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Dinosaur mysteries with Riley Black

31m 43s

Dinosaur mysteries with Riley Black

In this transcription, Riley Black discusses how paleontologists piece together dinosaur stories from fossils, acknowledging the speculative nature of reconstructions. Skeletons provide a starting point, but they are often incomplete; for example, early T-Rex models assumed three fingers until a related two-fingered species was found, prompting corrections. Similarly, Brachiosaurus is reconstructed using its relative Giraffatitan. Beyond bones, trace fossils—such as tracks, tooth marks, and coprolites—offer direct behavioral evidence, capturing moments like an aetosaur’s footprints, which Black discovered in Utah. These traces help estimate speed, size, and social interactions. However, many structures remain puzzling, like Ouranosaurus’s sail (possibly for display or head support) and Alvarezsaurus’s single claw (theories include ant-eating or egg-grasping). Black emphasizes that paleontology thrives on unanswered questions, blending hard data with imagination. The field relies on luck, such as finding skin impressions to infer color or behavior, but each discovery refines our understanding, reminding us that every dinosaur depiction is a hypothesis shaped by incomplete evidence.

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They come from a version of our planet that looks pretty different from the Earth that we walk on today. So how do we take these fossils and spin them into the stories about dinosaurs that I love to read and watch? The dinosaurs are dead. Yet in all imaginations, they are very much alive. I guess today, Riley Black has written a lot about how to piece together an entire narrative from fossils. Riley writes about how we know what we know about dinosaurs. [Music] Riley, thank you for being on the show. Oh my pleasure. I mean, you asked me to show up and bring my dinosaurs stuff. How could I resist? For our listeners, Riley brought some dinosaur models and a cast of a dinosaur hand along. But Riley, can you tell me a little bit about who you are, please, and what you do? Sure. So I'm a professional science writer. I've written about a dozen books about prehistoric life in one form or another. And I'm also an amateur paleontologist. I go out in the field and actually find some fossils. I mean, if you are going out into the field, what does amateur about it? So there's a bit of a divide sometimes between the professional paleontology side and the many, many, many amateurs and volunteers out there looking for fossils. So I call myself an amateur because I'm not a curator or I'm not a professor. But I've been out in the field from places from Alaska to Mexico. A lot of work in the four corners actually finding fossils that go to museums and are catalogued and studied there. So I do it for the love of it. But why dinosaurs? It's hard not to be into dinosaurs. I mean, from what I was told, I went through a very short phase with trucks and then elephants, which I still love. And dinosaurs are so big and loud. I guess as always, I think kind of into the American Museum of Natural History when I was five. And when you are small, not a small zamesezoic mammal, but still quite small and seeing these big skeletons. It's hard not to be impressed. And what I love about them and really any prehistoric life is you look at their bones or their traces or what they leave behind and there are all these questions of how did they move? What did they look like? What color were they? What did they sound like? What did they smell like? All of the stuff that we may or may not have answers to. So it was a chance to get to know this whole realm of science that's fueled by the questions where you encourage user imagination. I think this is a perfect transition into what I wanted to talk to you about today, which is how do we know the things that we know about dinosaurs? And so I thought maybe we could start sort of where the paleontologists first started, which is the skeletons that they left behind. So talk to me about how we sort of take a dinosaur skeleton, like a bunch of bones and turn that into a story about reptiles running through the world. I mean, this is how paleontology as a science started. I think it's important to note that people have been finding fossils for thousands and thousands of years. We have like stone and hand-axes of fossils in the indigenous cultures all over the planet have encountered fossils of different kinds and understood that these were once living things. So like we had this long recognition that there was life before us, but it's the late 1700s. We have geology, which is starting as a science and comparative anatomy mostly in Western Europe. And you put those two things together. People find these weird bones usually disarticulated, usually incomplete, but it's just big, big stuff, like a tooth from a reptile that's far larger than any crocodile or snake or anything that lives in that part of the world today. And they know this must be something. And they try and slide it into what they knew. So this is why the earliest representations of dinosaurs look like giant lizards or giant crocodiles. It's just like what's a reptile that must have been a hundred feet long. And then we get more complete skeletons and they're like, oh, okay, the body shape is entirely different, which is kind of funny. Brachiosaurus is a great example because we really only have the forelimbs and parts of the vertebra and some of the neck. And that's about it. So we're really basing it on other more complete animals. We wait. This dinosaur. Yes. We have like these parts that like the front legs, some of its neck. And what else? A few bits of its backbone along the spine, a couple limb elements. And that's it. There's some that I know are undescribed. There might be skull pieces. How do we make something like this from some forelimbs, some vertebrae, some other bones and a dream? Yeah, how we get to something like this, or for a breakfast. Exactly. So you're showing me right now a model you have of a beautiful long neck dinosaur with a long curving tail for lovely long legs, red and green coloring. For something like Brachiosaurus where we don't have the whole skeleton, even now, we look to their closest relatives. There's a related animal called giraffe that's found in giraffe. Yes. So like giant giraffe. Yeah, we have the arm lizard and we have the giant giraffe. Giant giraffe is more complete and we can they're close enough that you know, we know that they must have had similar bones like this is something like we know there are vertebrates, right? Based upon the bones that we find. So when you have a vertebrate, they must also have a circulatory system and a nervous system and skin. Even if we don't have the exact fossil, we can start filling in those pieces as a hypothesis. So anytime you see a complete dinosaur, unless it's really literally that specimen or that cast that someone's made a one-to-one of, it's hypothesis. Anyone's vision of a dinosaur like I can say T-Rex and the T-Rex I see in my head is going to be different from what you see in your head. And this is what I love about it is that we're taking sort of this bare scaffolding and based upon what we know and what we see from experience, filling in like what might have been there. But are some of the most interesting or maybe even counterintuitive ways that we have been able to say, no, I'm pretty sure this looked this way, just just by looking at the bones alone. So the bones alone usually we need a complete skeleton or fairly complete skeleton. It's how, but this little T-Rex hand that I brought in is a really good example in this animal that would have been more than 30 feet long and you can hold this hand in your hand. It would have been an arm about as long as yours. So I'm looking at just to be clear, sort of it looks like two fingers of a T-Rex hand that have very pointy claws on the end of them. And you actually have a little bit of a third finger there. So there's a little splint bone that's underneath the larger fingers and that third one, that splint is the remainder of the third finger. We always make fun of T-Rex for having tiny, tiny hands, right? Well, they used to have three fingers and their ancestors lost them. So this tiny little bone, this like this bone that's actually the size of my pinky is like an ancestral third finger, like a tailbone of a third finger that they have. Right. Which was lost. And we didn't know that. So when the first Tyrannosaurus tract was being reconstructed here in New York City, we used to think it was related to other carnivorous dinosaurs that we knew about. But there was no arm. We had the big ol' skull, we had the backbone ribs, all this stuff. No arms, the arms are tiny. Of course they'd probably wash away and not get buried. It wasn't someone actually found a T-Rex arm with the hand at the end of it. So early on they thought it was three fingers. Like all the other carnivorous dinosaurs do. And then someone found a related form in Canada and Alberta that only had two. And we know that they were closer to T-Rex. It's like, okay, we have to change the model and that's why T-Rex is two little fingers. Fascinating. Okay. So finding more bones to complete out a skeleton can really tell us, like, oh, we got this wrong, we got this wrong, etc. But you also had an article that you wrote that was also about tiny arms that was a little different that I loved. Can you tell me a little bit about Elvarezaurus? Am I saying that right? Yes. Yes, Elvarezaurus. I'm just talking about them because nobody talks about Elvarezaurus. This is like the indie band that like only does vinyl. So let me put this on. Yeah, I just want you to picture of Elvarezaurus, please. This is a little critter called Lanna Nikes. Oh, this is Lanna Nikes. And it belongs to a group called Elvarezaurus. So I'm looking at this very small, very cute creature that had, you know, very long legs. It was a really long neck. And then it just has these rinky dink little arms coming off of it that it's holding together in a little. Oh, like a little please, like a begging posture. Like, can I go home an hour early kind of pose? That's just one claw. That's what its name means is one claw. So what is it's one claw for? We don't know. We don't know because a skeleton can't can't really tell us exactly. what it's for in that it can give us the range of motion and we can reconstruct the muscular chair and things like that. But it can't really tell us like what did it use that muscular chair for? How did it move those? If we know it has a short range of motion, then to what purpose? What function? Are there ideas? Yes. Do people have theories? Okay. I love a theory. So my favorite one is that these were dinosaur ant eaters because they often have either no teeth or very, very, very small teeth. And this is something that we see happen with like a shift away from carnivorous foods and more towards like insects and plants and things like that. But we think that they were like ant eater dinosaurs using those little claws to basically stick their chest to the ground and just kind of scratch away at ant and termite mounds, which you know we're around at the time. We actually find dinosaur bones sometimes with termite damage to them. So theory one is they were ant eaters just like poking their fingers in there. What is the other, what are the other theories for what these tiny claws could be for? They might have been for grasping eggs. There was a species that was named a few months ago that they thought that they were just kind of clasping eggs to their chest. They're just kind of doing a little dip, picking up an egg and kind of skittering away with it. Okay. And that's really about it. So far we don't really like you look at that stubby arm is this kind of like what? And there's not a whole lot else. We don't have a lot of equivalence for arms like these other than animals that dig into the ground somehow. Okay. So we have T-Rex claws. We have albars sore claws. Are there other sort of dinosaurs where we're just sort of like well we have a bunch of bones? What could this possibly be? What does it look like? So dinosaurs love their bizarre structures like the fashion through the mesozoic was just something else like the ornamentation on these animals. Constantly like our little triceratops friends. Even though that's a very traditional three horned face. Look, there are lots of horned dinosaurs with all these different arrays of horns and spikes and hooks and everything else that help them differentiate each other. And that we have a fair handle on. But in terms of ornamentation, there are dinosaurs with like sails on their backs and we have no idea why. Sales? Yes. Sailback dinosaurs. So there's one in particular called oranosaurus. This is an herbivore. So everybody knows dinosaurs that got its name for the spines on his back. We're doing indie dinosaurs here. Spinosaurus can be like the girl like on the cover in that geo. We're doing again the deep cuts. So this is an oranosaurus. It is something related to a guana-donna or the duck-beat dinosaurs. And it has a sail on its back. Okay, so I'm looking at a dinosaur. It's very difficult to describe. So the middle part of it sort of looks like a regular dinosaur. And then on its back it just has like a whole fan of bones coming out. So I see what you mean now about a sail. What I feel like I know the answer and the answer is we don't know. But what is what's the sail for? We don't know. Amazing. There been a few ideas. One of which one my favorite sort of discarded hypotheses is that we see these long neural spines. So these flat bones that come off the backbone in things like bison or various mammals. They usually hold a hump or the end of a ligament that goes from the back of the head to between the shoulders. Because a lot of these mammals have big heavy heads. They need like an extra rubber band to help them keep their heads up. And we used to think that this was true for the dinosaurs as well. But then you'd have this basically mound-shaped dinosaur with legs. If you imagine like a little hill with legs kind of shuffling around, that's more or less what they would look like. But that was one of the ideas that this is sort of head support or something like that. Okay. What seems more likely is it's some kind of billboard. Basically it's dinosaur advertising that they're communicating to other members of their species. They're like I'm bigger than you or I'm an adult or I'm a juvenile or like different dinosaur sexes. Like a peacock tail almost. But on their permanent peacock tail on their back. Yes, always peacocking. Yeah. And with something that's that big and that elaborate and it takes energy to grow, right? This is an investment that this animal was making. Bone is constantly remodeling itself. It must have had formed some purpose in this animal's life. But unless we can see these dinosaurs interact, it's very difficult to tell what they were doing. Now there's some ways that maybe we can get at it. We can find some skin and find out what color that skin was, which is the thing we can do now. Maybe we can start to get at it. But again, it takes the luck of the fossil record to actually make such a finds. Got it. So if you could find like skin from another part of his body and then skin from this sail. And the skin on the sail was like neon. And the skin on the rest of his body was like fairly gray. It would be relatively clear. And the neon sign said like two for a dollar at Spinosaurus land. You'd be like, oh, it's a billboard. The paper wave aesthetic going on the sail. Amazing. So what you've told us to this point is essentially that skeletons can't tell us everything we need to know. Bones are not the the be all and end all. We still have a lot of questions. We have questions about the sails on dinosaurs like a ranosaurus or even spinosaurus or what alvarsores use their claws for. What else can we look at to understand dinosaurs in more depth? Yes. So you're getting to one of my favorite kinds of fossils. And those are trace fossils. Trace fossils. Yes. So these are things that animals leave behind in the fossil record. So it's not the tooth of the bone or whatever itself. But it's the marks that animal made in life. So we're talking about things like tooth marks and tracks and fossil feces. And all these other things that basically an animal leaves behind just through living. It's interaction. It's behavior. So like when you see a dinosaur trackway, it's not just footprints in the rock. That is moments in that animal's life. And we can calculate like how tall it was, how fast it was moving. Maybe the direction it was going in. Is there another animal nearby? Is it going in a certain direction like to get around an obstacle or to avoid something? So these are actually like moments of prehistoric time that we still have this fossils. More on that after the break. Hi Ryan Reynolds here for a Mint mobile. Are you looking for a beach read this summer? May I suggest your big wireless bill. It's got suspense, mystery, a slightly flat emotional arc and a shocking twist where you realize you've been overpaying the entire time. Fortunately though, Mint story is better. Every plan $15 a month, even unlimited. That's it. Happy ending, zero tears. Give it a try at MintMobile.com/switch. Up from payment of $45 for three months, $90 for six months, or $180 for 12 month plan required $15 per month equivalent to taxes and fees extra. The initial plan term only greater than 50 gigabytes may slow when network is busy. 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Try hint available at drink hint.com and in stores nationwide. What's one of your favorite? Are you pulling out the phone to show me something? Well now I get to brag a little bit. I have to talk about stuff that I have found right in the field. What's one of your favorite traces? One of my favorite traces. So what I'm showing you on the phone is it kind of looks like multiple toes. There you can see one, two, three, four. Yes. And then there's a couple small toes next to it. So it's basically the front foot and the back foot of a crocodile like armadillo thing called an aedisaur. Okay. Aedisaur. How do you know just is it like that's what it matches up that footprint? Yeah. So you can look at the skeletons and you can look at what other animals are found in that formation and see kind of whose foot matches what print. It's rarely one to one unless an animal literally dies and it's tracks. But sometimes this happen. It's hard to be a hundred percent certain. But in this case the hand-in-foot anatomy matched this armadillo like crocodile relative that was nerve-r-before that was living around when dinosaurs were really small. And just kind of it looked like the ground was giving me a high five. It was like impossible to. And so how did you find this? Yeah. So it's out on expedition with the naturalist museum of Utah out in the eastern part of the state. So like outside Arches National Park that kind of area desert country, your miles and miles from from anybody. And the rocks are very, very ancient there. So we're talking about the end of sort of the dawn of the dinosaurs, the triassic about 220 million years ago. you hop out of the truck, you have your water and everything that you need for the day, and you just go walking and looking for fossils. So I start picking around the rocks nearby. And you have to look at these walls of rock and kind of determine what layers are going to look at. Where you're going to go, like the angle of the sun that can matter in terms of what you're going to find. And I start picking along and I find these little invertebrate traces. Basically, little like beetle footprints. And I was like, okay, there are traces here. So I find those little beetle traces. I find a little plant fossil and then there's a dinosaur track. I actually have a brought one of the photos of that one as well. And this was like indisputable. That's what it was as soon as I saw it. Oh, yeah. So I'm looking at what is it looks like a footprint. Yeah, it just looks like a little trick and track. It's about that size really. Just those three toes at the claws at the ends. And then I start taking my field notes and start looking for other stuff. And I see that footprint from the A to A to sore as well as a whole bunch of other ones. Like now I'm just living this track. Basically having a happy little flashback here. But so you have these you have these footprints. What can those footprints tell you? Yeah. So footprints can tell you an animal's moving speed. There's a relatively simple calculation that you can use between footstries to tell how fast it was like moving. Longer apart usually means it's moving quicker. It's really basic like kind of like animal physics kind of stuff. One of my favorites, it's not this site, but it's at a place nearby where I found those tracks. It's Jurassic age site that has tracks that were likely made by an animal like Alessoris. So I think like a Jurassic T-Rex just three fingers a little bit smaller. And the stride lengths on one foot are different than the other. And what that means is that dinosaur's limping. So I got injured somehow. And we have an injured dinosaur trackway. And we don't entirely know what caused it. But it's just a great reminder of like these animals dealt with the same kind of like injuries and bone breaks and everything that we see in animals now. They were they were living lives. They were not sort of perfect specimens of dinosaur hood. They were each one was an individual dinosaur with its own little trials and tribulations I guess. Is there something that trace fossils have helped us? Are there ways that they've sort of changed our understanding of some of the skeletons that we've received or sort of upended things that we thought we understood about dinosaurs? Absolutely. So trace fossils are not just for dinosaurs all sorts of prehistoric things. Left traces and including traces on dinosaur fossils. So there's a place in Western Colorado called my got more dinosaur quarry. It's like 150 million years old. This is like hey day of allosaurus, digosaurus, a padisaurus like all those favorites. But everything there is in a jumble. So we don't get complete skeletons out of that site. It's this base of this pond where things were disarticulating and falling apart. And scavengers came by. There's so many bite marks on these fossils. You see the like the ends of thigh bones. They're just raked with these teeth from all the feeding and stuff. And we can tell from where those bite marks are. Sort of what were the favorite parts of like a sauropod body. So if you have an allosaurus coming to scavenge, where's it going to start? Some of it suggests that they were going into the cloaca to get at the pelvis after they'd taken off like the other tail meat and stuff. So they were going in through, sorry, to be crashed. Yeah. The butthole. Yes, they were. Yeah. They would enjoy like basically, you know, that there's a big tail muscle called the cartofemeralis that they take that stuff first. And when they're getting down to like the prime cuts, that's how they got into the rest of it. I'm such a child. So we have those bite marks on those bones, but we also have beetle damage. So a lot of museums use like domestic beetles to clean their skeletons, right? You have a skeleton. You want it to be clean for display. You put it in with the beetles and then you take it out before the beetle start to burrow into it because that's what they want to do. They want to. Sorry, I love that you're saying this for sort of like casually. And we all know, sorry, they use beetles to clean spes. Okay, great. Yes. Fact I learned. But yes. So those beetles normally complete their life cycle, they want to burrow into that bone. So naturally, that's what tends to occurs. And that's what we find on some of these dinosaur bones that they were exposed now in the open long enough that those beetles were like basically eating their way through the bone, leaving trails in them, which tells us those bones were exposed like on the surface for a while. So this whole idea of we need quick burial to make a dinosaur fossil, probably not true. Some of these bones were on the surface for months to even years before they got buried, which makes sense. Because even though we have our pint-sized brachiosaurus in front of us, the real animal would have been about like 60 feet long and way upwards of 20 tons, takes a lot of sediment to bury something like that. So by looking at what the insects were doing, the traces that they left is the same kind of stuff that forensic investigators use today to kind of determine how long a body has been exposed. We can do that with dinosaurs thanks to traces. So if we return to sort of the questions you were laying out at the beginning about, say like alversoirists, why does it have such tiny little finger claws? Could trace fossils potentially help us kind of answer the questions that are posed by these skeletons? Yes, because one of the things that we always want to know about dinosaurs right is what did they eat. And so often when it comes to the teeth and claws and other things, it comes down to a question of feeding and how are they acquiring that food and how they processing it. So we think of our little alversoir friends, a little friend like Mon and Icus. If they were sticking their chest against an ancient termite mound, which also like, ow, I hope they don't bite, with just sure as a strategy to pick. And digging away with their arms, we might be able to find a prehistoric termite mound that has scratch marks in it. We actually have scratches made by dinosaurs in the fossil record from Utah in different parts of the state than I was prospecting in. There is a mammal burrow that has claw prints from a velociraptor like dinosaur basically digging in that this dinosaur was trying to dig into the burrow to pull the mammals out. So we could find something like that with alversoir, these claw scratches on the insect mounds and that would give us some clues. More likely, we're going to get the answer through fossil poop, copper lights. So copper lights, that's a kind of trace fossil. It's basically what animals eating. It's the remainder of the gut contents. Sometimes you get gut contents. Sometimes you get something called the cola light, which is basically when it's in the intestine but hasn't exited yet. Copper lights just fossil poop. Usually contains if there were scales or exoskeletons or anything like that. It would be in there. So if alversoir is we're eating these little insects, we should be able to find a copper light from them. There'll be more copper light fossils than skeletal fossils because they'll be making them all the time, basically back in the Cretaceous. And they should be full of little ants or termites or some of that or maybe we'll look into them and find eggshell or little mammal bones or who knows what but that would be the test of the actual animal's behavior. We can look their skeleton and say like maybe they did this but traces like basically to have the remainder of what they actually ate. How would you know it was an alversoir is copper light? That's a great question because you wouldn't really be 100% sure except if it were exceptionally rare. So most of the time we find copper lights just by themselves. They're just individual fossils and we can say okay the body size matches or based upon what we've collected for other animals. It seems like it came from a similar sort of animal. If we found it as a cololite or found it associated with a skeleton then you could say like okay these are close together. There's some kind of association between them so it's probably that might be able to look at the geochemistry but here's the thing right like it goes back to what you were saying at the beginning for anything that we find the fossil record. It's like find one fossil here's a dozen questions. And what um I guess what keeps you interested in sort of trying to piece everything together. There's always something more to learn. There's always something that I didn't know. Nature is so surprising even familiar animals. Even the most basic questions about dinosaurs. We don't necessarily have answers for yet but in my lifetime the amount of things that we've learned that I was told even as a kid we were never ever going to know. For example dinosaur color you speak you know what? Do whatever colors you want. Nobody knows what color dinosaurs were. Make that neon pink you know T-Rax or you know a stegosaurus with you know bright yellow plates or what have you. Now we're starting to find out what colors they actually were by comparisons to modern birds and looking at you know skin and feathers and the microscopic nature of it that creates structural color. So you know in a way like it didn't kill the magic it just made it more interesting like okay we got some color now what other colors were they're what color patterns were there do they vary between different sexes or populations or species. So all of this curiosity it's incremental and cumulative and it changes our perception of what the ancient world was like I love the fact that the dinosaurs that I grew up with especially seeing older documentaries and books out of date museum displays are now fundamentally different it's the same species sometimes the same skeletons but they're rearranged they're brought to life in a different way and it feels like something that everybody can participate in and I love that paleontology can be welcoming in that way that it's something if you can put boots on and go look for fossils or even just like volunteer in a museum poking through drawers you can change the way people see ancient life. What's that Riley thank you so much for coming on talking to us about dinosaurs um if people want to read your books which one would you recommend that they start with. I would recommend the last days of the dinosaurs okay it is the first narrative book that I wrote so this is like if you were there 66 million years ago you're standing in ancient Montana from the day before the asteroid hits through the first hour the first day the first week through the first millionaires as you see life change it's basically the making of the worlds as we know it now with the reason why we're here. So if you really want to get a feel for not only what it's like to be there in the Mesozoic, but sort of the way that I think a paleontologist sees the world. The way that I see the world, when I'm out in the rocks, when I'm looking for these animals, the kind of visual and mental landscape that you kind of create from what you know, I think that's the best place to start. -Right. Riley Black, they are a science writer, amateur paleontologist and a wonderful guest. So thank you so much. -Oh, let's finish. If you want to know more about Riley's books, we will link to their website in the description for this episode. This episode was produced by Valerie Shankman and me for Pinkerton. It was edited by Joanna Solotarov. Our video editor is Alex Kohlz. Our animator is Karim Kareya. Our fact checker is Melissa Hirsch. Our studio engineers are Devon Howard and Jo Nebres. Mixing and sound design by Christian Ayala, music from Noam Hassenfeld and Meredith Hodnott runs the show. Special thanks, as always, to Brian Resnick for co-creating the show with me and Noam. And if you want to see the video version of this episode, you can find us on Netflix. If you have thoughts about the show, we would love to hear from you. Please email us at [email protected]. Or if you'd like to support the show, join Vox. Become a member. Just go to vox.com/members. And if you signed up because of us, please let us know. And thank you. Unexplainable is part of the Vox Media podcast network. And we will be back soon. 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Podcast Summary

Key Points:

  1. Riley Black, a science writer and amateur paleontologist, explains how fossils are used to reconstruct dinosaur life, emphasizing that interpretations are hypotheses based on incomplete evidence.
  2. Skeleton analysis involves comparing incomplete fossils to relatives, as seen with Brachiosaurus and T-Rex, where new finds can overturn earlier assumptions (e.g., T-Rex having two fingers instead of three).
  3. Trace fossils—like footprints, tooth marks, and feces—capture behavioral moments, offering insights into dinosaur movement, speed, and interactions.
  4. Many dinosaur features remain mysterious, such as the purpose of the sail on Ouranosaurus or the tiny claws of Alvarezsaurus, with theories ranging from display to feeding.
  5. Fieldwork, like Black’s discovery of a crocodile-like aetosaur track, shows how matching footprints to skeletons helps identify species and behaviors.

Summary:

In this transcription, Riley Black discusses how paleontologists piece together dinosaur stories from fossils, acknowledging the speculative nature of reconstructions. Skeletons provide a starting point, but they are often incomplete; for example, early T-Rex models assumed three fingers until a related two-fingered species was found, prompting corrections. Similarly, Brachiosaurus is reconstructed using its relative Giraffatitan.

Beyond bones, trace fossils—such as tracks, tooth marks, and coprolites—offer direct behavioral evidence, capturing moments like an aetosaur’s footprints, which Black discovered in Utah. These traces help estimate speed, size, and social interactions. However, many structures remain puzzling, like Ouranosaurus’s sail (possibly for display or head support) and Alvarezsaurus’s single claw (theories include ant-eating or egg-grasping).

Black emphasizes that paleontology thrives on unanswered questions, blending hard data with imagination. The field relies on luck, such as finding skin impressions to infer color or behavior, but each discovery refines our understanding, reminding us that every dinosaur depiction is a hypothesis shaped by incomplete evidence.

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They look to close relatives for guidance, using comparative anatomy to hypothesize missing parts, and then fill in details like skin and muscles based on known vertebrate anatomy.

Early reconstructions assumed three fingers like other carnivorous dinosaurs, but a related two-fingered fossil found in Canada showed T-Rex actually had two fingers.

Elvarezaurus is a small dinosaur with one claw on each arm. Theories suggest it used the claw to dig for ant and termite mounds or to grasp eggs.

Trace fossils are marks like footprints, tooth marks, or feces left by animals. They reveal behavior, such as how fast a dinosaur moved or whether it was avoiding an obstacle.

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