the living world is a bird, not a lizard, not a turtle. So sometimes it's not obvious looking at them. But when we go into the anatomy in detail, you find that crocodiles have a lot of things about them that you only otherwise see in birds and dinosaurs, and you won't see in a lizard or a turtle. And we do that a lot to separate these out. We try to understand these unique features. So dinosaurs are pretty far from mammals in the evolutionary history, but because they're big land-living animals, they sometimes evolve very similar features because they're doing similar things, or did similar things.
That's a good connection to this slide here. So here's a variety, like the last slide, a variety of dinosaurs. And what I'd like you to do is just look at them, look at the legs, and see if you have any thoughts about how they might have moved. Are there dinosaurs here... Well, let's just take a look at this animal on the top right. Let's look at the limb here. You can see some features here. The foot is pretty small. The bottom of the leg from the heel to the toe is quite long. The whole thing is quite skinny. If that was a mammal like on the last slide, what would you have said about it?
Maggy Benson:
We have fast runner, runner. All right.
Matthew Carrano:
Mm-hmm (affirmative). Yeah.
Maggy Benson:
There's some observations that this animal would run.
Matthew Carrano:
Yep. So exactly. So this is a dinosaur that's probably a pretty fast dinosaur. On the other end, you have this animal, which has a super short foot here, very bulky legs. In ways resembles an elephant. So probably not a super fast runner. But most of these things is this dinosaur walking here, this dinosaur walking on its toes, walking on its tip toe, walking on it heel. If you look at most of these, they're all doing the same thing. They're all toe walkers. Dinosaurs almost always walked on their toes. And these animals are like, they're hanging out in the middle over here. They're not built like an elephant, they're not built like a runner, they're just in the middle. So they're probably can run a little bit, but they probably walk most of the time. And I've captured a lot of the variety of dinosaurs here in terms of what their limbs do. So there's some things that you're not seeing here. What kind of movements aren't on this page?
Maggy Benson:
So we have received questions about if all dinosaurs live on land? That may be a clue about what these animals are all doing and have in common. But some of the things that are missing are diggers.
Matthew Carrano:
Diggers. I see someone said. Yeah. And so none of them are flying or swimming. Exactly. Dinosaurs are all land-living animals as far as we know. Now they probably can swim, but we don't see dinosaurs that are really just only spend their lives in the water the way a sea lion, or something like that does. No climbers. It's another good one. There's no dinosaur version of a primate really. And so, yeah, dinosaurs just... For all of the different species in the amount of time that dinosaurs were on Earth, they didn't ever do certain things that mammals do. We just never have found these dinosaurs that were specialized in those ways. Now they're weird in their own ways, but in turn of how they move, dinosaurs seem to have been much less varied than mammals are today. The only flying dinosaurs we have are birds, and there's a lot of birds. But that's a pretty specialized subset and most of the dinosaurs, no, are not birds.
Maggy Benson:
Matt, we've had a couple of questions about swimming dinosaurs. Someone observed that Spinosaurus spent a lot of time in the water. And some people have asked about a group of animals that includes Plesiosaurs or those dinosaurs.
Matthew Carrano:
Right. So you have a lot of mammals at the time of... sorry, reptiles at the time of dinosaurs that are able to do these things. So Plesiosaurs, and Ichthyosaurs, and Mosasaurs. Marine reptiles permanently water dwelling. But none of those are dinosaurs themselves, they're from different lineages of reptiles. So that might be one part of the answer. Maybe there were already other animals doing these things. And so there wasn't any ability for dinosaurs to evolve into those habitats. You had pterosaurs, flying reptiles around also not dinosaurs.
And so it's possible that there was a competitive problem going on as well. Spinosaurus, sure, maybe. It's very difficult to understand what Spinosaurus is doing. I think there's just a lot of new information coming. Maybe it was most of its time in the water, would be currently the only dinosaur like that. So we can go from zero to one out of the several thousand species. So it's possible. But we're still, I think, hoping there's a lot more Spinosaurus material to see. It's a pretty puzzling animal.
Maggy Benson:
There's a lot out there for future paleontologists for studying together.
Matthew Carrano:
Absolutely. Okay.
Maggy Benson:
So Matt, we have about 10 minutes left. So let's keep moving to-
Matthew Carrano:
Let's keep moving-
Maggy Benson:
... learn a little bit about the next.
Matthew Carrano:
... to the... That's right. So another thing we can do is I'm going to show you these three mammals, and this is a movement of the limbs. And I want you to look at the way the feet are moving. And so one thing you can notice is that the feet of the animals land in certain spots. So watch this elephant, watch this front foot when the front foot leaves the ground, it's the same place where the hind foot hits the ground. That's a walk. In this cat, where the hind feet land is actually behind where the front feet, or ahead of where the front feet go. And those various patterns for the different kinds of movement will give us like on the left, a different set of footprints.
So on the left, you're seeing different gaits. And let's take a look, for example here. So if you were to walk, most of the time if you're a four-legged animal, your feet and hands would land in the same spots and you'd make footprints in this nice regular pattern. If you were trotting, there would be offset a little bit. Front foot, hind foot, front foot, hind foot. If you were bounding like the cat, your hind feet would land in front of the front feet. And so you could look at these patterns and see what the animal was doing, even though you can't actually watch the animal in the process of doing it.
And that's helpful when you have fossil footprints. So these aren't dinosaurs, but these are fossil mammals from the time of dinosaurs. This is 170 million years ago in Argentina. And these little trackways show a mammal walking along or doing something. And I want to see if I mark out the front feet and the back feet, the same one as this diagram, can you tell me which of these patterns this animal was using?
Maggy Benson:
All right. So another poll will pop up on your screen. We want you to take a look at those trackways that Matt has added some circles to in a pattern with red and green. And we want you to look at the diagram on the left of that fossil trackway. And Matt, yeah, if you could just scooch something off of your screen so we can see it. You have the options of walks, which is all the way on the left, then trots, lopes comes next with three options, and then bound, hop. Matt's magic pen catch up, or gallop. So try to match those fossil trackways from the dinosaur to the diagram at the left to figure out how this animal was moving. Well, we have a very high majority right now in one.
Matthew Carrano:
So the opposite of the last poll.
Maggy Benson:
This is.
Matthew Carrano:
This is a runaway winner.
Maggy Benson:
All right. We'll give everyone five more seconds. 5, 4, 3, 2, 1. Pencils down. All right. Well done everyone.
Matthew Carrano:
So exactly you noticed very easily that these patterns are what you're seeing in that fossil. So this is a little mammal trotting along in the sand 170 million years ago. Maybe getting away from a dinosaur, who knows. All right. So let's just take a look at a set of dinosaurs now. Now dinosaurs, most of them are two-legged animals. They're bipeds. And so they don't have all of these different patterns. They have a walk and they have a run. They probably could jump occasionally, but you won't have four legs. So you don't have the same variety.
So mostly we can get speed is really what we're interested in. This is a trackway from Connecticut. It's about 200 million years old, and it's got a bunch of different dinosaur... What we'd say is a trackway, meaning a whole series of footprints. So I want to point out two of them here. Number one and number two, the red and blue boxes. I'm going to put them side by side. And just looking at them, think about one of these is probably moving at a different speed. Moving faster than the other.
We don't have to do a Q&A just yet. I just want you to think about it. Can you just from looking, get a sense of which one you think is faster. It's important to notice that the animal number two is a bigger animal. The feet are much bigger than the animal number one. So I'm going to shrink it down, so the feet are the same size and you can compare as if they were the same sized animal. So relatively speaking is one of these things going faster than the other? And you can Q&A that, right?
Maggy Benson:
All right. A poll will pop up on your screen. Now that Matt has enlarged that trackway, take a look and tell us what you think. Which animal is moving faster? Is it the one on the left with the one above it, outlined in red? Or is it the one on the right, the animal outlined in blue? The number two. Right. So we're trying to figure out which animal was faster. Was it dinosaur one or dinosaur two? And Matt, where did these trackways come from?
Matthew Carrano:
These are from Connecticut. These are from Middlefield, Connecticut if you're from Connecticut. These are in a very tiny town park, which I've been to, an old quarry. But I think we have a pretty clear-
Maggy Benson:
I think we have a pretty clear... We'll do a three second countdown this time. 3, 2, 1. We'll close it. All right.
Matthew Carrano:
All right.
Maggy Benson:
So we have [crosstalk 00:55:45] percent of our friends said that animal on the left, the one outlined in red was faster. And the one on-
Matthew Carrano:
Yep.
Maggy Benson:
22% for blue.
Matthew Carrano:
So imagine these are two animals of the same size. This animal takes three short steps in the same distance as this animal takes one big, long step. So this animal is probably running or closer to running, and this animal is just shuffling along. So the red, number one is probably going faster. Now that's all good. But we could actually try to get speed, real speed, actual speed from a trackway, using a little bit of cleverness. And we need a few pieces of information, and I'm going to show you what they are. We need the size of the animal, we'll start with the length of the foot. We need the length of a step or a pace, which is, say, right foot to the left foot. And we need a stride which is right foot to left foot to right foot.
So these three things will help us figure out the speed. And the reason that we want to work start with foot length is we know we can get it from the trackway. And in dinosaurs, what we found is that the foot length has a somewhat regular relationship with the hip height of the animal. Even if the dinosaur long tail long neck or whatever, the leg is a certain distance off the ground, and the foot tends to have a certain size. And so you get an understanding of the length of the leg just from the length of the foot. And let's take an example. I'm going to walk you through an example, so to speak of a dinosaur trackway, and just going to show you the kinds of calculations we can do.
So this is a trackway from Spain. It's about 125 million years old, four tracks here, 1, 2, 3, 4 of a predatory dinosaur. We know we have the length of the foot, and we know we have a length of a stride that is, say, in this case left foot to the next left foot. So we have a foot length of 27 and a half centimeters. And we can calculate the hip height, as I mentioned, which in this case ends up being about 1.3 meters. So the animal stood about, the hips would be about four feet the ground. The stride length we can measure is about three meters. Now people have looked at living animals and they've looked at their trackways, and the speeds that they use to make those trackways. And they've done work with other fossil trackways and they've come up with a formula that helps us to estimate speed.
This formula will take the stride length I mentioned and the hip height I mentioned, and we can just plug them in and calculate away. So let's start with stride length, which is the 3.05 meters. We'll square that to get 9.3. We'll add hip height, the 1.3 meters, multiply that out. And we just have three numbers to multiply together, which gives us a speed of just under three meters a second. Which means nothing to you because nobody thinks about speed in meters per second, but we could turn that into something we understand. 10.7 kilometers an hour, or 6.7 miles an hour. So this is a dinosaur that walked along in 6.7 miles an hour, 125 million years ago. Not too bad.
Maggy Benson:
Not that fast, right?
Matthew Carrano:
Not that fast. Most times when we get fossils of footprint, we're getting them in places where you probably aren't going to run that much, anyway. Usually it's muddy, soft ground. We do sometimes get running animals, but it's not that common. So now I want to do this a little bit more entertainingly. If you've seen Jurassic Park, this is a pretty famous scene, you'll recognize. If you haven't, it's a pretty famous scene you'll see eventually. You'll remember when you see the movie, this is a scene where Tyrannosaurus rex is chasing several of the characters and they're fleeing in a Jeep, and trying to get away. Now I'm going to show you this clip. I'm going to tell you this clip is five and a half seconds long. And what I want you to do is watch it and tell me how many steps the T. rex takes in this video. And hopefully the sound works and you can also listen, but see what you come up with. I'm going to play it three times. Okay.
Maggy Benson:
All right.
Matthew Carrano:
How many steps?
Maggy Benson:
Okay. 8, 8. Let's see, there's still coming in. 9, 8, 12, 7, 8, 8 with a lot of exclamation points. 10, 10, 8, 9. So we're right in that zone. We're in like 7, 8, 9.
Matthew Carrano:
Good observing on most of your parts, it is in fact eight steps in the five and a half second clip. So this is great because we can figure out how long a step is in a T. rex. In this video, the T. rex is walking very fast, but it is not running. The feet are never off the ground at the same time. So it means, we know that when it takes its foot off, the other one is on the ground, we know the leg length of a T. rex because we have its skeleton. So we can figure out how big a step is between one foot and the next. And that number is 2.6 meters for a decent sized T. rex. So eight steps in five and a half seconds, that's 1.45 steps every second. We know how big a step is. So that's 3.8 meters per second, 13.6 kilometers an hour, eight and a half miles an hour.
It seems faster. Doesn't it? In the movie they make it seem like it's very, very fast. But I'll tell you eight and a half miles an hour, you might be able to outrun it. You could certainly out skateboard. It's all done with filmmaking. When the people who made this movie decided how to animate the T. rex, they went and watched animals at the zoo and they came up with this as the fastest animation that they said didn't look ridiculous. And what's interesting is this is a number that scientifically, we would say isn't that far off from the maximum speed of a T. rex. It's probably like 10 or 11 miles an hour or something like that. So they got a pretty good answer to just based on observing modern animals and a good sense of aesthetics.
Maggy Benson:
Ethan has a funny observation here, why was the Jeep driving so slow then?
Matthew Carrano:
Yeah. Exactly. Right. I always thought that Jeep was driving like 25 miles an hour.
Maggy Benson:
Yeah.
Matthew Carrano:
And in fact it's in at least... The earlier part of the scene it's in at least third gear, so there's no way it's going as...
Maggy Benson:
Oh, Matt, we lost your audio.
Matthew Carrano:
I'm back. That was a phone call. I'm sorry.
Maggy Benson:
Matt. I do want to just pause for one second and recognize that it is 2:30. So we will wrap up our summary here and just take one or two extra questions to 2:35 ish. But we do recognize that some folks may have to go. But if you sign off, when you exit the Zoom screen, a survey will pop up and if you take that, it will help us improve our programs. We look at those every single time and address your concerns. So we would love to hear what you think. So let's turn it back to you, Matt, to wrap up.
Matthew Carrano:
Okay. Let's wrap it up. Yeah. So hopefully, I've given you a window into the different ways we can think about how dinosaurs move and how we might answer questions we have about that. And one thing I wanted to say is, why do we really bother with this? I mean it's cool to know it, but is there really a good reason? And I think there are a few things scientifically that we really want to know. One is because we know birds descended from dinosaurs and they do have such an unusual way of doing what they do. We want to know where they came from. What were dinosaurs doing and how did birds get to where they are today? And also, as I mentioned, dinosaurs, many of them are bipeds.
Dinosaurs in fact are the only significant radiation of two-legged animals. Most other land-living animals walk primarily on four. And this is pretty odd. In fact, when people were first discovering and reconstructing dinosaurs, it was a challenge to reconstruct them because there were so few things in the world today that they could model on. I mean think about, what are the two-legged animals you think of? You can just put this in the Q&A. What animals do you know in the living animals that are two-legged animals? And there's one, I hope you all get.
Maggy Benson:
Human being. Well done.
Matthew Carrano:
Yeah.
Maggy Benson:
That's a good one. A chicken and ostrich.
Matthew Carrano:
Ostrich, chicken. How about, how about one that isn't a bird and isn't a human, can you think of one?
Maggy Benson:
It'd harder.
Matthew Carrano:
It is harder there aren't... Kangaroo. Perfect. Perfect.
Maggy Benson:
Well done.
Matthew Carrano:
Very few. There's a few rodents that hop on hind legs. There are very few two-legged animals out there. And so on the left here, I want to show you that little blue circle is a kangaroo, a little wallaby skeleton. The pink circle is a bird. This is Louis Dollo reconstructing Iguanodon in the 1870s. And he used these animals. He could tell Iguanodon was a biped, so he used these as models, which is part of how we got dinosaurs standing very, very high up with their tails on the ground. Kangaroos do this. They rest on their tails all the time. On the right is a reconstruction of Hadrosaurus. This is even older, still kind of kangaroo like.
But Waterhouse Hawkins who was the man making the reconstruction, he did feel like, well, the animal is going to have to rest. And he used mammals to model that. So he had this deer, and you could see the deer on the right got the same posture as the dinosaur on the left. Today we would reconstruct them very, very differently. Iguanodon here on the left. Again, mostly a biped, probably could walk around on four legs a bit. We know from trackways that dinosaurs almost never put their tails on the ground. We understand from how the bones are put together when we find complete skeletons that the backbone is pretty horizontal.
So these animals actually stand almost like a four-legged animal would stand, even though they're only using two legs. And they can do this because they have a big tail on one end, and the body on the other end, and it bounces out over the hips. So here is Edmontosaurus, a relative of Hadrosaurus in our own museum. This is how we typically reconstruct most dinosaurs, whether they're walking on two legs or four legs. And this is a huge advance over what we did 100 years ago. And that was done, with some pretty basic techniques and basic understandings of posture and locomotion. But further understanding of living animals allows us to have a much better, and a much more detailed understanding of what dinosaurs are doing. So I think we're at the point where we can go back and look at dinosaurs with this new information from the modern world, and start to understand really, really interesting details about how they worked.
Maggy Benson:
Wonderful. Matt, thank you so much for telling us why it's important to study dinosaurs and how they moved, and how you do it as a scientist here at the National Museum of Natural History. We are just going to take one or two questions. We know we're over so everyone can leave, but we do have hundreds of questions. We're sorry that we couldn't get to all of them. A poll will pop up on your screen to ask you how you liked today's program. And you will also get a survey when you exit Zoom. So if you could take those at would be excellent. But in the meantime, I'm going to just ask one or two questions. And Granbury Middle School wanted to know why do some dinosaurs walk on two legs while others walk on all fours?
Matthew Carrano:
Well, it's an interesting pattern in the evolution of dinosaurs. The first dinosaurs to evolve were two-legged animals. So all the four-legged dinosaurs transitioned over time to being four-legged animals. It's the opposite of mammals. The first mammal were four-legged, and we transitioned to being two-legged mammal. So it's totally reverse. And usually what goes on with these four-legged dinosaurs is they tend to be getting much bigger, and they tend to be herbivores. And so what we think part of the story is, is that to be a herbivore, you need a huge gut. You need a lot of space to ferment and digest plant material.
And so that is going to be in front of your hips. So it just doesn't become very helpful as a two-legged animal to have all this weight. So they tend to proceed to rely more on their hands when they walk and then they become permanent four-legged animals over time. So the horned dinosaurs, also huge heads, horned dinosaurs, Ankylosaurus, armed dinosaurs, sauropods, all become permanently four-legged animals.
Maggy Benson:
Interesting. And we had a lot of questions that we didn't get to about the coverings of dinosaurs. People wanted to know if they're covered in scales, skin, feathers, and if they are related to reptiles, if they ever shed their skin?
Matthew Carrano:
Oh, good questions. So probably dinosaurs didn't shed their skin. And the reason I say that is reptiles, really it's lizards and snakes that do the shedding in the way where all of it comes off. Crocodiles don't really do that, turtles don't really do that. They do what we do, which is it just wears off, and new skin is growing, and you're not really aware when it's happening. And dinosaurs probably did that. So dinosaurs' skin, we do get skin impressions preserved, and it's quite variable. Some dinosaurs seem to have skin it's almost like leathery. And other dinosaurs seem to have skin where there is... It's more like pebbly, bigger, coarser type of thing.
So they do have a scale pattern, but it's not like in a snake where it's big scales that overlap, it's more like bird skin, like the legs of a bird or something, or even leathery like an elephant. On top of that, some dinosaurs then had feathery filaments. Some dinosaurs had real feathers. Probably there's a lot more softer stuff that was on the surface of a dinosaur that we don't know about because it won't preserve very commonly. So we're probably underestimating just how weird dinosaurs really looked. We're seeing them a little more naked when we reconstruct them, than they probably really were.
Maggy Benson:
Excellent. Matt, can you tell our friends where they can see dinosaurs and recommendations for visiting local museums and a little bit about our Deep Time hall before we say goodbye?
Matthew Carrano:
Yes. So I always recommend if you have any opportunity to go to a museum, by all means it's nothing quite like seeing a dinosaur fossil right in front of you. And most museums now are open. We're open. So if you come to Washington, and you can come to see our exhibit. But even, small museums will often have dinosaur exhibits because they're so important and popular. So wherever you live, I would just give a look. Don't be surprised if it's your local university that has the museum. Sometimes it's in the town hall. I've been to places where like city hall had the dinosaur exhibit. So just look around, people love dinosaurs. They're often in places you don't expect, go visit.
If you come here and see our Deep Time hall, we would be very excited if you came to see our Deep Time hall. It's pretty new. We opened it in 2019. Of course it's been closed for a bunch of times, so it's still pretty new, new. We remounted almost all of our fossil skeletons. So the dinosaurs, the mammals, everything has been... They've all been conserved and put in new positions. They're all hopefully very lifelike, and show you a little bit about what I talked about. Different postures, different ways of movement, things like that.
Maggy Benson:
Excellent. And now Matt, if our friends don't go to see dinosaurs, they can still look at other animals to start thinking a little bit more about how things move, right?
Matthew Carrano:
That's a great suggestion. Honestly, anytime you have a chance to look at an animal, just think about what it's doing when it's moving around. I mean maybe it's just a bird in your yard. Maybe you're walking your dog, watching what your cat does. Or you get to go to the zoo, and just watch what they're doing, see how their legs are used. You can pick up all of these interesting details, and you suddenly start to see lots of similarities, and lots of differences. And it can be interesting once you know what you're looking for.
Maggy Benson:
Excellent. And one of our friends in the chat did suggest that you can also take a virtual tour of our Deep Time hall. That is correct. You'll get an email after-
Matthew Carrano:
Excellent.
Maggy Benson:
... this program with a link to that. And if you want to watch animals move, you can also tune into the zoo's Crittercams. We can include a link to that as well. Matt, thank you so much for teaching us about dinosaurs today, and showing us how to think like a paleontologist, and think about how these extinct animals may have moved in the past. It's been really fun.
Matthew Carrano:
It has been my pleasure. Thank you for inviting me. Thank you everyone for coming. It was really great to see you all, and to take those great questions. Lots of really, really interesting questions. So thank you for that.
Maggy Benson:
All right. Thank you all so much. And we will send an email after this program with some links to explore more, and with more information on upcoming Smithsonian Science How Programs. Thank you all so much, and we'll see you next time.
