Episode 11: Dinosaur Biomechanics | John Hutchinson

Hello everyone. Welcome to Boom. Welcome to Boom. I'm Melissa. And I'm Hannah. And it's December Melissa. Do you know what that means? No. I'm not sure that I do. It means it's dinosaur time. Dinosaur December. Yeah. Dino December. Welcome to Boom. We have five Hannah sands. Boom. Boom. Boom. Boom. Boom. Boom. Boom. Boom. Boom. Boom. Boom. Boom. Boom. Boom. Do you know where the word dinosaur comes from? No. Dinosus. Is it Latin? It comes from the Greek language and it means terrible lizard. Apparently it was coined by English paleontologist Richard Owen in 1842. And it was meant to reference their impressive size rather than their scary appearance. So terrible isn't like their terrible things. No. It's like they're they're terribly large. Yeah. I would not want to be face to face. Today on the episode we talk with Professor John Hutchinson on dinosaur biomechanics and the evolution of dinosaur biomechanics. But first we are going to give you a bit of boom on dinosaurs. So even though we're going to hear a lot about dinosaur biomechanics on today's episode, one thing we'd like to tell you about is something that John Hutchinson our guest talks about in researchers. And that's how animals can use their muscles to do certain activities and determining how much actual muscle mass they need to do these activities. So while most mammals depend on muscles, actually small animals face problems because muscle power alone can't account for the the power that they need to generate. So their muscles are to like their animals are so small that their muscles are too small to generate enough power. Right. Like they can't get muscles big enough inside of their bodies. Oh interesting. So how do they make up for that? Yeah. So they're actually able to use their usually somewhat flexible structures in their bodies. Sort of like springs that they can cock and release. Kind of like an archer does when they pull back on a bow. And this spring enables the small animal to actually store energy slowly and then release it all in one go. And this amplifies its power. And this is especially useful as like when they're running for example because their legs are so small and in contact with the ground for only brief moments during each step. Yeah. So that really constrains how much energy each stride can release. But if they can use these cocking structures, for example, then they can kind of store up their energy and then release it all in one go. So they can sort of spring into action. Yeah. What? And do you know what animals do that? Yeah. There's lots of a lot of insects insects do this. You can imagine they sort of have these flexible exoskeletons that right. Yeah. That makes sense. Or outside their bodies. And then specific ones like frog hoppers are really amazing jumpers. Apparently the energy stored in their exoskeleton can generate as much as 65,000 watts per kilogram of body mass. So that's pretty impressive. That's pretty impressive. Very cool. We also have an interesting bit from National Geographic about Mr. Stubbs who was an American alligator that actually lost his tail several years ago while he was being transported illegally by a group of animal traffickers. So it starts off as a pretty sad story. He was brought to the Phoenix Herpetological Society and he was fitted with a prosthetic tail. But the one that he was fitted with was just a cast of another alligator's tail. So it didn't fit very well. And then he grew out of it and then they tried other prosthetics. But then he grew out of those as well. But then eventually Justin Georgi who is an associate professor of anatomy at Midwestern University in Galen Dale Arizona and his master's student decided to try to make a functional, like better fitting tail for Mr. Stubbs. And they were able to collaborate with stacks 3D to use a 3D scanner and create a specialized appendage for the gator. And if you look at the article, it has this really awesome photo of the alligator with his new fitted tail with the motion capture markers so they can see how well he moves with the tail. It's been really neat because I think he went into the zoo now and people have really connected with Mr. Stubbs and they've told Georgi that seeing the alligator with his new tail has actually made them more comfortable with their own prosthetic. Wow, that's awesome. What an awesome translation from the animal world to human. Yeah, yeah, exactly. Hey, Melissa, one here, dinosaur joke. Yeah, let's hear dinosaur joke. Okay. Why can't you hear a tarot actal going to the bathroom? I think I've heard this before. Is it because the pee is silent? You'd think that, but it's actually because they're extinct. You make a good point. Thanks, Anna. All right. So let's jump into our interview with John. So hello, boom. We're here today with our guest professor, John Hutchinson, who is an evolutionary biomechanist at the Royal Veterinary College in the University of London. It's actually four o'clock his time and right and early for us to see it here. So we're happy to be here. Thanks for talking with us today. So tell us about dinosaur biomechanics. How did you get started in this field? Well, you know, roundabout kind of way. I am an undergraduate. I was originally studying marine biology of invertebrates and then took some classes that dealt with biomechanics and kind of like them. And then I read the novel Jurassic Park and saw the film and started taking paleontology classes and got into that and went to a scientific conference where some people were presenting biomechanics research using like computer modeling to study cockroaches. And I thought, well, why couldn't you build a computer model of the dinosaur and kind of see whether the computer animations in Jurassic Park were realistic using physics. And they really like that idea. So I said, come do a PhD at Berkeley and that turned out to be my PhD project, studying T-Rex with biomechanics. Wow. Did you find that the Jurassic Park T-Rex biomechanics were accurate? Well, that's a bit of a long story. I mean, I could explain the T-Rex study from my PhD first and that ties right into the Jurassic Park thing in a funny kind of way. Can I go ahead? Yeah, please. Okay, well, from my PhD, I spent a lot of time trying to figure out from the bones of living animals and then fossil animals where muscles attached because it turns out they attach in pretty conservative places, whether you're a bird or a crocodile or a lizard and most of the changes tend to be in the sizes of muscles for the few exceptions. So I was able to figure out how to reconstruct the muscles of an extinct dinosaur like a T-Rex in terms of physicians and even to a certain degree in terms of sizes, relatively speaking. And that allowed me to build a really simple two-dimensional biomechanical model of a T-Rex with like masses and centers of mass and moment arms of muscles and a simple program with an engineer helping me in MATLAB software. This is a 2D simulation. Yeah, I think it's generous to call it a simulation. It was a very simple equation. It was just basic first year undergraduate statics, really. A free body diagram of T-Rex frozen at mid-step to calculate the torques at different joints, the moments around every joint and then how much muscle would be required based on the moment arm of the muscle and kind of an estimate of cross-sexual area, how much muscle would be required to balance the moment of gravity or ground reaction force, especially at fast running speeds. Ultimately, the model tested how much muscle would T-Rex need to run really, really quickly, like 40 miles an hour as some paleontologists had speculated. And I found that it would be really ridiculous amounts of muscle like more than any animal has ever had. in terms of relative musculature. You need to be more muscular than an ostrich. An ostrich is the most muscular animal we know of in terms of percent body mass. They're really adapted to be very muscily if you think of an ostrich. It's almost all legs in terms of, in terms of mass. They've gotten rid of the wings and the tail and most of the head and so forth. Whereas a T-Rex had a lot of other stuff, especially a big head and neck and a big torso. I didn't have much potential to have tons of muscle mass so I rolled out fast running and did a sensitivity analysis to see, well, are there all these unknowns that go into the model? How much does what we don't know really matter? Or testing how it could have moved and found that, all right, well yeah, it could walk. It could maybe run slowly, maybe like 10, 15 miles per hour or five meters a second or so. Maybe even if you really give it generous assumptions, the model might support 11 meters a second or 25 miles per hour, which isn't bad for a sick time animal. But there's no way we could find a set of assumptions that will allow it to go 40 miles an hour. So we ruled that out and very importantly, applied the same model to a bunch of living and extinct animals to see if it really worked, like validated the model. Using animals where we know that they can or cannot run and the model gave the right answers for those animals. Whereas T-Rex, we don't really know the answer but I think we got from my research. That actually, and from my PhD to my postdoc at Stanford, I was in the mechanical engineering at Stanford as a postdoc for two years and finished up and published it while I was a postdoc. - Well, in the meantime, I got in touch with animators at Industrial Light and Magic who made Jurassic Park movies. They got me to come over to San Rafael, California and give, well, kind of do a day of consulting with them while they were finishing up a Jurassic Park shoot, which one was it? This Jurassic Park three, wasn't it? Yeah, it was Jurassic Park three. - Pretty sure, man. - That's a long, I'm starting to flip off. But anyway, I got to talk with them and one of the main animators said, "Yeah, we had the T-Rex going 50 miles an hour at first when we animated it in a very first Jurassic Park, but it looked ridiculous. It looked like the roadrunner going off a cliff with its legs cycling so fast. I don't know what would believe it, so we actually slowed it down and it was never going more than 15 to 20 miles per hour. And if you watch the Jeep chase scene, that T-Rex never leaves the ground with both feet. In fact, its stride frequency is pretty slow. - Yeah. - And the Jeep won't runs it in third or fourth gear. So that's pretty well with it not running or at least running slowly. So it's an easy case where animators and scientists, I think came to more or less the same conclusion for different reasons. - Yeah, I feel like that's, I would assume that that's usually a rare thing because animators just want what looks good. And that might not necessarily be what the-- - Yeah, that is the goal to make things look good so that the audience is entertained and not taken out of the movie by just believing it. And therefore the movie will make money, which is the bottom line for them. They want to make money. Whereas science now, we just want to get it right and be honest and open and knit all of our uncertainties. And that's very grueling, but that's what we do. - That's awesome. Just out of, I have a curiosity question. You said that you were validating against, actually we're gonna ask you about validation because we weren't sure how that worked, but it makes sense that you would try it with a wide range of animals living and fossilized. You said you tried it with animals that can run and animals that cannot run. What are some animals that cannot run? - Well, so I built models of animals that cannot run on two legs like an alligator. Alligators never ever run on two legs. I can run on four legs, typically five. - That sounds terrifying. - Yeah. And I did the same with an iguana, a kind of iguana that does not run on two legs. Some lizards do. And I built some models of little basalist lizards that do run on two legs. And the model said, yeah, they can run fine with the anatomy that they actually have. They've dissected animals to measure their actual muscle sizes and everything. - Wow. - And models of kangaroos and humans and ostriches and emus and big birds, small birds, all kinds of stuff. And small dinosaurs all the way up to big dinosaurs. And it turned out that basically as dinosaurs got up to like a thousand kilograms, that's roughly where they seem to start to be losing the ability to run very well. Which is what we know of living land animals. That as you go from like a hundred to a thousand kilograms, locomotor ability really takes a big hit because of staling problems. - Yeah, that's a huge mess. - That makes sense. - What has been your most surprising discovery or development when studying dinosaur biomechanics? - I still am very proud of what we did with the T-Rex study. I think I'm very, very satisfied with the work that was in the first paper I published in 2002. And then we published like 10 follow-up studies to really keep adding layers to it, going into 3D modeling and just testing every possibility that we could do with our knowledge and the technology at the time. So I think that whole body of work, I really like. I'm still surprised that I kind of got the right answer, right? I'm quote, "In the first study and all the subsequent studies more or less held it up." That's satisfying. And other people have developed even fancier models and got more or less the same results. That's really cool. But at the same time, I'm a little tired of T-Rex. I don't really work on any more. I feel like, okay, 12 or so papers. That's probably a notch. I should ask some different questions. - Yeah. I'm more interested now in the evolution of dinosaurs and how they changed over time, which is something I'm focusing on now. - Yeah, I'd be great to talk a little bit more about that. - Sure, yeah. I was lucky enough to get a bunch of money for like a five-year grant from the EU. It could do kind of a dream project where we're now doing dynamic simulations or really, really fancy 3D simulations of a variety of living and extinct animals. Of the dinosaur group and the bigger group that contains dinosaurs, which is called the archosaurs or the ruling reptiles. But that's a group that includes crocodiles and a bunch of very extinct relatives and then dinosaurs. And dinosaurs today, we'd consider to include birds because birds are descendants of dinosaurs just like where mammals were, the mammal group. So we're looking at archosaurs as a whole. Back in the Triassic, about 230 million years ago when dinosaurs first appear, they're very small, kind of humble, look like they were pretty good runners. They have very long legs compared to other animals that they lived with. And the only other animals, or the dominant animals on land, I should say, were these other crocodile relatives that look like giant land crocodiles, some of which got up to like 20 foot long but very erect limbed, kind of like a, built more like a dog, able to run on land very well, probably. But heavily armored, big teeth, really scary animals, but they all got wiped out at the end of the Triassic and only dinosaurs and crocodiles survived to prosper thereafter. And dinosaurs really took over land from then onwards until they got wiped out at the end of the Patatius, about 170 million years later. So we're trying to figure out, well, what was special about dinosaurs back in the Triassic? There's this idea that they were able to move better than these big beefy crocodiles in some way because they had long legs well built in terms of leg musculature. And that's an interesting idea, but it's never really been tested, whether they were more athletic in some way, like running, jumping, whatever. But we're gonna use dynamic simulations to test how well all these different animals could perform and test those same methods with living crocodiles and birds, which we've collected a lot of experimental data from, and gonna do the same kinds of modeling with. So that will give us an idea how all these animals could run and jump and turn and have this research impacts the field of biomechanics and translates and modern. - Yeah, yeah, that's a great question. I really believe that biomechanics only get stronger than more broadly we apply it. And I think my T-Rex work, or I would argue, people might differ. I think my T-Rex work has helped test general principles of biomechanics, like our large animals fundamentally limited by their size or not. Some paleontologists have argued, well, you get to the size of an elephant, you're not necessarily limited to being as only as athletic as an elephant. And to a degree, that's right, although they weren't right in that a T-Rex could run 40 miles an hour, they seem to be sort of right that maybe it could attain an aerial phase, go airborne with both feet, unlike an elephant. Elfants never can do that, even though they can use a bouncing, running kind of gate that doesn't go airborne. So I've shown how there's locomotor diversity in extinct, in different animals. A T-Rex is so different from anything living today that allows us to shed light on what's really possible. Can a two-legged, six to seven-ton biped can it run at all in any sense of the word? Well, it looks like maybe. Maybe it's certainly within the realm of possibility, but not very fast if it did. And I think that adds something to our knowledge of biomechanics. I think it builds our confidence in our understanding of biomechanics. If we're again and again able to get plausible reproducible answers for extinct animals, if biomechanics is any good, any useful at all, it should be able to predict really hard problems like how to extinct animal move. If we can't do that, then there's something wrong with it. And there's certainly big gaps in our knowledge that need to be filled in or living animals. And that's why I studied living animals a lot. It's about half of my work. It's very much focused on living animals, because I believe we need to fill in that information. So we can understand living animals and also apply that to extinct animals. Yeah, totally. And thank you so much for sharing with us today. I think you're widely different than most of the people we've had on boom and had the pleasure of talking with, because you are applying biomechanics to these really sort of niche areas. But I like how you said it's a niche area, but it actually is really testing the general principles and robustness sort of of our biomechanics knowledge as a whole. So I think the work that you're doing is really inspiring. And I've learned a lot about what 2x can and cannot do. I really did think they could run. So I'm happy to know that I could potentially outrun them if Jurassic Park were to happen. It would be a close way. So my model suggests a top speed, maybe 15, 25 miles an hour, but that covers anyone's face. So I don't want to have to be prepared to test that. Yes, let's not test that. Yes, so quickly before we wrap up, we have two questions that we end on. The first is if you can recall a, we're calling them research fails or like some mess up you had in studying dinosaur biomechanics that led to you learning something or just something kind of funny to look back and laugh at now. So many, so many. I mean, I originally tried to express my T-Rex results in units of garbage cans, like 55 leaps of drums of muscle. Just that seemed to be an intuitive way of expressing units, but I love expressing things as percentage of body mass, which is a lot better. So I think that's a lot better than the actual body mass. I mean, I think that's a lot better than the actual body mass. In that future, you can take to be tomorrow or in the next year or five years or 10 years or 100 years. Just what do you see that's exciting in the future? Oh, many, many things. I mean, open science and like things like OpenSim have totally transformed the field. I could answer that. I would tend to answer this new-ish technology called X-ROM, which is a bi-planar fluoroscopy used to reconstruct skeletal motions or measure them. In very, very high accuracy, we use that a lot now. In vivo, 3D measurement of joint motion using X-rays. I think that has totally changed the field. And it's now people are using that to study muscle and tendon movement in 3D. I think, okay, I'll put it down to limb and say, well, if we can just get past the fundamental technological limit of not being able to measure a volume larger than a basketball with that method of X-ROM, that would totally open floodgates of new research. Like if we could image a whole human limb in 3D with X-rays. Yeah, lives, that would be amazing. That would be great without killing people with radiation. I think some clever person will come across a way to do that. Well, thank you so much for talking with us. We really appreciate it. Thank you. Yeah, this has been super fun and it's always fun to start the day with some boom. So thank you so much for sharing. Thanks a lot. Yeah, I've enjoyed it. That was really great. We learned a lot from John about dinosaurs and different biomechanics. And even that Jurassic Park is actually accurate. So animators and scientists came to the same conclusion, which I think was super awesome. Yeah, I think that's really cool too. A tag team, a more realistic animation. Why don't we talk about some research fails? Okay, that sounds good. Research fails. Yes it does. I have one that our lab experienced this past week in that we were testing a human subject and had all these different sensors on them. And the sensors are wireless so they have to communicate with our computer. And we were moving the patient to a different room and we realized that the wireless communication was going all wonky. And we were so confused because we clearly the sensors were on them and we were checking things and we were worried the system was going down. And then I walked back into the other room to pick up a paper, the room that we had been testing in earlier. And I saw one of the sensors on the ground. So maybe this is why. And apparently, yeah, it had just been removed for adjusting something. And I think it had just been forgotten to put back on. What's these? Yeah, that was a bit of a research fail. It's really good. We noticed that. Otherwise, we would have been missing a lot of data. That was really sad. We were doing a study recently where we were having cross-country athletes come in and run. And we had certain speed selected. And so we had just kind of made this protocol. So it was like the first couple of people coming in and someone came in. And they run really fast, like five-minute mile pace, which to them, they're just like, "Okay, this is fine. It's not a big deal, but it seems so fast." But we did some -- we went through the whole protocol with someone and it was like a couple of hours. And then we realized later that we had him running at the seat. We had him running at the wrong speed. Oh, no. That was really unfortunate. So we had to ask if he would come back. It doesn't -- it will matter to compare people across the same speed. Yeah. And it's really hard to get athletes in because they're so busy. And so you feel like so bad because you don't want to waste their time. But you also don't want to tell them that you wasted their time. But he was super nice and he came back in and helped out. So yeah. Blosset to that thing. Okay. Well, thanks for listening today. If you want to submit your research fail or request a biomechanics subject for boom or tell us a cool fact, you can email us at [email protected]. The ISB 2019 Congress abstracts are due at the end of January. Really excited for the conference in Calgary this year. There's also a lot of funding available through ISB and ASB. It's a joint Congress this year. So you can go on to isb2019.com for more information about the Congress and awards. You can also follow the International Society of Biomechanics on Facebook and Twitter at ISB.com mechanics. Do it, follow. Thanks for listening. Thanks. It was great. Bowman with you today and RIP to all the dinosaurs that contributed their fossils to the research we talked about today. Yeah. Thank you for donating your fossils to science. Biomechanics off our minds.