Uncovering Dinosaur Behavior Book Club
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Hello and welcome to I Know Dino. Keep up with the latest dinosaur discoveries and science with us. I'm Garrett. And I'm Sabrina. And today in our 522nd episode, we're doing something brand new. We're doing our first ever episode of a book club, which is all about the book Uncovering Dinosaur Behavior. Yes, by David Hohn and published by Princeton University Press.

And we should mention that this episode is sponsored by Princeton University Press, and they provided the books to us and also paid some promotion for it. So thank you very much to Princeton University Press for helping to support our show and going on this fun experiment of a dinosaur book club. Spoilers, we did like the book. We probably would have read it even if it weren't for this partnership. Yeah.

We also have dinosaur of the day Gasparini Sora. And our fun fact, which is that sauropods probably didn't swallow gastroliths to help them digest their food, which is a little unexpected. Yeah, because we always think these animals that swallowed plants whole needed something to help digest them, but...

Soar pods didn't for reasons that we will get into. Yes. Also, we are on parental leave because as of this recording, we are expecting our second baby any day now. But don't worry, we're going to have a great discussion. And for members of our community who want to keep the discussion going, we're going to have a thread going in our Discord channel.

Yeah, so go over to the books channel on our Discord if you want to talk about this book. You can also talk about other books, but I think most of the conversation is going to be about this book since that's the book club we're doing at the moment. And you may have already been discussing the book there as we've told you in the previous weeks about this upcoming book club. So hopefully you had a chance to read it already. But if not, you can always read it and then catch up with the discussion later. Mm-hmm.

But before we get into all that, of course, we'd like to thank some of our patrons for helping to keep our podcast running. And this week, we'd like to thank Eric, Juliana, Stygacosaurus, Shankylosaurus, Micah Marcos Music, Kumakani, Jesse, Paul M., David, and Sarasaurus Rex. Yes, thank you so much for your support and being part of our Dino It All community.

Yeah, and hopefully you have a chance to pop over to that Discord server and discuss the book with us and others. Yes, and if you want to join our community and take part in our book club discussion, then head over to patreon.com slash inodino and you'll have access to our Discord. All right, jumping into it, the full title of this book is Uncovering Dinosaur Behavior, What They Did and How We Know.

You always have to have a good subtitle when it comes to nonfiction books. Yes. This one is a bit unusual, I'd say, for a nonfiction dinosaur book geared towards adults. What they did and how we know. Because usually it's about other things.

I think usually it's more scientific terms that I've noticed. Oh, I see. Yeah. And that sort of speaks to what Dave Hohn said he was trying to do with the book, which is sort of reach a broad audience, but also not use really scientific nomenclature. So it's still approachable, even if you're not a super dinosaur nerd.

I actually think it fits really well with our audience because he does use a lot of dinosaur terminology in terms of dinosaur names, dinosaur groups, and things like that. But he doesn't get really into the Latin names of every bone and all sorts of really specific anatomical details that goes over your head often.

unless you're really, really invested. You're one of a few hundred people who spend their lives researching dinosaurs. So I actually think it's a very good fit for our audience. I think so too. And this book came out in November. It was published on November 5th, but we're airing this episode a few weeks later because we wanted to give everyone a chance to read it. Speaking of, if you haven't read it yet, because that's the beauty of a podcast is you can be tuning into this episode at any point.

Then we'll have a link in our show notes for where you can purchase a copy and you can use the discount code PUP30 and you'll get 30% off. Nice. I heard some people use that discount code to get some extra books at the same time. And we've talked about some of the other good dinosaur books they have. They have a lot of good dinosaur books. Oh, yeah. So I'd recommend if you're going to buy one, you might want to add more. I don't know how it works with shipping. You might save something there too if you do multiple books. I don't know, but it's worth checking out. Both non-avian and avian.

That's true. There's a lot of bird books as well. Mesozoic birds too. And also you could, if you don't want all the spoilers about our discussion of the book, just stop listening right now until you get the book and then come back to it once you get the book.

It's a pretty quick read too. So it's not like a huge compendium that's a thousand pages long. It's meant to be read cover to cover. And I even read it cover to cover in one day and I'm not the fastest reader in the world. So it can be done.

I took things a little slower because I wanted to really soak it in. So, you know, to each their own. Well, I mean, I did actually read it over two days, but it was like one day's worth of time. I read most of it in one day. There is an audiobook version, but I'd recommend getting the print version because there are some beautiful illustrations by Gabriel Uguedo.

Yeah. Yeah, they're fantastic. My personal favorite is one of Spinosaurus sort of

from a fish's perspective looking up. So it's like the mouth is breaking through the surface of the water along with the hands and the feet. So it's sort of the heron posture that Dave Hohn has talked about in the past of it standing in the water and then sort of reaching down with its mouth and or hands to grab fish out of the water. Oh, yeah. Yeah, that makes sense. There's a whole section that's a case study on Spinosaurus in the book that goes over...

It's actually a little different than what I was expecting based on what I know of Dave Hohn's research on Spinosaurus. It was a little more open-ended, I would say. Yeah, he did a really good job in general, I would say, of sort of...

being skeptical of everything, even in things that we know when talking to him personally, he might have a really strong opinion on. In the book, it's presented very balanced in terms of, well, I think this is the more likely situation, but we really can't rule out all these other possibilities, which is almost always the case when it comes to behavior, which the book is all about because behavior doesn't fossilize. You just get clues about the behavior. Yeah. Yeah.

And I love too, they were talking about tracks and say you've got a predator track next to an herbivore track and you might think, okay, that shows hunting behavior. But really it could be that they were just walking along the same path at different times. It could be that the one isn't even a predator because some theropods are herbivores. So it could be an herbivorous theropod walking with other herbivorous dinosaurs that aren't theropods. It could be

that the herbivore is chasing away the theropod because it's near a nest or something like that. There's a million different opportunities for dinosaurs to walk in the same general vicinity in a couple successive days. So it's really difficult to make any sort of concrete conclusion from these things, but you can make a best guess in a lot of cases. Garrett, what surprised you most about the book?

maybe the head-butting hypothesis and the fact that he was pretty, in terms of the

confident to not confident ends of the spectrum. He was pretty confident that Pachycephalosaurs were at least some of the time head butting. That was surprising to me because I know there has been a lot of research over the years. At first, a lot of people thought they head butted. Then it went back to, no, they probably didn't head butt because it would have damaged their head and or necks. And now it seems to have gone back a little bit the other way. But I was surprised that he was pretty confident

on team head-butting. Yeah. And I think it mostly has to do with the fact that there is decent evidence on the skulls themselves, the top of the heads, the dome heads on these Pachycephalosaurs that show some damage. Mm-hmm. And the damage looks consistent with the kind of damage you would get if they were butting heads. But...

Of course, they could be flank-butting more than they could be head-butting or could have bumped their heads into other things. But yeah, I was surprised that the head-butting hypothesis was pretty firmly supported. Also that they talked about sauropods being mostly high browsers.

And even things like Diplodocus and Apatosaurus that we often see depicted as having a pretty low head and being more low browsers saying that they were likely higher browsers most of the time. Because that's what differentiated them. Yeah. And sort of the analogy was, what would the point be in having such a long neck if you're just going to compete with all the other herbivores for food on the ground? Which is a pretty good point because there were a lot of different herbivorous dinosaurs around over the years.

And if you have a really long neck, it seems like you'd want to take advantage of that to eat up high. Although he did say there is some evidence of them eating some harder plants and some stuff off the ground.

but there was a good analogy there for giraffes because giraffes also eat food on the ground. They don't just eat food way up in the trees. If there's something good available down low, they'll eat that too. And sort of the analysis that sauropods probably were mostly like that. But maybe looked awkward doing it the way giraffes do. Yeah, exactly. And certainly some of the sauropods like Brachiosaurus, Cretaceous,

Giraffa Titan, some of the Camarasaurids probably spent more of their time more upright, maybe reaching higher, but that these other dinosaurs were probably still, you know, 10, 15, 20 feet off the ground most of the time. That was surprising. My big takeaway from this book is just to beware of inferring too much from the fossils because we have a limited record.

But when you combine multiple disciplines, multiple studies, and you look at everything from multiple angles, you can still learn and infer a surprising amount. So we may never know the details of, say, how dinosaurs made it exactly, but we can still figure out various dinosaur reproductive strategies. And even whether they made it at certain times of year or if they could have done it any time of year. Mm-hmm.

Stuff I hadn't thought about before. Yeah, that's very true. And I've found that personally too, when reading different scientific journal articles, that when there's multiple authors and they span a lot of disciplines, the papers are usually much more of a complete thought and presented in a more cohesive and convincing way where it's this dinosaur seems to be eating this. And we can tell because there are these sorts of micro wear patterns on the teeth that

The teeth have this shape, which is consistent with eating this kind of thing. Say it's a meat eater. It's got serrations. And then there's also, say, grooves in certain ways on the teeth that look like they're touching bone. And then you can also look at the skull and the musculature on the head to show that it had, you know, say, bone crushing force if we're talking about T. rex teeth.

and combining that with other details, maybe coprolite, gut contents, comparisons to modern animals. When you get it all together

It works so much better than if you just have a solo author who has expertise in one specific area, might be able to make a pretty good argument using one piece of evidence, but they might not have the background in the ecology side of things, as well as the biomechanics side of things and the phylogenetics and the modern animals, as well as some of the prehistoric plant life and other animals that might combine for a better audience.

overall view and a better full theory rather than just sort of a weaker hypothesis. If you could ask the author, Dave Hohn, one question about this book, what would it be?

I don't know if I have any questions to ask. I mean, he had 400 sources. And to me, the book is sort of a state of the science summary of just so many different topics. So I think if I wanted more information on any specific subject in there, I would just go to that source.

That was one thing I was going to say about it. I think this book does a great job. He did a great job of pulling together so much research and talking about what we learned from it in terms of dinosaur behavior. But one thing, and I get this is tricky to do, and maybe it's just me because we're 522 episodes in now, is the book often talks about a specific dinosaur discovery or a study that was enlightening, but doesn't always mention what the study was or the exact details. Right.

But because there's this extensive list of references, I could easily find the study mentioned in the back of the book. But being the dino nerd that I am, sometimes I would like to go deeper. Yeah. Yeah. There were a few of those cases for me. Usually just looking at the title of the reference in the back of the book was enough for me because... Jogged your memory of when we talked about it on the show? Either that or, yeah, because a lot of them I have read. But sometimes...

some of the times it was just, I wanted to know which dinosaur it was referring to. Cause it might be, one of them was a sauropod discussion and it was something about like sauropod nesting or something to that effect. And when I went and I looked at the reference number 285 at the back of the book, it mentioned nesting titanosaurs from the Aka Mahwevo and adjacent sites. And then I immediately knew what he was talking about. And I was like, oh yeah,

Those nesting sites and those dinosaurs, I'm familiar with that specific research. And that's an important nesting site. It is, which I'm sure is why I included it. I know too that it's a hard thing to do because this book is meant for people who are really into dinosaurs as well as a more general audience. So you've got to find the line somehow. And I think having all the references in the back is a good way of doing it.

Yeah, and also I think the pictures are a really good way to do it because there are a lot of times where the text is being more general about dinosaur behavior, sort of talking about these are the types of things that you can see with different research. These are the general conclusions you can and can't make by looking at different fossils about their behavior. But then there'll be a picture that's the actual hypothesis of a specific dinosaur behavior.

For example, you've got pictures of a titanosaur sauropod preserved in an egg as an embryo, and it can show you exactly why that's so useful when you see that example.

Or there's a picture, a couple pictures actually, of dinosaurs mating. And in those cases, a picture is worth a thousand words because it's sort of hard to describe just how awkward it might be for two stegosaurs to mate. But if you sort of show it and how tricky it is for them to line up, it gives you a better depiction of what is going on.

Another reason to get the print version of this book. Yeah. If you want to see the stegosaurus mating, you don't get that in the audio only version. It's not just mating illustrations too. You've got some really great photos of like Zool, for example. Yeah. Or what I really like too is the reconstruction of Musaurus growing up.

how it starts. They start with an egg and then you've got a quadrupedal crawling around like a baby is how I always think of it. And then it's slowly transitioning to being bipedal as an adult, which is just a really good illustration. Gabriel Ugueto did an amazing job on all of these illustrations. Oh, yes. They're so good. They are. My question for Dave Hone, though, would be

Just going back a little bit in the book, he mentioned some areas of dinosaur behavior research are deep and others are more limited. And that's for a lot of reasons. One of them is that people are just often more interested in large carnivores. So I'd be curious to know if there's one area of research he'd like to see more of.

For me personally, it'd be more on if dinosaurs lived in groups because there's a number of studies, often about bone beds. But as David Holm points out, they only preserve this one moment in time and they don't necessarily represent what that animal was like for most of its life, let alone what its relatives were like. Yeah. And the group thing is interesting because I know on the show we often say,

Seeing a bunch of fossilized dinosaurs together doesn't tell you that they live together, only that they died together and fossilized together. But as he points out in the book, it doesn't even really tell you that they've died together because they could die separately and then sort of get combined together.

through either weathering or just stratigraphically. They could have died years and years apart, and it just looks like they died together because there are fossils close to each other in the rock layers. So it can be really misleading finding a quote-unquote group of dinosaurs fossilized together. So you think that they're a group of animals living together, but that is often not the case. Yes. And then

That sometimes gets extrapolated to like, well, all these types of dinosaurs did this kind of behavior. Yeah, I thought that was a really good point, too, talking about, say, Deinonychus and Tenontosaurus. There are so many examples of all these dinosaurs.

Deinonychus teeth next to Tenontosaurus fossils. So the obvious assumption is, well, if there's all these shed teeth, that means that they were probably using those teeth on the Tenontosaurus. And that has been extrapolated into Deinonychus is hunting Tenontosaurus, which really you can't say. Although there is some good slash, I guess you feel bad for Tenontosaurus paleo art that

That depicts De Niro attacking or a pack of them attacking. Yeah, it does really get the gears turning. But I liked one of the things he said about it was that rather than saying predator prey with these different animal...

assemblages whether it's tenontosaurus and dynonicus or triceratops and t-rex or anything we should really say carnivore and consumed rather than predator prey because that includes whether it's either actually predating on the animal or if it's just eating it in another context most likely being scavenging or i guess just waiting for it to die in another way and then eating it

Because if there's a bunch of teeth around, it was probably eating it, but you can't really say for sure. Right. And then, like you were saying, a lot of times that gets extrapolated into raptors were pack hunters. Yeah. Because Deinonychus was shown to maybe eat Tenontosaurus in a group sometimes, which is just quite a leap because...

Even looking at modern animals, right? You've got just big cats where some of them hunt in packs and some of them don't. And they're really closely related. Some of these raptors lived tens of millions of years apart, totally different parts of the earth, were completely different body sizes.

There's no reason to think that they all behaved the same. So yeah, you're right. Extrapolating things from one specific genus to an entire family of dinosaurs is a really risky thing to do. I can see why it happens though. Yeah, because you have so little to work with. You got to use what you have and it might still give you the best guess, but you got to really be realistic about how certain you are of that fact.

All right, we'll break down and discuss each chapter of the book in just a moment. But first, we're going to take a quick break for our sponsors. It's your last chance to get your limited edition Allosaurus patch. Fun Allosaurus fact, there is evidence of Allosaurus cannibalism. It's unclear if Allosaurus killed each other or just didn't pass up on an easy meal.

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Again, to check out the new Allosaurus patch, sign up to get your own, or update your mailing address, head over to patreon.com slash inodino. That brings me to a quote from the preface.

We can get into each chapter separately in a moment, but in that beginning, Dave Hohn explains how we can't track or watch a non-avian dinosaur to see how they acted. So we do have to infer what they did from limited evidence and quote, therefore, always with at least a grain and sometimes a full cellar of salt. Yeah, very true. I have a couple of thoughts about the preface too.

I was a little bit worried at first because the preface talks about being unapologetically more focused on big carnivores, which isn't surprising because Hone is a big T-Rex guy and

So I was worried that, you know, my favorite, the ankylosaurs, and your favorite, the sauropods, might not be covered as much. But then I noticed that in the acknowledgements, they start with Victoria Arbor, who is the world's leading expert on ankylosaurs. It's probably because the list is alphabetical, but I think it could also be because Victoria Arbor is great. And there's a lot of good ankylosaur stuff in there. There is. Probably the alphabetical, though. Yeah, I think it's alphabetical. Yeah.

So going into each chapter, we'll start chapter one, an introduction to dinosaurs. Another quote I liked is how dinosaurs have, quote, become central to the study of the history of life on Earth. It makes sense since if you're talking about the study of life on Earth, dinosaurs

In terms of life on land on Earth, dinosaurs have dominated it most of the time. I remember doing a fun fact about that because the first tetrapods on land, if we're talking about vertebrates on land, it's like roughly 300 million years ago. And dinosaurs started dominating around 240 to 200, depending on how you count, up till 66 million.

So it's a large chunk of the pie of tetrapods on land were dominated by dinosaurs. Yes. If you're studying the history of life on Earth, definitely dinosaurs are going to be a big piece of it. Plus, we know fossils of dinosaurs from every continent. Yeah. And they're still on every continent. And there were so many of them. There's about 1,500 valid genera now of dinosaurs, even though the number, as we know, grows every year.

New ones are discovered almost every week. I mean, that's how we started this podcast. It was really interesting seeing a little bit of the breakdown, too. There's three main clades, the theropods, the sauropodomorphs, the ornithischians. But apparently, theropods have the most and sauropodomorphs have the least, which probably could have figured out from all our dinosaur of the days, but I haven't quantified it in that way.

Yeah, I was a little surprised by that too, because I feel like they're constantly getting names for new sauropods. Obviously, theropods is going to have the most because it includes modern birds. So you're going to have... Oh, but he wasn't including birds. Yeah, but even if you're just using mesozoic birds, there was just so much diversification in all the different flying little dinosaurs and all that kind of stuff. So the theropods being the broadest one wasn't that surprising to me. But...

It was slightly surprising that it's more than Ornithischia if you're going just Mesozoic because that has the huge group of all the herbivores when you've got things like Ceratopsians, but also Hadrosaurs and Ankylosaurs and every other plant eater basically. But sauropods being at the bottom, I guess, is a little surprising. I thought it was interesting too. He said there's strong evidence that many dinosaurs migrated annually. Yeah.

Because that's something it comes up for us occasionally, but not that often. Yeah. Strong evidence was surprising to me, too, because there are those isentope analyses that look at, well, in this, say you're around more saltwater versus freshwater, that changes some of the isotopes, eating different types of plants and how far...

regionally you stray can change the isotopes in your bones too because you are what you eat so there's definitely evidence of migrating but i don't know about strong evidence because they're usually pretty big error bars on those isotope analyses and a lot of times they overlap so yeah you gotta go through all 400 references yeah that's true i mean i think we've talked about a

When you were talking about dinosaurs being on all of the different continents and just how widespread they were, it also reminded me of a couple notes he had about other archosaurs. So mentioning that alligators have a great tolerance for cold temperatures was really surprising to me. Yeah. And it also immediately made me think, oh, I wonder if that's related to them surviving the mass extinction. I had the same thought. Because if you...

Yes.

I also thought it was really interesting that he said turtles might get classified as archosaurs soon. Of course, he brought up turtles. But

But isn't that surprising? That is surprising. Because archosaurs have always just been dinosaurs, pterosaurs, and crocodilians, as long as we've been talking about them. If there's also turtles in archosauria, that would be really interesting. And then I wonder if people would start doing studies on turtles or using that as part of the phylogenetic bracket, because usually... Oh, and how they acted? Yeah, exactly. How dinosaurs acted? Usually it's like, okay, we looked at a chicken and we looked at an alligator, and they have these things in common, and therefore...

If they both do the same thing, that means dinosaurs might have two since they're the living descendants from a more basal ancestor than dinosaurs. Maybe we'll find some more similarities between sauropods and turtles. Maybe. Yeah, one could hope. I don't know about all that, but it'd just be interesting if turtles got lumped into the dinosaur research somehow. They're really weirdly specialized though, so I don't know. Sure. Well, we'll see.

I thought it was interesting he brought up dinosaurs having asymmetric ears, which would allow them to pinpoint the directions of sounds effectively. And then that would be important for animals that are in low light conditions. Yeah, we've talked about that with alvarosaurids. Yeah. Where they're hunting for termites and things like that. I just always forget about asymmetric ears. Yeah. Basically like an ear that's higher up on the head on one side than the other. Like an owl. Yeah.

There was also a reconstruction of Baryonyx with lips, which was very surprising to me because I always think they're so crocodilian and crocodiles always have their teeth exposed and spending so much time in the water. But I guess Baryonyx might not have been all that aquatic, especially if you're in Dave Hone's camp. So maybe that's why he stuck lips on him. Maybe.

It also ended with some large gaps and areas of uncertainty in our understanding of dinosaurs and brought up some questions that I haven't thought about in a while. Like, how exactly did they divide up parental care? How much water did they need? Yeah, because birds, I think, don't need that much water because they have that interesting way of handling uric acid. But we really don't know what dinosaurs. Yeah. So there's a lot of reminders of what we don't know or don't yet know.

But it's good to keep in mind how influential dinosaurs were to their ecosystems down to the gut bacteria and how they affected the lives of much smaller animals, which we have talked about on the show a little bit, especially when we see it in sometimes in books or different media. And you've got like the mammals doing their own thing or the ants doing their own thing. And the dinosaurs are affecting them, but the dinosaurs have no idea. Yeah, that's very true.

So that brings us to chapter two, studying dinosaur behavior. And apparently I like quotes because I keep writing them down. But...

I liked what Dave Holm wrote, quote, dinosaurs would have eaten, slept, bathed, groomed, courted, mated, built nests, laid eggs, walked, climbed, swum, and in some cases flown, called, defecated, regurgitated, learned, fought, played, migrated, hidden, and hunted at various times in their lives. But how many of these behaviors can even be captured in the fossil record?

A couple. Oh, yeah. The fighting and the pooping. Maybe the migrating and climbing. A little bit. It's the sort of direct versus indirect capturing. The nests.

sleeping there are some well it looks like they're sleeping yeah a lot i mean all of them can be fossilized in some way in other words pieces of it can be fossilized but whether or not you can tell that that's definitely what was happening is a completely different question yeah because like we were saying the fossil only represents that moment in time

And when it comes to skeletons, it's the moment the animal was buried, not necessarily the moment it died even because you get the death pose. That's not what it looks like when it died. Very true. It's more like a rigor mortis type situation. Yeah. Trace fossils help like footprints, but you can't usually figure out what dinosaur made the footprint. Right.

And then there's biases in the fossil record. Like, it's hard to find dinosaurs that lived in the mountains. Juveniles don't preserve well because they're more likely to be eaten. And there's biases in what gets found, excavated, and published about. Because like we were talking about before, people like the large carnivores a lot. But, you know, we talk about hadrosaurs a fair amount on this show and they don't get as much love. I thought it was really interesting how he brought up, even with living animals, things can get weird.

For example, crocodiles sometimes eat fruit. And if that happens, you know, how much weird stuff happened with dinosaurs? Yeah. Yeah. And when you're looking at a fossil, you're just looking at one example of something. And I don't know specifically if it was in this chapter. It might have been mentioned more than once. But something like the fighting dinosaurs, right? It fossilizes and you assume, okay, yeah.

The velociraptor is preying on the proto ceratops. Actually, I think it was probably in the dinosaur feeding chapter, but really it's just telling you that these two fossilized fighting and it could be that one of them was defending itself. It could have been that one of them just.

was attacking something way larger than it normally would have because it was really desperate or it had something going on that was making it make really bad decisions. Yeah. Or any number of different reasons why this may have happened.

One example, too, was that maybe they were sort of wrestling on the sand that collapsed on it. So it could even be that, you know, it had to do with the environment around them that they got stuck together and then that led to a fight somehow. So it's so difficult to infer something about the dinosaur behavior of a species when you're only looking at one individual. Oh, yeah.

And going back to the food, because I love my gut contents, we might find seeds in one dinosaur's stomach. And that just tells us that at least once it was eating them. But like you're saying, it's hard to say the whole species. Although I have read a number of studies that talks about seeds or fruits found in the gut contents. And the idea was, well, it seems like they were eating them at different times of year, which would make sense. Yeah.

Yeah. Yeah. Cause there's not always fruit available, but even if you're mostly eating meat and then it's fruit season, there's just a huge abundance of fruit everywhere and you could use those vitamins. Might as well eat a little fruit. Yeah.

I also thought it was interesting, and this is something that's been coming up more and more in the papers that we've been reading lately, is how some terms are undefined, like social behaviors can mean a lot of different things. Yeah, there are so many terms that really need to be defined because they can mean different things to different people.

another one is semi-aquatic, right? Does that mean that they're spending almost all their time in the water and just coming out to lay eggs? Or does it mean that they spend almost all their time on land and occasionally go in the water to like grab a fish or

Because that's a very wide spectrum because then you've got a grizzly bear on one side of semi-aquatic and on the other side, you've got a seal or something. And calling them both semi-aquatic is technically true, but it's better to use more specific language so that you can say semi-aquatic and we're talking about animals that spend...

most of their lives in the water only coming out in these situations. And I think Dave does a good job in most of his papers of really being very specific about the language. And that was one of the points in this book was that when you're talking about dinosaur behavior, don't just throw out a hypothesis because you see something on the bone that might indicate something. Try to be more specific and more

clear on what your hypothesis is, why you're making it, what all the evidence is for it, and then specifically what you think that behavior would have exactly been like. Yeah. Just really narrow your focus. Yeah. And be precise with the language so that other people can either try to refute it, which is mostly what science is, or if you find another dinosaur or another piece of evidence later, you can build on it. Yeah. Yeah.

So that leads us to chapter three, the basis of dinosaur behaviors. And the three kind of main things that they brought up were movement, posture, and physiology. So what they're doing in their daily lives and what they could or couldn't do. And we can do things like scan inner ears, figure out if the dinosaur could hear high or low pitches, and then compare it to reptiles and birds and find some correlations with maybe how social they were or...

how vocal they were, although it's really hard to figure out the correlation in birds and modern crocodilians, which are much smaller and how they work, you know, when you scale up to huge tyrannosaurs and sauropods. Yes. And talking about that with how modern flightless birds even might seem like they'd be a better analogy for dinosaurs, but really there's such a weird specialized group, the flying dinosaurs, the birds,

And then there's another specialization on top of that going back to the land. And so many of the features of the non-avian dinosaurs were lost in the translation that it's very likely that their behavior is quite a bit different than the non-avian dinosaurs.

I thought it was interesting, again, going back to the idea that dinosaurs are only found where they're buried, not necessarily where they usually spent their time. And how sometimes dinosaurs can be abundant in an area but rarely preserved and vice versa. And one of the examples was ankylosaurs.

They might have preferred coastal environments because they're more commonly found in marine sediments. But that could be because of local extinction or just the absence of various clades in certain regions. I like to think that they spent a lot of their time up in the mountains, and that's why we don't find that many of them, but they were actually very abundant. It could be. It could be.

how warm could they keep themselves? I don't know. Well, they're endotherms, so they keep themselves warm. They got very thick skin that would also help to keep them warm. True. Well, another thing he brought up was how ankylosaurid and nodosaurid bodies, so the club tails and the non-club tails, seem to float differently. So maybe they got washed into channels and then traveled different distances, which would make it really hard to figure out how they lived or where they lived.

Yeah, the specifics on bloat and float. How long do they float once they bloat? Is there a difference? One might note. Let's make it Dr. Seussian. I was thinking you were thinking of Dr. Seuss. We've been reading a lot of Dr. Seuss too. So yeah, that's the chapter with the case study on Spinosaurus. If you wanted to skip ahead a little bit.

There's also a very cute picture of a hypothetical sleeping T-Rex posture. Oh, yeah. In that chapter, which is pretty enjoyable. Yes. Those two things alone are worth reading the chapter for sure. But I did like how at the end of the Spinosaurus case study, he talks about, well, it probably was like a giant waiting bird, a flightless one, which isn't surprising because...

All of the papers that he's authored or co-authored have said these things. Numerous, yes. But he did say he's still open to other possibilities and that we just need more data. He's a good skeptic. Good critical thinker. One of these days, Nizar Ibrahim will come out with the papers he keeps teasing us about. Yeah, and maybe if there's good enough evidence, Dave will be a co-author on...

pro swimming around all the time. Pursuit predator. Yeah. Maybe. I don't know about pursuit predator. He was throwing a lot of shade at that. Oh, well, we'll see what happens. So yeah, all of these things I think are just a good example of dinosaurs being a gateway to science, which we talk about a lot. So chapter four is group living. And that's one of those things where there's no clear term or definition for what it means to be in a group. Um,

You could be aggregated. They're just there together. Even some antisocial species will come together to mate. Like they've got a picture of some snakes that'll shelter together in the winter. Then there's gregarious. You're coming together maybe for migrating or mutual protection and you tolerate each other, but you don't necessarily have formal groups. And then you're social where you are living in groups and you have the social structures that go along with it.

Which I hadn't thought about before because a lot of times we see the term specifically gregarious and I think, oh yeah, friendly. But it's more nuanced than that. Yeah, it can be like Komodo dragons doing a feeding frenzy together and occasionally eating each other. Not so friendly. No. And then looking at the different groups too, this goes back to if you find bone beds,

With some modern animals like Cape buffalo, it might look like a large group, but it's actually multiple smaller herds traveling together. Something else I hadn't thought about with dinosaurs. Yeah. Yeah. Like a temporary group, sort of a Voltron situation. They just come together to form a big powerful combo temporarily and then go their separate ways. Yeah. Yeah.

And one of the reasons that they might go their separate ways is because for that short-term time that they're working together, it can be beneficial, but then they do need more resources and it takes longer for everybody to eat. Then you got to move farther to find food compared to being in a smaller group. So that makes sense. Yeah. This is something I noticed most research papers, most authors are pretty good about is you might find adults and juveniles and even babies together, but

And I don't think anyone says this was a family of dinosaurs because we don't know for sure. Oh, yeah.

Yeah, there are some very limited cases. I think with Musaurus and Myasaura, there was some inference of maybe them being a family because you've got from basically very young hatchlings to adults. And the presumption is that, okay, the adults are looking after their own young because that's usually what animals do. So I think sometimes people will say this is likely a family and likely the parents are

But in general, you're right. What they would just say is they would classify it as a multi-generational is the closer term. Or you might just say that it's not age segregated. Yes, which is good, even though I would like to think that they're the dinosaur families traveling together. Yeah. I mean, they could still be a family in a way, right? They're like choosing to spend time together. True. And even in the case of Ness,

One of those interesting points is that just because all the eggs are in the same nest doesn't mean they're all from the same parents. Because occasionally birds will combine eggs into one nest. So even in that very specific, it seems like a slam dunk. Oh, these are all siblings in this nest together. Might not be the case. And they might not even all be the same species because there could be nest parasitism going on. That's true. So there could be.

like how cuckoo birds do it. Somebody's sneaking their egg in with the other eggs. And I remember there was a hypothesis that he mentioned in there about maybe the reason that

dinosaurs developed colors for their eggs was so that they could tell the difference between their egg and a nest parasite. Because if you only lay blue eggs and then there's a red egg in your nest. Yeah, that's a sign. How'd that get there? Check it out. And we can now tell that because of melanosomes and some of the other

Pigments. Yeah. I thought it was interesting. He said crocodiles and birds can form groups. So dinosaurs would have had the capacity because they've all got the same common ancestor. Yep. That's that phylogenetic bracketing that you can do.

And maybe turtles too. I don't know. Maybe. I might have to learn a lot more about turtles. Yeah. Just like how we had to do with psilosaurids. That's the chapter two at the end to talk about all the details about the Tenontosaurus Deinonychus evidence. Yeah. If you want to check that out, including a map of a bone bed that really shows the details. Oh yeah. Of where the bones were and where the teeth are. I also thought it was interesting.

He's talking about when it comes to groups. And like I was saying, sometimes it's not helpful to be in too large of a group because you need more resources. And same goes if you're large yourself, like sauropods got so big and they'd be too big for predators in a lot of cases. And they themselves would need a lot of food, but maybe they didn't need the extra protection. So there'd be no benefits for them being too social. Yeah. There's always a cost with these things. Yeah. Yeah.

The next chapter, chapter five, is signaling. So ways to communicate and signal. Signal other animals, meaning. Yes. And these signals are sometimes the way they look. There's positive signals like dominance and sexual identifiers and the negative signals like threat or warning displays, as well as anti-signals like camouflage. Yeah, I like those terms. I don't remember seeing positive and negative signals before, but I like that specific detail. Yeah.

But I also hadn't thought of anti-signals as a signal itself either. Yes, it's sort of like the evolution of not a signal. Yeah. We've talked about it before in terms of like coloration, right? Like you could be bright orange and show off for potential mates or you could be brown and

And blend into the background. Or counter shaded. Yeah. Yeah. Don't look at me. Don't interact with me. Yeah. There were also. He talked about honest signals. Like the size of a horn. And then dishonest signals. Like an animal puffing up to appear larger. Yeah. I really like the honest dishonest signal thing too. I mean in dinosaurs. In paleontology at least. These don't come up that much. Because those types of signals. Those behavioral signals. Like puffing up.

don't fossilize. Yeah. So we haven't really talked about a lot of these things before. But so many birds puff up. Yeah. But coming from an ecology standpoint, it makes sense that you would talk about it. There were a couple other honest signals too, like

I think he was talking about pronking the thing that antelope do, which is basically like when they see a threat, a lot of antelope will just like spring up into the air, like jump really high. And nobody really knows for sure why they do it. But one of the hypotheses is that it's an honest signal that's basically the antelope showing I can jump really high and I can run really fast. Yeah. So don't bother chasing me. Yeah. So it's just like an immediate like, look at me. I'm very physically strong.

skilled and adept. Don't mess with me. So just leave me alone. Yeah. Let's not waste each other's time. I also thought it was really interesting how things that we normally talk about as like weapons or armor were probably signals like plates and spikes on stegosaurs and ankylosaurs. Yeah. Well, they can be both too. Yeah. But maybe they started off as signals and then turned into a weapon and armor. I mean,

It's complicated, right? Because we know that the Ceratopsians, for example, use their horns as weapons against intraspecific rivals. And that was another point in the book that most of these signals and most of these weapons and all this kind of stuff is evolved for intraspecific interactions. Yeah. And I liked the point of if you think about it, if you're going about your life and you're eating certain things and you're hanging out in certain areas, the most likely thing

animal for you to compete with is another animal in your species because you're going to be eating the same things. You're going to be looking for the same mates, the same pool of mates. All the stuff that you do is the most similar to people

Or in our case, people. But in their case, other dinosaur species. Right. That are the same species. So you're going to have to fight and sort of defend yourself the most against your own species. Whereas when you talk about it in pop culture, it's always like, oh, it's T-Rex versus Triceratops. Right. But really, most of the time, it's T-Rex versus T-Rex and Triceratops versus Triceratops. Well, speaking of Tyrannosaurs...

Another signal could be touch. And there's that whole study that about Tyrannosaurs might've had sensitive snouts or at least Displeatosaurus did, but, uh,

Having a highly sensitive face could be a problem because there's a lot of face injuries in large Tyrannosaurus. So it's unclear how sensitive it was, at least for the group. Yeah. And they also talked about the low and high cost signals, too, because some of the low cost signals could be things like just making noises. Yeah. Whereas high cost signals are the ones that are like, you know, growing huge horns or frills or something to that effect. Yeah. Yeah.

I also think it's interesting talking about Triceratops and T-Rex. We have a lot of evidence of Triceratops horns scratching other frills, or at least a fair amount of evidence. And there's a ton of evidence of T-Rex biting each other. There's all these holes in each other's faces from biting. But there isn't a ton of evidence of Triceratops-T-Rex interactions. There's a little bit, and there's some feeding evidence.

as I should put it, carnivore-consumed interactions. But there isn't a lot of fighting evidence between the two. Well, and speaking of T-Rex too, there doesn't seem to be a lot of these facial injuries for juveniles. Oh yeah, so it shows you the changing as it grows up. Yeah, and related to that is chapter six, reproduction. That includes mating, yes, but also nest building and parental care.

And I thought it was interesting, the different ways to reproduce. There's the R strategy where you have a lot of offspring, but you don't really invest in them. You don't really take care of them. Sauropods. Some, at least. Yes. And the K strategy where you have fewer offspring, but you invest a lot into them. Like Oviraptor, maybe.

Maybe. Or maybe actually maybe more like T-Rex or something. Presumably some of the big predatory animals that might have had to teach their young or maybe even something like Musaurus where you see a lot of them multi-generational potentially in one area. Yeah. Or dinosaurs could be somewhere in between where a lot of them have a lot of eggs, but they still care for them after they hatch. Mm-hmm.

Yeah, because there aren't very many nests with just like one egg that have been found. Well, I guess two because they had the two ovaries. So they were laying pairs of eggs. Yeah. Which brings us to the point of when you mate is important because you want the eggs to hatch at the optimal time. And so depending on where you live, you might have to time it so that the eggs hatch in spring. Yeah.

Or maybe you live in an area that has better weather, so you are more flexible in your timing. You already brought up the stegosaur image. Yes. There's some good questions he brought up too, like maybe sauropods could rear for mating, but could the female support the extra weight of this giant sauropod and would it damage the tail? Yeah. We don't know.

I think eventually there's a paper that's going to come out about that, but we're still waiting. Yeah. That might also be, I think that was one of the few ones that wasn't cited. I was looking for a reference for that point and he was a little bit more vague on it because. Well, if it's not out yet. We all know about it, but it hasn't been peer reviewed and published yet. Going back to the phylogeny bracketing.

Apparently most, although not all, crocodilians have parental care after hatching, which I didn't realize. And the same goes with birds.

mostly both parents are taking care of the baby birds. Yeah, I was surprised by that. I didn't realize both parents were involved with most birds. I did know about the birds. We read some studies on that. Didn't know about the crocodiles. So then it does seem likely that most dinosaurs took care of their hatchlings. Yeah. And like we were saying, there is some evidence that we've seen things like myosora. But it's also like, what does that mean? Because it could be they help them leave the nest and then they're done or they teach them to forage, which takes a lot more time.

But in the case of myosora, it seems like they were probably helping them for a while because they were getting older and it didn't seem like their bones were developed enough to really take care of themselves. Yeah. And they were still hanging around the nest area. Yeah. Yeah.

Chapter seven's all about combat. That was a fun one. As Dave pointed out, all dinosaurs would have fought at some point, but for some of them it was rare and others it was the norm, either between themselves or other species. Oh yeah, that was where he mentioned too that it's usually among themselves. Yeah. And there's also this ritualization aspect that's important. And you can have these behaviors evolve where animals are assessing their opponent before they start engaging in the fight.

So maybe large theropods did this. They're looking at, okay, what's the risk? How likely am I to get injured or die? That is one of the most interesting things in nature documentaries to those moments when the animals are sort of sizing each other up and deciding whether to even go through with this rigmarole.

And watching them, clearly they see things that we don't see. Right. Because they're looking at the size of the other one's tusks or, you know, the way that they're moving, the subtleties of their bodies. Yeah. Whereas we watch it and we're like...

Oh, they're going to fight. And they look the same size and like, I have no idea who's going to win. But then they walk away. One of them charges a little bit and the other one's like, okay, I'm leaving. Yeah. You're like, oh, okay. So presumably dinosaurs do the same kind of thing. Yeah. But it's just hard. That's one of those things that you would never fossilize, right? Right. A retreat. And then, you know, anything can be a weapon.

It could be the things that are obvious, like the claws and the teeth, but there's also the quote-unquote tusks of heterodontosaurs. Yeah, I wrote that one down too as an interesting thing. I never realized that the tusks on heterodontosaurs were considered weapons. It's one of those things where its main function might not be related to weapons at all, but you use what you got.

Or maybe it was because it does seem like why does Heterodontosaurus need these tusks? It's such a strange feature to have on a maybe herbivorous or omnivorous dinosaur. Yeah. And certainly things like elephants with their tusks use them as intraspecific combat. So it makes sense.

I liked the case study for this chapter about how ankylosaurs seem to evolve their tail clubs not to fight other species, but to fight each other. Mm-hmm. Which I guess goes with, we saw that Zool exhibit years ago. Yep, that's a Victoria Arbor paper. Mm-hmm. Basically, that Zool had the broken osteoderms on the side.

Where you would expect them to be if they sort of backed up towards each other and then bashed each other. Speaking of rituals, too, like why wouldn't one of them try to hit the other one in the head? It's like, well, because it's not really about trying to kill the other one. Right. It's just about trying to win the battle. Over territory or...

courtship or whatever. Exactly. It's like you don't need to kill the other one to win the battle. And it's better off not killing all of your species. You may not hate each other. You might just want to win this one occasion. Yeah. I also thought it was interesting he pointed out

A different group of dinosaurs, hadrosaurs. Maybe they body slammed each other and broke ribs and tails. And that could be some of the pathologies we see. But it's really hard to figure out just from fossils alone how that pathology happened. Yeah, because some of those, I can't remember which dinosaur groups, but some of them you do see a lot of broken ribs. It's like, why are there so many broken ribs? It's like, well, I guess it could make sense if they're body slamming each other, not just clumsy and falling down, which is what we usually assume with the broken ribs. Yeah.

So next up is chapter eight, feeding. Of course, we know all dinosaurs needed to eat, but what did they eat? When did they do it? Why? How did they forage? How did they eat? Was it accidental that they found their food? Was it deliberate? Were they eating occasionally, frequently? Yep. So many questions. One thing I found really interesting in this one was the body size determining herbivore diet. Because basically the...

analogy is if you're a huge dinosaur, you can eat a whole bunch of low-nutrition animals

plant food, but you've got such an enormous gut that it functions more or less like a compost heap and can digest and get most of the nutrients out of this low caloric value food. And it works just fine. It's a quantity over quality situation. But if you're really small, you don't have that time in the gut to digest this low quality plant life. So instead you have to be really selective and find seeds or shoots or some of the more nutritious nutrients

plant life that's out there. It might be in smaller quantities. It might be a little small pieces, but that's okay because you're small. So you can pick through the food, find the best pieces, eat those, and your body will be able to digest it. Yes. There was also the idea of looking at limb lengths to figure out. So hadrosaurs that have been found in what were coastal regions had shorter arms than ones that were more inland. So the ones living on the coast, maybe they were more bipedal and foraged at higher levels. Mm-hmm.

Yeah, that was interesting. Yeah. And then carnivores, that's something we talk about a lot. It's like, it's so hard to know if they were actively hunting or if they're scavenging. Yeah, that's that carnivore consumed instead of predator prey dichotomy. Yeah, because you need very specific evidence for predation or attempted predation.

You need to show that the marks on the bones have healed. So you know that the prey animal was alive when it was attacked. And then for scavenging, you need evidence that the animal was dead and went through a process like being transported before it was being eaten. Mm-hmm. Which is so hard to know. It is.

Yeah, I think one of the best ones for showing predator-prey relationships is that healing because then it shows what was attacked by this dinosaur. It's got like the tooth marks that are consistent with this predator on it and then it healed. So it's a failed predation. You kind of need the failed predation to really accurately show that.

if the animal dies, if it's successful predation, it looks the same as if it was scavenged. Right. Because it's just, well, you're just chewing on a dead animal that didn't heal afterwards. And that could happen either way. And that's what most of them are. But then you've got like fighting dinosaurs. That's a failed attempt. Velociraptor did fail to get that Protoceratops.

But we don't actually know what was going on there. Yeah, you don't know specifically that it was an attempt at eating. Yeah. Because it's more like stabbing it. It's not really chewing on it. Yeah. The Protoceratops is the one that's biting the Velociraptor. And we don't think the Protoceratops is trying to consume the Velociraptor for food. But it was grabbing at it in some way. Yeah. Well, the Velociraptor was sort of like stabbing at the gut of the Protoceratops. At least that's what it looks like. Yeah.

Yeah, so a lot of questions to consider.

for all these things, a lot of nuances to take into account. Yeah. I also liked the assumption. I would say that maybe the reason that there are a lot of tail injuries on some dinosaurs, especially the herbivores might be because hunting was happening by chasing. And as you're chasing a dinosaur as another dinosaur, they had such long, rigid tails that stuck up at like approximately mouth height and,

that you might snap onto that tail. Right. And if it got away, that might be a really common failed predation, just like damaging the tail, but not quite taking the animal down. Right. Or the tail got damaged some other way. It hit a tree or something while it was running away. Yes, that's true. That's the other side of the coin. It doesn't necessarily have to be a failed predation, but it would be cool if that was where some of it came from. Yeah. So that brings us to chapter nine, the summary chapter.

And it's like we've been saying all along. And what I think the main point of this book is, is that it's really hard to interpret dinosaur behavior. But you can still learn a lot. Yes. That's the other piece of the main point. Yes. And also just be careful how you interpret evidence. Don't be misled and make big generalizations. But on the flip side, like you were saying, Garrett, we've made so many advances when it comes to science, like

Studying isotopes from teeth, that's a relatively new thing. You get environmental data from rocks. You get all kinds of new information now. Gut contents seem to be appearing more and more in the research papers, which I'm a fan of. And just a lot of fossils have been found since people first started studying dinosaurs. And having a lot of skeletons of the same species helps to confirm some things.

And the fact that it's becoming more multidisciplinary and looking at it from different angles and points of view. Yeah, that's my favorite. But we do have to accept there's always going to be gaps. Yeah, you can never be 100% certain about most of this dinosaur behavior. Right. And we might never know anything about like the quirky behavior because that's a lot more rare. Yeah. And some of the things that, like they said, a dinosaur might only do once or twice in its life.

are unlikely to fossilize like dinosaur mating yeah really really unlikely to fossilize and even if it did fossilize you probably wouldn't be able to know for sure that that's what was happening right you wouldn't be able to rule out the alternatives in other words it's like was it mating or was it just laying down for another reason

I did want to mention the appendix is a really good resource because it talks about all the different dinosaur clades and it lists them, has brief descriptions and gives a lot of good basic information about the different groups. So if you want an overview of that, it's a good starting point.

And the 400 references are also very useful. Yes, if you want to dive even deeper. Yeah, that's why I think it's a very good state of the science in terms of dinosaur behavior, what all the research is without being a thousand page long encyclopedia. It's a easy read in terms of

getting all the information to you. And then if you really want to dive super deep into any of the topics, you easily can by going into the references and just grabbing whichever article it is. Oh, yeah, definitely.

So a great read for us dinosaur nerds. But you know what? Also a good gift, especially if you're trying to get more friends and family into dinosaurs. Yeah. Yeah. Especially people that might be interested in animal behavior. Say they just like learning about, you know, watching planet Earth or something like that, how these animals are interacting with each other.

We don't have videos of dinosaurs doing that, but this book is a pretty good example of a lot of the behaviors they might have done. And there's good illustrations to go with it. So definitely recommend it. Yes, what they did and how we know. Yeah, uncovering dinosaur behavior. And again, for our dino-idols,

We have set up in our Discord, in the books channel, a place to discuss this book even more. So you can join our Patreon and our Discord, sign up at patreon.com slash inodino. And thank you so much to Princeton University Press for partnering with us on this episode and also sending us copies ahead of time so we could read the book thoroughly and talk about it here.

And we'll get into our dinosaur of the day, Gasparini Sora, in just a moment. But first, we're going to pause for a quick sponsor break. And now on to our dinosaur of the day, Gasparini Sora, which was a request from PaleoMike716 via our Patreon and Discord. So thanks. It was an Elasmarian or Nithipot that lived in the late Cretaceous in what is now Rio Negro province in Argentina in the Anacleto Formation.

Originally it was thought to be a basal hypsilophodont, and then later it was found to be an elasmarian ornithopod.

And Elasmarians, they lived in the Cretaceous in what's now South America, Antarctica, and Australia. And many of them used to be thought of as quote-unquote hypsilophodonts. I think of them as sort of like skinny little ornithopods. Is that a good description of Elasmarians? Yeah, it's also they had modifications in their feet and tail that helped them run faster. Okay, so little, scrawny, and fast. Yes, which might have been the differentiator for them compared to Elasmarians.

other herbivorous dinosaurs of their time. That was their niche. Gasparini's sora is closely related to Anabicetia, which we covered in episode 499. I would say it looks like how many early dinosaurs looked. Walked on two legs, it had a long tail, a somewhat long neck. It was small. It was estimated to be about 5.6 feet or 1.7 meters long and weighed 29 pounds or 13 kilograms. Although we don't know its adult size.

Okay, so it was a juvenile. Yes. It had a rounded head that was somewhat long and large eye sockets that were high up on the head and a long back of the head, but a narrow brain case. It had diamond-shaped teeth in the upper jaws with ridges to strip plants. It had short arms, long, powerful legs, and long feet. Which in dinosaurs, those feet are sort of the lower part of the leg a little bit too. Yes. The type species is Gasparinisora synchosaltensis.

It was described in 1996 by Rodolfo Correa and Leonardo Salgado. The genus name means Gasparini's lizard. It's in honor of paleontologist Zoma Brandoni de Gasparini. And the species name, Cinco Saltensis, refers to Cinco Saltos, the city where the fossils were found. And those fossils were first found in 1992. They found a partial skeleton with a skull that was missing most of the spine.

The holotype skull is well-preserved and nearly complete. And then they found a second individual with a tail and parts of the legs. And since then, more than 14 specimens have been described, but they range from juveniles to sub-adults, which is why we don't know the adult size. From juveniles to slightly older juveniles. Yes. One specimen was found with a puncture mark that might have been from a crocodilomorph. Ouch.

They were found in a group and maybe they were trying to drink from a drying out water hole and they were scavenged or maybe they got attacked while trying to drink. One of those things that's hard to know because it has to do with behavior. In 2008, Ignacio Serra described the gastroliths found with Gasparini Sora, the first quote, unambiguous record of gastroliths in an ornithopod dinosaur, end quote. Unambiguous. Yes. Yes.

The gastroliths were found in three juveniles. They found clusters in three skeletons in the abdomens. Some of those clusters had 140 stones. That's pretty unambiguous. Yeah. Gotta give it to them. And in one individual, they found two clusters of stones. And they found over 180 stones in the largest individual. And then in the second individual, they found more than 40 stones and clusters.

The average length of the stones was almost 8 millimeters and the largest was 17 millimeters. The total mass of the stones found in one individual was over 51 grams or almost 2 ounces. That's a decent amount of rocks in the stomach. For reference, 8 millimeters is like a third of an inch and 17 millimeters is what, like three quarters? Yeah, that adds up for such a small dinosaur.

They're considered to be gastroliths because there are a lot of them, and they were associated with the bones. They were found in situ in the abdomen areas of the skeletons. And in two specimens, they were found inside the rib cage. And they were found in clusters, as well as there were no similar stones in the area outside the skeletons. And the fact that there's three individuals all found with the same types of stones in their gut area all helps show it's gastroliths. There were no stones found outside the abdomen.

These gastroliths are estimated to be 0.3% of the body mass. That's based on estimating how much the individual weighed using their femur. So they're estimated to weigh 18 kilograms or over 39 pounds. Based on the number of stones and their size and the fact that Gasparini Sora was an herbivore, it's considered that they swallowed it on purpose to help with digesting. And they didn't swallow these stones accidentally.

They did have good teeth for chewing, but they still used gastroliths, maybe to get as much nutrients out as possible. So maybe they ate really tough food. Now, based on histology, Gasparini's sora grew up fast and died young. It grew quickly until it got to about 60% the size of the largest individual found. Again, not an adult, so we don't know their full size, but the growth wasn't continuous. It did slow down more after reaching a certain size.

So maybe it didn't get much bigger. The largest found individuals were still growing, just a lot slower. Other dinosaurs that lived around the same time and place as Gasparini Sora include sauropods like Nukensaurus, as well as some theropods. And other animals that lived around the same time and place included crocodilomorphs, snakes, and turtles.

And our fun fact, like I said at the top of the episode, is that sauropods probably didn't swallow gastroliths to help them digest their food, keeping with this gastrolith theme. This was published in a dissertation by Oliver Wings in 2004. The thesis was a deep dive on gastroliths, and it concluded that even more research is needed.

But it talked about lots of aspects of gastroliths. So gastroliths, just to kind of recap, they are stones in the digestive tract of living animals and stones in the abdomen area of fossil animals. The name gastrolith means, fittingly, stomach stones. Mm-hmm. Yeah, lith for stone and gastro for stomach. Yeah, and that term gastrolith was coined in 1854, although people knew about them much earlier.

For example, there are stones in crocodile stomachs that are part of many African myths. And ingesting stones is known as lithophagy. Stone eat. Yes. But gastroliths are not only good for helping to digest food, they also help make an animal more dense and help them with controlling their buoyancy. So they can float or sink or remain neutral, like if they need to stay underwater. Emphasis on the sink. Yes. It could also be if they're really hungry, they just try to swallow something.

Or maybe they need more minerals, or they need to detox after eating something toxic. Or they ate the stone by mistake and they thought it was prey. Or it was some kind of play, like practice for going after prey when they got older. Or it could be some kind of pathological behavior, like they swallow stones when stressed. But that's hard to know, even for living animals. That's sad. It is. It's hard to identify gastroliths.

Sometimes things are incorrectly thought to be gastroliths, but then they turn out to be concretions, which are hard, solid masses of sediments. Yeah. So in other words, during the fossilization process, these things that look like rocks that were swallowed form, but they're really just chunks of rock forming in that area. Yes.

Or sometimes they look like gastroliths, but they just happen to be buried with the animal. Yeah, that's why when you were saying the unambiguous one, it's because there were a ton of them and they were all in that one specific area where we expect the stomach to be and not in the surrounding area at all. Yeah, and gastroliths can look different depending on what they were used for and how long they were in the stomach. They do, however, tend to be found in situ.

as well as found in deposits with no other stones like it. And they're clustered together, associated with articulated skeletons, and they're preserved in the right spot, like in the rib cage. Yep. Yeah, if you find all of those things together, it's a good chance that it's a gastrolith. Yeah. Though Wings did an experiment that found gastroliths don't always stay in the abdomen area. So he did this experiment with the carcasses of two ostrich chicks. They both died from bacterial infections on the same day.

And he ran an experiment to see the taphonomy. So he placed one on the ground and one in a barrel of fresh water. And then at the end of the experiment, all the gastroliths were found isolated at the bottom of the barrel, detached from the carcass, and all the bones were still articulated and floating. Yeah. So eventually the bones would sink, but they would be totally not where the stomach used to be. Yeah. Yeah.

One of the chicks was the one that was on land, weighed about two kilograms, and the other that was in the water was 11 and a half kilograms. So it seems like if it's under 12 kilograms after a short period, in this case three to six days, the floating carcass makes it likely to separate gastroliths from the body. Good to know. Yeah. In case you ever have a floating ostrich carcass in water. Yeah.

There's a sort of an example of you need all of these things to be able to show that the gastroliths are gastroliths. But many of the times there might be gastroliths fossilized with a dinosaur, but you just can't prove it. Yes. Because they've just been scattered too much. Yes. With gastroliths, sometimes we also talk about them being more polished.

So he also simulated making a gastrolith with a rock tumbler, stones, water plants, hydrochloric acid, and pepsin. And he found out at the end that the stones weren't polished. So it seems gastroliths got polished in other ways, like maybe it was wind or changes in the sediments that it was buried in. Oh, I see. So it could have been before they were swallowed or it could be afterwards. Yeah.

Now, speaking of ostriches, ostriches ingest stones of various sizes. Adults typically hold one kilogram in their stomach. And on average, that contains several thousand gastroliths. Another thing I hadn't thought about. Yeah.

Yeah, that's a lot. Thousands. Yeah. I would have thought you'd want fewer of them that are larger for better grinding, but I guess not. Or maybe it's hard to find the right shape in a large size or swallow them, maybe. Well, actually, you don't want them to be too big. I'll start by saying he studied gastroliths in ostriches in Germany and South Africa and

All of the ostriches, all 347 of them had gastrolyths. That's a lot. I know chickens do too. They ate grass with stones and then they mixed together into balls of grass to prevent blocking of the pyloric sphincter. That's a strong ring of smooth muscle that lets food pass from the stomach.

So ostriches without access to these stones actually die of constipation. Oh, wow. That's why you need the right shape. And I guess so many. And gastroliths are also known in relatives from the Eocene as well as Moas from the Miocene. So maybe it's all about constipation. Just digestion in general it helps with. Yeah. Well, now for the sauropod bit.

Not many sauropods have been found with unambiguous gastroliths, though the number is in the dozens. Dozens, literally dozens of them. Yes, have been found with gastroliths. But scientists have found that the gastroliths weren't capable of acting as gastric mills, like grinding up the food.

Because they found in these studies that the weight of gastroliths was about 0.03% of the sauropod's body weight, so that wouldn't have helped them much. Yeah, not much of the food. Not a lot of grinding capable with so little. Yeah, they would need several hundred gastroliths to help with digesting. And they're often found with under 10.

So maybe they swallowed them accidentally or maybe they needed more minerals like calcium. It does seem like accidental seems like maybe the simplest explanation because they were eating nonstop, right? So getting one stone out of every couple hundred or thousand mouthfuls seems pretty likely. Well, it could be that things got destroyed or transported too.

With sauropods, maybe a lot of these gastroliths aren't recognized or collected or they got moved by scavengers or removed as part of the fossilization process. So you're saying that maybe sauropods did have gastroliths? Maybe, but after studying the sites of sauropods, it seems like the most simple explanation is they just aren't there. So it's a bit of a mystery. Gastroliths have been found with other dinosaurs though, like Psittacosaurus, the Ceratopsian. And Psittacosaurus had dental batteries. So...

Maybe their food was really rough or they needed more minerals. And then theropods like Cyanorthomimus and Cotopterax use gastroliths to process their food. So they appear in a lot of different animals.

Just not sauropods. Well, they do a little bit, but just not enough to help them process their food. I was thinking with the compost analogy, you don't need to grind up your compost. You just let it sit for a while. You might turn it occasionally and sauropods could turn, right? They might have still had a gizzard or something going on that they could sort of slosh around.

their food. I'm sure the intestines too, it gets moved around. Yeah. But grinding is not a requirement if you have a really long period of time for stuff to digest. Yes. And on that happy note, that wraps up this episode of I Know Dino. Thank you for listening. Stay tuned in our next episode. We have our end of the year wrap up talking about the biggest discoveries of 2024. And it was a good year. It was a good year.

We also, a humble brag here, got an award this year for our podcast, in case we forget to mention it in our next episode. We got the Hubhopper Best Science and Technology Podcast Award of 2024, and I want to thank everybody who supported us and all of the kind words we got. Yeah, now we're an award-winning podcast. Yes. Got it in just under the 10-year mark. Well, yes, I am very happy and grateful.

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