Science Friday - Archeopteryx Specimen Unveiled | Trees And Shrubs Burying Great Plains' Prairies

Episode Date: May 13, 2024

The Field Museum has unveiled a new specimen of Archaeopteryx, a species that may hold the key to how ancient dinosaurs became modern birds. Also, a “green glacier” of trees and shrubs is sliding across the Great Plains, burying some of the most threatened habitat on the planet.Remarkably Well-Preserved Archeopteryx Specimen UnveiledThe Field Museum in Chicago just unveiled a new specimen of one of the most important fossils ever: Archaeopteryx. It lived around 150 million years ago, and this species is famous for marking the transition from dinosaurs to birds in the tree of life.The Field Museum now has the 13th known fossil—and it may be the best-preserved one yet. So what makes this specimen so special? And what else is there to learn about Archaeopteryx?To answer these questions, guest host Sophie Bushwick talks with Dr. Jingmai O’Connor, associate curator of fossil reptiles at the Field Museum, about what makes Archaeopteryx such an icon in the world of paleontology and why they’re so excited about it.Trees And Shrubs Are Burying Prairies Of The Great PlainsIn the Flint Hills region of Kansas, the Mushrush family is beating back a juggernaut unleashed by humans — a Green Glacier of trees and shrubs grinding slowly across the Great Plains and burying some of the most threatened habitat on the planet.This blanket of shrublands and dense juniper woods gobbling up grassland leads to wildfires with towering flames that dwarf those generated in prairie fires.It also eats into ranchers’ livelihoods. It smothers habitat for grassland birds, prairie fish and other critters that evolved for a world that’s disappearing. It dries up streams and creeks. New research even finds that, across much of the Great Plains, the advent of trees actually makes climate change worse.Now a federal initiative equips landowners like Daniel Mushrush with the latest science and strategies for saving rangeland, and money to help with the work.Read more at sciencefriday.com.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.

The Field Museum in Chicago just got its hands on an archaeopteryx fossil. Only the 13th one in the world. Oh, it's incredibly exciting. I think for any paleontologists, they would be really stoked to have a specimen of archaeopteryx because it really is the icon of evolution. It's Monday, May 13th, and you're listening to Science Friday. I'm Cyfry producer Kathleen Davis. You might know that birds, yep, all living birds, are dinosaurs.

And the fossil that helped prove that is archaeopteryx. We'll hear why it's so exciting to have another fossil of this ancient bird and what scientists are learning from it. But first, here's why planting trees isn't always a green solution. Here's guest host Sophie Bushwick. Since grade school, I've been told that planting trees is the height of environmentalism. Plant a tree save the planet, right? Well, it's a little more complicated than that.

Trees don't actually belong in every biome. And in some cases, they can be downright bad. That's the case for the Great Plains, where a wave of trees and shrubs is burying this threatened habitat. Joining me now to talk about this is my guest, Celia Yopis Jepson, host of the podcast Up From Dust from KCUR studios in Kansas City, Missouri. Welcome to Science Friday.

Great to be here. Let's talk about the great place. plains prairies. What makes this ecosystem so special? Yeah, so there is really nothing like standing on a healthy prairie where you can see this kind of ocean of grass and wildflowers that stretches all the way to the horizon. These are really special places with their own wildlife, including some very cool animals that, you know, were once widespread on this continent and just aren't anymore. highly specialized grassland birds, prairie chickens. What I love about grasslands for listeners who

maybe haven't set foot in a place like this is it's a really kind of amazing combination of awe and subtlety. You have like the awe of looking at the prairie stretching, you know, for miles in front of you. And then this subtlety that it may look all the same at first glance, but actually it's full of all these rich and wonderful details. And I live close to what's, left of the vast tall grass prairie, which isn't much that's left at this point. And the National Park Service calls this one of the most diverse ecosystems on the planet. But there are just fewer and fewer places where you can see a healthy tall grass landscape. I mean, I love that description of this as an ocean of grass, but just how big were the North American grass lands

back in the day? And then how does that compare to today? Yeah. I mean, it's hard to picture, right? But the easiest way to think of it is that one third of North America used to be grassland. I mean, just really vast, right? We're talking the center of the continent all the way from a little bit in what's now Mexico, up through states like Kansas, Nebraska, Montana, up into Canada. And within that, a whole lot of ecological variation, right? So in eastern Kansas, you have tall grass prairie that looks and feels very different, as you go west towards the Rockies and eventually transition into what's called short grass prairie.

These are all their own very special places. But yes, it is very much shrinking because of the trees and the shrubs that you referenced in the introduction. And you've, in your reporting, you call this a quote unquote green glacier that's eating up grassland. So what specific kinds of plants are we talking about here? Yeah. So I love this term because I think it really really.

paints a picture. Green Glacier is a term that comes from scientists at Oklahoma State University. You can kind of imagine this gradual glacier plowing right across the center of the country, just burying prairies. And it's a lot of juniper trees. They're called eastern red cedars, but they're these dense juniper trees and really aggressively spreading shrubs like dogwood thickets and sumac that are infesting, invading. what's left of North American prairies. Because I do want to be clear, North American prairies have largely become farmland, but what's left of the continent's prairies is in real trouble now. It's transitioning into woodland and shrubland. So Kansas State University studies this

super in-depth. So I went to one of their grassland ecologists to wrap my head around this, Jesse Nippert. And this is what he had to say. As a naturalist and a conservation person, I want the grasses back. But these areas that have turned into juniper forests, we're probably not going to get them back. I think we protect what we can protect. We try and restore the areas that can be restored. And a big thing to know here is this isn't just North American prairies that are collapsing. Scientists are seeing the same phenomenon in grasslands all around the world. And how did these trees and shrubs grow in such huge numbers. Well, humans have changed the atmosphere, right? So what Jesse Nippert explained to me

is that more carbon dioxide in the air literally means photosynthesis in these trees and shrubs gets more efficient. So here's what happens. Fires on the prairie often started purposefully by Native Americans used to keep woody plants in check. But now trees and shrubs can grow taller and a single year than they could when there was less CO2 in the air. So you have, you know, dogwood thickets and things growing taller faster. They shade out all the grass around them. And when they do that, they protect themselves against fire. So the next time a fire comes through, basically, they've removed the grass around them that catches fire so easily so that they can survive better and keep growing taller and taking over the prairie. And what are the consequences of that happening,

of this takeover where grasslands are lost to trees and shrubs? Yeah, for ranchers, this is a matter of their livelihood. As grassland gives way to woodland and shrubland, that means less rangeland for cattle. So from their point of view, you know, this green glacier is literally removing billions of pounds of grass from the ranching industry. In terms of ecological implications, prairie wildlife, they're losing their habitat. And at Kansas State University, they're seeing that prairie streams are drying up because the trees and shrubs create so many cracks in this kind of

very special rocky ground beneath the tallgrass prairie. So the rainwater seeps too deep here in the Flint Hills of Kansas and just disappears. And then finally, we've got to mention the wildfires. Wildfires are getting worse when, you know, you have drought and wind and things conspiring so that all these woody plants, these juniper forests, like, do finally go up in flames. We're seeing really intense catastrophic wildfires now in the center of the country. And just to give you an idea of how difficult it is to fight these fires, the University of Nebraska says that you can have flames that are 90 feet tall when you're dealing with these thick juniper forests compared to under 15 feet tall when it was

healthy prairie that wasn't infested with these trees. I can definitely understand why people are trying to cut back the trees in these grasslands. But who's doing this work? Who's leading this effort? Well, ranchers are doing a lot of it. Again, grassland is their livelihood. But it's a really daunting task. I spoke with Daniel Mush Rush about this. He's a third generation rancher. And he just, you know, kind of guesstimated that he and his family have probably killed maybe around like 10,000 trees just in the past three years, and they are nowhere near done. But, you know, they're trying to manage 15,000 acres of tallgrass prairie, which is an especially threatened kind of prairie. And that's why Daniel Mush Rush thinks, you know, people should really

pay attention to this and get on board with preserving it. If a coral reef is worth saving, if some pristine mountain stream is worth saving, then so are the Flint Hills. I think that's the message I want to send is just that it's not easy work, but it's worthy work. At least we have a roadmap forward. Are these ranchers getting any federal help to do this? Yes, they are. So that's the roadmap that Daniel Mushrush was just referencing.

So the Natural Resources Conservation Service launched a program. It's called the Great Plains Grassland Initiative. and they've been rolling this out in Kansas, Nebraska, Oklahoma, South Dakota. And this program brings expertise to landowners to help them figure out where to put their efforts, how to tackle these trees and shrubs really systematically, and also has the option of financial help to help them do this. It's a real morale boost for people like Daniel Mushrush, who describe feeling overwhelmed by the situation.

And the idea is to kind of like preserve core areas where there will be, you know, relatively intact, large expanses of grassland into the future. And that's important because, I mean, it's important for ranchers, clearly, but it's also important for wildlife that need these large expanses because kind of small postage stamp remnants aren't really enough to preserve this incredible biodiversity. And I imagine that a lot of the work to conserve the Great Plains Prairies is actually cultural, helping people to just reframe the idea in their heads that trees are inherently good for the environment. Is that a big challenge? Yeah. So I would say we definitely have a pro-tree culture, right? But the reality is that trees harm certain ecosystems. Trees on the prairie are a point of tension in a lot of places because you may have a problem.

ranchers who are desperately trying to hold on to their range land. And then nearby, you have landowners who welcome the trees and shrubs maybe. For example, they might not have a problem with transitioning to woodland because they're hoping it will improve deer hunting or they might want the privacy afforded by a tree landscape. So, you know, even in grassland regions, opinions can be very fractured. And I think we've got to mention that this kind of pro-tree culture runs really deep. Native Americans, as I referenced before, used to burn grassland regularly and very purposefully across much of this area to maintain rich hunting grounds and for other purposes. But then Europeans and their descendants came and of course, you know, killed and

forcibly removed Native Americans from most of this grassland region. The European Americans brought a different relationship to the land. There wasn't anything like these vast grasslands in the countries that they or their grandparents had come from. So it was just obvious that it's easier to build towns to live in the way that they, you know, that they were used to living if they would plant trees. That's actually the origin of Arbor Day. Nebraska's planting a million trees in a single day, if you can imagine that in the 1800s. That's so hard to imagine. I know.

Like, I really, you know, a million trees, right? And then that tree planting ramped up after the dust bowl. So what it means is that we've been transforming the landscape for many decades now. You add in the extra CO2 in the air now, and it just adds up, and it spells real trouble for the future of North American prairies. That's all the time we have for now. I'd like to thank my guest, Celia Yopee's Jepson. host of the podcast Up From Dust from KCUR in Kansas City, Missouri.

Thank you for joining us. Thanks so much for your time. The Field Museum in Chicago just unveiled a new specimen of one of the most, if not the most, important fossils ever, archaupteryx. It lived around 150 million years ago, and this species is famous for marking the transition from dinosaurs to birds in the tree of life. The Field Museum now has the 13th known fossil, and it may be the best preserved one yet. Joining me to talk about this fossil find and what makes Archaeopteryx so fascinating is Dr. Jingmey O'Connor, associate curator of fossil reptiles at the Field Museum in Chicago. Welcome back to Science Friday.

It's always a pleasure. How exciting is it to have an archaeoptery specimen in your museum? Oh, it's incredibly exciting. I think for any paleontologists, they would be really stoked to have. a specimen of archaeopteryx because it really is the icon of evolution. But my specialty is specifically Mesozoic birds. So for me, it's just like, I can't even say a dream come true because I never would have dared to dream something like this. But yeah, it's amazing. And clearly you have a lot of enthusiasm for archaeopteryx. So tell us about it. You know, what did it look like? How did it

move? How did it eat? Yeah. So Archaeopteryx was a small bird that ranged in size from about a pigeon to a crow. And in fact, even the largest specimen shows evidence it was actively growing. So we don't know how big they got. But you would identify it as a bird because it would have been covered in feathers and it would have had wings, but it would have had a long reptilian tail. It would have had jaws full of teeth. It would have had claws on its hands. So in this way, it's this perfect transitional taxon that's recording these very bird-like characteristics together with reptilian, non-avian dinosaurian characteristics. Now, we actually don't know what it ate. No specimen preserves stomach contents. And whenever we see a species that

appears to be carnivorous, but is very small. Our default go-to is that it was insectivorous. So that's what most people hypothesize for archaeopteryx, but I just want to make it clear that there's actually no evidence of that. And why is it such an icon of evolution? You know, I mentioned that it's this transitional taxon, right? And what was really special about it is that it was found just two years after Darwin published on the origin of species by means of natural selection. So in it, he puts forth his theory for one of the major mechanisms evolution, that organisms that are better adapted for their environment are more likely to survive and pass on these adaptations that led to their success.

But in the book, he also says, you know, the gravest objection to my theory is that we don't have fossils that are recording morphological transitions from, you know, a species adapted for one environment to a species adapted for a different environment, like, for example, non-flying theropod dinosaur to a bird. And that's exactly what archaeoptery's provided just two years after he published this book. And, you know, this theory needed evidence. It needed support. It was being, you know, heatedly debated in the, you know, academic and also religious sectors. So, you know, it was just perfect to have this iconic transitional tax on found and just the nick of time to support Darwin's theory. And for that reason, it's the icon of evolution.

So we know that birds are dinosaurs, but why didn't they die alongside their ancestors when the asteroid struck? So some birds did die. You know, there were lots of lineages of Cretaceous birds that go extinct alongside non-avian dinosaurs. But crown birds probably survived because of a combination of characteristics. Like I think you usually can't point to a single thing and say, this is why this one particular group went extinct. And it's probably because crown birds have very high metabolic rates. They had contact incubation and their eggs could move, which allowed their incubation times to be shorter, which means that the period in which you have to sit on a nest and you're vulnerable is reduced. We also think that they had a more efficient digestive track than perhaps other birds and non-avian dinosaurs.

Yeah, so those are the hypotheses that we're kind of leaning towards, maybe more efficient respiratory system as well. But again, there's really no strong evidence for all of this. it's really hypothetical. We don't, basically we don't know. Well, let's get into your particular specimen of archaeopteryx. How did the Field Museum get its hands on this fossil in the first place? So this fossil has been in private hands unprepared for over three decades. And the current owner was looking to sell it to another private collector.

But this private collector instead told us about the fossil to try to get the fossil into a public repository and make it available for scientists. So, yeah, that's how we were able to acquire it. And it was a total gamble because it was unprepared. And we could just see a little bit of the specimen. And we really didn't know what we were getting. And as soon as we got it to the Field Museum, we popped it in the X-ray machine.

And like, it's so perfectly three-dimensionally preserved that all the bones are still preserving all their hollow spaces inside. And so hollow spaces in an X-ray show up as black because it's very, very, it's the lowest density, right? And so the whole skeleton just popped on the screen. in black when we x-rayed it. It was just so, so exciting. And yeah, and also, you know, we're a scientific institution that's prioritizing the scientific value of the specimen and not just its beauty, which is what is more valued by private collectors. So we really meticulously

prepared this, or I didn't. It was Akiko Shinya and Connie Van Beek. 1270 hours of fossil prep have led us to, you know, really having a very strong argument for this being like one of the best archaeoptery. Without a doubt, one of the best, if not the best. What makes it the best? I would say it's the best because it's almost 100% complete, just missing the tip of one of the fingers. It's uncrushed, so we get the three-dimensional morphology of the bones. A lot of other specimens are crushed. We also have extensive soft tissues, including soft tissues that have never been seen before, like the scales that form the foot pads on the toes. It's also articulated. So all the bones are where they would be in place. And we also,

are spinning one negative to our advantage. So there are small counter slabs that we could have united with the main slab during fossil prep, but we chose not to. And this is because this is opening the array of analyses that we can do when you have a small sample. Like, for example, you can't take this giant slab

and stick it inside the chamber of a scanning electron microscope, but these little small counter slabs that we have, you definitely can, you can. And so, yeah, there's all sorts of cool, you know, analyses that we have planned for the future that are not possible to do on large slabs and basically all the other previously known specimens. So what can you specifically learn from this one that you wouldn't have been able to learn from the others, the other 12 known archaeoptery specimens?

So there's a lot of like chemical analyses that we're going to do that it would be very hard to do on a very large specimen. But actually, we're learning just a ton of basic new information. You know, I thought archaeopteryx, you know, there's 12 specimens. The first one was described 163 years. ago, I didn't expect that we were going to learn a lot of basic anatomical information. But actually, we're, you know, we're actually redefining some pretty important aspects of the skeleton, like just what the skull looked like, what the palate looked like.

We have the first ever complete vertebral column. We can show lots of different bones looked slightly differently than previously thought. And this might not sound that important. But if you really want to understand the relationship of archaeopteryx and other birds to non-avian dinosaurs, you really need to know, have an accurate understanding of the skeletal anatomy. And that's what this fossil is giving us. And like you mentioned, this is the 13th fossil, but do you still want more, Archaeopteryx fossils? What more can you learn from additional ones, do you think? Well, oh, I hate to sound greedy, but yes, I absolutely would love more.

I mean, there's still so many questions that we don't know. Like, we don't understand if the, if they all represent a single species. This is something that's very heatedly debated. Every specimen at some point has been considered to be a different species. So I don't know what that says about our 13th. If at some point somebody's going to claim it's a new species, but we also don't understand what the size variation in these animals mean. Does it represent a growth series or are we looking at evidence of developmental plasticity? Was there sexual dimorphism?

Like there are a lot of questions that you need a significant sample size to address and more would always be better. And you talked about how you can distinguish, you know, how many vertebra it had and how its skull palate is shaped. But why are those things important to know? What difference do they make? So, you know, if you want to understand the relationship of archaeoprics to non-avian dinosaurs, the only way for us to do this is to compare the shape of the bones. And so for us to be able to accurately compare archaeopteryx to the closest non-avian dinosaurs, we need to accurately know what it look like, right? So, for example, we're drastically changing what the skull looks like, and it actually looks more troodonted like.

And it's a hypothesis that I've had for a long time. I'm not alone in this, that birds may be a group of troodonted dinosaurs. So we could not even say that birds are living dinosaurs. We can say birds are living troodonted dinosaurs. I mean, this is still a hypothesis. But this is what this new information is strongly suggesting. And so I think that's really exciting to be able to give evidence for one of the most important research questions for somebody who works on, you know,

theropod dinosaurs and works on birds is where birds fit in the dinosaur entry. And Jingme, before we go, I want to know what other fossil is on your dinosaur shopping list? You know, what remains would you love to get your hands on? Oh, goodness. That's a great question. You know, I don't necessarily want them in my own institution. I just think it's wonderful to have fossils available for scientists around the world. But I guess what I would like are, you know, this is going to sound so boring and nerdy. want more late Cretaceous birds. So we actually have a very good sampling of the earlier part of avian evolution, mostly thanks to these early Cretaceous fossils from China. But we know very, very little

about birds in the late Cretaceous. And so this all-important question, why do crown birds survive the end Cretaceous mass extinction? We need late-cretaceous bird fossils to really answer that question. And so that's actually what I'll be going out this summer, finding a month in the field looking for. What did those Cretaceous birds look like? Birds are incredibly diverse now. There's a total range of shapes and sizes, and the same absolutely would have been true for birds in the Lake Cretaceous. We have birds like Hesperonus, which was a very large but flightless bird,

almost completely reduced its wings. It would have lived in the oceans and used its feet for swimming and paddling. There would have been tooth birds in the latest Cretaceous. There would have been birds the size of hummingbirds. There would have been birds the size of turkey vultures, you know, raptorial birds, arboral birds, very, very similar today, except for the presence of teeth in some of them, I suppose. I clearly, I need to appreciate birds more, both the ones we have now and, and they're distant

ancestors. Definitely. I think, you know, thinking about them as dinosaurs, like next time you see a bird and look at that pigeon on the street and say, that's a dinosaur and then suddenly, like, notice the way it moves, the way its neck moves, like, you know, and then think of that as a dinosaur and then think about things like Diononicus moving like that. And I don't know, it's pretty exciting and fun to think about it, and I hopefully will give you a greater appreciation for the dinosaurs alive today. Definitely. Dr. Jingmey O'Connor is Associate Curator of Fossil Reptiles at the Field Museum in Chicago. Thank you so much for sharing your knowledge with us. Oh, my pleasure. Thank you for having me. That's it for today. A lot of folks helped make the show happen this week, including

Annie Nero, Jason Rosenberg, Rasha Eredi, Shoshana Bucksbaum, and many more. Tomorrow, we'll talk with wildlife ecologist Dr. Ray Wynne Grant about her pursuit of a wildlife. I'm SciFRI producer, Kathleen Davis. Have a great day.