Science Friday - Dinosaurs’ Secrets Might Be In Their Fossilized Poop

Episode Date: August 15, 2024

To gaze upon a full T. rex skeleton is to be transported back in time. Dinosaur fossils are key to understanding what these prehistoric creatures looked like, how they moved, and where they lived.But there’s one type of dinosaur fossil that’s sometimes overlooked: poop. Its scientific name is coprolite. These fossilized feces are rarer than their boney counterparts, but they’re key to better understanding dino diets and ecosystems.This all raises an important question: How scientists know if something is fossilized dino poop or just a rock?At Science Friday Live in Boulder, Ira talks with Dr. Karen Chin, paleontologist and professor of geological sciences at the University of Colorado, Boulder to answer that question and much more.Transcripts for each segment will be available after the show airs on sciencefriday.com. Subscribe to this podcast. Plus, to stay updated on all things science, sign up for Science Friday's newsletters.

What can we learn from fossilized dino dung? These lowly little fossilized feces can actually give us a more holistic view of ancient ecosystems than we've looked at before. It's Thursday, August 15th, 2024, and you're listening to Science Friday. I'm SciFri producer Shoshana Bucksbaum. Sure, the fossils from dinosaur bones are super cool, but what about fossilized dino poop? scientific name copperlates. These fossilized feces are rarer than their bony counterparts, and dino droppings hold the key to better understanding dino diets and ecosystems. But how can scientists figure out if it's fossilized dino poop or just a rock? To answer that question and much more, Ira sat down with

one of the top copperlight experts in the world at Science Friday Live in Boulder, Colorado. Here's Ira. Now, if you're anything like me, whenever you go to a natural history museum, you make a beeline for the dinosaur. The dinosaur fossils. You want to see T-Rex skeleton. You want to be transported back in time. And dino fossils are how scientists understand what these prehistoric creatures look like, how they moved, how they lived, how they reproduced. But there is one type of fossil that's sometimes overlooked. And I'm talking about dino poop.

This special name for dino poop. Scientific name is cuprolites, cuprolites. And these fossilized feces are rarer than their bony counterparts. But you know what? Dino droppings hold the keys to better understanding dino diets and ecosystems. But how can scientists figure out if it's fossilized, dino poop or just a rock. That's what my next guest is going to tell us all about.

Joining me to answer that burning question on a whole lot more is one of the preeminent cuprolite researchers in the world. Dr. Karen Chin, paleontologist and professor of geological sciences at the University of Colorado in Boulder. Welcome to Science Friday. Thank you. I got to ask you first. How does anyone get interested in this?

I mean, you don't start out, being interested in dino, poop, do you? I did not start off saying, I'm going to dedicate my life to studying poop. No, I did not. No, actually, I used to be a park service ranger, an interpretive ranger, and I learned the value of when you see scat on the trail. Right. That tells you about what's living around you. You're more apt to see animal sign than you are to see the actual animal. So then when I started, I started to it in paleontology, and I learned that people have actually found fossilized feces. I thought that was the craziest thing. I thought it was so interesting, and I ran to my boss, Dr. Jack Horner, the proponent in Jurassic Park. He's a famous guy, yeah, very famous guy. I said, Jack, did you

know that some people have found fossilized feces? And he said, yes, and I found some too. and that began my journey. So how many fossilized feces, it's got to say those F words quickly together, do you think you have found in your career? How many of them? Can be a ballpark estimate. Okay, I'm going to cheat and say,

I'm going to talk about fragments, not a single pile, hundreds. Hundreds of them? And where did you find most of them? I found many of them in Montana. some in Utah, up in the Arctic, down here in Colorado. Wow. Wow.

Okay, so when you study them, what can they tell you about the dynos that just the other regular fossils can't? Yes, I like to emphasize to people that they're two kinds of fossils. The body fossils, like bone, shell, and wood, they tell you who the characters are in this drama of past life,

we're trying to reconstruct. But we have to kind of assume what their actual behavior was. Trace fossils like fossil feces, fossil footprints, and fossil burrows, they tell you about activity. And so they can actually fill in the picture of what these main, major characters were doing in an ecosystem. Such as, what kinds of things were they doing? Walking around, feeding.

The challenge is that it's sometimes difficult to link the character with the trace fossil. So in my work, I spend a lot of time acting like a detective trying to figure out who dung it. You really belong on this show. Well, you have to figure out who the pooperator was. Do you see other animals that come, fossils of other animals that the dino ate perhaps, you know, dung beetles? or something like that? Well, in a coprolite that may or may not be produced by a dinosaur, could be produced by fish or mammals,

you can see skeletal elements like bone, you can see shell. I've even found, we've even found fossilized muscle tissue, plant tissue, and you can also see burrows of coper phagas animals, animals that were feeding on dung, that have burrowed into that dung. Wow, now you have brought some sample. with you, right? Yes, I brought a couple samples here.

I brought these here that show a very typical size and shape. This looks like dog dung, but it's actually mineralized. Those are easy to recognize. Right. But when you're talking about feces from a large animal like a dinosaur, oftentimes they break up, either when they're falling from the animal or or stepped on or just through geologic processes, this is part of a dinosaur dung piece right here. But the original size was probably on the order of about six or seven liters, which is about

the size of a basketball. And how do you know it's dung and not a rock? That's a really difficult question because there's lots of fecal-shaped rocks around. And you have to look at a number of criteria. Actually, for dinosaurs, the shape doesn't give you many clues. So you can look at things like the chemistry. You can also look for the evidence of chopped-up biotic material, like chopped up plants, chopped up bone.

You look at the sedimentological context, and also you can look for evidence of Cobra-Fegas activity. Oh, the digging. The digging. All right, I know you have questions in the audience about dino dung. So make your way down while I ask a couple of more questions until you get there. One of the fossilized feces you showed us contains rotting wood. I'm sorry.

Why would a dinosaur be eating wood? I mean, what's going on there? Yes, that was really surprising to find rotting. wood and it was rotted before they ingested it. You can see from the distribution and the structure of the cells inside that the lignin that holds all of the cellulose together in wood is actually gone. And to take away lignin like that, it requires an oxidative process, which you cannot do inside a vertebrate gut.

So we know that those dinosaurs actually ingested rotted wood. They can get sustenance out of it because when you take away the lignin, all the cellulose becomes available. But it doesn't make sense for a dinosaur to focus on eating rotting wood because they can just walk out,

well, I guess they're not inside, but we can look outside and see lots of green plants. It's much easier to generate cellulose through the growth of leaves than to grow trunks and then rot them. Yeah. So I spent a lot of time thinking about this, and my hypothesis is that when the dinosaurs were reproducing, they actually required a higher source of protein to yoke their eggs.

And we see this in living dinosaurs today, the birds, because many seed eaters will actually change their diet when they're reproducing and ingest more insects. So if you think about 25, 30 foot duck-billed dinosaur that isn't built for running after mice or something like that, how are they going to get a good source of protein when they're reproducing? One way is to feed on rotting wood. There you have it. where they have lots access to crustaceans, insects, beetles, grubs.

I'm getting hungry, just thinking about it. Yeah, and we actually did find in some of the, this is a different coprolite. This is from Utah, and in those coprolites, we actually found pieces of crustacean. So we have evidence that these dinosaurs, these herbivorous dinosaurs, not only ingest, rotted wood, but they also interested crustaceans, probably like crabs. Wow, wow, wow. I get it. Okay, let's see if we get some interesting questions right here, yes.

Yeah, I have just wondering why some of them would petrify instead of decompose. That's a great question. I was so surprised when I learned that they actually fossilized because soft tissue readily decomposes. but if you bury the feces rapidly and the conditions are just right in terms of water and chemical situations and the bacteria, you can actually mineralize, lithify them

within weeks. People have done actualistic experiments where they have mineralized fossil muscle tissue, I mean, shrimp muscle tissue. And it happens within weeks. Mineralization of coprolites can actually happen quickly, but you have to have rapid burial. So animals that live in environments where things are buried rapidly, like lakes, their coprolites

cannot be too rare. I mean, I should say it differently, their coprolites may not be rare. Right. But if you're looking for coprolites from terrestrial animals, like large herbivorous dinosaurs, those can be very rare. All right. Let's go to this side. Yes.

Out of all the dinosaurs that you found, which one was, like, the most poop that you found of, like, the dinosaur? I don't know what I'm phrased it. Okay, I found more poop that was probably produced by duckbill dinosaurs than any others. Okay. Is that because where they do their poop that's better preserved that you would find? The setting in which they pooped was just happened to be conducive to fossilization. Actually, herbivore coprolites. from plant eaters are really rare because unlike carnivore diets where we have a lot of phosphorus

when we eat meat. Yeah. They have, they can help, the contents of the diet can help fossilize the feces. But herbivore coprolites or herbivore diets have very little phosphorus in them so they require an external source of phosphorus to mineralize them. Terrific. Okay. Over here.

Thank you so much. This is kind of born of an earlier question. We were talking about decomposition. And I'm curious, do you guys ever find, like, mycological processes? What kind of evidence do you ever see of, like, new life sort of growing via the corpulite? You want to explain that question? Like fungal growth? Do you ever see? Yes. We have found evidence for fungi in coprolites, for bacteria in coprolites. We have found evidence. the dung beetle burrows. So when we look at coprolites, we're looking at whole ecosystems that demonstrate decomposition

and recycling back into the environment. You know, I asked you how you can tell whether it's a rock or a fossil. And we've done a show on this with other scientists who say that I don't know how to put it. I'll put it the way they said. If you lick it, they can tell a difference.

Yeah. Well, I don't. Mostly they're talking about bone because just the texture sticks on your tongue. I don't lick it. Okay. No further words are necessary to explain that. We know that dinosaurs and birds are basically related. If you look at how birds poop, is there any relationship to how dinosaurs poop, you know?

Bird poop is usually very watery, and that's because they fly, they have to shed weight as quickly as possible. Birds are flying dinosaurs, but not non-avian flying dinosaurs. So theirs do not have to be so watery. And you can look at a modern example when you're thinking of goose poop. Goose poop is very dense. We know that. We know that. What's the biggest deposit you've ever found of dino poop?

The biggest deposit that I've ever studied was probably about three feet by nine feet. Not one dinosaur. Not one deposit. No. I was going all over the place with three feet by not one. Okay, good. I feel better for the dinosaur. Dinosaur. Is there a question that you're still looking to answer after all these years studying?

The dino poop. There are lots of questions, but I'd say one of the biggest questions is, I really would like to know what the big bronosaurs, the sauropods, were eating, and how big their feces were. Yeah. Those are the big herbivores. Yes. And why do you want that the most? What's there? Just because that's one of the biggest questions.

What we can say, we have gut contents and feces from duck-billed dinosaurs, but going back, especially into the Jurassic, those big animals, they were just so unlikely. Final question, I know you've been studying fossilized dino-poop for years, right? Has it changed the way you look at dino poop over those years? as your thinking evolved about dino poop over those years? Yes, when I first started studying coprolites, I was mostly interested in what they could tell us about diets. But as I've continued to study coprolites,

I have realized that coprolites document energy transfer in the form of carbon transfer, carbon resources, in an ecosystem. And this is actually really a big deal, because energy transfer in an ecosystem is one of the foundational characteristics of ecosystems. So to me it's really exciting. You can say predation, herbivory, recycling, copperfagy, and that means that these lowly little fossilized feces can actually give us a more holistic view of ancient ecosystems than we've looked at before.

Thank you very much for taking time to be with us today. Dr. Karen Chin, alienologist, a professor of geological sciences at the University of Colorado in Boulder. Special thanks to the team of people who made tonight's event really happen, including our amazing partners at KUNC. Thank you all. Everyone here at the Chautauqua Auditorium and the entire Science Friday team, let me bring them out. Kathleen Davis, Hershanna Buxbaum, Charles Berger. with Sandy Roberts, Diana Plasker, George Harper, Jackie Hirschfeld, and Jason Rosenberg. And that's about it for this hour. Wasn't that fun? If you want to see what fossilized dino poop looks like,

head to ScienceFriiday.com slash dino poop. That's sciencefriiday.com slash dino poop. And that's about all the time we have for now. Lots of folks help make the show happen, including Dee Petersmith, Felissa Mayors. Emma Gomez. Jackie Hirschfeld. Tomorrow, a roundup of the top science news of the week. I'm Cyfry producer Shoshana Bucksbaum. Catch you next time.