Webinar: Living and Fossil Ostracodes
Aired May 29, 2020
Maggy Benson:
Hello everybody. Welcome to Fossil Friday. Hey, I'm Maggy Benson and I'm a museum educator at the Smithsonian's National Museum of Natural History, and I am coming to you virtually from my home in Washington, D.C. Before we begin, I want to give a special thanks to our generous donors, volunteers, and other important partners who enable our team at the Natural History Museum to discover, create, and share new knowledge with the world like we're doing today, do it every day free of charge. While we wait for more of our friends to join, why don't you take a moment and find the Q&A button on your Zoom menu. It should be located at the bottom of your screen or at the top of the screen. It says Q&A and it has two speech bubbles on it. Use that Q&A button to tell us where you're tuning in from.
I'll read those off in a moment. Now you're going to use that Q&A button to send us questions you have during today's program for our experts to answer directly. You're also going to use that space to answer the questions that we ask you. So for example, where are you tuning in from? You're going to use that same space, the whole show, and you'll notice that you won't be able to see your friend's responses, but that's okay. Our team here at the Smithsonian can see everything. You'll notice that there are two tabs on that Q&A. One says all questions, and the other says my questions. Make sure to check that my questions tab to see if one of our chat experts, some of our Smithsonian scientists who are answering directly by text have responded to your question. And so today, we are lucky enough to be joined by some of, actually four Smithsonian paleontologists, and two of those experts are going to be answering your questions directly in the Q&A. So I want to take a moment right now to introduce them. So welcome Karma, welcome Camilla.
Camilla Souto:
Hi Maggy.
Maggy Benson:
Can you introduce yourselves for our friends watching?
Camilla Souto:
Hi everyone, I'm Camilla Souto and I'm a paleobiologist at the Smithsonian, and I study marine animals like sea urchins and sea cucumbers.
Maggy Benson:
Thanks for being here today, Camilla. Hey Karma.
Karma Nanglu:
Hey, and I'm Karma Nanglu. I'm also a paleontologist. I also study marine animals and so, I'll be helping to answer some of your questions, especially if they happen to be about gross things like worms, you should definitely address that to me.
Maggy Benson:
Awesome. Thank you so much, Camilla, thank you so much, Karma. So like I said, that Q&A is for you to answer the questions we ask you, but it's also for you to send us questions that you have throughout today's program. And Camilla and Karma are going to do their best to answer questions by text. So make sure you check the Answered column and the My Questions column on your Q&A to see the responses to their questions. Now, before I welcome you and read out some of the places where you're tuning in from today, I also want to point you to a new feature we have, which are live captions. So next to the Q&A button, you should see a closed caption button. It has CC on it. You can press that to either hide the live captions or change the settings on them so you can make the texts appear larger or smaller.
Now, please note that these are live captions, and so they will be a little bit delayed, and some words, it might not get perfectly. All right. So, I want to take a moment now to welcome you and to read off some of the places that you're joining in from. So we have friends from Maryland, Virginia, New York, Houston, Texas, Missouri, more Maryland, North Carolina, California, a lot of Maryland and Virginia, Florida, Minnesota, Washington State, Wisconsin, more Washington State, Colorado, Ohio, New York, Indiana, Grand Junction. All right, Massachusetts, Colorado, more Virginia, welcome neighbors. Canada, Texas, Pennsylvania, South Carolina. All right, Pennsylvania. More from California and Colorado. All right. Darby England, Martha's Vineyard, Michigan, Connecticut, Ohio, New Jersey. All right, welcome everyone. Georgia, that's a new state, Maine, Brazil, Ottawa. All right, Louisiana. Welcome everyone, we are so happy that we're able to digitally bring people together even though our museum is closed.
So without further ado, I want to connect you to our featured scientist today. Dr. Laura Soul is going to be facilitating a conversation with our featured expert, Dr. Gene Hunt. Today's conversation is going to be about 45 minutes long, and after we meet Gene, we'll take some of your questions and then he'll share with you his research on fossil ostracodes. And after he does that, we'll take more of your questions. And if you don't know what an ostracode is now, don't worry, Gene will tell you all about them. So I'm going to go behind the scenes and hand it off to Laura and Gene now. Hey Laura, hey Gene.
Laura Soul:
Hey, thank you Maggy, hi. Hi everybody. Thanks for the intro, Maggy. you've probably, most of you seen me before. I'm a paleontologist and an educator at Smithsonian Natural History along with Maggy and Gene who we will be talking to today. You might have noticed that there's a marine theme, so maybe you can guess where ostracodes live, but now I'll just hand over to Dr. Gene Hunt to introduce himself.
Gene Hunt:
Sure. Thanks Laura, let me get my screen going here. There we go. So, as Laura said, I'm a paleontologist at the National Museum of Natural History. And I've worked on my career in a number of different kinds of fossils. That picture on the right shows me holding a clam with pretty little spines, but most of the work I've done is on these little tiny fossils called ostracodes, shown here on the lower left, that's a picture of one blown up lots of times.
And sometimes people ask me, how did you get to be devoting your career to studying something that most people have never heard of? And it's true, I did not grow up wanting to study ostracodes. I didn't even particularly want to study fossils. I was interested in science in general, but I had lots of interests then. At age nine, I was pretty sure I was going to be a baseball player, but that did not work out. But what did happen is, at college, I actually got an internship to come to this museum, the National Museum of Natural History to study fossils, and it really kind of lit a fire under me, caused me to go to graduate school and eventually become the paleontologist I am today.
Laura Soul:
That's an interesting back story. I wonder what our viewers want to be and whether that will change as they grow up. I think we've got a few questions that people would like to know about you Gene, if that's all right. So the first one that lots of people are interested in is what do you like most about your job?
Gene Hunt:
I think what I like most is that I get to just be curious about the natural world and try to figure out clever ways of learning about it. And it's totally unstructured, I could do what I want to do and if I find something that's really interesting, I want to learn something about a particular fossil, about how particular fossils change over time, I just do it, and I really love that freedom to explore what I want to learn.
Laura Soul:
And another question be, when you decided, so you said you had an internship at the Natural History Museum. After that, how long did it take for you to become a paleontologist properly?
Gene Hunt:
Right, okay. So at that point I had finished my undergraduate degree, it was in biology. I took a couple years off and then I went to graduate school for six years. It took a long time to get my Ph.D. And then after graduate school, usually there's a shorter training period called a postdoc, which I did for about a year and a half before I got to my position where I am now. So I was 30 years old, I think when I started being a real true professional paleontologist, all my training was done.
Laura Soul:
And Stella would like to know, what is your favorite fossil?
Gene Hunt:
It's that one right there actually, on the screen. In the lower left, actually, it's something I'll talk more about, Poseidonamicus. It's a particular ostracod that I've worked a lot with.
Laura Soul:
All right. And then, lots of people want to know, and I think this is a great segue into the rest of what you're going to talk to us about, what are ostracodes?
Gene Hunt:
That is a perfect segue, yes. In fact, I think I have a slide with that very question on it here. So ostracodes are relatives of shrimp and crabs, they're crustaceans. They're around today, they're something like 20,000 species that we know of, probably many more that we don't know of. And they're tiny. They're related to shrimp and crabs. They're tiny, they're like a good size is a millimeter, which is about one 25th of an inch. If you're having trouble visualizing that, think of something really small like a poppy seed that's on a bagel or a muffin. And this hand here on the lower left has [inaudible 00:09:11] seeds. Those, each poppy seed is probably two or three times bigger than a good size ostracodes, they're even smaller than those poppy seeds. What they have is, they have these two shells that open and close, like a clam.
And inside that shell, they have these legs and things. It looks a little bit like a shrimp, at least vaguely. You can see some of the legs sticking out here. Let me show you a little more action shot. I said they're around today. And so we can show a little bit of video of some ostracodes wandering around an aquarium. This is some footage that was taken by David Horn, who's a specialist who studies ostracodes. You can see this guy swimming here with these little things sticking out. There's actually a little baby one right there that's getting run over really bad, tough guy.
Laura Soul:
Aw, that's cute.
Gene Hunt:
They have these things sticking out are actually an antennae, and that's how they usually swim or walk with. They use those to get around. They have all different kinds of color patterns. You're looking at from the side, these kind of banging into each other.
This is a top view, so we see two shells, two valves, one side and the other. And it's kind of, this is of a chubbier-shaped one looking from this way. And that shiny circle in the middle is actually an eye for those guys. Now this one is the last one I'm going to show. This is one that's slowly walking around and we see these oval, sort of in the back of it, these are actually eggs. So this is a mama ostracod and it's holding its eggs in the back there where it'll eventually when they get older, it'll release them once they're ready.
So, I said I'm a paleontologist, and we showed you some pictures of some living ones that are around. And if you were to look at those two shells, those two shells, and if you were to pull one off, you would see something that looked a little bit like this. One shell is there on the bottom. The top one has been taken off, and they have, these are the antennae in the front. These are some other limbs. This is part of the mouth. But when we're dealing with the fossil record, all this squishy bits rots away. And so that goes away, and what we're left with is just the shells.
And so that's overwhelmingly what we're looking at as paleontologists. And these shells are very durable. Here's a selection that we see from the fossil record, they're made of calcium carbonate, which is the same stuff chalk is made of. And they come in all different kinds of shapes and features and things like that. There are smooth ones, there are ones that are spiny, there are ones that have ridges, there are ones that have little wing-like projections on them. And scientists use these features to tell them apart and to learn about them and trace how they change over time.
So, one thing you might ask is, "Well, if these things are so darn tiny, how do you even find them?" Right? It's not as if you can look around the ground and pick something out that's half the size of the poppy seed. And that's true, we don't do that. If you're looking for dinosaurs, you look for a piece of bone sticking out of the ground, and then you start digging. In this case, what we're going to do instead is just collect a bunch of rocks or a bunch of sediments, bring it back to the lab, and then we process the ostracodes and other fossils under the microscope. So I'm going to talk about two different ways we get the rocks or the sediments that we could use to process to look for fossils. This one is showing sampling from an outcrop. An outcrop is just a exposed rock at the Earth's surface.
This is myself and a colleague, Rowen, who's doing all the hard work and she's going to dig out a bunch of that, it's sort of hard sand is what it was. And we took that sand back to the lab to process. This happens to be in suburban Maryland in Prince George's County, not too far from where the Washington Redskins play, in the middle of a suburb that had a creek and that creek exposed this rocks, which are about 68 million years old. So these rocks are around at the tail end of the time of the dinosaurs, when T. rex is walking around the land, these rocks captured some of the things living in the ocean. So how do we know to look there? And what we do is, we rely on the work of other geologists and other scientists to look for rocks that have the right age and the right kind of environments.
We're looking for things that are preserving the ocean environment. In this case, we're looking for things that are about 68 million years old. And one way we do that is by using something called a geological map. So you recognize this I think as, about the eastern half or so of North America. And for this map, the colors represent the ages of the different rocks that are appearing at the surface that are now outcrops. And the 68 million years ago that we were sampling, corresponds to light green that's right there above the orange, which kind of forms a thin band from Texas all the way up to New Jersey. Well, there's another way we can also get the sediments and the rocks to find the fossils in. And that is, we could collect them from cores taken from big oceangoing research vessels. So there's a number of big programs.
One is called the International Ocean Discovery Program, and it has these boats that has these big rigs on top. And what these rigs do is they have cores or basically tubes that are about this wide, and they bring those tubes down to the bottom of the ocean and kind of shove them into the sea floor. And these hollow tubes kind of go into the sediment to the bottom of the seafloor. Almost as you can picture like a straw punching into some wet sand. And then they bring that sand all the way up to the boat.
So the picture doesn't really do it justice, but sometimes this boat can be one or two miles or more above the seafloor, and they're sending these cores all the way down and they can send core down and bring it up and send another one out and bring it up and do repeat it over and over and over again to get a really deep, basically continuous core into that sediment. Once they bring it back on the ship, they can cut the core in half and this person is basically using a little scooper to get some of that sediment out.
Laura Soul:
Okay. So basically you are looking for really tiny fossils and somebody wanted to know, are they invertebrates or vertebrates?
Gene Hunt:
They're invertebrates. So they don't have a backbone, they are crustacean specifically. So they're relatives of shrimp and crab and lobsters in that group. No backbone, they're invertebrates.
Laura Soul:
Okay, so really, really tiny shrimp relatives.
Gene Hunt:
Yes, exactly.
Laura Soul:
Okay. And then, so we have these two different ways of finding them. Am I getting that right? You can either go to an outcrop and you just collect sand or rock and kind of hope for the best, or you have a big ship and you make a really big core.
Gene Hunt:
Yep, that's right. There's two different ways of getting the rocks you want to then search. And then, there's some processing that happens that I can talk about right now. So, when you get a bit of the sediment or the rocks from a core or from the outcrop, you basically soak it and then wash it through a screen that's called a sieve. You could think of it like the screen that's on your window or your door. And it's a fine enough mesh that the little ostracodes and other tiny fossils will [inaudible 00:15:29] on it, but the littler bits will go through like mud and clay and things.
Then when you dry it, you get something that looks like little sand in these vials. And then you tap the little sand onto this tray here and you take that tray and you look at through it under a microscope. And every time you see an ostracode or whatever kind of fossil you're interested in, you use a wet paint brush and pick it out. And you can often get an amazing number of these fossils in a little bit of sand. So for example, this is one sample about the same age as the other site I told you about, 68 million years old. This one's from Arkansas. And we have, I haven't counted these, but something like five or 600 ostracodes that we're able to [inaudible 00:16:06] just one little...
Laura Soul:
That's very pretty.
Gene Hunt:
Yes,
Laura Soul:
I like how they're very neatly arranged.
Gene Hunt:
Someone spent a lot of time gluing them down just so, so they'd be very tidy. And you separate them by species and so forth. So, I talked about these two different ways of collecting the sediment or the rock that you can then look for the fossils. And the question I have for the audience is, what do you think the benefit of doing it one way or another, why would you want a sample from outcrop like on the left, but why would you want to sample using a big boat and get these cores from the deep ocean? Have any ideas?
Laura Soul:
Okay, All right. Everybody who is watching, what do you think? What would be the difference in stuff that you would get from an outcrop versus stuff you get from a core? Why might we be interested in those two different places that you could find these fossils? Tell us in the Q&A. Anyone got any ideas?
Gene Hunt:
That picture on the right is showing some of the processing that happens on cores when they bring them back to the ship. They photograph them, they measure a bunch of things and then they bring them back to shore and they save them in these big libraries of cores.
Laura Soul:
Okay, so we've got some answers coming in. Some people are saying core would be undisturbed, age, because the ocean is a big environment, to find fossils of different ages, different types of rocks, covered and uncovered. So I guess that's uncovered in the outcrop and covered in the core. Ooh, differences in adaptations and diet. That's an interesting one. Are they kind of on the right track, Gene?
Gene Hunt:
They're all really great answers actually. One, the deep ocean is, like you said, [inaudible 00:17:44] ocean is very big, you could sample lots of places, you can get spatial coverage. For outcrops, often you have to be depending on what age rocks happen to be where you want to go. A big advantage is, or another thing you might consider is habitats. When you're sampling way out in the middle of the ocean, this is really deep water. So we are talking about animals, they're living a mile or two down below the surface [inaudible 00:18:05] environment, you might have different adaptation, different species there.
And if you want to study those species, you have to sample it that way. One [inaudible 00:18:12] to say is that the coring is much more expensive. You need this big boat, costs many millions of dollars, these expensive cruises and things like that. Where to collect fossils from an outcrop often you just need to shovel and a bucket or something like that [inaudible 00:18:23]. But one thing I wanted to mention that hasn't been is one of the other advantages of cores, you can keep going down [inaudible 00:18:30] lots and lots of cores.
Laura Soul:
Gene sorry, could you pause for a second? Your audio's shifting a little bit, so we'll just give it a moment to catch up and then we can go through this bit, a bit more slowly.
Gene Hunt:
Sure.
Laura Soul:
All right.
Gene Hunt:
So, is that better?
Laura Soul:
Yes.
Gene Hunt:
Okay. So, one of the advantages of the core is, as I said, you can put the core, you can get lots [inaudible 00:18:50] same spot going deeper and deeper and deeper into the ocean floor. And what you could do is if you keep track of when those cores come up, stack them again later and get this very long record. So I've just stacked two, three cores, I couldn't fit anymore in the screen. But really you could actually stack hundreds and you can get a thousand feet or more of this sediment that you're pulling up from the floor. And because of how these work, you get this really long record of changes over time and what's going on in the Earth. And if you look at the stuff at the bottom of the core that is older than the stuff at the top of the core, which is younger.
And that is because as each layer settles down from the ocean, it goes on top of the previous layers. And so as you go higher and higher in the core, you get younger and younger sediment. The net result is you get this really long detailed record and you could use that for all kinds of things. And one of the major things that's used for is actually for changes in Earth's climate over the past, this is a really good record of that. And if you compare the thousand feet, you could get from a core to, I don't know, we have maybe five or six feet of exposure at this outcrop. You could see it's a huge, much more continuous, much bigger record you can get from a core. You could think of the core as giving you a whole book and the outcrop giving you one ripped out page of the book a little bit in terms of the long record of changes you can get over time.
So one of the things I wanted to talk about was describing new species. People will often ask me, "Well, have you ever found a new species? Have you described a new species of fossil?" As it turns out, actually just colleagues and myself were working on describing a new species just last week. That's the species shown on the left, this shell over here, I'll talk more about in a second. It was from a deep-sea core shown where the red dot is in the Atlantic Ocean. This is Brazil, this is North America, there's Florida right over there. So at about 3,000 meters, which is about 10,000 feet of water depth. So this is really deep at the bottom of the deep ocean. And we named the species Poseidonamicus sculptus, and like all species names, it has two parts. The first part is the genus name, in this case Poseidonamicus.
The second part is the species name, sculptus. So you might have heard Homo sapiens refer to the human species. Homo is the genus, sapiens is the species. And this genus name Poseidonamicus is a bit of a mouthful. But the first part might be familiar, Poseidon. And those of you who know anything about or have learned about Greek mythology, Poseidon is the God of the sea and amicus is the Latin word for friend. So the idea is that, this genus is a friend of Poseidon because it lives in a deep ocean. Sculptus, the species name just refers to being carved or sculpted and it refers to all these lovely ridges and spines and things that are present on this shell.
Laura Soul:
So did you get to choose the name?
Gene Hunt:
We did. When you define a species, you get to choose the name and there are certain rules about how you're supposed to do that, which sometimes get broken. But that's one of the perks of actually being able to describe a new species. You can choose the name and you can name it after a person, a description or a place, however you want. And sometimes, when people describe new species, it's because they are the first people, so far as we know, to ever have that species, to ever laid eyes on that particular species. Sometimes however, people have seen that species before, but they just didn't know was a new species. And that's actually what the case was in this one, this species people had found before, scientists had seen it before but had thought maybe it was the same as another species, Poseidonamicus pintoi, which I show here on the right.
So this was a species that was described in 1972, it was named after a gentleman name of Ricardo Pinto who is a South American geologist. And people had found something like what we're calling sculptus on the left, but thought hey, maybe that's pintoi, I'm not really sure. But what we did is we looked very closely at a number of features and found a number of important differences that told us that sculptus was actually a different species from pintoi. And I'm going to ask the audience now to sort of be paleontologists with me and try to see if they could find some of the differences we identified that let us know that in fact this species on the left, sculptus, was different from this other species already known, pintoi, on the right. So take a close look and see what you can find.
Laura Soul:
Okay, so for those of you who have been tuning into Fossil Fridays for a while have really honed your observation skills at this point. So, I'm hoping for some good answers here. So everybody take a look, we're doing spot the difference. Can you see what might get us to define these two ostracodes as different species to each other? All right, someone says, thinner ridges on pintoi, side ridges, bigger. Someone says with a ... Angie says with a question mark, bigger. The right is smaller than the left. A few people are saying, I don't know, that's okay. That's a legitimate answer.
Gene Hunt:
And I said, this is actually a really hard problem. I mean because remember for 20 years paleontologists who studied ostracodes were like, "Yeah, I'm not really sure, it's going to take more work." So these are small differences we're trying to pick out here.
Laura Soul:
So what are the important differences there then?
Gene Hunt:
Right, so the easiest one probably to see is the size. And that's true, the pintoi is smaller, it's about 15 percent smaller than sculptus and that's consistent, it's not just the two specimens we looked at. Someone said the ridges are thinner, I think on pintoi, was that right?
Laura Soul:
Yes, they did. And lots of people posted things about ridges and the patterns as well. Several people mentioned the patterns on them.
Gene Hunt:
That's right, those are really good observations. That's one of the key differences that these ridges here in this part, in the middle back part of the animal are pretty even. They're about equal width, they're equal size. Where in sculptus, we have some really thick ridges and some really narrow ridges, and that's a key difference. Someone said something really observant too and that I think, edge ridges was thinner. And I think that refers to this, which is another important difference. This little rim here, it's quite thin in pintoi and it's probably twice as wide here over in sculptus. That's a really good observation.
Laura Soul:
Yeah, you all did a very good job with that. There was a lot of detail in those answers.
Gene Hunt:
There really was. One thing to know, a really cool thing about ostracodes is that, they've actually studied how these kind of ridges develop. And you see these little compartments here, these little boxes. It's been shown that each of these little box actually corresponds to a single cell. And so they're actually looking at the cells, the arrangement of cells on the animal. This isn't just a surface feature, it's showing you the actual arrangement of the cells.
Laura Soul:
Cool.
Gene Hunt:
So, I think the last thing I was planning on sharing with everyone is the observation that when you study these samples of ostracodes, you often find when you think you have a single species, it looks like to be basically the same thing. But we have two different shapes for the specimens in that species. And one of the shapes is already always more elongate. It's relatively stretched out in this horizontal way. And one of them is always shorter or less elongate. The top one is more elongate, the bottom one is less elongate. And we find this consistency over and over again in living and fossil ostracode samples we look at. And so my question for the audience is, what explains this? Why do we get these two different forms, these two different shapes within a species so frequently?
Laura Soul:
All right everyone, another question for you all. Why would we have two different sizes within one species? Okay, we've got answers coming in. So, Imogen says age. Mason says evolution. Someone has said sexual dimorphism with exclamation marks. I think they might have heard about this before. Lots of people saying sex, age or sex, evolution, sex type, adaptation, species in different places.
Gene Hunt:
Okay. So let me address some of those. So one of those is right, it's that these are different sexes, these are males and females. But the other guesses are really good. So, you might say, well the bottom one is smaller, maybe it's a juvenile or a younger form at the top. And the reason why we know that's not the case is, these shells have features on the inside, which you can't see from this angle that tell us that they're adults and therefore we know for sure these are full grown adults, both of these. Someone else said evolution or changes over time, and that could be possible if you had, these were from different ages, but in fact these were from the very same sample.
So they're basically from the same age. We didn't go from evolve from one form into another. But what we do see is that these are males and females and you might ask, well how would you know, say you believe that they're sexes. One reason we think that sex is because you find about equal numbers of them. Kind of like how in people you find almost the same number of males and females, but how do you know which one's male? And the truth is we wouldn't know really except that we can see the living ones today and we can look at their soft parts and we know for sure which ones are male and female and we see that the ones that are male have the longer shells. And that's how we know that.
Laura Soul:
So it sounds like a lot of the people that were coming up with those different answers had actually come up with some of the explanations that scientists had and then had to eliminate.
Gene Hunt:
Yeah, that's absolutely true. Some scientists, early on didn't necessarily understand that these weren't different growth stages. Sometimes they thought they were different species, they didn't recognize that they were males and females in the same species. And as only as people learned more about ostracodes and studied more and more samples, did they sort of figure this all out. So, now that you've sort of done the one example, let me give you another example here. Which one of these is the male, the top one or the bottom one? So just this one here. The male is more elongated, shaped differently. The female is shorter with a different shape. Which one is the male, top or bottom?
Laura Soul:
All right. Top or bottom, everyone. Okay, we've got a lot of people saying bottom. In fact someone has said, Clara says top with a question mark. Everyone else, bottom one, bottom one, bottom, bottom, bottom, bottom, bottom.
Gene Hunt:
Yes, it's a very tricky question. So one person got it right who put in the answer it is actually the top one. And it's a little bit tricky here, but the important difference that scientists have noticed is it's not the size but it's the shape. If it's more slender in shape, it's the male. And what difference is on the left, that species has males that are bigger than the females. You can see the top is bigger than the bottom. But this species in the right is a little bit different, it's males or smaller than the females. And in fact you can get both patterns within ostracodes. So again, the top is the male, the bottom is the female, because the key thing is the shape, not the size.
Laura Soul:
Okay.
Gene Hunt:
Again, these are the two ways that the males and females can be different. The males can be bigger or the females can be bigger. We see both of these in both modern and fossil ostracode species. Some scientists have suggested that species for which the males are much bigger than the females might actually have a greater likelihood of going extinct. They have a higher extinction risk than species for which the females are bigger than the males, where the opposite is true. And the argument in short has to do with the fact that for these large males they're spending a lot of energy, a lot of resources to grow large in this certain way. And that energy or resources might not spent in that way, might mean that they don't have resources to be able to adapt or adjust when environments change over time and the males might preferentially die and then the whole species might go extinct.
So, scientists have suggested this as a general idea for all kinds of organisms and some colleagues and I were interested in testing this idea using ostracodes because we can actually tell the males and females apart. Which is one thing I meant to say earlier, this is kind of cool. We could look at these fossils, which on the left that fossil is about 75 million years old. And I can tell you for sure the top one's a boy in the bottom one's a girl. That there's male and female. And that's very rare that paleontologists can do that. Almost never can we look at a fossil and know which ones are male, which ones are female. So ostracodes are really special in this way. So anyway, scientists wanted to know, well is this true? Can the kind of way males and females differ, can that affect whether or not they're more be more or less likely to go extinct?
And so how do you address this and how would scientists in general address this kind of question in the fossil record where we're interested in knowing if there's some kind of feature, some kind of trait which can increase your chance for extinction or decrease your chance for extinction, can cause extinction or protect against extinction. How do scientists get at that kind of question? And that's shown here on this slide, and let me kind of walk you through because there's some different parts to it here. So, on the side here, we have time going from older at the bottom to younger and I've showed those cores that I showed before, but it could also could be from outcrop, it doesn't really matter. So you have older at the bottom, younger at the top. And what these vertical lines represent is basically the life span of species in the fossil record.
So this one here in the upper left, it was first appeared here, say that was 70 million years ago, it was around for a while, scientists could sample it for a couple million years and then say 2 million years later, it goes extinct. That represents the whole lifespan of that species. And if this hypothesis is correct for those species where males are bigger than females shown on the left side of the plot, these lines should generally be short. These short lines means that those species have short lifespans, they arrive, they live for a while, and they live fast, die young, that kind of thing.
Contrast, if this idea is true, species that are different, where the females are bigger than the males, they should have long ranges, they should first appear in the fossil record and then we should find them for a long time until they finally go extinct. So these guys might last a million years or two, these might last eight or 10 million years, something like that.
And so what we did is we, compiled information just like this. We looked at a bunch of species, saw whether the males are bigger than females or the females are bigger than males, and then tracked how long they lasted in the fossil record. And this is actually in fact exactly what we found. We found, just what's shown here, that those species were males are bigger than females, they went extinct very quickly, they had a higher extinction risk than when species where females were larger than males. Now you might ask, well okay, we've learned this one thing about how ostracodes go extinct. Why does this really matter? Well I would say, well it's good to learn about ostracodes for one, but the other part of this is that paleontologists study the fossil record to learn about extinction in general. We want to understand what causes species to go extinct.
What are the rules by which species go extinct? What features protect species from extinction? What features cause extinction to be more likely? And the only way we can get at that is to look at the record of actual species that have lived and see how those different features have affected their extinction risk. And so, once we had that kind of rules or we understand some of those rules, we can apply it to the modern world. Because we have all these species around today that we want to protect, and this can give us information about what species might be more or less vulnerable. So we can take what we've learned for the fossil record, and apply it to conserving biodiversity of life on Earth.
Laura Soul:
Actually one of the people watching, Danielle asked, "Why should we study ostracodes, what can we learn to help?" It kind of sounds like that's part of the answer.
Gene Hunt:
Yeah, and I think there's an argument to be made, just to understand the world we live in, right? This world we live in has a history, we understand how it came to be and it's curiosity-driven. But there are also some practical implications for studying this. Some fossils are useful for telling you what the age of different rocks are and that could be useful for inferring climate, inferring finding oil. Some fossils can help you learn a little about ecology and evolution and extinction and that's kind of a usefulness that they have.
Laura Soul:
Okay, well thanks very much for that Gene. We have had lots of questions from people watching. If it's all right if we ask a few of those.
Gene Hunt:
Bring them on.
Laura Soul:
So, going back to what you were talking about at the beginning with you had the geological map and you had the ship. Jade wants to know, do paleontologists work with experts who are in other fields when they're doing projects?
Gene Hunt:
Yes, that's a really good question. It depends a little bit on the scope of the project, so if you're just going out to a local outcrop and you know the area pretty well, you probably don't need all that much help. But a lot of time, paleontologists work with chemists to understand the chemical properties of the rock, and that can tell you all kinds of things about the environment, the age, the climate of the area. And a really great example of this kind of work is those deep-sea drilling programs. Those are highly multidisciplinary. You have scientists who specialize on the age of the rocks, on the chemistry of the rocks, on figuring out the climates of the past. And you have a bunch of different paleontologists specializing on different groups all working together to get a really complete picture of those changes you might see in one individual core.
Laura Soul:
And then Joan asks, "Where do you find the fossils you study?" You mentioned Prince George's County, but there are other places?
Gene Hunt:
Yeah, so I've been working largely in two areas in the past say 10 years or so. I started out for my Ph.D., I worked largely on fossils from the deep sea and they came from all over the deep sea from a bunch of different ships and cruises and things like that. And some of them were at museums, some of them were at, they had these repositories you could request samples almost like a library. And I got samples from there, but they were from all over the world from the deep sea. More recently in the past five or seven years, I've done a lot of work on what's called the coastal plain, which is that stretch of from Texas all the way through Louisiana, Alabama, Mississippi, bits of Tennessee and Arkansas all the way up to New Jersey. Because there's a really good record from about 85 million years ago to about 25 or 15 million years ago in that area. And so I've been working in a lot of that area, a lot of samples from Alabama, Mississippi, Maryland up to New Jersey. That's been the main area.
Laura Soul:
The dinosaur experts among us might know that there was a very big extinction 66 million years ago. And it sounds like you have ostracodes that would go across that extinction right?
Gene Hunt:
We have, very few species made it across. So almost all the species went extinct. We have relatives found on the other side and we don't know if they are the descendants of the ancestors before or if they kind of immigrated in from somewhere else where, and their ancestors are elsewhere. But there was a really big extinction for ostracodes too. It doesn't get quite as much press as the dinosaur extinction.
Laura Soul:
No, okay. So it was bad for everybody, not just dinosaurs.
Gene Hunt:
It was a bad time to be on planet Earth for the most part.
Laura Soul:
All right. A few questions about ostracode biology. Matt would like to know are there freshwater and salt water ostracodes and several people would like to know what ostracodes eat?
Gene Hunt:
Yes, okay good. The first question, yes there are, ostracodes are found in basically every wet environment from, some even in moist leaf litter or temporary puddles. There are lots of them in lakes and rivers and streams as well, all the way down to the bottom of the deep sea. So they're found in all those wet environments, freshwater and salt water. The second question was what they eat? It varies, it's mostly little bits of a gunk. So little bits, they'll scrape little bits of algae or little bits of dead plants and animals. There are a couple that will be predators. There's a couple that have these piercing mouth parts, almost like a syringe. And they'll poke into algae and suck out algae and things like that. There are a handful of ones that are parasites. Yeah, that's about it. Most of them just eat gunk.
Laura Soul:
And to flip it around the other way, what eats the ostracodes? Do they have predators?
Gene Hunt:
Sure, yep. Fish, little fish will suck 'em in, en masse. So there are these snails that will take little, like a bony tongue or a sharp tongue called a radula and drill a hole in things like clams and other snails. But when they're babies, they can't tackle clams and snails. And when they're babies they'll attack little baby ostracodes. They'll attack ostracodes as well. So that's another thing we know, eats ostracodes.
Laura Soul:
Okay, that's interesting. All right. Stella would like to know, have you or I guess anyone taken DNA from ostracodes and how do you do that?
Gene Hunt:
I have not. I don't work with the DNA, although I do study some living ostracodes, but other scientists have, and it's done in a normal way. You gather a piece of tissue and there are these chemical processes where you draw out the DNA and then analyze it or sequence it. So it works much the same as you get DNA for other things. One difference is sometimes you need a bunch of ostracodes because they're small to get enough tissue.
Laura Soul:
And a question, so we kind of learned about extinction and extinction risk. Brad would like to know how you'd expect climate change to affect ostracodes?
Gene Hunt:
Yeah, it's a good question. So, one thing that's for sure, climates have changed a lot in the past and what you generally see, so for ice ages, ice ages come down and the colder weather gets further south if you're in the northern hemisphere and goes back and forth, and you generally find organisms will track these changes if they can. One thing that happened that's a little bit different in present day is that, it's harder for a lot of organisms to do this tracking now that we've built all this stuff over the Earth that kind of gets in their way. This is especially a big problem with land. It might be less of a problem in the ocean and what sort of remains to be seen. But I expect as the ocean warms you'll get species from warmer climates expanding into cooler climates. And some species in cooler climates might actually go extinct because they run out of the kind of environment that they prefer.
Laura Soul:
And another question related to the extinction. Does the male female size comparison ... Think I have a helicopter going past, sorry everyone. Does the male-female size comparison relate to extinction only for ostracodes or is it more broadly applicable to other species that we know of?
Gene Hunt:
That's a really good question. So, people have tried to address this question in other groups and looking more generally at, if the strong male-female differences with the males being larger, for example, as being related to extinction. And they found mixed results, but one problem is that these studies have only looked at living things and it's actually really hard to get at extinction when you only look at living things because living things are those things that have survived extinction to the present day.
And instead of actually looking at real extinction, they're looking at the threat status, whether or not they're endangered or critically endangered and things like that. And so, for those studies, some of them have found this to be the case where having males that are bigger or so more showy or have bigger weapons in some way or another than the females, those species are more likely to go extinct. But other studies have not found that pattern. So it's a bit of a mixed result.
Laura Soul:
And a couple of questions about, I guess their relatedness or genera and species and things. Jeanine would like to know are they related to copepods and Keira asks, "Are triops a form of ostracodes?"
Gene Hunt:
No, well, no and no for the most part. So, all those things are crustaceans. So copepods are another very tiny crustacean. Ostracodes are not especially closely related to them, but they're both [inaudible 00:42:46]
Laura Soul:
But they are in the same group.
Gene Hunt:
They're in the same larger group, so the same kind of area. But they're not particularly close to copepods compared to other crustaceans. Triops is this weird ancient looking thing that's sometimes called a living fossil. It's another crustacean, it has very similar to some of its extinct relatives and that has yet another kind of crustacean, but again, they're all crustaceans, just different kinds.
Laura Soul:
Okay. And Larry would like to know, how different the ostracodes of today are compared to earlier ancient species?
Gene Hunt:
So, a lot of the ones that I've been working on, say for the last 80 million years. They're similar to the ones around today. Some of the genera are around today and go back 60 or 70 or 80 million years sometimes. So some of the genera are pretty similar. As you go much further back, like hundreds of millions of years, you have a bunch of ostracodes that are totally extinct groups and there's no really living representatives of those, so those are much more different.
Laura Soul:
So we heard about a lot of different ways that you study these fossils. There's going out into the field and getting them, drilling cores, using microscopes, describing new species. But Advait has asked a question if you use lots of computers when you're studying fossils as well.
Gene Hunt:
Yes, Advait might have insider knowledge, I think. So yeah, I'm a paleontologist, I spend time getting fossils, I study fossils in the museum, I study them in the lab. But one of the things I really have to do is actually analyze data. So I do a lot of data analysis as well. More than at least a lot of paleontologists, I spend a lot of time writing computer code to analyze data from the fossil record. It's something that I enjoy and I think gives a powerful tool for learning about the past.
Laura Soul:
Yeah, there are lots of different ways to do paleontology.
Gene Hunt:
Right? Big tent paleontology, all different contributions are welcome.
Laura Soul:
All right, we're coming up towards the end of the program, so I just should report that Landon thinks that it's really cool that you studying such tiny animals, I agree with him.
Gene Hunt:
Thank you Landon.
Laura Soul:
And then I'm going to hand back over to Maggy.
Maggy Benson:
Hey everybody. I've been really enjoying learning all about ostracodes. Thank you so much Gene, and thank you Laura, that was great and I really enjoyed seeing everybody's great responses to all of your questions and students you asked the best questions so, this has been wonderful. Thank you so much Gene for joining us and thank you to Camilla and to Karma who are behind the scenes in that Q&A answering questions. I'm going to stay here for another minute or so, but make sure you check that Q&A to see if they responded directly to you. And I do want to apologize, we have a lot of viewers today, so we weren't able to get to all of the questions, but we're really appreciative for the time you gave us today, Gene, to learn more about your work.
Gene Hunt:
It's my pleasure. I always love talking about ostracodes.
Maggy Benson:
All right. So I do want to share with our friends just my screen for a moment to direct you to our website. If you want to see Gene's program after it's saved, and if you want to see the schedule for all of our upcoming programs, you can go to NaturalHistory.si.edu for a full schedule and at the bottom of that page, all the links to our recorded webinars, including all of our previous Fossil Fridays are linked there. We will be back tomorrow with a family program at 11:00 AM and one of our botanists will be showing us how to make our own plant press.
So that'll be a lot of fun. If you have any questions or comments, you can email us directly at ScienceHow@si.edu and we would love to hear your feedback after this program by filling out our survey. Once you leave the meeting and once it's ended in your Zoom window, a SurveyMonkey link will pop up and that's how you get into that. So we would love to hear your feedback. All right, well thank you all so much for joining us. Thanks again Laura, thanks Gene, Camilla, Karma, we really appreciate everybody here today on Fossil Friday. So thank you all so much.
Laura Soul:
All right, thanks everyone, bye
Gene Hunt:
Bye, bye.
