Exploring Dinosaur Behavior and Trackways

Alright, so we want to talk really about behavior and physiology of dinosaurs. We want to talk about how dinosaurs moved, how they ate, how their bodies worked. So that's really what physiology is, is, you know, how does metabolism work, how does how does their their bodies function from moment to moment. And, you know, there's there's only so many indications we can get of that for non-avian dinosaurs because non-avian dinosaurs aren't with us anymore, right? This is a lot easier if we're talking about a living wild animal, but with non-avian dinosaurs and any other extinct species, we have to deal with what sort of evidence we have remaining with us, all right? Now, dinosaurs left behind plenty of anatomical evidence of their existence, right? Bones and many cases of remarkable preservation, even including a mummified hadrosaur. However, there is actually another set of evidence that dinosaurs left behind for us, one that tells us something about behavior and about their levels of activity, and that's trackways. I think... Many of us are probably familiar with the idea that dinosaurs have left behind fossilized trackways. And yet at the same time, it's probably, at least, you know, the way I always thought of it as a kid at least, was that dinosaur trackways were the most boring dinosaur fossils to talk about. They didn't show you anything about what the animal looked like, right? However, At the same time, dinosaur trackways are really quite amazing. They tell us something that the anatomy, looking at the bones, the skeleton, the rest of the body, could never actually tell us, which is, how did that body move exactly? Actually keeping a record of that, right? So the trackways actually capture a few moments of that motion in stone for us. That's really amazing, right? And that can tell us not just about... how they moved and how quickly they moved. It can also tell us things about behaviors that they had. You know, it can tell us if they moved in groups. It can tell us if they if they move quickly, if they move slowly, etc. It can tell us what limbs they walked on and how they held those limbs. Alright? So this whole field of studying trackways, or really the traces that animals leave behind in the fossil record, is much larger than just dinosaur trackways. There are, it's really its own section of paleontology to study the the trackways that animals leave behind as well as their burrows, as well as other traces that they leave, like feeding traces that they might leave behind in the sediment. Trilobites, you know, the large arthropods that look kind of like horseshoe crabs, but with more pieces to their skeleton from the Paleozoic. They left behind lots of feeding traces because they would stir up the mud in order to grab worms that were living in the mud. And so there's a whole bunch of different types of things like this in the fossil record. It's, which does not really preserve the anatomy of the thing, but preserves really that behavior, that bit of motion that was there in the fossil record. So this whole field, the word for that field that was called in paleontology is technology. So, where does this word come from? How did technology begin? Well, technology actually begins with dinosaurs. So, the first time that there was really the realization that extinct organisms left behind tract ways, we have to go back more than 200 years ago to 1802. There was an 11 year old farm boy named Pliny Moody in Massachusetts, and he was preparing the fields in a in the autumn season, and he discovered right by a rocky overhang, there were tracks in the ground. And they were very large tracks, and they looked like the tracks of a bird with three toes on them. Pliny thought that was interesting, and so he sort of dug them up. He dragged these tracks in the rock home. They were actually in rock, sandstone actually. It's very common in Massachusetts. And... His family ended up using them as doorstops for a number of years. When he went to college in 1810, eight years later, he sold the tracks for a bit of money to the local apothecarist, Dr. Ello Dutch. Dutch thought they were interesting, and he decided he put them up in his apothecary shop to show to people who stopped by. And at some point, someone started calling them the tracks of Noah's ravens. We don't know if that was Dr. Dutch or Pliny Moody, but that's the story of the first known trackways that were found in New England. and were identified as, oh, these are something important, these are fossilized tracks. Now, in the 1830s, about 20 years later, a tradesman was splitting stones for sidewalks. This was a common thing. There wasn't really cement yet, and so people would instead split stones at quarries. And he found more bird tracks among some of the sandstone. This was just 30 miles away, Massachusetts still. He became interested enough to start looking around Massachusetts and figuring out where other sort of trackways could be found. He realized that they would only be found in sandstone, not in granite, not in basalt. Massachusetts has a wonderful... array of rocks in it. A local doctor walking through the neighborhood happened to see all the trackways that this tradesman had found laid out in his front yard and became excited enough, he started writing letters to the people he considered to be most notable scientists of the day and age. It actually took a number of repeated letters to finally get someone interested. Edward Hitchcock of Amherst College was really convinced that these were not very interesting tracks, just tracks probably of, well, actually he didn't even think they were tracks. He thought they were just sort of a mirage in the rock. When he finally saw it though, he realized that, wow, these must actually be tracks. And so he started publishing on this in 1836. So think about it, that's at the same time that Gideon Mantel is working on naming Iguanodon and other remains of dinosaurs from England. So Hutchinson, who was basically the first geologist of Massachusetts, really. He would have been a preacher, but he'd been overly interested in the natural sciences. His wife was an... an artist and who did figures for many of his publications and together they kind of produced this very rich artistic survey of the geology of Massachusetts and Hutchinson became really fascinated by these trackways He absolutely believed once he saw them that they were trackways and the idea that tracks could be preserved and left behind in the rock was for him really just sort of a really a huge shift in his worldview and he began to realize that all sorts of other behaviors that animals do might be captured within the rocks and he Because some of these tracks were really quite large, you know, I'll just sort of sketch out here, but I'll show a picture of what some of them looked like. Some of those trackways were really quite large, and at the same time, Richard Owen in England was describing the giant flightless birds of New Zealand, and Hitchcock thought, oh, these must be giant birds, just like those birds in New Zealand, in fact. And that was an idea that he took right to the grave with him, actually. He did not desist with the idea that these giant three-toed tracks were the tracks of birds. However, these rocks were Triassic. There are other tracks as well. There was also a five-fingered track that looked kind of like this. People thought that looked like a track of like maybe a bear or a dog, particularly in that the last digit sort of seemed a little off in it. But these five-fingered tracks, no one knew quite what to make of those. Through the work basically of Hitchcock, the doctor who'd been writing the letters, the tradesman who'd identified where all the different places the best- fine trackways were, Hitchcock was writing monographs right up into the late 1850s and the late 1860s about all the different trackways that could be found in New England. And he invented the word ichtnology. He initially called it actually something like ornitho, which means bird, ichtno, which means trace, so like a trace or like a burrow or a footprint. That's basically, I think it's actually really like quite literally like footprint in Greek. Ichtno, lithology, which means rock. That's what he called it, but another writer in Germany read Hitchcock's monograph where he used this word, and then he wrote sort of a response, but he cut out the ornitho, and he cut out the litho, and so it was just acknowledging. And then in the response back, Hitchcock wrote acknowledging, and after that it was acknowledging, and it's been acknowledging since. So, Hitchcock, to get his ideas really received in other countries, when he first started writing about these possible giant birds of New England, he had written to the great scientists of the time. Charles Darwin was actually very interested in this stuff. He was working on earthworms and their burrows, and so Darwin was really quite interested. He exchanged a number of letters with Darwin, but he particularly became friends with Richard Owen. Both Hitchcock and Owen had very similar worldviews. This sort of had to be worked into... a framework of the giant birds representing sort of a regime of animals that had lived before the age of man. And that there must be some way of sort of making this work with the ideas of the large reptiles that Owen had just described as dinosauria. Now, They, his friends, particularly Richard Owen and other paleontologists in England, they really kind of felt that these were probably actually large reptiles with bird-like feet rather than large birds, as Hitchcock argued. And this particularly... didn't go Hitchcock's way when first Leidy described Hadrosaurus from Philadelphia, which was bipedal, right, and had a three-toed foot. And then also Archaeopteryx was discovered and described from Germany. And this proto-bird was one, that's actually younger, by which I mean it's from rocks that are not as old as these three-toed trackways, and two, that was a really primitive looking bird. And so people argued, well how could there possibly be giant birds? way before this proto-bird from the Jurassic, right? The Triassic's older than the Jurassic, so clearly these could not have been giant birds. Hitchcock, though, held on to the idea right up until his death in 1864. But in some ways, Hitchcock was right, you know? He argued that these were like giant birds, that probably walked like giant birds, and in fact, in a sense, maybe he sort of knew better than anyone that dinosaurs actually were really actually quite like giant birds. The dinosaurs were where the giant birds are in a way, dinosaurs. So in some ways he's been sort of vindicated and actually right in hindsight. Now let's talk about the most famous case of footprints. Let's jump ahead and forward a little bit in history, okay? So that's how we all got started with dinosaur trackways. And so particularly trackways of large, large three-toed animals with claws and also Three-toed animals without claws, those were quite common in the fossil record. And that was true all the way up until the 1930s or so. However, 1908, there's a flood. The Pilexi River near Glen Rose in Texas, so that's a little bit west of Dallas. The Pilexi River floods, there's a really bad flood that year. And in 1909, there's a boy walking along a river, and he sees that there's these three-toed footprints. in the rock. There's some arguments about whether or not it's George Adams or it's his brother, and the timeline is not really very consistent, but let's say it was George Adams. He would have actually been a teenager. His brother would have been much older, actually. But so George Adams, he sees these three-toed footprints, and he actually brings his principal from high school all the way out there to look at them, and his principal sees them. George, or whoever it was, refers to them as giant turkey tracks, which was a very common way of referring to these large three-toed tracks when people would find them in North America. In fact, giant turkey tracks was a common folklore story that maybe Native American tribes told as well that these were giant turkey tracks. Well, his principal correctly identified them knowing about the stories about like the footprints that Hitchcock had found, etc. That these were actually probably dinosaur tracks. And he actually took some sketches and he sent off a letter to the Smithsonian and the Smithsonian confirmed that yeah, those are those are dinosaur tracks, rather standard three-toed dinosaur tracks. and a researcher came out eventually and named some of them, that's all. Alright? Well, a few decades later, it's the 1930s, and now we've got George. George is out of work, he needs things to do during the Great Depression to make money, and so he and actually a few other people start shipping out some of the footprints that you can find, because it turns out that the more you look around Glen Rose, the more footprints you find, and shipping them out, selling them by the side of the road. George also becomes involved in selling moonshine for a while. But George discovers that, you know, chipping out these footprints, you can damage them. And then, you know, it's hard to sell them if they're damaged. So you know what becomes a little bit easier? Just taking rocks and carving out a footprint out of those rocks. He finds those sell pretty well, actually. Who knows the difference? And his footprints start appearing actually in souvenir shops and gas stations for quite a wide area. Now, Robert T. Byrd, he was a self-trained fossil collector who worked for the American Museum of Natural History, much like the boss who hired him, who was... Barnum Brown. Now, Bird stopped into a gas station and trading post in New Mexico and saw some carved footprints. Now, some of them we think are probably dinosaur footprints and these carved dinosaur footprints, he could tell immediately that they were carved, but he could also tell that, wow, the person who carved these probably saw the real thing, right? So he could kind of tell that just by looking at it. So Bird got into his car, he just finished excavating some stuff in New Mexico, and he drove out down the road to Glen Rose in Texas. He gets to Glen Rose and he starts asking around. He meets George Adams, he finds the guy who carved the footprints, and he also meets George's brother, Ernest Adams. Ernest Bull Adams actually was a former champion football player from Baylor and a lawyer of some renown and had actually been the first Rhodes Scholar from Baylor. Ernest Well, we think it was Ernest. Some stories also say it was George. Showed, took Bert around, took Robert Bert around and showed him places where they, you know, you find footprints. One of those places, Byrd saw some tracks that George and Ernest and other people in the area called the elephant tracks. Large circular depressions like this, but much larger actually. Let me just draw it to scale. When Byrd saw these, he knew immediately what he was looking at. He was looking at the first tracks known to science of sauropods. So What did Byrd do? He made up a big batch of plaster. He made some molds of some of the tracks. He tied them to the top of his car and he drove to New York City. He showed them to his bosses and they immediately gave him the money to come back. And for the next two years, Byrd and his team dammed the river, dammed the Paluxy River, and then started excavating trackways that had been exposed by the river, cutting into the limestone and showing these layers of where tracks had been. Um, so... He and his team would cut out basically large blocks as big as they could conceivably get out. And some of these trackways were quite long, sequences of multiple tracks. And one of the most famous ones actually is a sauropod. And there's large footprints of a theropod that seems to be following the trackways of the sauropod. All right, so a large predator following a herbivore. It's known as the chase sequence. Well, those trackways were chiseled out. They were put onto railroad cars and they were sent to New York City. And he ended up sending off three trackways in that way off to the AMNH. Now, there's a lot of trackways still at Glen Rose and in fact new trackways always being exposed there and the area where Byrd excavated is actually now part of a state park, Dinosaur State Park. In fact, I just got the most recent issue here of Texas Parks and Wildlife and look what is on the cover, nothing more than our great Dinosaur State Park where you can see trackways. And that park was established in 1972. One of the things that marked its opening was that Texas was able to get two of the large life-size dinosaur replicas that the Sinclair Oil Company had made for the World's Fair in 1960. All right. So now. Today, only one of those trackways remains at the AMNH. The other two trackways, one was moved to the Smithsonian, and the other was moved to the Texas Memorial Museum in Austin, which, whoops, I believe just recently reopened. It was closed for a while during the pandemic. Now, you might know that there's a little bit more to this story. There's a little bit more that makes this really notable. The first trackways that Byrd saw in that gas station in New Mexico were not dinosaur trackways. You might have noticed a little hesitation from me when I was saying that a bit, right? What was going on? The first trackways he saw actually were big human footprints. Really, really fake-looking human footprints. What was going on? Well, George Adams discovered that, you know, the big bird-looking footprints sold okay, but the things people really loved, giant human footprints carved into rock. Okay, so they actually had these really, like, long toes on them. I don't think... apparently George would... He would take a rock that already had depression in it, he would go sit under a tree for an afternoon, and then while the sun beat down he would chip very slowly in order to make the human foot. Looking at it, I can only say that I'm not certain George was studying his own feet even when he was carving out these feet, but yeah. Now these carved footprints, they kind of got confounded with some other footprints that we also see at the Paluxy River. They're called the moccasin prints. Some of them look kind of like this. like that, or like this. Sort of funny and two-globed looking. And so the story was is that these footprints represented people walking in moccasins, or that these were, you know, the human footprints walking among the dinosaurs. And certainly these footprints, they come from the same layer and everything as everything else, they're really hard to explain, right? You know, like what dinosaur would have made footprints that looked like this? So between George's carved out fake-looking human footprints and these moccasin prints that people talked about finding along with the dinosaur trackways, well there's particularly a guy named Charlie Moss who talked a lot about these moccasin footprints. Those stories got put together by a guy called Charles Burdick. He was the founder of the Deluge Society and he published in a magazine in the 1950s that all of this showed that humans and dinosaurs had lived side-by-side. Burdick apparently really believed in giant footprints that George Adams had carved, that those were authentic. I don't know what to say about that. Anyway, here's a picture of Burdick with those footprints. Well, anyway, so in the 1970s, this was followed by a documentary film about the Adams footprints and those moccasin tracks. So scientists really were kind of curious, though, what could explain what these moccasin tracks were? What would make these sort of two-lobed, bean-shaped tracks? Now, one is they're bigger than human footprints, all right? They're bigger than a modern human's feet. So... Definitely not a modern human at least, so we can say that much. And also the stride length is wrong. It would be like a nine foot tall human. So Bigfoot, I guess. But Bigfoot without toes? I don't know. Bigfoot wearing very large moccasins? I don't know. All right, so what was going on with this? Well, actually it turns out that some of these, when you start looking and studying these moccasin footprints, some of them look like this. And you can actually see that there were claws, three claws, on those moccasin footprints. So it's clear that, in fact, that these were being made by a creature with three toes and three claws, just like dinosaur footprints are being made. But you have this long, exaggerated section over here. Well, you have to remember, like, tracks get made. They're not exact representations of the feet that made them, right? So you have to consider what are the actual circumstances by which the tracks got made. Alright, well, the Glen Rose limestone, which is all these tracks are in, represents some sort of lagoon condition where there was lots of carbonate being made. Basically, it would have been sort of a shallow sea type area. It would have looked very pretty and pristine and tropical like the Bahamas at the time. And this would have been sort of like really kind of thick mud that they were trudging through that left these tracks behind. Well, apparently it was thick enough that if you think about a dinosaur, so remember dinosaurs, they almost all, especially the bipedal ones, they walk. I'm going to just use this sauropod footprint here. They don't walk on their heels like we do. They walk with their heels up in the air. Right? And so there's this long section which we call the metatarsals that are being held up in the air when they're walking. In fact, it's kind of like if you were walking on your hands, but you're holding your palms up. Okay? So they're digigrade. That's what we, when we see this, we know that, okay, digigrade. Digigrade. I always get this a bit mixed up. I can never remember if it's an A or an I in there. I think it's a, well, I think it's a, I think it's a, it's a, it's an I. I probably misspelled it in my own notes. Well, anyway. So, digit grade, dinosaurs were digit grade. They walked on their toes, and they walked with this long, these long metatarsals held up in the air, okay? You know, you probably saw, have seen this, I mean, I noticed it when I was a kid and I watched Jurassic Park, was how the dinosaurs walked funny as if they had two knees, right? And that's really their heel that they're holding up in the air. Well, it's just that the mud was deep enough that when this These dinosaurs are walking, these theropods are walking through the mud. Their metatarsals are actually sinking into the mud too. They're walking up to their heels in mud. And then when they pull their feet out, it partially collapses, which sort of obscures the toes and the claw marks in a lot of these cases. And so you get this long metatarsal print back here. So there's the metatarsal. print, the toes kind of go away and you end up with these deformed two-lobed impressions that are left behind in the trackways at the Paluxy River. And so that's where these moccasin tracks come from. They're the tracks of dinosaurs, but they're the tracks of dinosaurs that weren't big enough to keep the bottom portion of their leg out of the mud. And when they pulled their feet out, the mud kind of collapsed back onto the footprint somewhat. And that's why you get these moccasin footprints. Okay, so that explains the mystery of the moccasin footprints. Now, you might wonder to yourself, okay, well who were the dinosaurs at the Paluxy River, right? So if you see big three-toed theropod footprints, we think this is all early Cretaceous, so we think Acrocentosaurus. which means high-spined lizard, and that's referring to the Acrocatasaurus was like an allosaurid theropod that had long neural spines on its back, kind of like a spinosaur, not very closely related to actual spinosaurs, but kind of convergent on being a spinosaur with those long neural spines. Okay, if you see other three-toed footprints at the Paluxy River, if you go to Dinosaur State Park, If they don't have claws, they're probably of small ornithopods, so some sort of anithopod, something kind of like a guanodon. I'm not going to say it's a guanodon. We're not really certain, actually. It turns out there's some mysteries about what really is a guanodon. Gideon Mantell did not keep very good track of the fossils he found, so in a lot of cases, reconstructing what some of those taxa really are is actually very difficult. Some of the stuff he found actually has been... ...put into a renamed genus called Mantellosaurus. Okay. But it doesn't matter, right? So a small ornithopod that seemed to be walking bipedally, we actually think that iguanodons, really big, really big relatives of iguanodons, actually probably walked quadrupedally. So like, ornithopods were like what we call facultive quadrupeds. They could run bipedally if they needed to, but they could also walk quadrupedally, and they seem to walk with their hands down. They kind of make a very small, almost hoof-like impression with their forelimbs. And then of course we have our big sauropod. What is our big sauropod? Well, if you remember our sauropod lectures, the state dinosaur of Texas was originally named for, because it was presumed that this was the big track maker, and that was Paluxysaurus. Which we now think it has to be synonymized with another big sauropod from the same age that was found in Oklahoma, but found earlier and named before Paluxysaurus. Sauroposeidon. And we think that that's the state dinosaur for Texas. So that's what we think is going on there. So the big chase trackways, we think that that's this Acrocanthosaurus chasing a Sauroposeidon. Neither of which are the dinosaurs that Sinclair sent, but they went with the ones that were as similar as they had at hand, which was they went with a Brontosaurus and a Tyrannosaurus rex. So still a big theropod and a big sauropod. So pretty close, right? Um, so this... is a really great story that tells you a lot about the nature of dinosaur trackways, the difficulties of identifying who makes some tracks, and the needs to consider the mechanics of how the behavior works and how it gets modified by the mechanics of sediments and everything else that happens after that, like weathering and erosion, in order to understand what is making things like these moccasin tracks. So I'm going to erase all this. And then... We're going to come back and I'm going to talk a little bit more about Australian trackways. So, one, two, three.

This is a lot easier if we're talking about a living wild animal, but with non-avian dinosaurs and any other extinct species, we have to deal with what sort of evidence we have remaining with us, all right? Now, dinosaurs left behind plenty of anatomical evidence of their existence, right? Bones and many cases of remarkable preservation, even including a mummified hadrosaur. However, there is actually another set of evidence that dinosaurs left behind for us, one that tells us something about behavior and about their levels of activity, and that's trackways.

I think... Many of us are probably familiar with the idea that dinosaurs have left behind fossilized trackways. And yet at the same time, it's probably, at least, you know, the way I always thought of it as a kid at least, was that dinosaur trackways were the most boring dinosaur fossils to talk about. They didn't show you anything about what the animal looked like, right?

However, At the same time, dinosaur trackways are really quite amazing. They tell us something that the anatomy, looking at the bones, the skeleton, the rest of the body, could never actually tell us, which is, how did that body move exactly? Actually keeping a record of that, right?

So the trackways actually capture a few moments of that motion in stone for us. That's really amazing, right? And that can tell us not just about... how they moved and how quickly they moved. It can also tell us things about behaviors that they had.

You know, it can tell us if they moved in groups. It can tell us if they if they move quickly, if they move slowly, etc. It can tell us what limbs they walked on and how they held those limbs. Alright?

So this whole field of studying trackways, or really the traces that animals leave behind in the fossil record, is much larger than just dinosaur trackways. There are, it's really its own section of paleontology to study the the trackways that animals leave behind as well as their burrows, as well as other traces that they leave, like feeding traces that they might leave behind in the sediment. Trilobites, you know, the large arthropods that look kind of like horseshoe crabs, but with more pieces to their skeleton from the Paleozoic.

They left behind lots of feeding traces because they would stir up the mud in order to grab worms that were living in the mud. And so there's a whole bunch of different types of things like this in the fossil record. It's, which does not really preserve the anatomy of the thing, but preserves really that behavior, that bit of motion that was there in the fossil record. So this whole field, the word for that field that was called in paleontology is technology.

So, where does this word come from? How did technology begin? Well, technology actually begins with dinosaurs. So, the first time that there was really the realization that extinct organisms left behind tract ways, we have to go back more than 200 years ago to 1802. There was an 11 year old farm boy named Pliny Moody in Massachusetts, and he was preparing the fields in a in the autumn season, and he discovered right by a rocky overhang, there were tracks in the ground.

And they were very large tracks, and they looked like the tracks of a bird with three toes on them. Pliny thought that was interesting, and so he sort of dug them up. He dragged these tracks in the rock home. They were actually in rock, sandstone actually. It's very common in Massachusetts.

And... His family ended up using them as doorstops for a number of years. When he went to college in 1810, eight years later, he sold the tracks for a bit of money to the local apothecarist, Dr. Ello Dutch.

Dutch thought they were interesting, and he decided he put them up in his apothecary shop to show to people who stopped by. And at some point, someone started calling them the tracks of Noah's ravens. We don't know if that was Dr. Dutch or Pliny Moody, but that's the story of the first known trackways that were found in New England.

and were identified as, oh, these are something important, these are fossilized tracks. Now, in the 1830s, about 20 years later, a tradesman was splitting stones for sidewalks. This was a common thing.

There wasn't really cement yet, and so people would instead split stones at quarries. And he found more bird tracks among some of the sandstone. This was just 30 miles away, Massachusetts still.

He became interested enough to start looking around Massachusetts and figuring out where other sort of trackways could be found. He realized that they would only be found in sandstone, not in granite, not in basalt. Massachusetts has a wonderful... array of rocks in it. A local doctor walking through the neighborhood happened to see all the trackways that this tradesman had found laid out in his front yard and became excited enough, he started writing letters to the people he considered to be most notable scientists of the day and age.

It actually took a number of repeated letters to finally get someone interested. Edward Hitchcock of Amherst College was really convinced that these were not very interesting tracks, just tracks probably of, well, actually he didn't even think they were tracks. He thought they were just sort of a mirage in the rock.

When he finally saw it though, he realized that, wow, these must actually be tracks. And so he started publishing on this in 1836. So think about it, that's at the same time that Gideon Mantel is working on naming Iguanodon and other remains of dinosaurs from England. So Hutchinson, who was basically the first geologist of Massachusetts, really.

He would have been a preacher, but he'd been overly interested in the natural sciences. His wife was an... an artist and who did figures for many of his publications and together they kind of produced this very rich artistic survey of the geology of Massachusetts and Hutchinson became really fascinated by these trackways He absolutely believed once he saw them that they were trackways and the idea that tracks could be preserved and left behind in the rock was for him really just sort of a really a huge shift in his worldview and he began to realize that all sorts of other behaviors that animals do might be captured within the rocks and he Because some of these tracks were really quite large, you know, I'll just sort of sketch out here, but I'll show a picture of what some of them looked like. Some of those trackways were really quite large, and at the same time, Richard Owen in England was describing the giant flightless birds of New Zealand, and Hitchcock thought, oh, these must be giant birds, just like those birds in New Zealand, in fact. And that was an idea that he took right to the grave with him, actually.

He did not desist with the idea that these giant three-toed tracks were the tracks of birds. However, these rocks were Triassic. There are other tracks as well. There was also a five-fingered track that looked kind of like this.

People thought that looked like a track of like maybe a bear or a dog, particularly in that the last digit sort of seemed a little off in it. But these five-fingered tracks, no one knew quite what to make of those. Through the work basically of Hitchcock, the doctor who'd been writing the letters, the tradesman who'd identified where all the different places the best- fine trackways were, Hitchcock was writing monographs right up into the late 1850s and the late 1860s about all the different trackways that could be found in New England.

And he invented the word ichtnology. He initially called it actually something like ornitho, which means bird, ichtno, which means trace, so like a trace or like a burrow or a footprint. That's basically, I think it's actually really like quite literally like footprint in Greek.

Ichtno, lithology, which means rock. That's what he called it, but another writer in Germany read Hitchcock's monograph where he used this word, and then he wrote sort of a response, but he cut out the ornitho, and he cut out the litho, and so it was just acknowledging. And then in the response back, Hitchcock wrote acknowledging, and after that it was acknowledging, and it's been acknowledging since. So, Hitchcock, to get his ideas really received in other countries, when he first started writing about these possible giant birds of New England, he had written to the great scientists of the time. Charles Darwin was actually very interested in this stuff.

He was working on earthworms and their burrows, and so Darwin was really quite interested. He exchanged a number of letters with Darwin, but he particularly became friends with Richard Owen. Both Hitchcock and Owen had very similar worldviews. This sort of had to be worked into... a framework of the giant birds representing sort of a regime of animals that had lived before the age of man.

And that there must be some way of sort of making this work with the ideas of the large reptiles that Owen had just described as dinosauria. Now, They, his friends, particularly Richard Owen and other paleontologists in England, they really kind of felt that these were probably actually large reptiles with bird-like feet rather than large birds, as Hitchcock argued. And this particularly... didn't go Hitchcock's way when first Leidy described Hadrosaurus from Philadelphia, which was bipedal, right, and had a three-toed foot. And then also Archaeopteryx was discovered and described from Germany.

And this proto-bird was one, that's actually younger, by which I mean it's from rocks that are not as old as these three-toed trackways, and two, that was a really primitive looking bird. And so people argued, well how could there possibly be giant birds? way before this proto-bird from the Jurassic, right? The Triassic's older than the Jurassic, so clearly these could not have been giant birds.

Hitchcock, though, held on to the idea right up until his death in 1864. But in some ways, Hitchcock was right, you know? He argued that these were like giant birds, that probably walked like giant birds, and in fact, in a sense, maybe he sort of knew better than anyone that dinosaurs actually were really actually quite like giant birds. The dinosaurs were where the giant birds are in a way, dinosaurs. So in some ways he's been sort of vindicated and actually right in hindsight.

Now let's talk about the most famous case of footprints. Let's jump ahead and forward a little bit in history, okay? So that's how we all got started with dinosaur trackways. And so particularly trackways of large, large three-toed animals with claws and also Three-toed animals without claws, those were quite common in the fossil record.

And that was true all the way up until the 1930s or so. However, 1908, there's a flood. The Pilexi River near Glen Rose in Texas, so that's a little bit west of Dallas. The Pilexi River floods, there's a really bad flood that year.

And in 1909, there's a boy walking along a river, and he sees that there's these three-toed footprints. in the rock. There's some arguments about whether or not it's George Adams or it's his brother, and the timeline is not really very consistent, but let's say it was George Adams.

He would have actually been a teenager. His brother would have been much older, actually. But so George Adams, he sees these three-toed footprints, and he actually brings his principal from high school all the way out there to look at them, and his principal sees them.

George, or whoever it was, refers to them as giant turkey tracks, which was a very common way of referring to these large three-toed tracks when people would find them in North America. In fact, giant turkey tracks was a common folklore story that maybe Native American tribes told as well that these were giant turkey tracks. Well, his principal correctly identified them knowing about the stories about like the footprints that Hitchcock had found, etc.

That these were actually probably dinosaur tracks. And he actually took some sketches and he sent off a letter to the Smithsonian and the Smithsonian confirmed that yeah, those are those are dinosaur tracks, rather standard three-toed dinosaur tracks. and a researcher came out eventually and named some of them, that's all.

Alright? Well, a few decades later, it's the 1930s, and now we've got George. George is out of work, he needs things to do during the Great Depression to make money, and so he and actually a few other people start shipping out some of the footprints that you can find, because it turns out that the more you look around Glen Rose, the more footprints you find, and shipping them out, selling them by the side of the road.

George also becomes involved in selling moonshine for a while. But George discovers that, you know, chipping out these footprints, you can damage them. And then, you know, it's hard to sell them if they're damaged. So you know what becomes a little bit easier? Just taking rocks and carving out a footprint out of those rocks.

He finds those sell pretty well, actually. Who knows the difference? And his footprints start appearing actually in souvenir shops and gas stations for quite a wide area. Now, Robert T. Byrd, he was a self-trained fossil collector who worked for the American Museum of Natural History, much like the boss who hired him, who was... Barnum Brown.

Now, Bird stopped into a gas station and trading post in New Mexico and saw some carved footprints. Now, some of them we think are probably dinosaur footprints and these carved dinosaur footprints, he could tell immediately that they were carved, but he could also tell that, wow, the person who carved these probably saw the real thing, right? So he could kind of tell that just by looking at it. So Bird got into his car, he just finished excavating some stuff in New Mexico, and he drove out down the road to Glen Rose in Texas. He gets to Glen Rose and he starts asking around.

He meets George Adams, he finds the guy who carved the footprints, and he also meets George's brother, Ernest Adams. Ernest Bull Adams actually was a former champion football player from Baylor and a lawyer of some renown and had actually been the first Rhodes Scholar from Baylor. Ernest Well, we think it was Ernest.

Some stories also say it was George. Showed, took Bert around, took Robert Bert around and showed him places where they, you know, you find footprints. One of those places, Byrd saw some tracks that George and Ernest and other people in the area called the elephant tracks. Large circular depressions like this, but much larger actually. Let me just draw it to scale.

When Byrd saw these, he knew immediately what he was looking at. He was looking at the first tracks known to science of sauropods. So What did Byrd do?

He made up a big batch of plaster. He made some molds of some of the tracks. He tied them to the top of his car and he drove to New York City.

He showed them to his bosses and they immediately gave him the money to come back. And for the next two years, Byrd and his team dammed the river, dammed the Paluxy River, and then started excavating trackways that had been exposed by the river, cutting into the limestone and showing these layers of where tracks had been. Um, so... He and his team would cut out basically large blocks as big as they could conceivably get out.

And some of these trackways were quite long, sequences of multiple tracks. And one of the most famous ones actually is a sauropod. And there's large footprints of a theropod that seems to be following the trackways of the sauropod.

All right, so a large predator following a herbivore. It's known as the chase sequence. Well, those trackways were chiseled out.

They were put onto railroad cars and they were sent to New York City. And he ended up sending off three trackways in that way off to the AMNH. Now, there's a lot of trackways still at Glen Rose and in fact new trackways always being exposed there and the area where Byrd excavated is actually now part of a state park, Dinosaur State Park.

In fact, I just got the most recent issue here of Texas Parks and Wildlife and look what is on the cover, nothing more than our great Dinosaur State Park where you can see trackways. And that park was established in 1972. One of the things that marked its opening was that Texas was able to get two of the large life-size dinosaur replicas that the Sinclair Oil Company had made for the World's Fair in 1960. All right. So now.

Today, only one of those trackways remains at the AMNH. The other two trackways, one was moved to the Smithsonian, and the other was moved to the Texas Memorial Museum in Austin, which, whoops, I believe just recently reopened. It was closed for a while during the pandemic.

Now, you might know that there's a little bit more to this story. There's a little bit more that makes this really notable. The first trackways that Byrd saw in that gas station in New Mexico were not dinosaur trackways. You might have noticed a little hesitation from me when I was saying that a bit, right? What was going on?

The first trackways he saw actually were big human footprints. Really, really fake-looking human footprints. What was going on? Well, George Adams discovered that, you know, the big bird-looking footprints sold okay, but the things people really loved, giant human footprints carved into rock. Okay, so they actually had these really, like, long toes on them.

I don't think... apparently George would... He would take a rock that already had depression in it, he would go sit under a tree for an afternoon, and then while the sun beat down he would chip very slowly in order to make the human foot. Looking at it, I can only say that I'm not certain George was studying his own feet even when he was carving out these feet, but yeah.

Now these carved footprints, they kind of got confounded with some other footprints that we also see at the Paluxy River. They're called the moccasin prints. Some of them look kind of like this. like that, or like this.

Sort of funny and two-globed looking. And so the story was is that these footprints represented people walking in moccasins, or that these were, you know, the human footprints walking among the dinosaurs. And certainly these footprints, they come from the same layer and everything as everything else, they're really hard to explain, right? You know, like what dinosaur would have made footprints that looked like this? So between George's carved out fake-looking human footprints and these moccasin prints that people talked about finding along with the dinosaur trackways, well there's particularly a guy named Charlie Moss who talked a lot about these moccasin footprints.

Those stories got put together by a guy called Charles Burdick. He was the founder of the Deluge Society and he published in a magazine in the 1950s that all of this showed that humans and dinosaurs had lived side-by-side. Burdick apparently really believed in giant footprints that George Adams had carved, that those were authentic. I don't know what to say about that. Anyway, here's a picture of Burdick with those footprints.

Well, anyway, so in the 1970s, this was followed by a documentary film about the Adams footprints and those moccasin tracks. So scientists really were kind of curious, though, what could explain what these moccasin tracks were? What would make these sort of two-lobed, bean-shaped tracks?

Now, one is they're bigger than human footprints, all right? They're bigger than a modern human's feet. So... Definitely not a modern human at least, so we can say that much.

And also the stride length is wrong. It would be like a nine foot tall human. So Bigfoot, I guess.

But Bigfoot without toes? I don't know. Bigfoot wearing very large moccasins?

I don't know. All right, so what was going on with this? Well, actually it turns out that some of these, when you start looking and studying these moccasin footprints, some of them look like this. And you can actually see that there were claws, three claws, on those moccasin footprints.

So it's clear that, in fact, that these were being made by a creature with three toes and three claws, just like dinosaur footprints are being made. But you have this long, exaggerated section over here. Well, you have to remember, like, tracks get made. They're not exact representations of the feet that made them, right? So you have to consider what are the actual circumstances by which the tracks got made.

Alright, well, the Glen Rose limestone, which is all these tracks are in, represents some sort of lagoon condition where there was lots of carbonate being made. Basically, it would have been sort of a shallow sea type area. It would have looked very pretty and pristine and tropical like the Bahamas at the time. And this would have been sort of like really kind of thick mud that they were trudging through that left these tracks behind.

Well, apparently it was thick enough that if you think about a dinosaur, so remember dinosaurs, they almost all, especially the bipedal ones, they walk. I'm going to just use this sauropod footprint here. They don't walk on their heels like we do.

They walk with their heels up in the air. Right? And so there's this long section which we call the metatarsals that are being held up in the air when they're walking.

In fact, it's kind of like if you were walking on your hands, but you're holding your palms up. Okay? So they're digigrade. That's what we, when we see this, we know that, okay, digigrade.

Digigrade. I always get this a bit mixed up. I can never remember if it's an A or an I in there. I think it's a, well, I think it's a, I think it's a, it's a, it's an I.

I probably misspelled it in my own notes. Well, anyway. So, digit grade, dinosaurs were digit grade. They walked on their toes, and they walked with this long, these long metatarsals held up in the air, okay?

You know, you probably saw, have seen this, I mean, I noticed it when I was a kid and I watched Jurassic Park, was how the dinosaurs walked funny as if they had two knees, right? And that's really their heel that they're holding up in the air. Well, it's just that the mud was deep enough that when this These dinosaurs are walking, these theropods are walking through the mud. Their metatarsals are actually sinking into the mud too. They're walking up to their heels in mud.

And then when they pull their feet out, it partially collapses, which sort of obscures the toes and the claw marks in a lot of these cases. And so you get this long metatarsal print back here. So there's the metatarsal.

print, the toes kind of go away and you end up with these deformed two-lobed impressions that are left behind in the trackways at the Paluxy River. And so that's where these moccasin tracks come from. They're the tracks of dinosaurs, but they're the tracks of dinosaurs that weren't big enough to keep the bottom portion of their leg out of the mud. And when they pulled their feet out, the mud kind of collapsed back onto the footprint somewhat.

And that's why you get these moccasin footprints. Okay, so that explains the mystery of the moccasin footprints. Now, you might wonder to yourself, okay, well who were the dinosaurs at the Paluxy River, right?

So if you see big three-toed theropod footprints, we think this is all early Cretaceous, so we think Acrocentosaurus. which means high-spined lizard, and that's referring to the Acrocatasaurus was like an allosaurid theropod that had long neural spines on its back, kind of like a spinosaur, not very closely related to actual spinosaurs, but kind of convergent on being a spinosaur with those long neural spines. Okay, if you see other three-toed footprints at the Paluxy River, if you go to Dinosaur State Park, If they don't have claws, they're probably of small ornithopods, so some sort of anithopod, something kind of like a guanodon.

I'm not going to say it's a guanodon. We're not really certain, actually. It turns out there's some mysteries about what really is a guanodon.

Gideon Mantell did not keep very good track of the fossils he found, so in a lot of cases, reconstructing what some of those taxa really are is actually very difficult. Some of the stuff he found actually has been... ...put into a renamed genus called Mantellosaurus. Okay.

But it doesn't matter, right? So a small ornithopod that seemed to be walking bipedally, we actually think that iguanodons, really big, really big relatives of iguanodons, actually probably walked quadrupedally. So like, ornithopods were like what we call facultive quadrupeds. They could run bipedally if they needed to, but they could also walk quadrupedally, and they seem to walk with their hands down. They kind of make a very small, almost hoof-like impression with their forelimbs.

And then of course we have our big sauropod. What is our big sauropod? Well, if you remember our sauropod lectures, the state dinosaur of Texas was originally named for, because it was presumed that this was the big track maker, and that was Paluxysaurus. Which we now think it has to be synonymized with another big sauropod from the same age that was found in Oklahoma, but found earlier and named before Paluxysaurus. Sauroposeidon.

And we think that that's the state dinosaur for Texas. So that's what we think is going on there. So the big chase trackways, we think that that's this Acrocanthosaurus chasing a Sauroposeidon. Neither of which are the dinosaurs that Sinclair sent, but they went with the ones that were as similar as they had at hand, which was they went with a Brontosaurus and a Tyrannosaurus rex.

So still a big theropod and a big sauropod. So pretty close, right? Um, so this...

is a really great story that tells you a lot about the nature of dinosaur trackways, the difficulties of identifying who makes some tracks, and the needs to consider the mechanics of how the behavior works and how it gets modified by the mechanics of sediments and everything else that happens after that, like weathering and erosion, in order to understand what is making things like these moccasin tracks. So I'm going to erase all this. And then...

We're going to come back and I'm going to talk a little bit more about Australian trackways. So, one, two, three.

Transcript for:Exploring Dinosaur Behavior and Trackways

Transcript for:
Exploring Dinosaur Behavior and Trackways