Digging For Answers To Avians’ Ancestors

17:08 minutes

This story is a part of Breakthrough, a short film anthology from Science Friday and Howard Hughes Medical Institute (HHMI) that follows women working at the forefront of their fields. Learn more and watch the films on our Breakthrough spotlight.

One of the biggest questions in paleontology is figuring out how dinosaurs transitioned into the modern birds we see today—and all of the intermediate steps involved in that process. 

China is becoming one of the latest hotspots for unearthing fossils of these prehistoric birds and bird-like dinosaurs. Paleontologist Jingmai O’Connor is featured in our second season of ‘Breakthrough: Portraits of Women in Science,’ a video series profiling scientists and how their lives and work intersect. Here, she discusses her work in China, where she’s spent ten years trying to uncover clues about the diversity of ancient birds by examining their bones and preserved soft tissues, like lungs and ovaries. 

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Segment Guests

Jingmai O'Connor

Dr. Jingmai O’Connor is Associate Curator of Fossil Reptiles at The Field Museum in Chicago, Illinois.

Segment Transcript

IRA FLATOW: This is Science Friday. I’m Ira Flatow. One of the big questions in paleontology is figuring out how dinosaurs transitioned into the modern birds we see today and all of the steps that were involved in that process.

China is one of the latest hotspots for unearthing fossils of these prehistoric birds and bird-like dinos. A real prehistoric bird boom is going on there.

My next guest has been working in China for the past 10 years to uncover clues about the diversity of ancient birds. She does this by examining their bones and preserved soft tissues, like lungs and ovaries. And she’s here to share with us her work and what excites her about it.

Jingmai O’Connor is the associate curator of fossil reptiles at the Field Museum of Natural History in Chicago. She’s also an adjunct professor at the Chinese Academy of Sciences in Beijing.

She’s featured in our second season of Breakthrough, Portraits of Women in Science, our video series that profiles scientists and gets a closer look at how their lives and work intersect. Welcome to Science Friday.

JINGMAI O’CONNOR: Thank you so much, Ira. It’s a pleasure to be here.

IRA FLATOW: Oh, it’s so nice to have you. Jurassic Park I think got a lot of people hooked on paleontology and dinosaurs. And kids really became fascinated with dinosaurs then. Were you one of these dinosaur kids?

JINGMAI O’CONNOR: I most definitely was not. I found paleontology much later in life. I actually kind of stumbled upon it while in college. But I did become interested in geology by my mother, who is also a geologist. And she went and did her PhD when I was about eight years old. So she would drag us along into the field with her. And I started falling in love with geology itself.

And then I went to college, met a paleontologist, and just found my passion in paleontology. So actually, the first Jurassic Park movie that came out since I became a paleontologist was the Jurassic World movies. I got really excited.

I have to say I was a little bit terribly disappointed because the whole point of the Jurassic World movie was they make these genetically modified, half dinosaur, half crocodilian chimeras. And I mean, to me, dinosaurs and just basically all extinct animals are so fascinating in their own right, that to me, you shouldn’t have to make these GMO dinosaurs just to get interest. So I was a little disappointed by that.

IRA FLATOW: Yeah, you’re finding out that fact is stranger than fiction.

JINGMAI O’CONNOR: Yeah, exactly. Every time we find this animal or some animal, and we make hypotheses, I always find how our human imagination is so limited. Because when we get additional information and we actually find out what was really going on, it’s always totally different than what we had imagined. And I think that’s really exciting. That’s one reason I love science.

IRA FLATOW: I know you study ancient birds, and not dinosaurs necessarily. Give me the distinction between the two. Why are ancient birds interesting to you, rather than dinosaurs?

JINGMAI O’CONNOR: First of all, birds are dinosaurs. So, yeah. So I do technically study dinosaurs. And also, in order to understand these earliest birds, we have to look at the dinosaurs that they evolved from. So I do sometimes study dinosaurs, small, feathered dinosaurs closely related to birds.

Based on the programs I got into, I had a smattering of choices. And in the end, I chose early birds because at the time, and still continuing today, all these fantastic discoveries had been coming out of China, four-winged dinosaurs like microraptor.

And I’m half Chinese and very, very proud and fascinated by my Chinese culture. I really liked the idea of being able to combine my interest in China with my new interest in paleontology. So I just saw this as a perfect opportunity to intersect these two interests.

I was studying Chinese in college, and I had just been to China, to mainland China, for the first time. So I was really excited about that. So everything just kind of came together, naturally precipitated, I suppose.

IRA FLATOW: Why is China such a great place to study what you’re doing, the evolution of birds, there?

JINGMAI O’CONNOR: Well, China is actually a great place for all different types of paleontology, everything from some of the earliest animals, all the way to paleoanthropology, like Peking Man and that kind of thing. So it’s not just the birds.

But yeah, I think it’s partially because science there is really starting to get going at a very high pace only in the past few decades. So that means that there’s just a ton of work to be done, a lot of new discoveries to do, whereas paleontology in America is a little bit older. A lot of these badlands that have produced some of these really big famous dinosaurs have been picked over for over 100 years, whereas it’s much newer in China.

But in the particular area that I work on, all these small feathered dinosaurs, including the earliest birds, it’s really– it’s a numbers game. Paleontologists, if at all, we spend a couple months a year in the field. And then the rest of the time, we’re processing the specimens we found. We’re studying them. We’re teaching. We’re curating, all these other duties that we have.

And in China, it’s the same, of course. However, this region where all these feathered dinosaurs come from– it’s called Liaoning. It’s northeastern China. The first feathered dinosaur was found by a farmer who was just cultivating his land. And so this kind of– this made the cover of Nature. And it sparked this huge amount of interest.

So of course, paleontologists also started digging in earnest. And they had also been working there before, looking for fishes, actually. No feathered dinosaur had been found before. But also, a lot of these local farmers realized, hey, if I find a feathered dinosaur or just one of these beautiful fossil birds, I can sell it for a lot more money than I make farming.

So you have a lot more farmers than you have paleontologists. Because of these numbers, the amount of people who are looking for fossils and looking all year round, you just have a huge number of specimens being unearthed. So for example, T-rex, everybody’s favorite dinosaur, big guy, there’s about 40 fairly complete specimens. People have been collecting T-rex for a long time.

Now, take in another theropod dinosaur, but a small, feathered theropod dinosaur named Anchiornis. And Anchiornis was only described in 2009, so 11 years ago. And there’s already about 250 specimens that are known that are 90% complete or more. So this is not just because there’s more material there. It’s because there’s more people spending more time looking for these things.

IRA FLATOW: Wow, you sound pretty excited.


IRA FLATOW: It sounds like you have a pretty good job.

JINGMAI O’CONNOR: I love my job.

IRA FLATOW: Is working in China different than working in the US?

JINGMAI O’CONNOR: Most definitely. But every place is different, and even within the US, where you might be working would be different. Neither is better. Both has good and bad sides.

So in China, you have– for example, Mao Zedong said that women hold up half the sky. So there is not this chauvinism against women in China the same way that it exists in America. So that’s one thing that’s really nice.

Another thing is you don’t have all these fundamental Christians who are saying that evolution doesn’t exist. And science itself is not under constant attack in China, the way it is here in America. And also, the government recognizes the importance of science. So there is a ton of money to do research, which is not the case in America.

You have more and more people applying for the National Science Foundation grants. But you have the amount of money that is being allocated for research not really growing in proportion to the number of people who are applying for this money. So those are some of the really nice aspects of working in China.

But of course, now I’m back in America. I’m also really excited about that. I’m going to be at the Field Museum. And I mean, there’s something really incredible about working at an institution, a grand, old institution with these collections that are over 100 years old and that scientists, for such a long history, have been slowly contributing to.

And it’s really exciting to be part of that history, to be another scientist who’s going to contribute to this wealth of knowledge that is being held in this beautiful, old institution.

IRA FLATOW: Your excitement has gotten me really interested about some of the stuff you’re doing over there. And I want to specifically look at mesozoic birds, what, around 150 to 65 million years ago. Can you give me an idea of what bird diversity was like back then? If I were able to be alive, what would I be looking at?

JINGMAI O’CONNOR: So specifically 165 to 150 million years ago, the only bird you would have is archaeopteryx. Archaeopteryx first appears 155 to 150 million years ago in southern Germany. And it is the oldest and most primitive fossil bird that we know of. And really interestingly, it was the oldest and most primitive fossil bird when it was discovered. And now, 150 years later, it still has this position.

But if you move in to sediments that are a little bit younger, say, 130 to 120 million years old, this is where all the famous Jehol Biota from Liaoning province. So if you’re in Liaoning 130, 120 million years ago, you would have definitely not the diversity of birds you have today.

But you would have birds with long, bony tails that show that they came from reptiles, that they are reptiles, that they descended from dinosaurs that also have this trait. But you also would have some of the earliest birds with beaks, a group called the Confucius ornithoforms, mostly this group called Confuciusornis– of course, named after Confucius.

And so this is the earliest bird with an abbreviated tail, earliest bird with a beak. It has really weird, long, narrow wings. So I mean, I think it would look maybe like a crow with weird wings, too. But it essentially has the plan of a modern bird, except it has these big claws on its wings. So that’s really weird.

We still don’t exactly know what these claws were for because these claws are bigger than the claws we have in the dinosaurs that are closely related to birds. So we think, in the evolution of birds, that they’re losing their claws, they’re losing their teeth. But we also have birds with big teeth, more teeth than the dinosaurs that they’re related to, or bigger claws than the dinosaurs they’re related to.

And then you would have a group called the enantiornithines, which is what I did my PhD on. So enantiornithines, we consider the first major avian radiation. And a lot of people say that this parallels the radiation of modern birds that we saw after the KT extinction. And modern birds are the most diverse group of animals living on land today.

So if you take all the species of lizards and you take all the species of mammals and you add them together, there are more species of birds. So that’s incredible diversity, right? So comparing that radiation to the radiation of enantiornithines isn’t very fair.

Because if you’re in the Cretaceous, you don’t have owls. You don’t have penguins. You don’t have ostriches. You don’t even have any birds that have these types of ecologies. You know what I mean? You don’t have large, flightless birds running around. You don’t have specialized night hunters.

You don’t have any birds with extreme aquatic specializations, at least not in the early Cretaceous. So you would have a lot of different birds, but you wouldn’t have this shape and size diversity that we see today.

IRA FLATOW: I mean, those descriptions are terrific. I’m still back with the bird that has claws on its wings, trying to figure out how crazy that must be. I know that you work with fossilized soft tissue, like lungs and ovaries.

JINGMAI O’CONNOR: This is extremely rare. It’s not like 40%. It’s 0.0001% that we get these other types of tissues preserved. So I’ve studied a bunch of birds that preserved traces of the ovaries. And that was also very cool.

And so, for example, living birds all have only a single– OK, not all, but most living birds have a single functional ovary and oviduct. And this is unique to birds. All other animals with ovaries have two, a pair of ovaries, like humans do, like crocodilians, the avian, the closest living relatives to birds. They all have two functional ovaries.

But these fossils that preserve these soft tissue showed us that the earliest birds had already lost function of one of the ovaries, same as living birds. And that was really– it’s interesting because it confirms the idea that this one ovary was lost because of flight in order to reduce weight.

As you imagine that this bird is pecking on the ground for food, and a predator startles the bird and it needs to escape really quickly. If it has two developing eggs inside it, it’s really heavy. It makes it difficult to fly, especially because these early birds weren’t as good at flying as living birds.

This is what ornithologists had hypothesized was the reason they lost one ovary. And now we can show that since the earliest birds already had a single ovary, that this kind of supports the hypothesis that the appearance of flight coincides with the loss of one of the ovaries.

And of course, a lot of people think, no, these kind of things they can’t preserve. There’s no way ovarian tissue can preserve. And I mean, I understand there are reservations. And I also will be completely transparent that my first study of these soft tissues was extremely superficial.

But I have since gone back with a postdoc of mine, [INAUDIBLE], and we have gone deeper into these traces. We’ve done– well, she has mostly done– a bunch of really cool analyses. And we’ve been actually able to prove that these are indeed ovarian follicles.

IRA FLATOW: I’m Ira Flatow, and this is Science Friday from WNYC Studios. I also know that this year, you had a study published about what would have been the world’s smallest dinosaur. And this study was retracted. Can you talk about that? How did you discover that the results were inaccurate?

JINGMAI O’CONNOR: I think it’s very important for scientists to own their mistakes. I don’t want to just pretend that didn’t happen. I think it’s important to face that and say, yes, I was wrong. It turned out it was another specimen that proved us wrong, that there were also some researchers who were able to see, once we published the paper, who were able to see from just the skull that we described alone, that that was a lizard. But these are also people who focus more on lizards.

So we were basically a group of mostly bird workers who had what I call now avian tunnel vision. And there were a lot of features that were weird that were unusual for a bird. In hindsight, they maybe should have been red flags, but we just thought it was a very unusual bird. It turns out it’s a very unusual lizard.

So but it’s still a really fascinating specimen. Yes, the paper was retracted. But it wasn’t retracted because our methods were wrong or because there was fudged data or any of these other reasons that papers are usually retracted. It was simply retracted because we were wrong.

And fair enough, journals can make whatever decisions that they choose. But the fun fact is that because we named a species in this paper, the paper will always continue to be cited, according to the ICC and this code that dictates all the zoological nomenclature. Even though the paper is retracted, the nomenclatural acts in the paper are still valid.

So it’s this weird gray area. But yeah, the important thing is we are trying to fix this problem and talk about the mistakes that we made and talk about observations that– just kind of talk about this controversy. But because of this moratorium on publishing on amber specimens, a lot of journals just don’t want to touch it.

So it’s really hard now to go and kind of rectify this problem because nobody wants to review the papers. No journal wants to publish these reports. So yeah, it’s weird kind of purgatory, I guess.

IRA FLATOW: Yeah, well, you have a lot of other work to keep you busy, though, in the meantime. And it’s exciting to listen to your enthusiasm. Thank you for taking the time to be with us today.

JINGMAI O’CONNOR: Thank you so much. It was my pleasure. It was really nice chatting with you.

IRA FLATOW: Jingmai O’Connor is the associate curator of fossil reptiles at the Field Museum of Natural History in Chicago. She’s also an adjunct professor at the Chinese Academy of Sciences in Beijing.

And you can watch her Breakthrough video and see and learn more about ancient birds. Here’s the link, breakthroughfilms.org. It’s a really great film. You’re going to want to see it. Breakthroughfilms.org.

We’re having a watch party for our next Breakthrough video, featuring neurologist, Bianca Jones Marlin. She’ll be discussing the video and it’s co-hosted with Black in Neuro Community Group. Join us online Saturday, October 10th, at 1:00 PM Eastern time. And you can find out more at sciencefriday.com/watchparty.

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