...if dinosaurs had feathers? (with Jingmai O'Connor)

Perry Roth-Johnson: 0:06

Hello! This is Ever Wonder? from the California Science Center. I'm Perry Roth Johnson. When the new Jurassic World movie came out last month, we invited Dr. Jingmai O'Connor, a paleontologist at the Field Museum onto the show to help us think about whether or not humans could ever coexist with dinosaurs. Now, she blew our minds a little bit when she told us that we already have dinosaurs living among us today, birds. But, if birds are examples of living dinosaurs... Ever wonder if prehistoric dinosaurs had feathers like their modern counterparts? In this short, Jingmai explores our relationship with birds, how birds evolved from prehistoric dinosaurs, and how we know that some dinosaurs had early versions of feathers. Here's more of our conversation with Jingmai. Maybe in the context of the dinosaurs that have evolved and survived into to present day. Is there a dinosaur that might be the most helpful in your opinion to our society? Like, I think this might be a bad analogy, but people were trying to, uh, like use pigeons to carry messages like, uh, during battles and things like, is there an example of that, uh, in the present day that you think is like really helpful to our society?

Jingmai O'Connor: 1:22

I think like feathers is probably the most important thing that we get from birds, because with feathers, we have our down jackets, we have our, our down blankets. These are like feathers are the best material for trapping heat. And so thanks to that material, we are able to, uh, live in beyond in, in areas where it would be very difficult for us to live otherwise, you know, cold environments essentially. Um, there all birds are also important source of food though. This is something that is pretty interesting. Birds have really only been an important source of food fairly recently in human history where actually like mega farms made it made birds like viable. I guess birds don't really offer enough meat that, uh, they're not really worth it in most settings, but, uh, but eggs, maybe eating the bird's meat has, has only been important, very recent in human history, but eggs have been important for long periods of time, you know, and also birds have fascinated humanity for as long, you know, as we've been around, if you look at every culture, every culture has mythological birds, or like, you know, or like even the American symbol, it's like, it's an eagle, you know?

Perry Roth-Johnson: 2:29

Yeah.

Jingmai O'Connor: 2:30

And birds have been symbols of so many different nations. It's like birds on the Mexican flag, you know, it's all, you know, the Germans use the eagle, like the, the Romans use the eagle, like, yeah, birds are, are, are very important for, you know, I guess stimulating human imagination even, you know, and I think that could be considered even more important than just sustenance and, you know, feathers for our bows and arrows or for fishing or that kind of thing.

Perry Roth-Johnson: 2:55

Right. Right. I mean, humans have had a fascination with flight and, you know, I guess in the context of all of human history, we only recently learned how to fly. Like it's been a little over a hundred years. It make sense that that, that birds would, would, uh, be really fascinating to kind of look up to, um, I, I wanna go back to the feather thing for, for a little bit though, because I feel like in the mainstream, uh, consciousness, it's only recently where people are starting to think of dinosaurs as having feathers. Um, is, is that, is that true?

Jingmai O'Connor: 3:29

Yeah. So actually the first feathered dinosaur was found in 1996. Well, okay. The first feathered dinosaur was Archaeopteryx that was found in 1861. Sorry, but the first non-avian feathered dinosaur was found in 1996. And at that time there were people who were still kind of arguing about whether or not birds were dinosaurs. It was still like debated. I mean, most people were on the side of like birds are dinosaurs, but the, the side that said birds is not dinosaurs was very vocal, you know? And, um, but then you discover a feathered dinosaur, and this is now tangible evidence that anyone not just a paleontologist, any layman can look at and see that link between birds and dinosaurs because feathers are today. Something that is uniquely avian the only animals that have feathers are birds. But now we can see that birds inherited this unique feature from dinosaurs. However, the first feathered dinosaur that was found preserves what we call proto feathers. So in a modern feather, if you look at it is an incredibly complex structure. So you have that like central rachis and then coming off of it, you have these barbs that interlock with each other. That's how you can like pull them apart and like zip it back up. Right?

Perry Roth-Johnson: 4:45

Right.

Jingmai O'Connor: 4:45

And so that interlocking is because coming off of each barb, there are barb like barbules and then like little hooklets that then hook with each other. It's just, it's when you look at it under microscope, an incredibly complex structure, but the earliest feathers obviously had to start off as something simple. So they actually looked more like a hair. It was a single strand. Yeah. Actually a single barb of a feather basically. And so, so they doesn't really look like modern feathers. So some people looked at that first feather dinosaur, and they're like, oh, are those feathers, are they, you know, and honestly, fair enough. Right. You're looking at the smeared fossil. It's not perfectly preserved. It's not 3D you, you know? So that was a valid, you know, uh, you know, kind of concern. But then just two years later, another feathered dinosaur was found now preserving modern looking feathers because this dinosaur was a little bit more closely related to birds than the previous dinosaur. I mean, they were all theropod dinosaurs. Theropods are your, are your bipedal carnivorous dinosaurs. That includes like Velociraptor, T-rex, right? Also includes Sinosauropteryx a Compsognathid dinosaur—that was the first feathered dinosaur. And also Caudipteryx, which is an Oviraptorosaur theropod dinosaur that, um, now preserves like modern bird-looking feathers. And, uh, and then as you get, so basically, you know, if you think of dinosaurs, you're like dinosaurs don't look like birds! Because that's, cause you're thinking of you have a, you know, a Brontosaurus or a Stegosaurus, like those are not bird-like.

Perry Roth-Johnson: 6:19

Right.

Jingmai O'Connor: 6:19

But they're not very closely related to birds. So then you go to theropod dinosaurs, which are bipedal—like, birds, right? And as you like, so basically, you know, like you have this whole diversity of theropods, but you know, and they keep splitting into different lineages and evolving more. And one lineage is evolving more and more bird-like traits or bird traits, essentially. A lot of things that birds inherited from this group of dinosaurs. But all these bird traits only evolved in theropods. And then one lineage of theropods, we call birds and that one lineage survived. So if you like try to compare a bird and a Stegosaurus, there's not a lot similar. And you'd be like, I really don't see it, birds being dinosaurs. But if you compare a bird to Caudipteryx, like this Oviraptorosaur dinosaur, then you'd be like that dinosaur looks like a bird, right. It's very, very birdlike. Uh, you know, it does things like contact incubation and lays colored eggs, things that again, today are uniquely avian characteristics. Um, but at the same time they, you know, had a long tail and they had teeth and they couldn't fly. And there's a lot, there's a lot of differences, but um, but basically in this one lineage of dinosaurs, they get more and more birdlike and really where you draw the line and you say, now it's a bird. And on the other side of the line, it's not a bird that is, is it's really what it is. It's just a line drawn there because it's, you know, evolution

Perry Roth-Johnson: 7:45

Sort of arbitrary?

Jingmai O'Connor: 7:45

does not produce like, yeah, it doesn't produce these black and white. Like now I'm a new species or now I'm different, you know? Uh, it's really humans that are arbitrarily being like, this is that. And we're gonna label this something else, you know, like that's us doing that. So yeah, there are differences that we use to separate different groups. So, how do we separate birds from non-avian dinosaurs that are very closely related? Um, we used to say it was flight, but now we know that flight evolved a bunch of different times in dinosaurs. So now we have to say it's flight, but in that one lineage, if that makes sense. So this is very complicated. It's like the question of what makes a bird a bird is honestly, probably one of the most complex paleontological questions you could ask, even though it sounds like a simple question, it's a very, it actually is a very complex one.

Perry Roth-Johnson: 8:32

Right? Well, I mean, that's like basically your career, I'm guessing. I mean, you're an avian authority on this, this stuff.

Jingmai O'Connor: 8:38

Yeah, what is a bird?

Perry Roth-Johnson: 8:41

I wanted to ask one follow up question. Cause I thought you said T-rex was in that category of dinosaurs that is related to birds. Is that...

Jingmai O'Connor: 8:50

Yeah.

Perry Roth-Johnson: 8:51

So, so T-rex should have feathers.

Jingmai O'Connor: 8:54

Well, okay, so that is a question. That's a very important question. So actually living birds, plus Tyrannosauroids and everything in between those theropods that forms a group together that we call Tyrannoraptora. So T-rex has never, we've never found a T-rex that preserve preserves feathers. And in fact, we have found T-rexes that preserve patches of skin. So we know an adult T-rex was at least not fully feathered, but in China, in these same early Cretaceous deposits that preserved that yielded these first feathered dinosaurs—Caudipteryx, Sinosauropteryx, etc—two feathered Tyrannasauroids have been found. One is called Dilong, but Dilong was small. So you could be like, oh, small Tyrannasauroids had feathers, but then a few years later they found Yutyrannus, and Yutyrannus was like 30 feet long. So it was a big Tyrannasauroid and it preserved feathers—but proto-feathers, cause still Tyrannasauroids are

Perry Roth-Johnson: 9:52

Sure.

Jingmai O'Connor: 9:52

are not very, very, I mean they're relatively closely related to birds in the grand scheme of dinosaurs, but they're not as closely related as, as some other groups. So they still have these proto-feathers, these kind of hairlike things. So then this started the debate: Did T-rex have feathers? Cause now we know that these early Cretaceous Tyrannasauroids did have feathers. So would like they have been lost later into, in Tyrannasauroid evolution and T-rex doesn't have them anymore? Or what's going on there? So what we hypothesize is that baby T-rex, which was quite small, you know, like the size of a little terrier or something was feathered. It had like proto-feathers. It was a fuzzy little guy, very cute. But as it became really big, maybe around like the midpoint in its life, cause it goes through this growth spurt as a teenager and like just doubles in length, which means it's like tripling its size. That's huge. So, um, probably about that point, it lost its feathers or it restricted them to very small patches that were used as ornamentation during mating rituals. Because as you get bigger, your surface area is only ex increasing at a square. Right? But your volume is increasing at a cube. So as your surface area is only doubling in size, the volume within it is tripling in size. So what happens is because your metabolism like as a product of metabolism, you, it produces heat, right? All these chemical reactions going on in your body produces this body heat. So if you have a lot of surface area relative to your volume, you're losing all your body heat. So like skinny, small people have a higher surface area, you know, have more surface area relative to their volume. So they get colder more easily. Now as T-rex got really big, suddenly it has very little surface area for us, enormous volume. And it's still got all these metabolic processes going on. So it actually would've had the problem of getting rid of body heat, not producing it. Right. So, um, so having feathers all over the body, would've made it even harder for it to get rid of its body heat.

Perry Roth-Johnson: 11:54

Like wearing a big down jacket.

Jingmai O'Connor: 11:56

Exactly. So we hypothesize that probably did not have a lot of feathers as an adult, but it had them as a baby when it had a very high surface area to volume ratio and it, and it needed to keep warm. And this is why we think proto-feathers evolved to begin with—as thermoregulation. Because we think that the ancestors of Pterosaurs and dinosaurs were very small. And so they evolved some kind of proto-feathering, uh, to, for, for thermoregulation, for insulation. And then in different dinosaur lineages as gigantism evolved, then these, uh, proto-feathers were lost. So like for example, sauropods did not have feathers. They're huge, but uh, you know, very small dinosaurs like birds were heavily feathered.

Perry Roth-Johnson: 12:39

Cool. Thank you for indulging me. I just, I have to ask all bird questions.

Jingmai O'Connor: 12:44

Of course.

Perry Roth-Johnson: 12:44

That's our show, and thanks for listening. Until next time, keep wondering. Ever Wonder? from the California Science Center is produced by me, Perry Roth-Johnson, along with Jennifer Aguirre. Liz Roth-Johnson is our editor. Theme music provided by Michael Nickolas and Pond5. We'll drop new episodes every other Wednesday. If you're a fan of the show, be sure to subscribe and leave us a rating or review on Apple Podcasts. It really helps other people discover our show. Have a question you've been wondering about? Send an email or voice recording to everwonder@californiasciencecenter.org, to tell us what you'd like to hear in future episodes.