Webinar: Journey Through Time to Explore Ancient Oceans
Aired June 15, 2020
Meaghan Cuddy:
All right. I think we have just about everyone. So I'm really excited to get started today. Like I said, we're going to be talking about marine paleobiology, and I am really excited to introduce our guests for today, Dr. Brian Huber, and exhibit specialist Jill Johnson. So Brian, Jill, how are you guys doing?
Brian Huber:
Doing great, thank you.
Jill Johnson:
Good.
Meaghan Cuddy:
Awesome. So nice to see you both. Where are you joining us from today, Brian?
Brian Huber:
I am here in my home in Northern Virginia, in my office.
Meaghan Cuddy:
Very cool. And Jill, where are you from?
Jill Johnson:
I am joining you from my dining room in Silver Spring, Maryland.
Meaghan Cuddy:
Very nice. So all in the D.C. area, but all at our kitchens and our home offices. Well, Brian, Jill, before we get started, I'm sure people are interested in learning a little bit about your jobs. So can you tell us a little bit about what you do at the museum, Brian? What is it like to be a curator?
Brian Huber:
Well, first it's a great job. I've got three major responsibilities. First, is to oversee a large collection of microscopic fossils, and you can see all the trays, and the drawers behind me in that photograph on the left. My second major job, and really what takes a lot of my time, is collecting data, doing field research, and publishing. Then the third role is to do education outreach activities, such as this one. But I've also done work on two major exhibits, Ocean Hall with Jill, it opened in 2008, and then the Deep Time Hall just opened a year ago. A lot of my research focuses on evolution, extinction, climate change, and that research has taken me to many really fantastic places worldwide, including Antarctica.
Meaghan Cuddy:
That is so cool. You have a really cool job. And Jill, I know you have a really cool job too. So what do you do as an exhibit developer?
Jill Johnson:
Well, I get to work with small teams of people that include scientists like Brian, and designers, educators, evaluators, writers, and we all develop what the content is going to be in an exhibit. From the specimens to models, all the way down to the photographs, and the final credits that go in the exhibit hall. I've had the great opportunity to be with the museum the last 40 years, and work on exhibits like the permanent Sant Ocean Hall, Objects Of Wonder, which is a temporary exhibit where we brought out collections from all seven of our scientific departments. And I've been there long enough, that I've actually renovated our African Elephant exhibit twice in my career.
Meaghan Cuddy:
That is so cool. It's really amazing to hear about the different types of science jobs, and jobs that are in a museum. I know before I working at a museum, I didn't know that there were all these different science careers, like working in exhibits and collections, and being a curator. So it's really interesting to hear about some different careers that are not just being a researcher, or working at a university. But I'm curious about how you guys got to these points in your life? So Brian, did you always want to be a paleobiologist ever since you were young?
Brian Huber:
Well, there was a time when I was two, and my teddy bear was much more important to my daily life. But I think my real interest in the fossil record began by finding arrowheads on our farm, on our family farm, and just looking at the arrowheads, and thinking about where that landed, and what that landscape was like. Who shot the arrow? Who made the arrowhead? I've always had a love of history, and a paleontology professor in my undergraduate years was very inspiring, and really got me interested in studying paleontology, but particularly microscopic fossils.
On the upper right, I'm shown as a master's student, when I got a fantastic opportunity to go to Antarctica, actually three times, five weeks at a time, camping in a tent, looking for these microscopic fossils that nobody had found on the island before. Then I've done a lot of field work. On the lower left, I led a field expedition for several years to Tanzania, where we drilled in the sediments to get microscopic fossils. Then a couple years ago, I was co-chief scientist of an ocean drilling expedition. So I've been at the museum for 32 years. I should mention that too. I'm one of the old veterans now.
Meaghan Cuddy:
Well, you've gotten to do some really amazing stuff in your time there. Jill, what about you? How did you end up working in exhibits?
Jill Johnson:
Well, I always had a love of water in the ocean, which my dad captured in the picture on the left, when I was three years-old there. I loved my biology class in high school, and went on to get a bachelor's degree in marine science from a small school out in Long Island. I had the opportunity with one of my professors, to come to a symposium down in Washington D.C., and we got to go into the Natural History Museum, and visit the marine algae collections, and also visit a curator who had a model coral reef ecosystem, a living ecosystem, down in the basement of the museum. After I graduated, I got a job with that curator, who happened to have money to do this living model ecosystem of a coral reef as an exhibit, in the old Sea Life Hall. So the picture on the right, that's the early 1980s when I first started at the museum, and was collecting for corals and fish, and all different kinds of specimens for the Exploring Marine Ecosystems exhibit.
That's when my eyes got opened up to this whole other career of exhibit development, which I didn't know anything about. I absolutely loved it, and I've been able to work on some fabulous exhibits here. On the lower left, the most recent one, is with scientists from Southern Methodist University, and we have an exhibit in the back of the Ocean Hall, called Sea Monsters Unearthed. And it's about some amazing fossils found in the cliffs of Angola.
Meaghan Cuddy:
That is amazing. And I know you both have worked on the Sant Ocean Hall. You're both really involved in the design of that hall, and there is a huge part of it that's devoted to marine paleobiology. So today we're going to talk a little bit about marine paleobiology, but before we dive really deep into it, Brian, can you actually tell our viewers what marine paleobiology is?
Brian Huber:
Sure. Paleobiology literally means ancient biology. So it's the biology of fossil organisms, that lived in the ocean. And paleobiologists like to try to answer the question of what the environment was like when they were living. And to do that, they'll reconstruct the ocean temperatures, try to figure out what the ocean depth was, figure out was there enough oxygen, what was the direction and energy of the currents when they were alive. How long did the organism live? How fast did it grow? Who was its predator? And what was its prey? There're all kinds of neat questions you a can ask from fossils. And believe it or not, there's a lot that fossils can tell us. And the example on the left, on the lower left, is a crinoid from Crawfordsville formation in Indiana. This specimen is 350 million years-old, but it preserves information on these moments of time when it was under attack.
First, you can see that there's regeneration of an arm on the right, where a fish or some predator attacked it, and then the arm started growing again. So you can see the size change in the arm. Then you can see where there's a swelling in another arm, and that's where a parasite got into this specimen. Then the growth of the mineralized arm swelled up. On the underside of the specimen, believe it or not, it was under attack by a snail. So this poor specimen was getting it from all sides. Now this specimen is shown closed up. Fortunately, we have modern crinoids that live in the deep sea, and we can see how they fed. They were filter feeders, they're actually animals called sea lilies, and they open up and they passively feed on organic matter, as the organic matter floats by.
Meaghan Cuddy:
That is so incredible, and it's amazing how much we can learn about what these animals actually did when they were alive, simply from the fossil specimens. And Jill, so as an exhibit developer, it's your job to sort of communicate this science to our visitors at the museum, and tell stories to get them excited about marine paleobiology. So how do you guys do that in the hall?
Jill Johnson:
Well, first of all, we think about what specimens do we have, for example, that are going to allow us to tell some of the stories that could take us from the very early beginnings really of our planet and development of the ocean. And so here's an example where we used an artist's painting, to take a look at what Earth may have looked like, what the ocean may have looked like three and a half billion years ago, in this arcane world. Then we just chose specimens and stories that would allow us to move, take a journey through time, all the way up through the evolution of whales today. And if you take a look at the images that came up on the graphic in the middle there, at the very bottom, this is a terrestrial mammal, and they basically started to go into the ocean. There was a lot of available food and started feeding there.
And then over time, they evolved into species that were fully aquatic, ancestors to the whales that we know today. And went from toothed whales, to the evolution of baleen whales, because of very productive areas in the ocean with really tiny, tiny food. So all the way up to the whale model, in the middle of our Ocean Hall, is a full-sized model of a North Atlantic right whale, a baleen whale that feeds on really tiny things like copepods. And so being able to tell these stories, sometimes we use specimens, sometimes we models, sometimes we use paintings, and sometimes we use video. It just depends. So if you want to take a look, this is a view into the Journey Through Time Hall, and we have stories that focus on extinctions, stories that focus on evolution of particular groups, stories about ecosystems that you might find in the shallow water. And that leads into the story that Brian's going to share with us, about his specific work that's highlighted in the hall.
Meaghan Cuddy:
Yeah, that is so cool. Your work is such an interesting combination of art and collections and science. And Brian, I know you were really involved in this design of this hall, and these stories that Jill told, and your research is a part of it. So I know you work on the extinction event that happened on our planet 66 million years ago, on animals called foraminifera. So can you tell us a little bit about them and what they are?
Brian Huber:
Sure. These are single celled organisms that are like an amoeba, but they make a shell. And they have a fossil record that goes back over 540 million years old. The earliest foraminifera were benthics that lived in the seafloor, and then eventually planktic foraminifera evolved. And those are a kind that float in the seafloor. These things, the shells are very distinctive, and you can identify them by species. Each one has a time when it evolved, and when it became extinct. So scientists like me, just by identifying the species, can identify an age range of when these things were alive. So now by doing this, we have a constraint for telling about environmental history. If we know what the age is, then we can line up different times and different places, to see how Earth's environment changed through time. Most foraminifera are quite small. So pretty much everything you see here, is smaller than the head of a pin.
Meaghan Cuddy:
Wow.
Brian Huber:
So on this one, the specimens on the upper right are the planktic foraminifera, the floating kind. The two on the lower right are benthic foraminifera. Their shells provide a chemistry that allows us to reconstruct the temperature when the shell was formed, which is a pretty powerful tool. So you've got floating kinds that can tell you the temperature of the ocean's surface, and you've got the benthic kind that live on the seafloor, and then tell the temperature of the ocean bottom. They tell a lot of other environmental information as well, like how much oxygen was there, and whether or not the ocean was deep or shallow. So they're very powerful tools for reconstructing environments.
Meaghan Cuddy:
That's really cool. It's amazing that these little teeny-tiny organisms are holding so much information that can teach us about our ancient climate. So how do you actually go about acquiring them? Where do they come from?
Brian Huber:
Well, when foraminifera die, their shells sink to the seafloor, and become part of the sediment. And in the world ocean, we have that sediment buried below the ocean, and we can access that through the drill ship called the JOIDES Resolution shown on the left. This is a scientific ocean drilling ship, that has the technology to send a pipe to the seafloor, and then core into the sediments, and core by core we get into older and older sediments, and you can see them pulling core to the right.
The next slide, shows us about the time interval that I studied when I went to sea two years ago, we were really after the peak of Earth's warming in the hottest climate of the past couple hundred million years. And this particular core recovered an interval we were really going after. And so we're pretty excited about getting this interval. So you can see the core is split in half and laid out on the table there. A lot of science goes on, on the drill ship, and so that we get all kinds of information while we're at sea. And we're at sea for about two months at a time, 30 scientists from 15 different countries, working together for the same scientific objectives of the expedition.
Meaghan Cuddy:
That's incredible. And these cores look so cool. It's amazing that you can pull them out of the ocean, and get this information. So how does studying forams actually help us learn about extinction events and what killed the dinosaurs?
Brian Huber:
Well, a lot of people know by now about what killed the dinosaurs. A lot of people know about the asteroid impact. What's pretty amazing, is how the whole story of the asteroid impact came together. And a good part of that, came from deep sea cores, and studying the foraminifera and other things that went extinct. The impact occurred 66 million years ago. It left a crater 110 miles in diameter. In the lower right, there's a map showing where the asteroid hit, that yellow dot, and around it are these tektites or spherules that were quite large. Identifying the size of the tektites helped them determine about where that asteroid landed. By analyzing the Earth's crust, they found the crater, identified that it occurred at this time of extinction. And knowing that this traveled so fast, the heat energy was so great, that forest fires and ejecta blackened out the sunlight for weeks to months, causing the end of photosynthesis on Earth for weeks.
So as a result, many organisms starved, and of course a number of organisms went extinct. And so it's only those organisms that had some kind of food supply, that were able to survive this event. So if we go to the next slide, we've looked at these cores in detail, and a colleague and I cut a slab through one of the cores, right at the impact event. And you can see that layer identified as the ejecta bed, that is with the impact spherules itself. And what's cool is the impact spherules are biggest on the bottom part of that bed, and they get smaller as you go up. That's because the biggest spherules rained out of the sky first right after the impact. Now there's a huge difference in the planktic foraminifera before and after. On the right, you can see that the Cretaceous-age foraminifera just before the impact are quite large and very abundant in the sediments.
And right above that, you can't even identify any. In fact, there's a 90 percent extinction of all planktonic foraminifera species from that impact event. What's weird is that the benthic, which lived in the seafloor, suffered almost no extinction whatsoever. Now the difference is the planktics fed on things that photosynthesize in the surface waters in the upper ocean. Whereas the benthics had plenty of organic matter to feed on in the ocean sediments. So this is why there's a big difference between the extinction of the benthics and the planktics. The benthics had plenty to eat during these weeks to months of darkness.
Meaghan Cuddy:
Okay, cool. It's really incredible to see this represented in a core like this. It's so clear that something happened there, and it's amazing that with the tools that we have, we're able to really unpack that, and understand it. And use these little tiny creatures to understand life on our planet millions of years ago. But Jill, I know this isn't the only story that we tell in the Journey Through Time part of the hall, and we have an enormous marine collection at the Smithsonian, with millions of specimens. So how on Earth do you decide, Jill, what is going to connect with visitors, and what is going to help communicate these interesting marine paleobiology stories to them?
Jill Johnson:
Well, if we take a look at the slide that pulled up, again, we go and we take a look at what specimens do we have. And you can see here on the left, this is an amazing diversity of specimens from shallow-water communities over probably a couple hundred million years. And we can put them all out at once, or we can pick very select ones that might be able to tell some of those stories, like Brian shared before, about predators and prey. We look for specimens that we might be able to put out that people could touch. So on the right hand slide, on the top, there is this large ammonite that's really sturdy. And so we can put that out, and people can actually touch that. So that's one of the things that we look for.
One of the things that we did at the very beginning of the Journey Through Time Hall, is that we went through time, taking a look at top predators. And so in the ocean there is always going to be some animal that's going to be a top predator. So it allowed us to go from very early history, in geologic time, all the way up to the top predator today, which would be a killer whale for example. On the left, this is an amazing fish, a placoderm fish that lived probably about 400 million years ago. It's known as an armored fish, and it had these razor sharp jaws. It was the largest fish in the ocean, it was about 25 feet long. And this specimen that we have, was collected in Ohio. So the ocean looked very different over time. And the ocean was in what we now know as Ohio in the United States.
On the right, these are the amazing jaws, serrated teeth of a top predator, that is a mega-toothed shark. It's a fossil shark that's similar to mako sharks today. For a long time we thought it was related to the great white shark, but just recently they have made the connection that it's more closely related to mako sharks. So this is an amazing photo opportunity for visitors, to get behind there. If you wanted to, you could come and visit the museum, and we have a full-size model of this Carcharocles megalodon. There it is hanging over our cafeteria, 50 feet long, and it is indeed a top predator. And today, we have top predators like killer whales, giant squid, and even humans. Humans are top predators in the ocean today.
Meaghan Cuddy:
Absolutely. And it's so cool to hear the thought process that goes into taking visitors through this story of predation, from millions and millions of years ago. And we have these foreign looking animals, all the way up to modern animals now, and how our ocean has changed over time, using these incredible collections that we have. Brian, do you have any other favorite fossil stories from the hall?
Brian Huber:
Well, in Ocean Hall we feature a number of stories about organisms people aren't so familiar with, but one of my favorites is the story of the evolution of the trilobite. Trilobites are a type of arthropod, somewhat related to the horseshoe crab and lobsters, scorpions, insects, they're all in the same major group. But trilobite went extinct 252 million years ago. Early in their evolution about 520 million years ago, a little bit older, they were very two dimensional. And so the specimen on the left was quite large, and in fact the species were very diverse. And so they were one of the dominant organisms on the seafloor. But the one on the right, you see has a bunch of spines. Now why would they grow spines? Well, it turns out predators had evolved the ability to lunch on trilobites, and by growing hairy and spiny they're not going to look so yummy.
But eventually the predators got big enough that they didn't care about those little spines, and just crunched them anyhow. So we see in the fossil record that the diversity, the abundance of species in trilobite really drops dramatically not too long after their heyday, in the Cambrian period. And so the story of the trilobites is a sad last gasp, so that by the end of the Permian there's only a few species left. And then at 252 million years ago, there's a huge extinction that caused the very end of the trilobites. So this is one of those stories about extinction and relationship paleobiology to the things around them. And so understanding the environment, and predators and those things is really important.
Meaghan Cuddy:
Awesome. And then I know we have a couple more things to cover before we get into our visitor questions. I'm really curious about how this connects to our modern ocean. So the main point of the Sant Ocean Hall, the main theme of it, is that the ocean is a global system essential to all life on our planet. So how does telling stories about the ancient ocean connect to our life right now, and our ocean today? Brian, what do you think?
Brian Huber:
Well, as Jill said, we've got stories that go back 3.5 billion years about evolution of life, and included in that are a lot of extinctions and changes, evolution, changes in plants and in organisms through time. And one of the biggest changes of course has also been climate. I show a photograph of Antarctica today, which is completely ice covered, and not a place you're going to find fossil forests, or living forests, or animals year round, other than a few penguins. My experience in Antarctica set the stage for my research career, because there I was, working in the field, it's really cold, nasty wind, but I'm finding fossil wood and all these beautiful fossils in the sediments. So I had this curiosity, how warm was it in the past? Because clearly there were forests in Antarctica in the past. Well, the illustration on the lower right was just published a few weeks ago in the journal Nature.
They actually drilled beneath the ice in Antarctica, and they cored into this plant debris that they dated at about 92 million years ago. This is a time of this hot greenhouse Earth, that I've been so interested in trying to reconstruct. Clearly we have evidence directly in Antarctica, that we had quite rich fossil forests living there in a climate that was much, much warmer than today. In fact, it's called the Cretaceous Hot Greenhouse Climate. And so I've recorded a lot of these data with my colleagues from sediments all around Antarctica, and from the deep sea worldwide.
We wonder why did it get so hot? How long did it stay hot? Why did it cool? And what did the ocean system, how did the ocean system respond? How did organisms respond? So that's been a lot of research, just to try to understand how the system works. By understanding how the system works, we can better predict how climate's going to change in the future, as we get into warmer and warmer temperatures around the Earth, and in the ocean. And of course sea level's going to go up, and with increased carbon dioxide burning, we get more and more ocean acidity. So having all this valuable information in the fossil record, and teasing apart that information, using our best analytical tools, to understand them, helps us better predict the future of Earth and life on Earth, as a result of global warming and change.
Meaghan Cuddy:
Those questions that you ask as a paleobiologist, of how does the climate change, what causes it to change and what does life look like when it changes? As well as the other questions we talked about. So how do predators and prey interact? And how do things evolve? Those all sound like questions that modern biologists also ask. So this link between fossil life and current life on our planet is so interesting to explore. Jill, as an exhibit developer, how do you then take all of these things and use it to get people excited and motivated in the Ocean hall?
Jill Johnson:
Well, what we did was wrap up the very end of the Journey Through Time hall with a graphic that talks about this current age that we're in, this current age of humans, referred to as the Anthropocene, where we are having an impact our species on a global scale. And we are making an impact that is going to be seen in the fossil record, right? It's going to be in the geologic record. So human population, if you take a look down on the lower left there, just skyrocketed after, from the industrial era, World War II. So our impact on the planet has dramatically increased. And so our use of resources, overfishing, overhunting, There's an example on the right of Steller's sea cow that was discovered and went extinct very quickly due to overhunting.
We're looking at radioactive waste that is being seen in the sediment. And so it's looking at the past, and the information that paleobiologists like Brian are able to bring to light, that allows us to kind of measure what might potentially happen today. So what can we do as a species to be better stewards of the ocean, because the ocean is a global system that's essential? So the last slide gives you just a couple of examples of the kind of things that you can do. On the left is a beach clean-up. There's beach clean-ups that can go on anywhere, and plastics are a huge issue in the ocean. Microplastics are going to be buried in that geologic layer, because we have so much plastic. So just being able to clean up the beach, makes a really big difference. And then think about how you commute to work, or commute to school, and use public transportation, bike, walk, because that's not using fossil fuels, and that's really going to make a difference on our planet, on a global scale.
Meaghan Cuddy:
Absolutely. I think that that is such an important part of coming to the museum, is we get to see all of these amazing things that have been collected over time, and experienced these wonderful collections. But then also learn a little bit about how we can continue to maintain that diversity on our planet, and make sure that we have collections for future generations to enjoy as well. So thank you Jill and Brian both so much for sharing all of this with us today. It was just so cool to hear about what you guys do in the Journey Through Time Hall. Do you think you have some time to answer some questions from our audience now?
Brian Huber:
Oh yeah, you bet.
Jill Johnson:
Sure.
Meaghan Cuddy:
All right. We have a lot of questions that have come in, and also a number of comments saying that they thought your work is really cool, and that trilobites are amazing. We have some comments about trilobites specifically.
Brian Huber:
I agree.
Meaghan Cuddy:
Me too, for sure. The first question is a general question for both of you. A couple viewers are wondering about your journey to your careers that you had, and what made your mentors good mentors for you? And what inspired you to follow the career paths that you have? So Jill, do you want to talk a little bit about people who mentored you in your life? And what keeps you excited about your job?
Jill Johnson:
Okay. So I think that my dad was one of them, because he had this love of outdoors, and we used to go camping all the time. So that just led to an absolute love for nature, and we would almost always end up at a beach somewhere. So that's where my interest in marine life ... I had a fabulous biology professor in high school, that I knew, "Okay, I want to be a marine biologist by ninth grade, 10th grade." I had a couple of fabulous professors in my undergraduate school, that really inspired me to just do amazingly well in terms of the different types of classes that I took.
So I had a really great range of opportunities, and being able to come to the museum, the curator that I started with, Dr. Walter Adey, he just encouraged us to go and explore, and that led me into this field of exhibits. I had some fabulous mentors in my early years in this field, of exhibit development, because I had no idea what it was all about. I just think every exhibit I work on is new and I have new teams of people, and new scientists that just keep me really excited about this job.
Meaghan Cuddy:
That is so cool. Brian, what about you? Have you had any really impactful mentors?
Brian Huber:
My ninth grade Earth science teacher was really the first one who got me interested in study of the Earth. I think his lectures were very engaging, and he really invited questions. You could go up after class and talk and he would answer as long as you had questions. Then I mentioned my undergraduate paleontology professor who I really enjoyed, because he inspired curiosity about how these organisms lived. Then for graduate school, I had a mentor who was very supportive. Before I even started my master's, I got to go to Patagonia because he suggested me as somebody to participate on an expedition. So he gave me lots of great opportunities. And I think my colleagues, collaboration is something I really enjoy. Working with colleagues is one of the more satisfying things I do in my career. I think the points of view of multiple people, is much better than the point of view of one. I like sharing ideas, and then sort of eureka moment when something comes together, and we say, "Yeah, we figured that out."
Meaghan Cuddy:
Yeah, that's my favorite thing about working at the museum actually, is getting to work with people like you guys, who work in all kinds of fields, and we're all reunited in this common goal of learning more about our planet, and then communicating that with the people who live here. So that's my favorite thing about my job too. Cindy has a question for you, Brian. She's curious, do you know why trilobites became less diverse as they got closer to their extinction? So what happened with trilobite extinction and their diversity?
Brian Huber:
I would bet that the major factor is the age of fishes, and if you remember the Dunkleosteus that Jill showed, it's hard to be a trilobite and compete against organisms that big with such big teeth. And even though those fishes probably didn't grub around in the sediments, they were just bigger and bigger predators. And trilobites just could not compete against those more efficient predators. There's something we have in the Ocean Hall called the Predator-Prey Arms Race. And so as the prey got bigger and more efficient for hunting, sorry, as the predators got bigger and more efficient, the prey found ways to get better defense. Now the spines were one way of defense, but that just wasn't enough to survive the efficiency of these big hunters.
Meaghan Cuddy:
Yeah, I can't imagine being a trilobite and having to compete with the jaws of that placoderm fish. I can imagine that it wouldn't go super well for me. Jill, Hunter has a question for you. He'd like to know what family of species do you think tells the most interesting story of adaptation in the hall? So do you have a favorite story that we tell in the Sant Ocean hall?
Jill Johnson:
Well, I think the example there that we used of whales, I mean that is just such an amazing story to me, that we think about life evolved in the ocean, and then it kind of walked out on land, and we had land animals, and then it turns around, you turn around and look back and see this amazing food resource. And in really a blink of an eye, in geologic time, you go from this terrestrial mammal, through these different species of whales, that become fully aquatic, streamlined, and then go from toothed whales to baleen whales that have evolved different types of baleen to sift out different size organisms. And to me that is just, they're adapting to the ocean as it is changing over time, due to changes in the environment. I just think with the collections we have, and then the modern story we have of our North Atlantic right whale today, that's one of my favorite stories in the hall.
Meaghan Cuddy:
Yeah, that is one of my favorite ones too. And I always love to point out to visitors those fossils that we have of ancient whales with feet. It always makes their minds explode, and I think it's always a really fun story to share with them. Brian, we have another question about the placoderm that we were just talking about. Wyatt from Virginia would like to know, "Does the placoderm fish have a tail?"
Brian Huber:
Yes, it's got a tail fin like other fish. Unfortunately what gets preserved, is the bony skull, and we don't see the fleshy outline of the rest of the body. So we don't have direct knowledge of that. But we know because it's a fish, and all fish have that kind of tail fin, reconstructions are going to be accurate presenting it in that way, with this vertical tail fin.
Meaghan Cuddy:
Cool. We have a question that a lot of our viewers have asked Ama, Garash, and Mia, and I apologize if I mispronounced any of your names, are curious about how Antarctica changed from being a hot place, to a snowy and icy place. So Brian, can you talk a little bit about how that happened? That seems like a really big change in climate.
Brian Huber:
Sure, and that's right up my alley, because that's a lot of what my research has been. So Antarctica now is very cold. One of the reasons it got so cold, is because with continental drift, South America and Africa and Australia all pulled away northward, isolating the continent of Antarctica around the pole. But that's not the only reason. As you go back in time, we know from analyzing the shells of organisms, and getting the estimates of temperature from past geological times, that Earth's climate was much warmer, and particularly the polar climate was much warmer. That's largely due to carbon dioxide that got pumped into the atmosphere, from lots of volcanoes. We know from studying plate tectonics that there was a phase of rapid seafloor spreading, meaning the continents were moving on the mantle much faster. And during that phase there's a lot more subduction, which means a lot more volcanic eruptions.
With those volcanic eruptions, a lot more carbon dioxide gets pumped in the atmosphere. CO2 is a greenhouse gas, it's a warming blanket around the Earth, insulating the Earth. And so the temperature, from the tropics to the poles, was not that different during these times of extreme warmth, particularly that time I showed that forest in Antarctica. So this is one of the ways we know that carbon dioxide is directly linked to climate. So increased carbon dioxide, you get increased temperatures. As you bury carbon dioxide, global temperatures start to cool. Okay, so with the greenhouse warming we have now, with all the industrial fuels that are getting burned over the last couple hundred years, we're obviously in this warming because of all that carbon dioxide.
Meaghan Cuddy:
All right. That is a really incredible story, and it's amazing that we are able to go back in time, and find out what our climate used to look like. And then figure out how it might then be translated to our future climate as well. I know that's a really important story, that you all tell, Jill, as part of the exhibits team. So you have time for one more question. From Ellen, Jill, I'm going to pose it to you. She would like to know, "Do you like your job, Jill?"
Jill Johnson:
Sometimes I have friends that say, "She just loves her job so much." And maybe they're friends that don't love their job, but I love my job. I can say like 97.8 percent of my 40-year career, I have absolutely loved it. So it's been so exciting. It's something I didn't know about, and it's the people, and the stories, and the collections, that have just made it so rewarding.
Meaghan Cuddy:
Yeah, it is such an incredible career that you both have had and I love working at the museum with both of you, and I can't wait until we can get back there, and see all of our amazing collections in person again. So thank you guys both so much for joining us today, and for taking some time to talk to our audience. And thank you everyone watching. We really appreciated all of your awesome questions.
