Chatting Ichnology with Dr. Tony Martin

To take a deep dive into different paleontological concepts, the Time Scavengers team is starting to conduct interviews! We start with a list of questions that we share ahead of time with our speaker and then we move with the flow of the conversation. Our first interview was on ichnology, or the study of trace fossils, with Dr. Tony Martin.

Ichnology focuses on studying the preserved behaviors of animals in the fossil record. These behaviors can look similar and quite different throughout time and play an important role in understanding past and future environments here on Earth. Tony, Adriane, and Jen chat through various ichnological topics, explore SciComm, and there is even some surprise dancing!

We touch on the idea of ichnofacies and their importance in unraveling the complex history on Earth. If you are interested in learning more about how groups of ichnofossils can tell us about ancient environments here are some links:

We have published the full interview on YouTube and we have a transcript with additional links to get more information on specific content discussed.

Watch our full chat on YouTube:

Listen to it via PodBean:

Transcript of the Interview

See below or click here for a Google Doc of the transcript!

Jen: Hi everyone! Thank you for tuning into Time Scavengers’ first interview. Today we are talking about ichnology with Dr. Tony Martin. Dr. Adriane Lam and I will be conducting this interview. Tony is a professor at Emory University and an author of popular science books surrounding ichnology, the Georgia coast, and the intersection of the two. Join us as we chat about what ichnology is, how Tony became an author, and there may even be some surprise dancing near the end.         

Adriane: I’m Adriane Lam from Time Scavengers and I’m here today with Dr. Jennifer Bauer and Dr. Tony Martin and we’re going to be talking with him about ichnology. So hello, Dr. Martin!

Tony: Hello! And I am so happy to be here to talk about ichnology because I consider myself an ‘ichno-evangelist’ and I’m ready to convert everybody to the Church of Ichnology. Which has a holy trinity: substrate, anatomy, and behavior. Amen, sisters!  

Adriane: I love it! I’m sold. So let’s start off by just talking about, for those who are listening who are unfamiliar maybe, what is ichnology?

Tony: Ichnology is the study of traces, tracks, trails, burrows, borings, tooth traces, gnawings, anything that an animal, or a plant, can leave on a substrate that shows its behavior. And that’s really important to the difference between, say, a trace and a drag mark of a stick going along the bottom of a lake. The latter is not a trace because it’s not behavior. There has to be behavior. And that’s what I really love about ichnology is that it reflects behavior. You can actually tell what an animal was having for lunch 500 million years ago, through ichnology!

Adriane: That is so cool and very interesting. So, I’m a big fan of ichnology, um, obviously I am a big fan of coprolites, I think they’re just the coolest things ever! 

Tony: Coprolites are the best!

Adriane: They are so cool! So for those that are listening coprolites are fossil poop, and they come in a variety of shapes and sizes, as you well know Tony. But, you know, a lot of paleontologists study coprolites but also these other trace fossils to get a sense of animal behavior through time. So why is it important that we study this animal behavior in the geologic past?

Tony: What’s great about trace fossils as a way of looking at animal behavior is trace fossils oftentimes are in the same place where the tracemaker was living. So this gives us insight not just of the behavior of the plant or animal that was making these traces at that time, but the place. And it tells us how that animal or plant was interacting with its environment. For instance, if an insect walked across a Permian dune 260 million years ago, we can look at that and say ‘that insect was walking across a dune’. We don’t just say ‘yeah, there’s an insect and it was walking’. We know something about the environment and the context of the environment in which that insect was living. So that gives us kind of a snapshot of behavior that was happening in the ancient past related to the bigger picture of how that trace maker fit into its environment. 

Adriane: So what is your favorite trace fossil then, and why?

Tony: That’s kind of like asking a parent what’s your favorite kid. It’s a tough one to narrow down. One I picked out that I always like to point to is a study I’m very proud of published about 10 years ago in PLOS One, was about a fish trail. Where the fish had swam along a lake bottom in Wyoming about 50 million years ago. This fish, when it swam along the lake bottom, first of all it showed there was enough oxygen at the bottom of that lake for that fish to be there, to be swimming in the first place. But it left fin marks, and the fin marks, I’ll try to do it with my hand, the fin marks kind of made these double sine curves. So those were from the pelvic fins. Then there was the caudal fin. The caudal fin was doing a bigger sine wave. Then it had a smaller anal fin that was on the bottom of the fish, and it was leaving a smaller sine wave. In the middle of all those traces were these little ‘pop pop pop’ pock marks made by its mouth. That’s when I looked at this trace fossil I think in 2008 was the first time I saw it, and I was like, ‘it was feeding!’. It was feeding along the bottom of the lake. And there was only one fish in this formation, the Green River Formation from Wyoming that had a mouth that pointed down. And that was Notogoneus osculus. So I knew which fish made it, what it was doing, when it was doing it, it told me about the lake like I was saying earlier, you have it in the context of its environment. And using a little bit of math, we were able to figure out how big it was because the sine waves told us a bit about, uh, putting it into a formula that told us how big it was! This is the one that got away, and it was this big.

Adriane & Jen: Whoa!

Tony: That was 50 million years ago! That’s a pretty darn good trace fossil. So yeah that one’s my favorite I think. 

Jen: So, I have kind of a follow-up question. So that one is kind of easier because we can watch how modern fish behave and make interpretations based on the fossils and kind of match up the different fin types and think about movement, but not all animals have these modern comparisons. So how do you interpret trace makers when things are maybe a bit murkier. 

Tony: Oh boy, yeah, that’s a tough one. So there are ways we can, we can look at something like a sauropod dinosaur; those sauropod dinosaurs, we don’t have anything like that alive today. The biggest elephants we have today are maybe around 7 tons. Some of these sauropod dinosaurs may have been more than 50 tons. So we have no modern analogues for anything like that. In that case, we have to look at, through maybe computer modeling, or experiments, to look at weight loading, and other ways that we can mathematically predict ‘here’s what those traces should look like’. But then again we also have the trace fossils themselves. So we have sauropod tracks, and we have traces made by other animals that there’s no modern analogue whatsoever. So there we have to be really good detectives. We have to look at what was left by the animal that was a part of its behavior but also taking into account that this behavior may be unlike anything we have today. It’s a really tough problem for when we don’t have the exact modern analogues, then we have to use something that’s close enough. Does that kind of answer your question? It’s a really tough one to answer, especially when we get into really big animals. 

Adriane: And I kind of have a follow up question to that as well. And I don’t know if a lot of people listening are aware that when we name these ichnofossils, we don’t name them after the animal, right? And, can you just elaborate why that is, and I think you pretty much touched on that but just to restate it. 

Tony: Yeah, there’s a little rule in ichnology is that one tracemaker can make many traces. Related to that then, you can also have many different tracemakers, many different species of tracemakers, can make very similar looking traces. So if you started naming trace fossils after the tracemaker you think made it, mmmm, you might be wrong. If you start naming trace fossil based on, well I think a variety of different tracemakers made it so I’m going to put all their names in the name, that’s not going to work either. So what we try to do with naming trace fossils is base it on consistent form. So if we see a trace fossil that has a form and it occurs in a substrate, such as sand or mud or wood or stone, if it occurs consistently in a particular kind of substrate then we give it a name that’s consistent. One example I can think of, for instance, is Ophiomorpha nodosa. ‘Ophiomorpha’ refers to it’s snake-like form, because when these were first named, they looked kind of snake-like. The ‘nodosa’ part refers to little nodes, and these are fecal pellets, well not fecal pellets, but pellets that were put on the side of the wall of these burrows. These were actually burrows made by crustaceans similar to, say, modern ghost shrimp, that makes this form Ophiomorpha, and then it has these nodes, nodosa, that I can say to another paleontologist, say in Poland, or Czech Republic, or China, I can say Ophiomorpha nodosa, and I just communicated what that trace fossil is and what it looks like. Without going into ‘well it’s kind of snake-like, and it branches, and it has little nodes’. That would get lost in translation pretty quickly.  

Jen: Ophiomorpha is one of my favorite trace fossils! 

Tony: As it should be! It’s a gorgeous trace fossil. 

Jen: That brings up a question that I’ve had as a museum professional. So a lot of my work recently has been database management, and the taxonomy of ichnofossils is a very hard thing to reconcile. And the way that databases are kind of structured are in like a hierarchical model, so similar to Linnaean taxonomy. So I have essentially a tree that’s my taxonomy tree, and I have bins that I can bin the different types of animals into, but I’ve kind of just put ichnofossils as a phyla, and that’s what I’ve seen done in other databases. But, do you have advice for people who have this problem, like me?

Tony: Huh, yeah, short answer: no. And it’s funny because I’ve sometimes been labeled by my ichnological colleagues as a ‘hyper-lumper’. In paleontology, we have lumpers and splitters, and this is very useful because, of course there are people in between; I guess that would make them splitters, hmm? Ok but yeah, with the people in between they say ‘well, sometimes we need to lump in these different names that are really the same fossil’. The splitters say ‘no, we actually need to have a lot of different names’. I’m more of a lumper in that, does this trace fossil show these 3 or 4 characteristics? Then OK, let’s call it that ichnogenus. Ichnospecies, then I start going ‘oohhhh, no no no’. I don’t necessarily want to do ichnospecies. But I understand if some of my colleagues, again for communication purposes, start classifying them differently. For your purposes, for putting them into a database, in a museum collection, it’s probably best to do at least the ichnogenus if you can. That at least narrows it down. Then, I would hand it over to the experts who know more about how do you split it from there in that ichnogenus. So for instance, Ophiomorpha is an ichnogenus. Under that, you can have, gosh, I think I’ve seen 4 or 5 ichnospecies. And I’m only going to name nodosa because people get annoyed and get in arguments after that. Does that kind of make sense?

Jen: Yeah, I’m having more of a problem with everything in between. So I have a phyla, or phylum, and I have ichnogenera and whatever is underneath them. But the in-between is just empty. 

Tony: Yeah, so for example, I have a cast of a dinosaur track here, that I’m going to hold it up next to my head. And it’s um, I bought it, it’s an epoxy resin cast that was taken from a real dinosaur track, there you can see some of the 3 dimensions of it. I think it was labeled as Late Triassic, and it was Grallator. So Grallator is the ichnogenus we give to that dinosaur track. Then the people who study dinosaur tracks, they can communicate with one another by saying ‘Grallator’. They have ichnospecies under that. Now me, I see that and go ‘Ah, that’s a therapod track!’. And I might write down ‘Grallator, question mark’, and leave that up to the experts to classify further. ‘Therapod’ is an interpretation, so then I’m interpreting this dinosaur track, I’m interpreting this as a dinosaur track. Leaving open that it could have been made by another animal, though. That’s a hypothesis. But the name we give is based on the form, the form of the track. And that leaves it open for the possibility that something other than a therapod dinosaur made it. How’s that for an explanation?

Adriane: Perfect!

Tony: Good!

Adriane: So do you want to move on to talking about your book and your science communication?

Tony: I would love to, yeah! So I’ve been, oh, since 2013, I started writing books. I’d written a few books before that, but 2013 is when I published this big thick book called ‘Life Traces of the Georgia Coast’. It’s more of an academic-y book, but I wrote it for a general audience too; for people who are naturalists, interested in, when they go down to the Georgia coast, and they’re on the barrier islands, they see burrows, they see tracks, or other traces, and they go, ‘hmm, I wonder what that is?’. So it was a book to answer those questions, but also something that my academic friends in paleontology could use. It was published by Indiana University Press and part of their Life of the Past series and their paleontology books that Indiana Press puts out. So I was really proud to do that. Then I started following that up. In 2014 I did ‘Dinosaurs Without Bones’, here’s the paperback version right here. That beautiful cover by the way, the cover art is by paleoartist Peter Tressler, he’s an Australian paleoartist, so you should look up his work. That was about the concept of, what if every dinosaur skeleton disappeared tomorrow? Every dinosaur bone vanishes; how would we even know dinosaurs existed? And I was like, well, fortunately we have trace fossils! So the book is about that, and I wrote that overtly for popular audiences. It’s a trade book, but it has a lot of references back for, again, for my academic friends if they wanted to learn more from that. I followed that up in 2017 with ‘The Evolution Underground’. And the subtitle is ‘Burrows, Bunkers, and the Marvellous Subterranean World Beneath Our Feet’. The subtitle should have been ‘How Burrows Change the World’, but Malcolm Gladwell probably would have sued me. Ah, with that, I want you to think about how burrows helped animals survive, especially mass extinctions, and then how burrows changed the world in marine environments, terrestrial environments, all environments, and actually changed everything. Kind of a big-picture book. That was a fun one to write! Now my newest one is ‘Tracking the Golden Isles’, and this is again a trade book meant for a general audience, it’s more about a specific place. So the subtitle you see is ‘The Natural and Human Histories of the Georgia Coast’. So it’s returning to the Georgia coast, but I wanted to give more of a view for people who live here in Georgia, as well as outside of Georgia, of how traces give us stories. That there are stories written in the sands, in the muds, in the bones, in the driftwood, that we see that tell us what happened in this place, then give us insights on how humans and other organisms interacted with those places through time. So this is part of my ichno-evangelism, I want to teach people about traces and why traces matter. 

Adriane: Perfect. So a follow up question to that is: You’re a scientist and you are trained as such, just like Jen and I are, and through grad school, we learned how to do science writing, we publish these journal papers. How did you transition, and teach yourself, how to write for a scientific audience, um, or transition from writing for a scientific audience to a more general public audience? Was that something you practiced over the years? Is it self-taught? Because, it’s a, it’s a hard skill to learn. 

Tony: Yeah, you’re, yeah I agree one-hundred percent; it’s a hard skill to learn. And in the case of people who are trained to write academically, there’s some un-learning to do too. That we are oftentimes rewarded with our scientific writing, to be as technical as possible and use a lot of jargon. So there was, in my writing process, I had to un-learn. This is where I thank my students, because for years at Emory, I taught non-science majors. And I still do sometimes. But non-science majors, I had to strip out the jargon in my teaching. So there was part of that training I think in the classroom, being able to clearly communicate different scientific concepts, particularly in geology and paleontology, that would translate well to people who are non specialists. Then if you can do that on the page, if you can write on the page, then that helps too. Here’s where I credit blogging. So I started blogging in the late two thousands. That was writing I did, then through practice for a general audience. That’s also how I got more of a, what we call, an author voice. I started finding my voice as an author and a distinctive style. I didn’t want to be, say, like Stephen Jay Gould, or Pat Shipman, or some of these other writers who I really admire. That I read their writing and I go, ‘Oh, I love their writing! I’m going to write exactly like them’. I needed to find my own voice. I think after about four to five books, I have found that voice. But it came through teaching first, and then blogging, and writing, really getting into a daily practice of writing, however small. Two-hundred and fifty to five hundred words a day, that’s my typical book-writing regime. I just try to do a little bit everyday, and then when you do the math, it adds up. Next thing you know, over the course of a year, year and a half, you have a book! And that’s where the editing comes in. That’s part of the process too.  

Adriane: So can you tell us a little about the editing process. Because, Jen and I, you know, we blog, and that’s mainly what Time Scavengers is; we have a lot of blogs. But we’ve never written anything as substantial as a book, and we know that the peer review process and editing process for a paper is much different from a book. But can you kind of walk us through that process, what is it, how long does it take?  

Tony: Yeah, and writing a book, especially for a general audience, I oftentimes, I will write it first, without criticisms, self criticism. So I have to put duct tape over my mouth, silence my inner critic, and just ‘zzzzzzzz‘. You know the GIF of Jim Carrey doing that? Ok so I do that, I just type, I put down the words, then I set it aside. Later, I’ll come back to it and then I’ll go through it and edit it. Sometimes along the way I’ll self-edit. But usually I just set it aside, come back to it, and then go through and edit. My favorite way to edit for a trade book is actually, I’ll print it. I know, poor trees. But I do recycle. I’ll print it, and I’ll hand-edit. That’s actually my favorite way to edit. In my most recent book ‘Tracking the Golden Isles’ I was so grateful that University of Georgia Press actually did send me a printed copy of the page proofs and I went through and I hand-edited through those page proofs. So the editing process is multi-layered, it’s multi-stepped. Once I’ve gone through it in a way that I think it’s pretty good, and I’m not embarrassed, then I’ll hand it over, say, to a copy editor or other peer reviewers. And actually, my last four books have been peer reviewed as well, or I’ve had other experts read the book, look for factual content, as well as how well does it read. Does it read, does it read okay? ‘The Evolution Underground’, for instance, I think the peer reviewers I had on that were Sally Walker, Dr. Sally Walker, and Dr. Patricia Kelley. They were really good peer editors, being able to look at it in terms of content, but also, did it make sense. And they also are fantastic teachers, so I really trust their instincts on, ‘did this sound good enough that a, someone who’s not an expert will get what I’m writing about?’  

Adriane: That’s awesome. Do you also get, during this process, do you have other friends that are non-scientists read the book? 

Tony: Oh, yeah, absolutely! And I’m really glad you mentioned that, because ‘Life Traces of the Georgia Coast’, the people who actually read that book first were non-scientists. I was in a small writing group at Emory, and there were just three of us. One of them, you’ve probably heard of her, she’s famous: Isabel Wilkerson. She wrote this absolutely fantastic book that should be required reading of every American. It’s called ‘The Warmth of Other Suns’. It’s about the great migration of African Americans from the South to the North. And she tells it through three different people. She was in our writing group, and she’s a Pulitzer Prize winner, who’s writing this award-winning book and the other member of our group, Christine Ristaino, she was writing a book that was about more personal, more about personal traumas, that she had had happen in her life. Three very different books, three very different people. We got together once every two weeks or so, over the course of two years, we read our writing to one another. Which I now do in our classes when I teach my students writing, I have them do that as an exercise: read it out loud to one another. When you read it out loud, as an editing process, and that person reading your work out loud, that’s right, hand it to the other person, they read your work out loud and they’re not an expert in your field. They’re going to find where you’re unclear. They’re going to stumble over your words; they’re going to go ‘rrmmmrrm, uhhh, what, Ophio-what?’  And they’re going to help you find how to make it better. So I am forever grateful to Isabel and Christine for being in this group with me, where they really taught me to be more clear with my writing for people who are non-experts in my field. Yeah thanks for asking that, that’s [chuckles]. 

Adriane: Yeah of course. But with Time Scavengers, we have an editor, and she is not trained as a geoscientist, and you know, her feedback for us is invaluable for us too, and we owe her a lot too for saying..

Tony: Absolutely. Yes. 

Adriane: … ‘what are you talking about?’ Yeah, it’s, it’s such a critical part of science communication that I think a lot of scientists don’t realize, is getting outside of your science circle, get in touch with your friends, and hand them something and say ‘Does this make sense?’ And I’ve even had my mom email me and say ‘I don’t know what you’re talking about in this blog, fix it!’  

Tony: Right, right, yeah isn’t that perfect?

Adriane: I love it!

Tony: Even if your mother has a PhD in some other science, she might read your blog and go ‘Oooh, I didn’t quite get that?’ So that, that really helps when you have somebody from outside of your field helping you. And especially the non-scientist, people who may be experts in whatever field, political science, or sociology, if they can read your blog and go ‘Oh yeah, I get it!’, then that’s a high compliment. It means that you’re using a minimum amount of jargon and you’re using it in an engaging way, hopefully with a good narrative structure too. That people are following a story along the way.  

Adriane: Exactly. And you touched on something that I think is really important too when we’re doing science communication, is storytelling. When you’re writing your book, do you keep this in mind, that you want to write it as a story? Are you trying to bring people in, and then bring them along on a journey with you; do you think that’s the most effective way to do this?

Tony: Yes, I do. And there’s a class I teach at Emory that, uh, I’m going to be teaching it every Spring, I’ve taught it three times now, called ‘Environmental Science Communication’. In that, I work with them on narrative structure, making sure they have some sort of narrative structure. Now what’s that? The very simple way to do this is how Randy Olsson, science communicator, has written several books on this. He uses uh, he calls it the ABT: the And, But, Therefore Framework. So that’s something I work with the students [on] and we experiment with it. We test it throughout the entire semester. We’re good scientists while we’re doing our communicating! And this ‘And, But, Therefore’ is that we give information, so ‘I was following these tracks, they were in the sidewalk, preserved in the cement, BUT I’m not sure what animal made them?’ Suddenly I’ve created some dynamic tension in that story. ‘BUT I don’t know what made them’: Now there’s a mystery afoot. Ah! ‘THEREFORE, I need to come to some conclusions towards the end to resolve that, I can’t just leave the audience hanging. There has to be some way, then, to carry on the narrative. So the ‘And, But, Therefore’ as a framework works really well, then, for me to hang my stories. That I make sure that when I’m writing that, and oftentimes I start the chapters in my books with a, with a little story typically told in the field. That structure helps me, keeps me on track, pun intended, to keep the narrative structures so that the reader is going to be engaged and interested. The deadliest mistake we make is when we do the ‘and and and’. ‘And then I looked at the tracks, and then I saw it had four toes, and then I saw it had claw marks, and then I looked at the heel…’ Oh my gosh, you are snoring already! Just stop, kill me! You want to make sure you have some sort of structure there, and you’re not doing the information overload.  

Adriane: That is excellent advice and so true. So, just to finish wrapping up talking about your book, where can people find your book if they wanted to go and read these and buy them? Are they available online?

Tony: Oh I’m so glad you asked that! So ‘Tracking the Golden Isles’, what’s great right now, go the University of Georgia Press website. They have a coupon code there. You can get fifty percent off! Can’t find a better deal! So do that, don’t, don’t buy it through that thing, ya know, that Amazon… Instead, go save yourself fifty percent, go the University of Georgia Press website, U-G-A Press dot org, go there, the coupon code is there, look it up, use the coupon code. And that’s good until the end of June. They did it in may, they’re going to do it in June. Now my other books, you can get them, those, look for those through, there’s a website indie bound dot org. I-N-D-I-E,, that you can look up your nearest independent bookstore. Because right now, with the pandemic still going on, independent bookstores are having a really tough time. I LOVE independent bookstores. So what you can do, is uh, I think you can just put in your zip code, and that will tell you the nearest independent bookstore, order the books then through those bookstores. What’s great is now ‘The Evolution Underground’ is available in paperback, so you can save some money there. And then, same with ‘Dinosaurs Without Bones’, also in paperback. So you can save money there. And then some people prefer either on Kindle, or Nook, or other e-readers, you can get your e-version as well. And occasionally there are good sales on those. So wait for the sales, too. Because I want people to save money for important things, like pizza and beer.     

Adriane: Very important things.  

Jen: I’m sure they’re also available through, like, public libraries.

Tony: Absolutely! Yes! Yeah, I’m always happy when somebody says ‘hey, look what I found at my library!’ and they post a picture on Twitter. I’m like, thank you, I love hearing that libraries have my books too! So if your library, your public library, does not have my book, then please persuade them to get them. But do it quietly, you don’t want to get shushed. 

Adriane: So we have three more questions we were going to ask, just getting into more of the  ichnology side of things, and traces and tracks. Um, so the other question we have for you, along the lines of ichnology is, sometimes traces are found within or around other fossils that can tell us a compelling story from a snapshot in time. Can you tell us about one such trace fossil?

Tony: Yeah, one that comes to mind is, I was working with a group from Indiana University Fort Wayne, and it was Jim Farlow working with the group. They were studying dinosaur tracks in Dinosaur Valley State Park, outside of Glen Rose Texas. It’s a world famous track site. I was there of more of the invertebrate ichnologist, where I was looking at the invertebrate burrows that were associated with the dinosaur tracks. So there were these U-shaped burrows that, we give them the ichnogenus name ‘Diplocraterion’. It’s a mouthful, but, people who know it know what it is. Those were associated with some of the horizons below where the dinosaur tracks were. But there was one place where a dinosaur actually stepped on one of the burrows. So this brings in the question: Did that dinosaur step on the burrow while there was a little, say, crustacean, inside the burrow. And I think the answer is ‘no’. The reason being it looked like the burrow was barely compressed. And this was a big therapod dinosaur that stepped on it. It probably weighed at least a ton. It should’ve compressed it more had it had been muddy and it had been squishy. This tells me that the invertebrate burrow, with the dinosaur track, tells me something about aaahhhhh, that burrow was probably long abandoned, its maker was probably dead, maybe for decades, then it was buried, then it was emerged, and this dinosaur stepped on it while it was a firm ground. While it was firm, and not muddy. This is the way you can tell sometimes the gap in time between trace fossils; that despite they’re being together, doesn’t mean they were there at the same time. This also gets you thinking about how these gaps in time, trace fossils are sometimes valuable for us to be able to figure those out.  Another example I’ll give you is, again using dinosaurs, is thinking about dinosaur bones. I wrote about this in ‘Dinosaurs Without Bones’, that, I cheat a little bit, I do talk about dinosaur bones in it, but there are bones that have tooth marks in them. Tooth traces where another dinosaur chomped on the dinosaur. So I think Stephanie Drumheller and Julie McHugh, for instance, published a paper recently about this with Allosaur tooth marks. Those tooth traces, then, tell us that the dinosaur that was being eaten had to have been dead, because to get through all that meat, to get down to the bone, it wasn’t just sitting there, saying ‘yeah, ok, you got down to my bone’. It was dead. So this tells us again a little bit about the gap in time between when did a dinosaur eat another dinosaur but also what dinosaur ate another dinosaur. These are ways that you can take trace fossils, put them together with other fossils, and be able to figure out some of the relationships between these different organisms, and sometimes at different times. How’s that?

Adriane: That’s really cool! 

Tony: Yeah it is!

Jen: I think that is also really cool because Adriane and I used to collect Diplocraterion in the Ordovician, um, and you’re talking about a much younger example. So just thinking about the same shape burrow, maybe different tracemakers, maybe very different tracemakers, given hundreds of millions of years in between. But that’s, that’s a really cool thing I think about ichnology, is that maybe is lost a little bit on people.

Tony: Thank you for mentioning that because I actually got my start as a paleontologist  in the Ordovician. I did my master’s thesis work in the, uh, in the Cincinnati region, I went to Miami University.

Jen: All of us did, that’s awesome!

Tony: The ‘real Miami’, as I like to tell people. Miami was a university before Florida was a state, they had the t-shirts there. But what was great were the trace fossils there, a lot of those trace fossils that I saw then, again, yeah, like you said you can see some of the same ichnogenera in rocks of much younger, much younger rocks, geologically speaking. The Ordovician, more than four hundred million years ago, and then the ones I was talking about from Glen Rose, those are a mere ninety-five million. Yeah, those are baby traces compared to the Ordovician. So yeah, that’s pretty cool that we can look at these trace fossils then, and we can think about the very different animals that would have made those very similar-looking trace fossils, maybe representing the same behaviors, and behaviors that are repeating through time. 

Adriane: Awesome. 

Jen: I had kind of a wild-card question. So I remember taking Ichnology, uh, with Dan Hembree at Ohio University, and we got on the topic of eggs, and are eggs trace fossils. Because technically there’s  some sort of biomineral, but technically they’re not a hard part of an animal. What are your feelings on this?

Tony: Oh, I, I don’t just have feelings, I have certainty! 

Jen: [laughing] Okay!

Tony: Eggs are body fossils. They’re body parts. This is one of my favorite quiz questions, test questions for my students. So any Emory students that are going to be taking my classes, you’re learning this now. Any that have taken my classes, they’ve already learned this. Eggs are body parts because it’s an extra body part for the developing embryo. So the eggshell itself, it’s like a body part. Same with a, uh, same with a pupa, for instance. And because you had classes from Dr. Hembree, he’s into insect traces. So a pupa, pupal case, is a body part of that insect, of that, of that insect as it’s developing. A cocoon that’s preserved as a fossil that shows the actual silk weave, that’s a trace fossil. 

Jen: Okay. 

Tony: Yeah. So eggs, what’s also cool though is that there are trace fossils of hatching windows, of where a little baby dinosaur poked its head out of the egg. That hatching window, that’s a trace fossil. If you had an egg, that a dinosaur stepped on it, that would be a trace fossil of the dinosaur stepping on the egg. If you had, uh, the old stereotype of the mammal eating an egg, if you had those tooth traces in the eggshell, that would be a trace fossil, but of the mammal. So you can have trace fossils in the eggs themselves, but the egg, eggshell, that’s [not] a trace fossil.   

Adriane: Well I learned something new!

Jen: Yeah!

Tony: Yeah, there you go! Now, just to complicate it even more though, if a Troodon, which was a therapod dinosaur in the Late Cretaceous about seventy-five million years ago, its eggs are paired. So it actually had the eggs paired which has been hypothesized as indicating it had dual oviducts. They are also long eggs that are oriented vertically that were probably partially buried by the mother and or father dinosaurs. In the nest, that orientation and the duality of those eggs, those are trace fossils. But the eggs are body fossils. See, we could do an entire exam on this! But I won’t. 

Jen: I figured you would have an opinion on it.   

Tony: Yes. 

Jen: I just remembered that from class, like, it’s debated, and heated arguments. 

Tony: Oh you could go on and on with it; it’s fun!

Adriane: Really cool stuff. So getting back to Georgia specifically, because you live there, you write a lot about it, what can ichnology tell us about Georgia’s future specifically?

Tony: Yeah, the Georgia coast, I write about this in ‘Tracking the Golden Isles’ in the last couple of chapters. In fact, chapters I talk about sea level change, and how sea level change, and especially storms, we’re going to have an increasing number of storms, we’ve had two hurricanes hit the Georgia coast recently, uh, Matthew and Irma. Those are going to change those environments very quickly, literally overnight. What happens then is that’s new real estate that the trace makers come in, and they start occupying that real estate right away. So for instance, there’s a salt marsh on Sapelo Island that over the past ten years I’ve watched it disappear. And it’s gone. The last time I was down there in, um, February, it was gone. It is now under several sheets of sand. So the salt marsh that had fiddler crabs leaving there little burrows in it, that had mussels attaching to the surface, that had root traces from Smooth Cordgrass, those traces have now been replaced by a layer of sand that has fiddler crabs, sand fiddler crabs, and ghost crabs, and now insects that are burrowing in the top of that. These traces give us a prediction, a prediction of what’s going to happen with climate change on the Georgia coast as sea level goes up, but also storms. That storms are going to go over the pre-existing environments, and we’re getting what we call Walther’s Law happening in real time. We’re actually watching these laterally-adjacent environments go over one another vertically. And we’re seeing this happen over the course of just, in a few years we can watch it. This is where traces give us a prediction. We can say that this environment is going to change into this environment, and these are what animals and plants are going to be moving into that new neighborhood once that change takes place. 

Adriane: So, relatedly then, this can probably be extrapolated to other states along the eastern coast of the U.S., right? Because we’re all kind of part of the same, you know, in North Carolina, we have the Outer Banks barrier island systems, um, so what can ichnology tell us about the more global implications of anthropogenic climate change?

Tony: Yeah, this is, this is a really good question because I like to point to the east coast of the United States, and particularly its barrier islands, as being kind of canaries in the coal mine. We have, on the east coast of the United States, going from Florida all the way up to Maine, we have barrier islands that people have modified a lot of them, but then there are a good number that have not been modified so much. The Georgia coast has some of the best examples of that, of barrier islands that have not been modified so much by humans. What we can do is look at those as canaries in the coal mine and think about how as climate change starts impacting those environments, how do traces inform us about those changes all the way up the east coast? Now, globally, globally a lot of geologists, sedimentary geologists, study the barrier islands of the eastern U.S. as examples, that they then apply worldwide. So of course barrier islands vary worldwide, but the east coast ones are often a model for what we see worldwide with coastlines, and how coastlines are changing. Especially because of human interactions with those coastlines. Traces, I think, are another tool that we can put in our toolbox. That we can use traces and ichnology to better understand these changes as we go into this uncertain future with storms, greater storms, fiercer storms, and then sea level rise. What’s going to happen? Traces are yet another tool in our Swiss Army Knife of tools that we use to predict how the, how the present is going to tell us something about the future.

Jen: I think it’s also important to mention, um, we’ve been talking a lot about how we think about like different groups of traces, being in certain areas, um, there’s a lot of, uh, like seminal work that really explained things like oxygen content, the type of substrate, and why you expect to see these different types of traces in these assemblages. So some things do better in high energy, some animals do not like high energy and need something a little bit away from the coastlines to kind of really thrive and establish their burrows. Uh, but maybe, uh, Adriane and I can include some links, and maybe you have some links you could send us so we can include them in a little document for people who are interested in kind of diving more into getting a better understanding of these assemblages. Because they are very valuable.

Tony: I agree completely and I’m really glad you’re going to do that because one of the, um, I think one of the applications to paleontology that we’re seeing today with climate change and thinking about how climate change fits in with paleontology, is this whole field of conservation paleobiology. And both of you have expertise in this, and then we have lots of other paleontologists who are working in this discipline. Now working with biologists and conservation biologists in particular for how can we, how can we use our knowledge of the past to better inform ourselves about what to do in the future. Particularly with conservation biology and preventing extinctions, and those kinds of, those kinds of measures that we need to act now on it. And, we’re here to help. So, great idea! I’m looking forward to helping with that.   

Jen: I have sort of a, sort of a question I think uh, our followers would be interested in. So you’re a faculty member, who teaches, does research, and you’re also an author, but there are other jobs for ichnologists if people are interested in studying trace fossils. Do you have any suggestions for them?

Tony: Yeah, traditionally, with ichnology, a lot of the ichnologists have been employed in the, um, well in the energy industry, for lack of a better term. They used to say petroleum but then it became petroleum natural gas and all the fossil fuels. As that is waning, as we are seeing this transition now from a fossil fuel intensive economy, as we’re going into alternative fuels and the future is happening now in that… It’s not necessarily those ichnologists are going to be out of a job. So what I just said is, our working with conservation biologists, I see that as part of the future of more traditionally trained ichnologists. However, I would also like to point out that there’s a whole discipline of conservation biology of people who work with tracks. And they work with tracks, of say, endangered animals, or doing surveys of animals in protected ecosystems. I think this is something where we ichnologists can also contribute to the people who are out there tracking animals, taking data, uh, GIS data,  say through CyberTracker, or other GIS mapping. I think this is something where we can contribute to, that we can work together with conservation biologists, and better see, I guess what you would say is the unseen biota, the, the animals you don’t go out and just witness everyday. Traces add an extra dimension, and really expand your, your world view of what lives in a given place. Does that help?

Jen: Yeah that’s an excellent answer!

Tony: It gets…Yeah, and it gives hope for those, those people who love ichnology now, that yes you will get a job somehow! You’re not useless.

Jen: Yeah I was remembering in ichnology class, I don’t think we focused on cores, but I remember Dan brought out some cores, and I was like, oh boy! Like trying to look at the like, just the side and the little squiggles. But, like that is also like, that is a challenging puzzle to try and do if you’re interested in really examining these minutia of bioturbation long ago, in these core segments. 

Tony: Here’s what’s really great though about, you’re all trained as geologists, and a lot of ichnologists are trained as geologists, is we really get these basic principles though, like cross-cutting relationships. Once you have that little Steno principle, you can apply it with trace fossils where, with cores you can say ‘this burrow is cutting across this burrow; this burrow is cutting across this one’, and you can work out the sequence. And then you can see where it goes from a soft ground to a firm ground, to a hard ground, you can work out that time sequence relatively speaking. This is where we, being trained as geologists, we really have a, I won’t say an unfair advantage, but I’ll just say, yeah, we’re pretty darn cool! That we, we actually have those skills that we can apply in universal ways.

Adriane: That’s so neat that you mentioned cores, and that came up and you can see these 3D relationships within the core. So I also sail with the International Ocean Discovery Program, and we sailed in 2017 to the Tasman Sea. And when we were coring there, we brought up this core, and they had, I think the sediments were of Oligocene or Eocene age, beautiful Zoophycos in them, and a lot of them were pyritized. And going back to what you talked about, certain traces mean certain things, and I was like ‘Ah, I’ll bet this means it was really deep, you know, deep water, maybe low oxygen, maybe low nutrients if I’m remembering correctly from our ichnology class years ago’. I got really excited over that, and I don’t know if other people did but…

Tony: I’m excited now!  

Adriane: I think I have… Hold on, I might have that pyritized zoophycos piece in my desk.

[Tony and Jen gasp with excitement]

Tony: Can it get any more thrilling?!   

[All laughing]  

Jen: It can! So actually Alycia used to do these dances, and I’m pretty sure she has a Zoophycos dance. Am I wrong? I think, I’m pretty sure. I’m pretty sure she would go like this, and, she, like, this is supposed to be like simulating the feeding, and she would turn around in circles. 

Tony: Oh, we need to get that. 

Jen: And she’d dance in front of her classroom!   

[All laughing]

Tony: And by Alycia you mean Dr….

Jen: Stigall

Tony: Yeah that’s what I thought; okay. I think we need to get video and we need to post that sometime. 

[see video for Alycia’s Zoophycos dance]

Jen: Yeah she has one for lophophores, Zoophycos, and I, I’m sure I’m missing a couple. 

Tony: Yeah, yeah. So this is something I do in my classes is I will sometimes imitate trace making behavior. So I’m really glad to hear Dr. Stigall does this too. 

Jen: It’s not just you! 

Tony: Yeah! It’s not just me.  

Adriane: Yeah unfortunately I can’t find that pyritized Zoophycos; this is really mean, oh I wish I had it!   

Jen: Well if you find it, get a picture of it and we can pop it in 

Adriane: Oh true, yea!

Tony: That’s fair. Yeah. Yeah and what’s really, what’s neat is that you mention the pyrite, and I got really excited about that because pyrite, people who don’t even know paleontology or ichnology they know about prite; it’s fools gold. That really tiny pyrite that they call framboidal pyrite, that is facilitated by, uh, sulfate-reducing bacteria. So there’s a story there! You have these anaerobic bacteria that are facilitating the reaction of iron, and sulfur, causing those to react. And that pyrite then, this is kind of a trace of the bacterial behavior, if you want to call it that, interacting with the organic substrates made by the Zoophycos making animal. And absolutely, yes! It tells you something about what was happening with the oxygen levels on the seafloor. That’s why I got so excited when you said that.

Adriane: Yeah it was really great when we pulled up this core and sliced them open, and they were on the table and I went ‘Oh my God, look at all these Zoophycos!’. It was great fun!  

Tony: I’m so glad you shared that.  

Adriane: I’m just sorry I wish I had thought about getting that specimen earlier. That’s okay I’ll keep looking for it and I can put a picture in.

Tony: That’s okay. 

Jen: I don’t think we had anticipated coming to cores in this conversation, it just happened. 

Adriane: It did, it was….

Tony: You never know! It’s kind of like, I don’t know, uh, a meandering trace fossil. Sometimes it just meanders all over the place and you never know where it’s going.  

Adriane: Exactly. Well Tony that’s all the questions we had for you, we’ve been going for about an hour. Is there anything else you wanted to talk about that we wanted, that you wanted to cover that we didn’t cover. Jen was there anything else?

Tony: Yeah I guess, I guess as a, just an inspirational message for everybody is that traces are everywhere. Traces are everywhere, and even in quarantine conditions, you can go out and you can find traces. So this morning I went out for a little walk, I’m in my neighborhood here in Decatur, Georgia, next to Atlanta, just walking through my neighborhood and my, I took pictures of, um, dog tracks in cement, cat tracks in cement. I even found what I’m pretty sure are mourning dove tracks that were left in cement. That, I was doing field work this morning, and it felt like paleontology, it felt like ichnology. But if you want modern traces, you can go to your local park, look at ant nests, look at some of the bee nests, that were, um, just a month ago were bee nest, ground nesting bees that were in the park next door. Traces are everywhere! Once you start looking, you’ll find them. So, if you’re, if you’re quarantining and you’re just like ‘uh, I’m so bored!’, go out, you’ll find some traces, you’ll get excited! They’re everywhere, just look for them.

Jen: And it would be cool, oh sorry. I was going to say, it would be cool to think about every trace fossil like my cats could make. Do they make similar trace fossils or different trace fossils, and what behaviors are represented with like the suite of what remains.

Tony: Yeah, yeah. I’ve thought about doing a book like ‘The Ichnology of Cats’; it would have a catchier title! But we have two cats here and oh man, uh, yeah that’s, that’s a book that would write itself pretty quickly. 

Adriane: Yes. Well I have a question, thinking about modern traces, I had this weird question. Are mosquito or bug bites on us, are those traces?    

Tony: Oooohhh, yeah. So, yeah, here’s the thing: if you have a wound, okay so a wound, it is a trace temporarily of that mosquito’s behavior, or parasitic dipterans in general. So it’s a trace of its behavior however temporary. But then, if it heals, you don’t see it, well, then, then it’s not preserving it. Now if you had some sort of scar, like if you had a good, a good bite from something, or a pinch from one of those, I don’t know, shell crushing crabs, I wouldn’t want that. If it left an actual scar, then that’s a trace that lasts. So then it, it really does depend on, is the substrate conducive to preserving that trace. In my book ‘Dinosaurs Without Bones’ I actually talk about, there’s a wound that was in dinosaur skin. I think it was a, a Hadrosaur that actually had a wound preserved in that fossil skin. So that’s a trace fossil of whatever inflicted that. Now, the authors thought maybe it was a tooth trace, but I also allow for the possibility that it stumbled into a thorny plant. In which case, that would be a trace of the Hadrosaur being really derpy and clumsy and ‘whoops!’ stumbling into a plant. That’s not a trace of the plant. So good question, and yet another question that I can ask my students to torture them; thank you. 

Adriane: Yeah, of course, yeah. Speaking of scars and cats, I’ve got some scars on my arm  from where my cats have bitten and scratched me over the years, so that’s cool now that I can say those are Felis catus tooth traces.

Tony: That’s right. See if they make it into the fossil record.  

Adriane: Yeah I doubt it, but we’ll see! 

Jen: There are cool fossils of echinoderms, they actually heal. So if something, like, bites them or like nibbles on something, sometimes you can find, find the like trace of that in their skeleton. It’s like, it was clear that it wasn’t a postmortem, because you actually see them trying to patch their body back together. Which is so cool!  

Tony: Absolutely, yeah, and there are bite traces, I’ve seen them in modern sand dollars on the Georgia coast, that yes, it heals, then you see fossil examples that are healed bite traces in, uh, trilobites too. Um, yea, this is actually, yeah I can’t reveal it, but the next book I’m going to do is getting more into hard substrates and those kind of really cool traces too. 

Jen: Cool!       

Tony: Yeah! So that’s neat. Thanks for mentioning echinoderms, which are among the coolest animals ever, right?

Jen: I had to!

[All laughing]

Tony: Well, yeah! Okay, anything else?

Adriane: I…. I could probably keep going and talk all day, but….

Tony: Yeah, this is, this is such fun! 

Adriane: I know, yeah, I really enjoyed talking trace fossils. I haven’t really thought about them so critically in so long, so this has been a really fun, dredging back up what we learned in ichnology. 

Jen: Yeah, we’ll have to send that to Dan! The video, when it’s done, see what he thinks of it. 

Tony: That’d be great! Yeah, I would love his input on it. And we’ve got to get that dance on tape.   

Jen: Oh Alycia’s? Yeah! I’ll ask her about it. Maybe we can get Dan to do it? 

Tony: Even better!

Jen: Doubt it!

[All laughing]

Adriane: That’s so great. Well thank you Dr. Martin for coming and talking to us today about trace fossils and ichnology and what they can tell us about the past and the future. We greatly appreciate it! Um, and we hope everyone goes out and looks for traces, modern day, on yourself if you even feel the need to, through scars or bug bites, and around ponds and nests, um, so thank you so much for joining us today, we greatly appreciate it!   

Tony: You’re very welcome! Thank you for asking me to be on Time Scavengers; it’s been a pleasure! 

Jen: Thank you everyone for sticking with us to the end of our first interview. This was certainly an interesting learning process. So we had a really great time chatting with Tony. If you have any questions for Tony, Adriane, or myself, please leave them in the comments below and we’ll do our best to address them. We look forward to sharing more areas and facets of paleontology with you through these interviews.


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