Webinar: Fossil Leaves and Ancient Atmospheres
Aired June 5, 2020
Maggy Benson:
Hey, everybody. Welcome to Fossil Friday. Welcome, everyone. Welcome. Hey, everybody. We're just waiting for a couple more people to join us. Welcome. We're so happy to have you here on Fossil Friday. All right. Welcome, everybody. Thank you so much for being here today for Fossil Friday. I'm Maggy Benson, and I'm a museum educator at the Smithsonian's National Museum of Natural History.
And before we begin today's program, we want to acknowledge our current events and let you know that the National Museum of Natural History stands with the Secretary of the Smithsonian, Dr. Lonnie Bunch, in expressing our deepest sympathy to the families and communities impacted by discrimination and violence. Today we are sharing our secretary's response and a resource in the Q&A developed by our colleagues at the Smithsonian's National Museum of African American History and Culture, Talking About Race. This resource has tools and guidance to empower your journey and inspire conversation about race. You can find those resources linked in our Q&A. And we feel privileged to have your time today to bring you, our learning community, together during this time.
So to see where our community is joining us from, we would love for you to find the Q&A and tell us where you are coming in from. I am joining you from Washington, D.C., and we have several other paleontologists who are joining you from the D.C. area who we will be introducing you to in a moment. Okay. So we have Chicago, Laos, New Jersey, Virginia, Virginia, India, Florida. All right. Nevada. More Florida. Canada. California. Massachusetts. More from Massachusetts. New York. Colorado. Baltimore. Missouri. A lot of Maryland and Virginia. Illinois. Silver Spring. Hey, neighbor. Georgia. Falls Church. Ithaca, New York. All right. More Maryland and Virginia. Colorado. Georgia. More California. All right. Welcome. I'm scanning to see if there's any states I haven't mentioned yet. Minnesota. All right. South Carolina. Ireland. Wow. All right. Oregon. Arizona. More from Nevada. Wonderful. Wonderful. England. New Delhi. Wonderful.
We are so happy to be able to give everybody a safe space here today to learn about fossils. Now, today we are going to use that Q&A function, like our other Fossil Fridays, so that you can send us all of your questions but also the responses to the questions that we ask you. Today's program is about 45 minutes in length. And first we are going to meet Dr. Rich Barclay and Laura Soul, who are both paleontologists at the Smithsonian. Laura's going to be hosting that conversation with Rich, during which you're going to be learning about fossil leaves and what we can learn about them.
All right. We'll take some questions after we meet Rich. Then he's going to teach us about reading these fossil leaves. And then we'll take as many questions as we can. Now, to help us answer your questions throughout our program, we have the lucky opportunity to be joined by paleontologist Vera Korasidis and Heather Killen. So let's meet them now. Hey, Vera. Hey, Heather.
Vera Korasidis:
Hi. How you going? Hi, everyone. You may remember me from a couple of weeks ago. I'm a palynologist here at the museum, and today I'll be helping answer some of your questions about paleobotany.
Maggy Benson:
Thanks for joining us, Vera. Hey, Heather.
Heather Killen:
Hi. I'm so excited to be here. My name's Heather Killen. I'm a science educator with the Fossil Atmospheres Project.
Maggy Benson:
Wonderful. Thank you, Heather. So today during our program, remember that Vera and Heather will be responding directly to you in the Q&A. And so you won't see your other friends' messages being posted, but you will see all of the answered questions in that Q&A. So make sure you check both tabs there, which says My Questions and All Questions, to see what has been responded to. And we'll do our best to get to as many as we can.
All right. And I did want to point out before I turn it over to Laura that we do have closed captions. If you want to turn them on or off, just find that closed caption button. It should be located next to the Q&A either at the bottom or the top of your screen. It depends on what kind of device you have. And there should be a little arrow there that allows you to activate the settings to hide them or display them.
All right. So without further ado, I'm going to turn it over to our featured paleontologists, Laura Soul and Rich Barclay. I'll be on standby behind the scenes. Hi, Laura. Hi, Rich.
Rich Barclay:
Hey, Maggy.
Laura Soul:
Hey, Maggy. Thank you. Thanks for handing over. Yeah. So as Maggy said, I will be helping moderate the questions today, like I have been doing for Fossil Friday recently. Hopefully some of you are familiar with me by now. I'm a vertebrate paleontologist and educator at Smithsonian. But I actually work on the Fossil Atmospheres Project as an educator with Rich. So I know lots about this project too, and I hope you find it as exciting as we do. But, Rich, do you want to take it away and introduce yourself?
Rich Barclay:
Yeah. Hi, everyone. I'm a paleontologist, a paleobotanist in particular. So I study fossil plants, and I'm a research scientist at the Natural History Museum, and I spend a lot of time, as you'll find out, running an experiment out at the Smithsonian Environmental Research Center, kind of in Southern Maryland. So I work on fossils as well as modern plants.
Laura Soul:
Thanks, Rich. And I think that you had some slides that you wanted to share with us to tell us a bit more about yourself?
Rich Barclay:
Yeah. Get that loaded up here. All right. You're looking at a map. This is a map of the state of Washington, which is where I grew up. I grew up in the town of Spokane over here on the eastern side of Washington State [inaudible 00:06:48] all the fossils that you can find in Washington State. So one of the great things about Washington and the United States in particular-
Laura Soul:
Hey, Rich. Could you just hold on for one second?
Rich Barclay:
Yep. Yep.
Laura Soul:
Your connection's a little unstable. So we'll pause for a second. The audio should catch up. All right. I think I heard you say that you grew up in Spokane.
Rich Barclay:
Yes. I grew up in Spokane, which is over here on the right side of the map, the east side. And I was lucky enough to grow up here where there are just fossils everywhere. There are fossils in every corner of Washington as well as across the United States. So I was lucky enough to grow up here. I went to school up in Bellingham and was able to study some fossil plants that were up there. But my journey through ... Let's see if I can get this to advance ... to paleobotany started at a young age.
When I was about eight or 10 years old, I went to a local creek called Deep Creek and was able to collect fossils from a fossil plant locality. It's about 15 million years old. One, five. And it's a fossil of cottonwood, things that are called poplars, and it looks exactly like the plant that's growing right next to it. So it was a really cool experience for me as a Cub Scout, collecting these plants and then looking to my left and right and finding the same exact plants in that place as you would have been able to find if you were there 15 million years ago. So I was lucky to grow up there, but all of you that are listening can go out into your backyards and find fossils too.
I have moved on. I'm older, as you can see from all the gray hairs, and I now do this professionally. So I go out and do geological field work in lots of remote places, one of my favorite being Western Greenland, but also in the United States, in Wyoming, where there are really good exposures of rocks where we can find fossils and bring those back to the museum. So we go do field work, and we endure the hot days that are required, but we come back with really cool stuff.
And I just wanted to mention that you might have the sense that we go and do this all by ourselves, and that really just is not the case. We have all kinds of support and help from ... In this case, in this project is particularly the case. We have hundreds of people that have been involved to get us to where we are. So I just want to dispel that notion that there's some genius working in the basement, creating scientific results. It's really the whole community's getting together and producing these scientific data. So thanks to all the people that have helped with the project.
Laura Soul:
Yeah. That certainly looks like a lot of people. And that image that you had of the leaf next to the fossil is amazing. They really do look exactly the same. That's why I love fossil leaves.
Rich Barclay:
[inaudible 00:09:58]. Go ahead.
Laura Soul:
So I do have some questions for you from people who are watching, if that's okay.
Rich Barclay:
Okay. Yeah. Go ahead.
Laura Soul:
All right. So first question is, "If you had to pick one fossil to study, what would it be?"
Rich Barclay:
I think that's ... You'll hear a lot about that in the rest of the presentation. I think the plant fossil I like the most is ginkgo. Ginkgo is native to Asia these days, but it used to be distributed across the globe. It has a really long fossil record. It goes back at least 200 million years. So if I had to pick one, that's what I would pick.
Laura Soul:
Good choice. And what is it that you like about your job?
Rich Barclay:
I like that it lets me work outside. I get to use my hands. I get to go travel around the world and see lots of really cool places. But it's really those aha moments when you spend a lot of time collecting information and finally come to a conclusion and you learn something interesting about what you've been studying, and those aha moments are pretty cool.
Laura Soul:
Yeah. You mentioned kind of traveling around all over the place, and you had those amazing images of you doing field work. What criteria is it that you use to figure out which area or regions to go do research in?
Rich Barclay:
Yeah. That's a really good question. We try to be question-based. So we want to study something that's interesting that happened in the geological past. And so what we do is we go find a place that has rocks of those age with enough detail in them that we can actually ... and they have to have fossils. That's necessary. But we pick a time period that has something interesting going on. We go to a place in the world where it has the best record of that. And oftentimes that's on the other side of the world.
Laura Soul:
Okay. And I think now it would be a good time for us to learn a bit more about the kinds of things that you find out when you get there. So if you want to start your presentation again.
Rich Barclay:
Yep. All right. So this is a reconstruction of a place in North America, something called the Dakota Formation, and this is a reconstruction of what that landscape looked like. And we just wanted to ask you what you see, if you can send us in what you see in this photograph in terms of geology or the plants or whatever else you see.
Laura Soul:
Okay. So everybody who is watching, open up that Q&A, and tell us in the Q&A what things can you see in this image that Rich is showing you. So this is a reconstruction of an ancient ecosystem. What things do you notice? What observations can you make? So Abigail says creatures. Lots of people have said dinosaurs. Although some people are not sure about the dinosaurs. Two dinosaurs. Ferns. Trees and a dino. Close to a swamp. Someone's mentioned there's a swamp. Lots of plants. Dinosaurs. River. A log. A dead tree. Bushes. Someone says that there's a ginkgo in there. Water. Vegetation. Okay. So we're getting lots of comments about the trees, which is good, and the water, [inaudible 00:13:18] bushes, and some people saying they can see some dinosaurs.
Rich Barclay:
Yeah. Those are all really good responses. Those are the main complements of an ecosystem like this. This turns out to be a reconstruction of what Denver, Colorado looked like about a hundred million years ago. At that time, there was a seaway that went all the way through North America and cut it into two pieces, left and a right half. And this is a shoreline in Colorado of a seaway, with dinosaurs walking along the beach, plants growing in the sand.
And one of the things that I wanted you to notice but I didn't hear or we didn't notice any questions about was the ... What I really study is the atmosphere and the climate. So if you look kind of in that middle distance, it's kind of misty. I can tell you that it was probably a warm place. So when we reconstruct these things, they're based upon fossils, and the fossils themselves, the plants that lived there, tell us a lot about the climate of that place. And if you were living on that, you'd have a nice siesta on the beach. It'd be a nice warm place. It'd be a cool place to hang out, as opposed to a really cold place that's full of ice.
Laura Soul:
So when you say reconstruction ... That's a word both you and I have used a couple of times now. We're basically saying that we take all those fossils or that information that you were just talking about and use it to reconstruct, so to figure out or to paint a picture of what the past looked like. Is that right?
Rich Barclay:
That's exactly right. Yep. And every component of that image was reconstructed based upon data we got from fossils in the geological record.
Laura Soul:
Okay. Great. So should we find out a bit more about all of the different things that you've used to reconstruct that ecosystem?
Rich Barclay:
Yeah. So if you take a look at this image, this reconstruction, and you notice the atmosphere, the plants tell us a lot about the atmosphere. And one of the two main things we'll go over today are the temperature of the atmosphere, because that's really important, and then the carbon dioxide concentration of the atmosphere, because that actually helps to determine how warm a place is as well.
And plants are really great indicators of that. They are planted in the ground. They're stuck there. They have to deal with whatever weather comes their way. They have to deal with that climate. And one of the things we can reconstruct from our understanding of the modern world is temperature. And if you go to a place anywhere in the world and you look at the plants, if it's warm, it has mostly plants that have those smooth margins, this image on the left side, where there's no bumps on it. If you go to a colder place, it has leaves that have a predominance of these teeth on the plants.
And what we can do then is we take this understanding of how that works in the modern world, study modern plants, places where we find these assemblages and plants, and then we can apply that to the same thing we find in the fossil records. So we can go collect the plants, get all the species we can out of the deposit, reconstruct how many of them have smooth margins versus toothed margins, and we can reconstruct temperature of that place even though it was a hundred million years ago that those plants were deposited.
Laura Soul:
So people could go outside to their own backyard or something today, and would they be able to do this as well?
Rich Barclay:
Absolutely. You can go out to your neighborhood, your local forest, take one leaf from every species of tree, and then figure out the percentage of those plants, those leaves that you have, that have either teeth or not teeth, and then that correlates very strongly with temperature of the place that you live. And we can provide some links to those, some resources that allow you to do that. But I've tried it in many different places across the United States, and it's amazing, but it works everywhere we go.
Laura Soul:
That's awesome.
Rich Barclay:
So that's reconstructing temperature from fossil plants. That's one of the main things we can do. Those fossils were impressions of plants. So the plant is gone. It's smashed in the mud. We come along a hundred million years later, and we pull that fossil out. We can see that it was a leaf, but none of the leaf is there. That's not always the case. Sometimes we get much more lucky and the plant itself is preserved as a compression. So the image you're looking at in the middle of this is a fossil ginkgo leaf that's about 50 million years old. Ginkgo has a really long fossil record. This image on the left is from Afghanistan, and it's a ginkgo leaf that's about 200 million years old.
So ginkgo has a really long fossil record, part of why I said I like that fossil, and it's one of my favorites. But oftentimes we get the leaf itself is preserved. So not only does it look exactly like the modern leaf does, but we can see the venation. And if I go to the next slide here, if you take an expensive kind of fancy microscope, a scanning electron microscope, which allows us to see the leaf in three dimensions, we can look at a fossil - this is a 56-million-year-old fossil - and look at the morphology. The cellular structure is still preserved on a fossil that's, in this case, 56 million years old.
Laura Soul:
It's amazing that you can still see that level of detail.
Rich Barclay:
Yeah. Those are individual cell wall lines, and we'll talk about these structures here in a minute. But it's not an impression. It is the leaf. The leaf material is 56 million years old. It's still the original carbon. Pretty amazing. So I think at this point we wanted to ask them what those are.
Laura Soul:
Yeah. Do you want to go back to the-
Rich Barclay:
Yeah.
Laura Soul:
... slide? Okay. So Rich was interested to know whether you all could work out what you think ... So if you look at this slide, you can see there's some parts in it where there are little holes. Rich, could you use your mouse to point out one of them?
Rich Barclay:
There's one here. There's one over. One over there.
Laura Soul:
They've got that hole in the middle and then two kind of sausage-shaped cells around the outside. And we wanted to know do you viewers have any idea what those are. What might a leaf need holes in it for? What would those be used for?
Rich Barclay:
So remember you're looking at a leaf. This is actually from the inside. And then these are holes through the leaf. And if you were able to stare through that, you would see the outside world.
Laura Soul:
I think we have some botany experts in the Q&A here.
Rich Barclay:
That's good.
Laura Soul:
Lots of people are saying air, breathing, for gas exchange, for air, for gas exchange. But there are actually lots of other people who are saying stomata.
Rich Barclay:
Excellent. Well, those are all correct. The technical botanical term for that structure here, that pore, is a stoma, or two of them are stomata, so botanically that's a perfect way to describe them. But that's a little more complicated than is necessary. All we need to know is that that hole allows gas to go in and out when those pores are open. So that's where the plant exchanges gases with the atmosphere. And one really important one is carbon dioxide, which goes into the leaf, and the plant uses that to photosynthesize and create all the rest of the structures of the plant. So really good answers. That's not an easy question to answer, so great job on that. All right. So great answers to that.
Let's move on. So that's a fossil ginkgo. And let me just go back one slide. So it turns out that the number of those stomata, those pores on the leaf surface ... That correlates to how much CO2 there is in the atmosphere. So this is a fossil. We can count the number of pores on this and get a sense of how many there are in a given area. And then we're left wondering ... Well, we want to know how much CO2 was in the atmosphere, and that's why we started a great big scientific experiment that we're running out at the Environmental Research Center where we can study modern ginkgo, Ginkgo biloba, living today. You can see them in their chambers here, these green plants. And we're growing them at elevated CO2 concentrations. This is an aerial view looking down in. The chambers are open from the top. So you can see the tree in the center there.
And so what we can do with this experiment is understand how modern ginkgo ... how it adapts to elevated CO2 conditions. And we're growing them in conditions that are really quite high. CO2 today is about 415 parts per million, and we're growing ... This tree in particular right here is growing at 1,000 ppm, something we haven't seen for probably 50 million years. So we're using the results of this experiment to understand and interpret those fossils, but also to help us understand how the plants are going to respond if we continue to emit carbon dioxide into the atmosphere.
Laura Soul:
So basically the idea is you have trees growing in lots of different amounts of carbon dioxide in the atmosphere, and then you can take them and look at the leaves and count the pores and see how the pores relate to the carbon dioxide they were growing in? Is that right?
Rich Barclay:
Exactly. Yeah. Yep.
Laura Soul:
Okay.
Rich Barclay:
Today we have CO2 that's at about 400. If the plant is living in an atmosphere that has a thousand parts per million of CO2, it doesn't need as many of those pores to get the same amount of carbon dioxide into the leaf. So that can actually reduce the number of pores on the surface, which makes them more water-use efficient. It's an open pore, so water goes out, and we know as transpiration, CO2 comes in. So they can become more efficient. They adjust their morphology under elevated CO2 conditions. So that's what we're studying is their response in the modern day, and then we can take those results and apply them to the fossils we get from whatever age in the last 200 million years for ginkgo and reconstruct what carbon dioxide levels were tens of millions of years ago.
Laura Soul:
That's very cool.
Rich Barclay:
Yeah. So one of the things that we wanted to do was to bring in the public to help us with this project, and one of the ways in which we do that is we created a site on the Zooniverse website. It's a citizen science website. And we provide those scanning electron microscope images of the plants that come from the experiment, and we allow the public to come in with some tools and count those stomata in the cells and give us the data that we need for the experiment. So we're letting the public do the research for us, help us with the research and learn about the project and find out how the scientific process really works. So this is a site we set up with Zooniverse, and it's something you can go and do, and we'll provide the website details for you to go do that.
Laura Soul:
Yeah. You are all the public, so we would really like your help. This is a great opportunity for anyone watching, if they want to, to become a citizen scientist. And like Rich said, we're going to post the link at the end. It's on a website called the Zooniverse, and you can actually help Rich do his research, which I think is kind of cool.
Rich Barclay:
I have so many things on my plate trying to do that if you guys can come help me do this research, we'll all be the better off, for sure. So I think at this stage we wanted to ask them to count how many stomata they see in this image. So what we'd like you to do is to take a look at the image on the left there and count how many of these are in this box. Any of it makes it into the box, we count it. So if you can spend a couple of seconds counting up how many fit in that box, we'll put those answers in the Q&A, and we can see how many of you think there are in that white box.
Laura Soul:
Okay. And so this is your extremely quick training for becoming a citizen scientist for Fossil Atmospheres. Look inside the white box. If there's any part of those pores or the sausage-shaped cells inside the white box, then you have to count them. So lots of people have got answers coming in, but I'm going to give people a second so that everyone can submit what they think. So you just go around, and you count them, and you see how many you think there are. And when you do the actual project, you also have to count those other cells, but we're just starting with a practice here. Okay. So lots and lots of people are saying eight. Some people are saying seven or seven and a half. Maybe there's some uncertainty about seven or eight. One person saw nine. But yeah. I think the general consensus is there are eight.
Rich Barclay:
General consensus is eight? I would definitely agree with you. This one probably down here in the bottom-left corner probably creates issues for people. What we like people to do is if any of it makes it into the box, we want you to count it. So I've got a graphic here that is, on the right, my count. So I get eight of them. So I would agree with most people. This is biology though, so there's ... Especially when you're counting the other cells, these epidermal cells, sometimes it's not always obvious, and we want many opinions on how to count those, because not everyone is going to interpret something exactly the same way. And so the more voices we get, the better off we are.
So the next slide I want to show you is when we get many, many, many, many people counting the same image, repeat counting, we get something that looks like what we see on the right, where every one of those dots is one individual mouse click or kind of a vote of where people think those stomata, those pores, as well as the other epidermal cells. So the stomata are in yellow, and you can see that this is about 350 different people counting this. They all come up with a pretty good consensus, and they actually get eight stomata cells, just like most of you did today. But we also get these clusters of dots, these green dots, that tell us where the epidermal cells are, the rest of the cells. It turns out the more accurate way of estimating CO2 from modern plants and from fossils is to look at the ratio of these stomata relative to the total number of cells that are in that box.
Laura Soul:
Okay. So basically what we've got is lots and lots of people. You said 350 have gone onto this and gone on the website on the Zooniverse and clicked in the middle of every cell, and it's kind of painted a picture, really. Hasn't it?
Rich Barclay:
Yeah.
Laura Soul:
It looks to me like everybody sort of filled them in a bit.
Rich Barclay:
Exactly. Yeah. Yeah. So they did a really good job. Turns out that if you get enough people counting, enough opinions on where things are, they actually get the right answer, which is why we wanted to involve the public, because collectively, if we get enough people counting, you guys get the right answer.
Laura Soul:
That's a nice message for us all.
Rich Barclay:
And which is really pretty amazing. Sorry. I was talking over you, Laura. What did you say?
Laura Soul:
I just said it's a nice message for all of us. If we all work together, we can get the right answer. [inaudible 00:30:04].
Rich Barclay:
Exactly. Yes. Unity is the catchword of the day.
Laura Soul:
Oh. We should also say just quickly before you move off that there are some pink dots on there as well. Could you tell us what those are?
Rich Barclay:
Yeah. The pink dots. We know that this is hard, and we know that it's not always obvious. And what we did was we allow you to say, "I'm just not sure." So those are the pink dots. But you can see the people that were mostly unsure ... Those end up in the clouds of dots. So they probably were just a little tentative, and that's okay. You can just go ahead, plow through. When you're unsure, you can just click the unsure tool and then move with greater confidence back to the green and yellow tools.
All right. So that gives us a sense of how this works. The scientific metric that we have, the data that we get, is a percent of the cells in this box that are stomata relative to the epidermal cells. And so it's a percentage. We have eight stomata, and let's just say 92 epidermal cells. So we would have 8% of that area would be stomata. So we get a percentage, which is basically parts per 100. And then we do this for many, many plants. And that percentage is over here on the left side of this diagram. So this is that percent of the stomata in that box, going from four to 14 percent.
And then we've plotted that data against CO2 concentration. So going from a modern day here, about 400, up to 600, 800, and a thousand. And we took samples that from about 1890, when CO2 was on the order of 300 parts per million, and we do that for plants throughout the last 130 years, and we get the data that's here. So that plots where these red diamonds are. So we see that that decreases over the last 130 years. As CO2 has been going up, the plants don't need as many of those pores, and so they've been steadily reducing the number of pores in their leaf.
But what we want to know is ... We have lots of evidence for the geological past that suggested CO2 was much higher. Temperatures were warmer. We get that from the fossil leaves. And so what we want to do, and this is where the experiment comes in, is we want to grow these plants at 400 up to a thousand parts a million and see how the number of pores on the leaves change in the experiment. And then we can take the data from that and flip it on its head and reconstruct CO2 in the geological past. So we take modern plants growing at elevated CO2, and we use that as a tool to reconstruct CO2 in the geological past tens to hundreds of millions of years ago.
Laura Soul:
Okay. So if we think back to the beginning of your presentation, you were talking about how we work out temperature. Now we have this way as well of maybe looking at a fossil from millions of years ago and knowing how much carbon dioxide was in the atmosphere. So if we know the temperature and we know the carbon dioxide and also we can see how the ecosystems were changing and how all the different animals and plants responded to that amount of carbon dioxide, does that potentially tell us about what might happen today?
Rich Barclay:
Yeah. We're using this modern experiment to understand the geological past in the way that you just described, where it tells us what the place used to look like, and we can understand and reconstruct that ecosystem. And then in a way this is a way to forecast what's going to happen in the case that we continue in a business as usual scenario, where we continue an economy just the same way we do now, where we emit carbon into the atmosphere. And if we don't change our ways by the year 2100, we're going to get up to on the order of 800 parts per million. So that just means that we're going to have a world that's very different than it is today, and we can use this tool to understand how it might change and allow us to prepare for any future changes to climate.
Laura Soul:
Okay. Great. Yeah, so that's really interesting. It's like drawing a line between the past and the present into the future.
Rich Barclay:
Yeah. So yeah. This is what paleobotany can do for us. We can go reconstruct ancient landscapes, we can reconstruct the climate of those places, and we can then try to put changes that might happen in the future into context so we can understand if we continue in the mode we're in now, then this is kind of what you can expect in the future, with the caveat that not all geological analogs are great analogs for the modern day, but we can get a pretty good sense of how things are going to change going forward into the future.
Laura Soul:
Okay.
Rich Barclay:
And then just one last thing to say. We'd like to get people involved. Science is something that you can do. And just like you can participate on the Zooniverse website where you can count stomata and epidermal cells, collect data from the experiment, we also want to get a sense of what ginkgo is doing all across the United States. And ginkgo is planted in cities. There's probably one in your town. And this coming August, depending upon how the pandemic materializes in different places, you can go outside, collect ginkgo leaves from your town, and then send them to us in the museum, and that gives us a snapshot for one month of what ginkgo was doing in the year 2020, and we can use that data to inform experiment and to better interpret events in the geological past. So you can go to the website. The address is up on the top left, at the Smithsonian website. And you can find out more information about how to go collect leaves and send us leaves to the Smithsonian this coming August.
Laura Soul:
Yeah. So all these resources, the web addresses, will be posted in the Q&A in a minute. And I do see that lots of people have lots of very good questions for that Q&A. But yeah. As Rich said, we would love you to join in with the Fossil Atmospheres Project. So you can go check out that website. You can go on the Zooniverse. Or you can collect leaves for us. But yeah. We'll ask a few questions now that have been coming in throughout the show. The first one comes from the Patterson family, who'd like to know why smooth leaves are found in warmer places and the toothed ones in colder.
Rich Barclay:
Yeah. That's a really good question. Why in warmer places are the leaves smooth? Most of the species have smooth leaves. And why in cold places are most of the species do they have toothed leaves? And it's something that we can observe in an empirical basis. So we can go to a place, go to many places, take the temperature from meteorological stations, and look at the leaves in those floras, plot that data. So we can see it in an empirical standpoint. In terms of how it works, that's a little less well understood, but it's probably has to do with ... In cold climates, plants are deciduous, and-
Laura Soul:
What's deciduous?
Rich Barclay:
They drop all their leaves in the fall. And then in the spring, they grow their leaves, and the faster they can grow their leaves, the better off they're going to be. And to do that, you need to have lots of water move through the leaves, and that's really a function of the two. So it probably has to do with the fact that in cold places it's cold, plants don't keep their leaves, they drop them, and then they try ... It's an advantage to try and grow their leaves quickly, and teeth really help with that.
Laura Soul:
Okay. And we'll switch back to some paleontology questions, I think. So lots of people want to know, how many fossils have you found?
Rich Barclay:
We don't count them, but definitely thousands of fossils. When you find a fossil deposit, you usually find hundreds to thousands of fossils in that same exact place. So depending upon what we're trying to do, we collect hundreds of them or thousands of them, and then we move on to the next one. So tens of thousands, I would say, plant fossils I've collected over time.
Laura Soul:
Yeah. That is a lot.
Rich Barclay:
Not as many as Vera with the pollen, but they're much bigger and harder to work with.
Laura Soul:
Yeah. Pollen's kind of cheating. It's so small.
Rich Barclay:
Yeah. It's a million of them in a cubic centimeter. That's not fair.
Laura Soul:
Ellias would like to know where you find the plant fossils. Where can you find plant fossils?
Rich Barclay:
Well, you can probably go find plant fossils close by to where you live. Not all places were once terrestrial, so that's not always true. But plant fossils are the most common terrestrial-based fossil you can find. So you need to know a little bit where to look, but there are lots of resources on the Internet where you can go and find localities and go collect them. They're not as restricted as collecting for vertebrate fossils, so usually you just need permission from whoever owns the land. But most people can collect fossils in places that are nearby to them.
Laura Soul:
Okay. And actually it kind of links into the next question. So you said a couple of times, "Terrestrial." So that means it's growing on the land. So these are fossils that came from things that lived on land. And Katherine would like to know, if you have stuff on the land like that, how do those leaves actually turn into fossils?
Rich Barclay:
Yeah. The way to turn a plant leaf into a fossil is to bury it rapidly and to get it away from anything that can eat it, bacteria, or anything that can oxidize it. So really it's burial, rapid burial, and then being left alone for tens of millions of years. That ginkgo fossil where it is the leaf and it has the cellular detail ... It's 56 million years old. It still preserves all that detail. It got buried rapidly in a stream deposit, got covered in sand, and then just kind of got dropped down into the Earth and wasn't exposed until about 50 million years later.
Laura Soul:
Okay. So it sounds like if you're a leaf and you want to become a fossil, you should try falling into a stream.
Rich Barclay:
Fall into a stream, get buried in sand, or fall in the mud, get buried quickly.
Laura Soul:
Okay. So going more, I think, to the kind of experiment things, another question is, "Why were there high CO2 levels in the past? Was it from volcanic activity, or something else?"
Rich Barclay:
That's spot on. Yeah. One of the ways in which we think that the atmosphere has changed its carbon dioxide concentration is through more volcanic activity during that particular period of time. So yeah. I think that's a really good answer. There are submarine, under the water, sources for CO2, but volcanoes on land as well. Yeah. I think that's a great answer. That's the major source for carbon dioxide.
Laura Soul:
Okay. And another fossil leaf question. Sophie asks, "In fossil plants, you can sometimes see insects tunneling in the leaves. Does the tunneling preserve?"
Rich Barclay:
It does, yes, and in spectacular detail. There are paleobotanists who work at the Natural History Museum that study exactly this same thing. This is one of the best ways to understand insect faunas through time is by looking at the damage that they do to leaves, and this shows up in impressions as well as compression fossils. So we can get a really good sense of the biodiversity of different kinds of insects and other critters that are eating on leaves from that damage. That preserves really well.
Laura Soul:
Okay. So even if the insects don't necessarily preserve in fossils, we can still see what they were doing to leaves.
Rich Barclay:
Absolutely. Yep.
Laura Soul:
Okay. Then Bradley would like to know ... I think this is referring to the experiment and trying to figure out what CO2 does. "Do you control for temperature? Does the temperature have any effect on the stomata numbers?"
Rich Barclay:
That is a really great question. We don't think that temperature has a great influence on the number of stomata on the leaves. It really does mostly correlate with CO2 concentration. And so it's something we aren't controlling in the experiments, and that's because we want ... We're growing them outdoors, and we want to compare our modern trees that we're growing under elevated CO2 conditions with fossils that were growing outside and dealing with all the weather and all the different parts of the climate. So yeah. We don't think it has a big effect, and it's not something we're controlling for.
Laura Soul:
And to follow up on that, the same person asked, "When you're doing each scenario, so you have those different CO2 concentrations or whatever, how do you decide which factors to change or to hold constant? How does that work?"
Rich Barclay:
Yeah. This is a little bit of a different experiment than you might see in most experiments where you control everything and then only change one variable. And we're doing it differently because we're trying to compare to fossils that were growing in real environments. So we don't let them dry out, but we only water them when we really need to. The rest of the things, we let the environment around them change as the seasons change, and we think that's a more realistic ... We want a realistic response from these plants, and if we controlled everything, you don't get a realistic response of how these plants grow.
Laura Soul:
Okay. So we're just about out of time now. In a second, I'm going to hand back over to Maggy. But just to finish up, somebody has asked, "Can I send ginkgo leaves from England to Rich?"
Rich Barclay:
Yes. Absolutely. We've gotten some ginkgo leaves from as far off as New Zealand, France, from Central Europe, Japan. We have some slightly different protocols sending them internationally. But yeah. You can find all those details on the website for the leaf survey. And we'd love to have them from England.
Laura Soul:
All right. So yes. Everybody all over the world, send us leaves.
Rich Barclay:
Send us your ginkgo leaves.
Maggy Benson:
Absolutely. Rich, thank you so much for teaching us about how you study both fossil and modern ginkgo leaves. It's so fascinating to learn about past climates and atmospheres and how they might help us predict for the future. So cool.
Rich Barclay:
Yeah. Well, I'm really thankful for the opportunity to talk to all of you today. And if you have further questions, go check out the website, and hopefully we can answer your questions there.
Maggy Benson:
Speaking of that, one of my colleagues should be posting the resources in the Q&A. So take a look at your Q&A to find some of the links for Rich's work. And, Rich, this si.edu/fossil-atmospheres link ... Is that where they can learn most about the Citizen Science Project?
Rich Barclay:
Yeah. That's our landing page, and you can access the Zooniverse page from there as well as at least their survey that will occur in August of this year. So that's the main site to go visit, and you can see most of the things from there.
Maggy Benson:
Wonderful. So yeah. My colleagues have posted that in the Q&A, so you can take a look at the hyperlinks there and follow those links to learn more about Rich's work and the Citizen Science Project. Who knows? Maybe it could be a really fun summer project for you to work on. Also included in that list of links is the Natural History Museum's website. That's where you can see a full schedule of our upcoming programs and the recording of Rich's program today. It's available on our live program page, which you can access from our homepage on naturalhistory.si.edu. And if anybody has any questions or comments, you can always email us directly at sciencehow@si.edu. And thanks to those of you who have sent us notes. We really appreciate those letters of appreciation.
And so I also want to say thank you to Vera and Heather for answering questions. They've been doing a great job at responding to all sorts of things in that Q&A. And to Laura, our featured paleontologist host. That was an awesome conversation. So thanks all of you for providing all of your awesome expertise and guidance, and thank you, viewers, for joining us today for a great program, and all of your questions are just awesome and inspiring.
I did want to also note one more time, if you missed it at the beginning, that we do have links in the Q&A also to a resource that our friends over at the National Museum of African American History and Culture have created called Talking About Race. It has tools and resources to begin conversations about race. So that's at nmaahc.si.edu. The link is in the Q&A.
When you leave this program, a survey link will pop up on your screen, and we would appreciate to hear back from you, so please take that survey. And we do hope to see you at another program. We will be back tomorrow for a family program and back next week, so check our website for that listing. Thanks, everybody. I hope you have a wonderful, safe, healthy weekend. Bye-bye.
Laura Soul:
Bye, everyone.
Rich Barclay:
Thanks, everybody.
