On Paleontology: Prehistoric Arthropods

Alex Re

Hello, welcome to on wildlife. I'm your host, Alex Re, on this podcast, we bring the wild to you, we take you on a journey into the life of a different animal every week. And I guarantee you, you're gonna come out of here knowing more about your favorite animal than you did before. We're changing things up a little bit this week and next week, because we're going to be talking about some animals who haven't been around for a little while. Actually, they haven't been around for millions of years. I got to interview Dr. Paul Selden, a paleontologist and professor at the University of Kansas. So let's hop in our time machine to go back a couple 100 million years to learn about prehistoric arthropods.

When you think about fossils, you think about huge dinosaur bones like the T rex or the Triceratops. But there's a lot more to paleontology than just that. Today, we're going to talk about fossil arthropods, which come in all shapes and sizes. You may be wondering what arthropods are and if they're still around today? And the answer is yes, an arthropod is an extremely broad category that encompasses insects, spiders, scorpions, and even crustaceans, like crabs. And arthropods have been around for much longer than even the dinosaurs. They did back all the way to 500 million years ago. And they're also Paul's specialty. And he really focuses on fossilized spiders. He's written multiple books on paleontology, and has been doing this for longer than I've been alive. So you know, he's got some really cool stuff to say. And if you know me, you know that I'm always gonna try to bring it back to the conservation of today's species, which Paul is going to give us some more insight into as well. All right, let's take a quick break. And then you'll hear my interview with Paul.

The person that I'm going to recognize On today's episode of notable figures in science is Dr. Harold a most of microbiologist who lived from 1918 to 2003. After serving in France, in World War Two, he graduated with his PhD from Harvard Medical School. After graduating, he taught for multiple years, and eventually became the department chair for the medical school. This made him the first black man to become a chairman at Harvard in the medical department. During his time there, he published over 70 different scientific papers, mostly on bacteria. And he's given us a lot of the information that we know about today regarding bacteria. Aside from also being an advisor for the Nixon administration, he was one of the founding members of the Harold, a most Medical Faculty program, which helps give people of color better opportunities to become faculty members at Harvard. He achieved many milestones in his life, which is why it's so important to recognize him. If you want to learn more about Dr. Amos, or this series, you can visit on wildlife.org. Okay, we're back. Enjoy the interview. Hi, Paul, thank you so much for coming on the podcast today. You're welcome. It's nice to be invited and glad to be able to help. I'm glad and I'm really excited to get into talking about arthropods today. So first, can you just tell us a little bit about yourself and how you became interested in paleontology?

Paul Selden

Yeah, well, I mean, I suppose I started off being interested in in natural history, you know, in animals as a kid, I watched birds and collected butterflies and moths made a collection of those and but I also got interest, you had a very good geography teacher at school who got us interested in the landscape, you know, and and, and geology and that kind of thing. So, when I was choosing a subject to do at university, it really had to be like a double honors, you know, on geology, I did geology and zoology. Also, annum combining animals with, with geology, and I wasn't particularly interested in fossils, but that's naturally how those two subjects come together. So by the time I got my degree, I was you know, well and truly, and we had some excellent teachers in the university who, you know, got you fired up about about collecting fossils.

Alex Re

Yeah. That's awesome. And I always think that good education starts with a good teacher. If you could get the kids interested in what they want to learn, then you can teach them anything, I think

Paul Selden

And it's so much easier if you can go out and actually find stuff. You know, at the moment, we're all stuck here, unable to do very much. But if you can get out there and find things make a collection, you know. And you really, you really learn much better that way than through books and TV and so forth.

Alex Re

Oh, absolutely. And going off of that, so have you dug for fossils in the field yourself?

Paul Selden

Well, I mean, apart from doing it as an undergraduate, and also teaching it in University, where you take, take students and show it to them, I mean, the actual digging process is something that the public always imagine that paleontologists do. Well, it's true for things like dinosaurs, because you find a bit of a dinosaur, then you go back with a team and you spend days and days digging. But the fossils that I study are actually extremely rare. And if I were to spend all my time digging for them, I I'd never find one I rely on on very keen amateur people, mostly who spend their, their weekends digging, collecting everything. And then, you know, my, my particular interest is fossil spiders and things like that. arachnids, which are extremely rare, but you know, one in every, you know, acid out of a place that say rich in insects, maybe one in every 10,000 is a spider. Now, hmm. As I say, they're very rare. But once they're found, they make their way to the museum, hopefully. And then they, they say, hey, we've got this fossil spider, come and come and study it. And that's when I go to the museum and borrow it or study it there. But I like to go and visit where it came from to get a feeling for the whole. You know, how it relates to everything else in that that rock strat?

Alex Re

Oh, that's so cool. And how can you? Let's say you you just like, stumble upon a fossil? How do you tell that small fossil from just a regular rock?

Paul Selden

Oh, well, yeah. I mean, you you learn eventually, you know, I get sent a lot of sort of oddly shaped pictures of oddly shaped stones. You know, for people who think Well, I think this looks like a bird's head or an egg, you know, dinosaur tooth or something? Well, generally that the fossil isn't the Shaped Rock. It's, it's within the rock. So normally, you find it imbedded in rock and you see a pattern and you get you get used to the patterns. So I mean, an Ammonite, you know, a curly whirly thing becomes fairly obvious. After a while,

Alex Re

Ammonites were shelled creatures that lived over 200 million years ago.

Paul Selden

seashells of any kind are kind of obvious, but often you see them in cross section, you know, so you have to do a bit of three dimensional thinking to imagine what you're actually looking at. And it certainly does take some practice.

Alex Re

Yeah, absolutely. That's, that's really awesome. And so you were talking a little bit about how, when you're actually looking for those big dinosaurs, it's very different from spiders and arthropods. So how does the study of fossil arthropods different from other areas of paleontology? Well, it's, it's

Paul Selden

not different generally. But it's, you know, each each particular group of animals has its own way of being studied. If you're simply interested in the fossil itself, then you just take it back to the lab. And that's where you can start preparing it. And how you prepare, it depends on how it's preserved. So it's very important to know how it's preserved. If it's an amber for example, then you know, you'd have to polish the amber in a particular way and get the light just right. If it's squashed in rock, you can sometimes pick out where the rock still covering it in places. And the fact that it's squashed means you have to sort of try and imagine it three dimensionally. Whereas in Amber, for example, it is three dimensional. Yeah, so if there's so many factors come into play, you have to you have to know what you're actually looking at, you know, whether it's the actual skin or the shell, or whether it's sometimes it gets replaced by some other mineral, you know, and all of those factors define how you interpret it.

Alex Re

Yeah, definitely. I cannot even imagine how hard it must be to find one of these fossils because fossils are rare in general, very few organisms ever are made into fossils. So it and so your the organisms that you're studying could get caught in Amber, could you just talk a little bit about what that what that means?

Paul Selden

Well, something that's trapped in amber is a rather specific type of preservation. Amber is is fossilized tree resin. So some trees exude resin as a result of damage or this variety of reasons. Some trees do it much more than others. But it's it's has a rather sweet, sticky sort of smell to it. And this attracts insects, for some reason, I don't know why but they they get attracted to it, they then get covered in it and the struggling insect will attract, you know, a lizard or a spider or something that thinks it can capture it, and then they get caught. And so it's rather specific. I mean, it's it really samples, things that live around tree trunks. Eventually, you know, when the when the forest dies, and the the at the amber sort of floats away and gets deposited in in mud. And you can find it, you know, by by digging up the model, or even look walking along the seashore where it gets washed out.

Alex Re

And that's, that's really amazing. And I don't know if you've ever seen Jurassic Park, but that's how they extracted that DNA. But I don't think that's really realistic.

Paul Selden

No, but like all good science fiction, you know, there's a grain of truth that they kind of built on, you know?

Alex Re

Absolutely. So how do you determine how old the fossil is?

Paul Selden

Okay, well, you I mean, you really can't date the fossil itself. Normally, unless it's very, very young. I mean, if it's something like a tree that died, say 10,000 years ago, you could probably use use carbon dating on

Alex Re

carbon dating is one of the ways that we can use chemistry to figure out the age of something, we know exactly what carbons Half Life is, which is basically how long it takes for half of a carbon sample to decay. It's pretty complicated. But because we know carbons HalfLife, we can test the fossils, chemical composition, and figure out how old it is.

Paul Selden

But for a true fossil, something that's like millions of years old, where the carbon is no good. What you have to do is, is look at the layer of rock that it's in now. We have throughout the world, we have a sequence of rocks that's been studied all over the world to give, give us a generalized geological column is the study of that score stratigraphy where you're looking at the strata. And, you know, we know if you find a trilobite, for example, you know, you've got to be in the Paleozoic, because they, they became extinct at the end of the page. So, if you find a dinosaur and Ammonite, you know, you've got to be in the Misa. So because they didn't evolve until you know, the end of the Triassic died out at the end of the Cretaceous. Well, if you if you sort of continue that process down to individual species, certain species only lasted for a certain length of time. So you can build up a chronology of, of what is younger than or older than, and the whole sequence of events. But in terms of actually putting dates on it, you then have to use radioisotopes. And that's where within this these this generalized geological column, there are certain horizons that will have things like say, volcanic ash, so when a volcano erupts, it's an instantaneous thing that is fixed in time. And you can study the minerals in there. And those minerals will have a ratio of, of parents and daughter isotopes, that you can use a bit of calculation to work out the precise age and millions of years. And so a number of these horizons have been determined throughout the whole geological column. So you can, you can very rarely say, Well, this is exactly 63.75 2 million years old. You can only say, well, it's somewhere between 63 and 64 million years old, which is good enough.

Alex Re

Yeah. And it's really insane how we're able to do this and that we can even get those dates like not it doesn't really mattered that it's a 64, maybe 63. But still, we if we can get it in that time range, it's it's amazing that we can do that.

Paul Selden

Well, I consider it it's a bit like when you study history, I mean, the exact date. I don't think it's quite so important as imagining everything else that was going on around at the same time, you know, what battles were going on? What kings and queens were around what presidents were, you know, what other things were happening you you build up a whole picture? So if you say to me, oh, that's Pennsylvania. And he, I have a picture of these big forest of trees and giant dragonflies and stuff, you know, and that's the immediate picture. If you say 360 million years old, I have to scratch my head and work out. Well, when was that? Exactly?

Alex Re

Yeah. And that kind of brings me into my next question, which is, what can you tell about an ecosystem by looking at the fossils and the area around those fossils?

Paul Selden

Well, there's actually more than just the fossils that will tell you a lot about the ecosystem, because it's the rock that they're in as well. That's important. So for example, if you look at a limestone, limestone, these are normally normally made in that they, they they originate in warm shallow seas, they're actually made of the remains of little animals, plankton that would have been there and other things corals may be. So you start as you look at the limestone, you find corals and things you find maybe some fish or something, you know, and you begin to build up a picture. And so you do you compare two things, you're comparing the different kinds of animals and plants that were there, and comparing them to the present day. So there's, there's something that we say in inshallah, to the present is the key to the past. So you've got to understand, for example, what a coral reef looks like, in order to interpret a fossil coral reef. So a modern coral reef, we call it a coral reef that is most of the algae, but it's, you see a lot of corals there, and, and mollusks and fish in one thing and another. If you are a fossil coral reef, you may well find it's dominated by sponges rather than corals, for example, but you can still gain an insight by comparing with the present day. And also the the actual, as I said, the Rockets in I've mentioned Leinster say it's a sandstone whilst that sand is being produced today, you know, in rivers, and in Delta's, it doesn't go far out to sea. Because it's too heavy. Once the river drops its speed at the Delta, it drops that sand, so meet another workplace sand is formed this in deserts. But that's a different kind of sand. So, I mean, you can immediately get an idea, okay, I'm dealing with a river sand. Or I'm dealing with a desert sand, then you start looking at the fossils, and the desert sand may well have dinosaur footprints, say, because it's formed on land, the river sand may well have fish or, you know, mollusks in it. So you that's you, you don't just use the fossils, because as you as you've already said, a great many things never get preserved, you know, soft things, worms don't get preserved. So you have to sort of interpret the total environment, then imagine there probably were worms there. Otherwise, what were the fish beating? So you gradually build up a total ecology based on what you've got. And then what you kind of infer was probably there, even though you may not have direct evidence for it.

Alex Re

Absolutely. And that that really just shows how paleontology isn't just looking at fossils, you need the context of present day you need the context of all the rocks, it's it's really complex and amazing.

Paul Selden

Yeah, yeah, it's a it's quite a broad. A broad. I mean, something is following on from that is that there are things called trace fossils, which I've kind of mentioned already. I mean, a dinosaur footprint is not a dinosaur. So it tells you that a dinosaur was there and it kind of tells you what it was doing, you know is walking, right. Yeah. You might have you might, you may not get worms but you might have worm burrows. So it tells you that the worms could live in the in in the sand. So the sand was had oxygen. You know, it wasn't It wasn't a horrible black, you know, sort of putrid sand. It was a nice clean so. So the two go together, you can make interpretations, even if you don't actually have the fossil there.

Alex Re

Yeah. And you talked about trace fossils a little bit with larger dinosaurs, is there anything that you use to determine the behavior of smaller, like spiders and arthropods and other insects?

Paul Selden

Yeah, you can see, you can see tracks of things. Like for example, the Coconino sandstone, which is just below the Rim of the Grand Canyon contains a lot of Scorpion tracks. And we know the scorpion tracks, you count the number of legs, you can see the occasional drag of the tail. It's it's a desert sand, you know, and so we can interpret them as a scorpion. So it doesn't tell us what kind of Scorpion days, but it does tell us that they were there and what they were doing.

Alex Re

That's really cool. And I think a lot of people are wondering what they looked like back then. So have you noticed any huge changes in the more morphology of arthropods from then to now? Well,

Paul Selden

then the real answer is no. I mean, first of all, you know, if you find a fossil Scorpion, you know, as a school of fingers, it looks like a scorpion. So it's no different. What we tend not to find is something that's half Scorpion, half spider, because they and clearly such a thing never existed. But just occasionally, you do find a sort of missing link. I mean, when Archaeopteryx was first discovered, it was a he was like a little dinosaur, but it had feathers on. Okay, so that that's, that's kind of different. But it wasn't unexpected.

Alex Re

Archaeopteryx looks like a mix between a bird and a dinosaur. And scientists call it a transition species, because it's evidence of the evolution from dinosaurs to birds.

Paul Selden

And similarly, in recent years, we've we've discovered some rather curious sort of protos spiders, which are clearly very spider light, but have tails. Now, no living spider has a tail. But some of this relatives do. So, and these aren't particularly old. I mean, they're simply things that we sort of thought might be there, because we've got the spider and then we've got it's next nearest relative, and there's nothing much in between. So when something like this pops up, you think, Wow, and but they live for an awful long time. And for all we know, they might even still exist somewhere in the deep jungles where we've never explored.

Alex Re

Yeah, definitely that there's a lot that we haven't explored about our own Earth. So that would be really cool if they were out there. So what's one of the most interesting things that you've found during your research? Oh, well,

Paul Selden

I suppose the the sort of missing link things are probably the most interesting because it it kind of started when we were studying fragments from rocks from Devonian age now that we're talking 400 million years ago now. And these are rocks, the shales, so they compress things absolutely flat. But there's some up in New York State, which were being studied by paleo botanist because that they contain some of the oldest trees that we know about. But you can tell a lot by taking these shales and dissolving them. And you could dissolve shale in hydrofluoric acid, which is a horrible thing. It dissolves rock, but it leaves behind organic matter. And so you get little flakes, you get spores, plant spores, and you get bits of bits of STEM and stuff. But in amongst them, they're little animals. But a lot of these little animals, very few of them were complete. They were mostly fragments. So you'd get a leg and a head and bits and pieces. And so we we were trying to put together that the whole animal, it's like if say you have a jigsaw puzzle, and you've only got half the pieces and you haven't got the box lid. So you're trying to put this these things together. And they're just occasionally you get it wrong, you know, and there were some sort of sort of whipped like, pieces that look like they had the right pattern to go with. These spiders, but they we couldn't fit them on anywhere. So we just ignore them, more or less. And it's later on that I found a spider turned up in Russia. It came from a place called perm, which is what the Permian period is named after. And it looked exactly like a primitive spider like you find living today in Southeast Asia. But it seemed to have a tail. And we thought, well, it can't be a title because spiders don't have tails. Anyway, eventually, long story short, we found some peace, some of these fragments from the Devonian, with the actual tail attached to the body so that, you know, we we were, we were rather we were wrong in assuming spiders don't have tails, because there were some there back in the past that did. And we now know that they did. And we've even found them in the Cretaceous, and then the amber from me and mark.

Alex Re

That's so amazing and interesting. It makes you wonder what, how they lost tails. And why no spiders have tails today? Huh?

Paul Selden

Yeah. Well, it's that this group was obviously successful for millions of years. And but modern spiders went a different way and became extremely successful.

Alex Re

Yeah, definitely. And so does, does studying the fossils of arthropods give us any information about arthropods today and their conservation? Because I know you were talking about how we have to use what we know today to figure out what was happening back then. So can it go the other way around?

Paul Selden

It can do I mean, you can you can look at the thing about paleontology and geology, so you've got the dimension of time of a long time. So whereas today, you might have been studying a forest for 50 years, I mean, geological record will give you the record of the forest over millions of years, or 10s of 1000s of years. And so you can, you can track you can track things, which, and hopefully then it can be predictive, you can say, Okay, well, this forest died out. Because if you can find the factors that caused it to die out, then that will be predictive to be able to say, Well, okay, if we, you know, if this forest is subjected to too much of this or too little of that, in the future, then this is what might happen to it, because we seen the evidence of what happened in the past.

Alex Re

Yeah, absolutely. And we've seen extinction events happen, and sometimes we know what caused them. And obviously, we can't stop a meteor from from hitting the earth, but we could stop some other things that could be preventable. So is there any way that the average person can support your research or the field of paleontology in general,

Paul Selden

there's various ways, I mean, one ways to become interested in is to go out on you know, if you can get out on a trip and look at fossils, you can go to a museum, I mean, museums are fantastic. And the more you know, before you go, then the The more you get from from a museum collection. And I mean, they exist to tell you about, about paleontology, and of course, museums, you know, ranked according to the number of visitors they get, so it helps them if you go. And the there are these kind of crowdfunding sites now, which I know some of my students have been involved with where you can, you know, you put so much money in, and it helps a young student, you know, who say going out, collect, you know, wants to go and collect fossils somewhere. And in return, you kind of get bulletins of what they found. And the thing is, if you if you find a fossil, that's, that's new, and you, you donate it to a museum, the researcher will study it, and then they'll nearly always name it after you. So if you've got that kind of thing, then that's always you know, that if you find interesting fossils, there's always that sort of year. And so fossils must go to museums. And unfortunately, nowadays, there's a lot more trade in fossils. And so a lot, a lot of fossils command high prices that museums can't afford, you know. And so you know, if you You want to say to collect, I'd you know, Amber fossils, make a good collection, and then donate it to a museum, then, you know, you'll get remembered by by having the collection named after your specimens named after you, even if that, you know, because the museum itself may not have had the money to buy the collection. So those are those are ways you can you can help, I think,

Alex Re

yeah, that's really amazing. And I don't really know anybody who wouldn't want a fossil named after them. That would be really cool. Yeah. Well, Paul, thank you so much for coming onto the show again, you really taught me a lot today. So thanks again. Well, thank you very much for inviting me and good luck. Absolutely. That was so informative, who knew that the field of paleontology was so complex? I love the idea that we can use the past in order to better understand the present. If you want to support paleontology, you should definitely check out the paleontological society, and try to visit your local museums. Because I live in New Jersey. I love to visit the Museum of Natural History in New York City. But there are tons of other museums that you can visit as well. Thank you so much for coming on this adventure with me as we explore the world of prehistoric arthropods. You can find the sources that we used for this podcast and links to organizations that we reference at on wildlife.org. You can also email us with any questions at on wildlife dot podcast@gmail.com and you can follow us on Instagram at on underscore wildlife or on tik tok at on wildlife. Don't forget to tune in next Wednesday for another awesome episode. And that's on wildlife.

Jess Avellino

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Transcribed by https://otter.ai