The Paleozoic Diet Plan

Given the truth that the Atlantic horseshoe crab (Limulus polyphemus) is more awesome than any mythical animal on the Georgia coast (with the possible exception of Altmaha-ha, or “Altie”), it’s no wonder that other animals try to steal its power by eating it, its eggs, or its offspring. For instance, horseshoe-crab (limulid) eggs and hatchlings provide so much sustenance for some species of shorebirds – such as red knots (Calidris canutus) and ruddy turnstones (Arenaria interpres) – that they have timed their migration routes to coincide with spawning season.

Ravaged-Limulid-SCISomething hunted down, flipped over, and ate this female horseshoe crab while it was still alive. Who did this, what clues did the killer leave, and how would we interpret a similar scenario from the fossil record? Gee, if only we knew some really cool science that involved the study of traces, such as, like, I don’t know, ichnology. (Photograph by Gale Bishop, taken on St. Catherines Island, Georgia, on May 4, 2013.)

Do land-dwelling birds mammals eat adult horseshoe crabs? Yes, and I’ve seen lots of evidence for this on Georgia beaches, but from only three species: feral hogs (Sus crofa) and vultures (Coragyps atratus and Cathartes aura: black vultures and turkey vultures, respectively). In all of these interactions, no horseshoe-crab tracks were next to their bodies, implying they were already dead when consumed; their bodies were probably moved by tides and waves after death, and later deposited on the beach. This supposition is backed up by vulture tracks. I’ve often seen their landing patterns near the horseshoe-crab bodies, which means they probably sniffed the stench of death while flying overhead, and came down to have an al fresco lunch on the beach.

Nonetheless, what I just described is ichnological evidence of scavenging, not predation. So I was shocked last month when Gale Bishop, while he was monitoring for sea-turtle nests on St. Catherines Island (Georgia), witnessed and thoroughly documented an incident in which a raccoon (Procyon lotor) successfully preyed on a live horseshoe crab. Yes, that’s right: that cute little bandit of the maritime forest, going down to a beach, and totally buying into some Paleozoic diet plan, a passing fad that requires eating animals with lineages extending into the Paleozoic Era.

Limulid-Death-Spiral-SCISo what’s the big deal here? Horseshoe crab comes up on beach, gets lost, spirals around while looking for the ocean, and dies in vain, a victim of its own ocean-finding ineptitude: the end. Nope, wrong ending. For one thing, those horseshoe crab tracks are really fresh, meaning their maker was still very much alive, then next thing it knows, its on its back. Seeing that horseshoe crabs are not well equipped to do back-flips or break dance, I wonder how that happened? (Photograph by Gale Bishop, taken on St. Catherines Island, Georgia, and you can see the date and time for yourself.)

Here is part of the field description Gale recorded, which he graciously shared with me (and now you):

“Female Horseshoe Crab at 31.63324; 81.13244 [latitude-longitude] observed Raccoon feeding on upside-down HSC [horseshoe crab] on south margin of McQueen Inlet NO pig tracks. Relatively fresh HSC track. Did this raccoon flip this HSC?”

Raccoon-Tracks-Pee-Limulid-Eaten-SCIWell, well. Looks like we had a little commotion here. Lots of marks made from this horseshoe crab getting pushed against the beach sand, and by something other than itself. And that “something else” left two calling cards: a urination mark (left, middle) and just above that, two tracks. I can tell you the tracks are from a raccoon, and Gale swears the urination mark is not his. (Photograph by Gale Bishop, taken on St. Catherines Island, Georgia, and on May 4, 2013.)

I first saw these photos posted on a Facebook page maintained by Gale Bishop, the St. Catherines Island Sea Turtle Program (you can join it here). This was one of this comments Gale wrote to go with a photo:

GB: “This HSC must have been flipped by the Raccoon; that was NOT observed but the fresh crawlway indicates the HSC was crawling across the beach and then was flipped – only tracks are Rocky’s!”

[Editor’s note: “Rocky” is the nickname Gale gives to all raccoons, usually applied affectionately just before he prevents them from raiding a sea-turtle nest. And by prevent, I mean permanently.]

My reply to this:

AM: “VERY fresh tracks by the HSC, meaning this was predation by the raccoon, not scavenging.”

In our subsequent discussions on Facebook, Gale agreed with this assessment, said this was the first time he had ever seen a raccoon prey on a horseshoe crab, and I told him that it was the same for me. This was a big deal for us. He’s done more “sand time” on St. Catherines Island beaches than anyone I know (every summer for more than 20 years), and in all my wanderings of the Georgia barrier island beaches, I’ve never come across traces showing any such behavior.

(Yes, that’s right, I know you’re all in shock now, and it’s not that this was our first observance of this phenomenon. Instead, it is that we used Facebook for exchanging scientific information, hypotheses, and testing of those hypotheses. In other words it is not just used for political rants, pictures of cats and food, or political rants about photos of cat food. Which are very likely posted by cats.)

Now, here’s where ichnology is a pretty damned cool science. Gale was on the scene and actually saw the raccoon eating the horseshoe crab. He said it then ran away once it spotted him. (“Uh oh, there’s that upright biped with his boom stick who’s been taking out all of my cousins. Later, dudes!”) And even though I trust him completely as a keen observer, excellent scientist, and a very good ichnologist, I didn’t have to take his word for it. His photos of the traces on that Georgia beach laid out all of the evidence for what he saw, and even what happened before he got there and so rudely interrupted “Rocky” from noshing on horseshoe-crab eggs and innards.

Raccoon-Galloping-Limulid-Death-Spiral-Traces-SCIAnother view of the “death spiral” by the horseshoe crab, which we now know was actually a “life spiral” until a raccoon showed up and updated that status. Where’s the evidence of the raccoon? Look in the middle of the photos for whitish marks, grouped in fours, separated by gaps, and each forming a backwards “C” pattern. Those are raccoon tracks, and it was galloping away from the scene of the crime (toward the viewer).

Raccoon-Galloping-Pattern-SCISo you don’t believe me, and need a close-up of that raccoon gallop pattern? Here you go. Both rear feet are left, both front feet are right, and the direction of movement was to the left; when both rear feet exceed the front, that’s a gallop, folks. Notice the straddle (width of the trackway) is a lot narrower than a typical raccoon trackway, which is what happens when it picks up speed. When it’s waddling more like a little bear, its trackway is a lot wider than this. Conclusion: this raccoon was running for its life.

Although this is the only time Gale has documented a raccoon preying on a horseshoe crab – and it is the first time I’ve ever heard of it – we of course now wonder whether this was an exception, or if it is more common that we previously supposed. The horseshoe crab was a gravid female, and was likely on the beach to lay its eggs. Did the raccoon somehow know this, and sought out this limulid so that – like many shorebirds – it could feast on the eggs, too, along with some of the horseshoe crab itself? Or was it opportunistic, in that it was out looking for sea-turtle eggs, saw the horseshoe crab, and thought it’d try something a little different? In other words, had it learned this from experience, or was it a one-time experiment?

All good questions, but when our data set is actually a datum set (n = 1), there’s not much more we can say about this now. But given this new knowledge, set of search patterns, and altered expectations, we’re more likely to see it again. Oh, and now that you know about this, so can you, gentle reader. Let us know if you see any similar story told on the sands of a Georgia beach.

You want one more reason why this was a very cool discovery? It shows how evolutionary lineages and habitats can collide. Horseshoe crabs are marine arthropods descended from a 450-million-year-old lineage, and likely have been coming up on beaches to spawn all through that time. In contrast, raccoons are relative newcomers, coming from a lineage of land-dwelling mammals (Procyonidae) that, at best, only goes back to Oligocene Epoch, about 25 million years ago. When did a horseshoe crab first go onto land and encounter a land-dwelling raccoon ancestor? Trace fossils might tell us someday, especially now that we know what to look for.

So once again, these life traces provided us with a little more novelty, adding another piece to the natural history of the Georgia coast. Moreover, a raccoon preying on a horseshoe crab was another reminder that even experienced people – like Gale, me, and others who have spent much time on the Georgia barrier islands – still have a lot more to learn. Be humble, keep eyes open, and let the traces teach you something new.

(Acknowledgement: Special thanks to Dr. Gale Bishop for again spotting something ichnologically weird on St. Catherines Island, documenting it, and sharing what he has seen during his many forays there.)

A Good Bird Track is Easy to Find: Flannery O’Connor, Her Birds, and Their Traces

Authors of books are sometimes lucky enough to get people interested enough in both them and their books. Even better, these authors are sometimes invited to talk about their books to a receptive audience. Yet I’ll bet few authors get the opportunity to talk about their books with fellow book lovers while also standing on the front porch of a great American author. Even less probable is that the author of a natural history book – one related to paleontology, no less – would somehow have to relate his or her work to a deceased author best known for her Southern Gothic fiction.

It’s a sign! Upon my arrival at Andalusia Farm, the former home of Flannery O’Connor, this sign greeted me at the door, reminding me why I was there. It was fun to think that during Flannery O’Connor’s life, this is how she might have announced a lecture at her place, using a sheet of paper with words, posted on her door. (For the sake of imagination, just ignore that the notice was created and printed by person using a couple of 21st century devices.) Photograph by Anthony Martin.

This past Sunday, I was just so fortunate and challenged, having been invited to speak about my new book, Life Traces of the Georgia Coast, at Andalusia Farm, the former home of famed American writer Flannery O’Connor. Andalusia is located just north of Milledgeville, Georgia, and despite many previous trips to Milledgeville, this was my first visit to Flannery O’Connor’s former haunts. The house and grounds are in a formerly rural setting, its clay-laden driveway just off a busy highway and directly across from a chain hotel. Yet her house is still surrounded by more than 500 acres of forest, streams, and a pond; the pond is visible from the front porch of the house. These natural areas are what attracted me to coming, and provided an avenue for connecting themes of my book with this place.

A view of the main house at Andalusia Farm, where Flannery O’Connor spent more than a third of her life. Her bedroom, where much of her writing also happened, is just to the left after passing through the front porch. Photograph by Anthony Martin.

A sign telling about the recent history of Andalusia. Sadly, it does not include any mention of the Alleghanian Orogeny that contributed to the Piedmont Province there, nor does it inform visitors about the maximum extent of the Cretaceous and Eocene seaways just to the south, nor does it acknowledge the former presence and effects of the Pleistocene megafauna that used to live there. But I suppose all of that would have required a much bigger sign. Photograph by Anthony Martin.

O’Connor is much revered in the Southern U.S. and elsewhere, a loyalty that stems partly from the fact that she was indeed a terrific writer of Southern-inspired literature – consisting of short stories, novels, and essays – and partly from a wistful longing of “If only”: namely, if only she had lived longer. Born in Savannah, Georgia in 1925, she traveled to what was then called State University of Iowa (now the University of Iowa), where she earned an MFA, and soon afterwards began her illustrious writing career. In 1951, she was diagnosed with the same disease (lupus) that killed her father while he was still relatively young. She lived with this debilitating condition for the next 14 years, the last 12 of which were at Andalusia. She was only 39 years old when she died in 1964.

So how did I become a character in a Flannery O’Connor story? I blame it all on a paleobotanist friend of mine at nearby Georgia College and State University, Dr. Melanie DeVore, who suggested to me several years ago that I come to speak at Andalusia about my upcoming book. “Why?” was my first response. After all, as a long-time resident of Georgia, I was embarrassed to admit that I had read very little of O’Connor’s works until just recently. I also could not figure out how the plant and animal traces of the Georgia barrier islands could be related to a Southern author whose home was just above the fall line, between the Piedmont and Coastal Plain provinces of Georgia. Even the Cretaceous seaway from 70 million years past had not washed onto the landscape of O’Connor’s home. Thus I felt hard-pressed to come up with a way for my book to be relevant to her literary contributions and a sense of place.

Still, Melanie continued to encourage me to think about it. Admirably enough, she was trying to find ways in which natural scientists might contribute their perspectives to the considerable scholarship behind O’Connor’s works and the popular appeal of her former home. So I delved into O’Connor’s biographies, and searched for an ichnological connection between what she did and my interests. This is when I found the key, the theme that united: birds.

It turns out that O’Connor was a great lover of birds, and the thought that perhaps she had too many birds never occurred to her during her last years at Andalusia. Peafowl were her favorites for many reasons, some of which she explained ever-so-eloquently in several essays, including one of her most well-known works of non-fiction, The King of Birds. Domesticated birds also abounded on her property, including chickens, ducks, geese, and swans, all part of her avian menagerie. At one time, she evidently owned more than a hundred peafowl, a daunting number when one considers the vociferous qualities of these birds.

A peacock in a spacious enclosure just outside of Flannery O’Connor’s home, graciously displaying his tail feathers for us. See those feet? We’ll take a closer look at those soon. Photograph by Anthony Martin.

One of two peahens in the same enclosure, not nearly as resplendent and gaudy as her male companion, but still a very attractive bird. Of course, I was looking at her feet too, thinking about the tracks she would make, and how these might differ from those of the peacock. Photograph by Anthony Martin.

O’Connor’s earliest few minutes of fame were also bird-related, and established her life-long association with oddities of the South. When she was only five years old, she somehow taught a chicken to walk backwards. This feat attracted a film-reel company (Pathé News), which sent a crew from New York to Georgia to record this atypical avian mode of locomotion. The film reel, shown in theaters in 1932, also parodied O’Connor’s childhood accomplishment by reversing the film for other walking domestic animals, making these animals also appear to also walk backwards.


It’s one thing to read about Flannery O’Connor and her backwards-walking chicken, but it is another to actually see an original film about it. In the reel, she is mistakenly identified as “Mary O’Connor,” but no matter, as it was a start to her enduring fame for inventing quirky actions, plots, and characters reflecting the off-kilter cultures of her Southern environs. Incidentally, just how would you tell the difference between tracks made by a chicken moving forward or backwards? Maybe that should be the topic of a future post…

O’Connor’s link to paleontology was an oblique one, in that (as far as I know) she did not express any interest in it as a subject. Nonetheless, she was a great admirer of paleontologist, Jesuit priest, and philosopher Tielhard de Chardin, and the title of one of her anthologies, Everything That Rises Must Converge (1965), came directly from one of his writings. Also, in an “if only” moment of my own during my talk on O’Connor’s porch, I wondered what sort of fiction or essays would have come out of O’Connor had she lived long enough to learn that birds are actually living dinosaurs, and hence she had unwittingly surrounded herself with the progeny of those Mesozoic monsters.

Oh yes, my talk on O’Connor’s porch. How did that go? Fantastically. Because of the gorgeous weather that day, Craig Amason, my host and executive director of the Flannery O’Connor-Andalusia Foundation, thought that we might hold the discussion on the screened front porch, rather than inside in one of the more spacious rooms of the house. I was all for this idea, partially for its atmosphere (I mean, how cool would it be to talk about Flannery O’Connor with some of her fans on her front porch?), but also because we planned to have everyone walk on the trails with us later, looking for tracks and other traces of the animals that live there. Melanie and I had already scouted the trails in the morning and found a few surprises, so we knew that part of the program would be great fun, too: might as well get them halfway outside already by being on the porch. Fortunately, all of the dozen or so people who showed up also approved of this plan, which was helped in no small part by a heaping helping of cookies and soft drinks, enticing them to stay right there on the porch for a spell, and perhaps even relax in a rocking chair.

Dr. Bruce Gentry of Georgia College and State University, having just bought a copy of my book, opens it to take a look inside. Dr. Gentry is a scholar of Flannery O’Connor works and heads the Flannery O’Connor Studies Program at Georgia College and State University, in nearby Milledgeville. Meanwhile, I’m in the background, gesturing grandly to the delicious cookies on the table next to me while also introducing everyone to the topic of bird tracks and sign. Photograph by Melanie DeVore.

A sample of our front-porch chat about Flannery O’Connor and her birds, in which I point out the close resemblance between a rooster’s feet and those of a peacock. Although the peacock tracks would have been noticeable larger than those of her chickens, their overall forms would have been nearly the same, with three long thin toe-prints pointing forward, one shorter one pointing backward, and all four ending with clawmarks. Video footage by Craig Amason, exceutive director of the Andalusia-Flannery O’Connor Foundation.

A close-up of a rooster’s feet. Think about the tracks this would produce, whether walking forward or backwards. Rooster was known as “Tom” (R.I.P.), formerly owned by Carol Ruckdeschel on Cumberland Island, Georgia. Photograph by Anthony Martin.

Now compare the rooster’s feet to those of this peacock at Andalusia Farm, and you’ll see for yourself how close they are to one another in their overall form, despite the rear digits being hidden in this photo. I could not help but think that O’Connor, while seeking the pleasure of the company provided by her birds, also saw thousands of similar-looking peacock and chicken tracks every day she went outside. Photograph by Anthony Martin.

The talk itself was mercifully brief on such a fine day, with tracks and other sign awaiting us. So I simply expressed my gratitude for being there with all of us gathered in this special place, talked about Flannery O’Connor’s love of birds, and jumped into a speculative discussion of what tracks she might have seen every day on the farm. My presentation was decidedly low-tech, in which my only visual aids were paper print-outs of bird tracks and feet and a couple of my illustrations from the book, which were of bird-track categories and nests. These were supplemented by my acting out birds motions (walking, mostly), demonstrating how these behaviors would result in certain trackway patterns. One of these, much to the amusement of audience, was of a peacock doing its little circular and sideways-stepping dance, which was followed by my asking them to imagine the trackway patterns that would have resulted from such courting.

I also did a short reading from my book that introduces the topic of bird tracks, which fairly drips with admiration for the complexity of behaviors captured by such traces, thus hopefully echoing O’Connor enthusiasm for birds. Many questions were asked and observations of bird behavior offered, a give-and-take that I thoroughly enjoyed in the role of a “guide on the side” rather than a “sage on the stage” (or a “torch on the porch”). Once done, we had a short break for people to buy my book (thanks, y’all!), then walked onto a nearby trail to look at what the wild animals had left us the previous few days.

This outing was enjoyable, a bit of a treasure hunt and an eye-opening experience for many of how much animal activity is embodied by their traces in a typical Piedmont forest and its water bodies. Some of the traces I had seen earlier in the day while out scouting with Melanie, but we saw more, such as previously missed raccoon tracks and woodpecker sign. The highlights included the discovery of fresh (less than 12-hour-old) beaver tracks on one of the stream banks. This delighted several people, who told me that beavers had supposedly moved out of the area years ago, so they were pleased to know that at least one was back in the neighborhood. I was also excited to find coyote scat on the trail, which inspired earthy, amusing comparisons between the territorial markings of mammals in the wild versus those of corporate board members and academics (which, not surprisingly, are not so different in practice).

Coyotes just can’t help themselves: where we see a human footpath, they see an advertising opportunity. Here I excitedly point out an example of coyote scat, which had been strategically placed in the middle of the trail so that all other mammals would know this was her/his territory. You know, just like you might see happen in a professional meeting. Photograph by Melanie DeVore.

Fresh beaver tracks on a stream bank! This was a happy find, as it demonstrated that at least one beaver was in the area, following a nearly five-year absence of their species. These tracks show the beaver turned to its right and walked down the bank and into the water; look for the large rear-foot track to the left, and the tail dragmark in the middle. Swiss Army knife is about 6 cm (2.4 in) long. Photograph by Anthony Martin.

Once this short, ichnologically-infused hike was over, people thanked me and bid goodbye, but a few of stayed behind to take a gander at the peafowl, which were in a large enclosure just behind O’Connor’s house. One male and two females are kept there, and our timing was impeccable, as the male was in full display mode, feathers fully erect and dazzling as he strut about the grounds, while the peahens stayed in the background, mildly impressed or nonchalant. (“Oh yes, he does that all of the time,” I imagined them thinking, mildly bored.) Nevertheless, as far as we non-avian bipeds were concerned, he was indeed the king of birds.

But that’s when my ichnologist hat popped onto my head, askance from its sudden appearance. Craig had told me earlier about the peafowls making a dust bath in the confines of their enclosure, and sure enough, there it was. It matched the width, depth, and shape of dust baths I had written about in Life Traces of the Georgia Coast, only for wild turkeys. Birds make dust baths for alleviating skin parasites, in which they hunker down in them, using their wings to distribute enough fine-grained sediment on them to smother the offending lice or other arthropods. Could such traces preserve in the geologic record, whether they were made by feathered dinosaurs, birds, or mammals? How could we recognize or distinguish these from other shallow depressions? And most importantly, did Flannery O’Connor ever see such dips in the landscape, and if so, did she know their meaning?

A dust bath made by peafowls, about 50 cm (20 in) wide on its longest dimension, and looking a little less dusty after several days of intense rain the preceding week. Still, this was a cool trace to see, and conjured some imaginative thoughts about these as trace fossils. (Peafowl feces extra in the pit: no charge.) Photograph by Anthony Martin.

Another ichnologically inclined thought occurred to me while there at the enclosure, and is worthy of further experimentation. How might we tell the male (peacock) tracks from those of the female (peahen)? Take a look at the following photo, and you tell me. Anything there that might leave a distinctive mark identifying the gender of its tracemaker?

Here comes the groom! Any aspect of this tracemaker’s anatomy that might leave traces telling you he was a boy bird? Photograph by Anthony Martin.

So from this day trip to Andalusia Farm, I was awed, inspired, and ever slightly more enlightened by it all, and hoped that a small amount of the same feelings had been experienced by others who participated in this special day. Still, I was also humbled, realizing how little I still know about Flannery O’Connor, why she connected so well with birds, bird traces and behavior, or how these traces might manifest themselves to us and grace us with wisdom as recognizable trace fossils made in a distant past. Hence from my time there and into my future, I will endeavor to keep in mind the words spoken by Dr. Block, a character of O’Connor’s in The Enduring Chill from the anthology, Everything That Rises Must Converge:

“Most things are beyond me,” Block said. “I ain’t found anything yet that I thoroughly understood.”

Acknowledgements: Many thanks to: my good and long-time friend Melanie DeVore for encouraging me to visit Andalusia to share my science and sense of wonder; Craig Amason for being such a gracious host; Bruce Gentry for his continuing contributions to teaching his students about the complex and varied dimensions of Flannery O’Connor, a great American writer; the people who showed up and made for lively company; and of course the birds and their traces, which will outlive all of us, no matter the lengths of our lives.

Further Reading

Elbroch, M. and Marks, E. 2001. Bird Tracks and Sign of North America. Stackpole Books: 456 p.

Martin, A.J. 2013. Life Traces of the Georgia Coast: Revealing the Unseen Lives of Plants and Animals. Indiana University Press: 692 p.

O’Connor, F. 1955. A Good Man is Hard to Find, and Other Stories. Harcourt, Brace and Company: 265 p.

O’Connor, F. 1965. Everything That Rises Must Converge. Farrar, Straus and Giroux: 320 p.

Simpson, M. 2005. Flannery O’Connor: A Biography. Greenwood Books: 152 p.

The Traces We Leave Behind: A Tribute to Jordi Maria de Gibert

Paleontologists have an odd relationship with death. We often joke about how our livelihoods depend on what has died before us, or we experience great delight when we find an exquisite fossil, which probably was buried alive for it to be so well preserved. We also blithely talk about “death assemblages” and happily explain this gruesome term to non-paleontologically inclined students, friends, spouses, and partners without much thought about how it sounds to people outside of our field.

For ichnologists, who mostly study the tracks, burrows, and other vestiges of these lives that preceded us, our perspectives become even more skewed. Once-live animals, through their behavior, made trace fossils. Yet we almost never see what made them. Hence we also spend much of our time among the living, watching them make traces that we can use as analogs for those trace fossils left by their ancestors. Sometimes we find ourselves identifying with modern animals, developing empathy for what they experience as they form traces, a sensitivity that can extend to their trace-fossil equivalents. Hence for ichnologists, these parts of the fossil record become just a bit less removed from death, and we end up feeling for our tracemakers, both long gone and extant.

Jordi Maria de Gibert, contemplating and lamenting the loss of dinosaurian tracemakers from mass extinctions. The window display was in Basel, Switzerland, one of many places visited by Jordi in his quest to learn all things ichnological. (Photograph by Anthony Martin, who is also pictured in the reflection, along with ichnologists Luis Buatois and Gabriela Mángano, taken in 2003.)

In this sense, our small and close-knit international community of ichnologists was shocked to learn about the sudden loss of one of our own “tracemakers” this past weekend, Jordi Maria de Gibert. His death was unexpected and its impact accentuated because he and the rest of us had just gathered together only last month for the International Congress of Ichnology (Ichnia) in St. Johns, Newfoundland. We also anticipated seeing him again in his home city of Barcelona in 2016, where he died on Sunday. None of us had prepared ourselves to reflect on his legacy, let alone contemplate the possibility that his cognitive traces would cease any time soon.

The aftermath of the first Ichnia football match (sometimes known as “soccer” to you Yanks) between ichnologists of Team Gondwana and Team Laurasia, which took place on a pitch near Trelew, Argentina. Jordi, in the middle of the back row, is either signaling “Peace,” “Victory,” or, most likely, ordering two beers: one for him, and one for you so he can sit down to argue about trace fossils with you. (Photograph by Anthony Martin, taken in 2004.)

Most of our dismay about Jordi’s departure is because we loved him as a person, but it is also surely connected to our witnessing an ascendancy cut short. For instance, at the end of the meeting in St. Johns, Jordi addressed all of us as the newly elected president of the International Ichnological Association, and he had volunteered to serve as the main organizer for the next Ichnia meeting four years from now. His larger-than-life personality was on full display during his informal and impromptu speech: enthusiastic, cheerful, witty, earnest. In the days before then, he delivered multiple presentations on ongoing research projects, most of which revolved around his continuing interests in crustaceans and their traces, as well as those of marine bioeroders, animals that make a living by boring into rocks. Jordi was a prolific publisher of peer-reviewed papers on these topics, and was well known for his cooperative spirit, coauthoring with many ichnologists and other types of paleontologists on these papers.

Jordi (right, seated), in his preferred life habit, talking about fossils with colleagues (and friends) at an outcrop. And this wasn’t just any outcrop, but was at Mistaken Point, Newfoundland, which has one of the most spectacular Ediacaran fossil assemblages in the world. This had to have been a dream come true for him, as it was for many of us.

Jordi showing off his “Bama booties,” required footwear for the sacred ground of Mistaken Point, as some other ichnologist vainly attempts to “photobomb” him with his own blue-footed bootie. (Photograph by Ruth Schowalter.)

I had known Jordi since 1995, having first met in Bornholm, Denmark at a small ichnological meeting there. He and I were still new to our discipline (we were about the same age) and quite green, but eager to learn from our elders. As is typical with many academic friendships, over the next 17 years we would see each other at various meetings, and by my count we saw trace fossils and toasted one another in six countries (Denmark, U.S., U.K., Switzerland, Poland, Canada). Each time together, I grew more impressed with his intense and tenacious will to seek out more knowledge, digest it, and pass it on to others. He was a fierce intellectual who relished the debating of ideas, and was never satisfied with a conversation if he did not leave it wiser. This, of course, benefited all who were brave enough (and lucky enough) to enter into such discussions with him.

A happy time at the Ichnia 2004 banquet in Trelew, Argentina, with (from left to right) Renata Guimarães Netto, Jordi, and Ludvig Loewemark, where the exchange of ideas and good cheer flowed nearly as fast as the wine.

Jordi was young as far as ichnologists go, and as I argued in my previous post, the best ichnologists are the most experienced ones. So he knew as well as any of us that gaining more experience in the field was essential, and traveled to many places and studied traces of all ages – from the Ediacaran to the present – and traces of all kinds, from plant roots to dinosaur tracks. Accordingly, because of his dedication and broad interests, he had already become one of our best. In this vein, one of the metaphorical jokes ichnologists tell is how our academic success can be measured by how deeply we can burrow: shallow tiers are the least successful, whereas the deepst tiers are the most successful. Jordi was assuredly well on his way to the deepest tier, but we are all saddened about his unexpectedly reaching the historical layer before so many of us.

Los quatros amigos, posing happily toward the end of an ichnology field trip in Switzerland in 2003: from left to right, ichnologists Noelia Carmona, Gabriela Mángano, Luis Buatois, and Jordi, sporting some distinctive headgear and proudly flouting conformity. (Photograph by Anthony Martin.)

I learned about Jordi’s death on Sunday through our mutual ichnologist friend, Renata Guimarães Netto, who had likewise known Jordi for more nearly 20 years. Quickly the word spread through social media, e-mails, and phone calls, our sadness multiplying and magnifying worldwide. Only last month, we had celebrated with him, and now we mourned him, and expressed our sorrow to his family members, and close friends.

To ease some of this pain and enjoy an otherwise beautiful Sunday in Decatur, Georgia, my wife Ruth and I went for a walk. Without thinking, I suggested that we meander in one of the largest, quietest green spaces in Decatur, which turned out to be its cemetery. (Yes, I know. All I can say is that the subconscious is more powerful than we know.) While we strolled, I thought about times spent with Jordi on field trips and in conferences, while also recalling papers he had written and discoveries he had made. As mentioned earlier,  Jordi’s interests were varied, but perhaps his favorite research topic was crustacean burrows, especially the burrows of crabs, shrimp, lobsters, and other 10-legged crustaceans. Too bad we were nowhere near the Georgia coast, I thought, as it would have been a fitting and comforting homage for Ruth and I to take in the many decapod burrows of the Georgia beaches and salt marshes, which Jordi had never seen in person.

That’s when an eerie coincidence happened. During our walk, we spotted a former pond on the cemetery grounds, now drained for dredging. There’s something about a big pit of mud that appeals to every ichnologist, so I excitedly suggested that we go take a look to see what traces were there. We expected to find lots of tracks, such as those of birds, raccoons, squirrels, and coyotes, and maybe a few other urban fauna. Instead, though, the muddy surface was perforated by decapod tracks and burrows.

Need to see some crustacean traces, but you live in the landlocked part of Georgia? Just go to a dried pond and look for tracks like these.

These were the traces of crayfish, decapods that diverged from a common ancestor to modern lobsters more than 250 million years ago to live in freshwater environments as their brethren dispersed throughout the seas. A few years back, I studied Cretaceous crayfish and their burrows in Australia, but had never seen a live crayfish in its burrow here in Georgia, let alone seen so many of their tracks in one place. We even saw some crayfish (probably a species of Procambarus) poking their heads and claws out of their burrows, or walking around on the mudflat. So it turned out we did not need to go to the Georgia coast after all to see traces reminding us of Jordi: they had been right here with us the whole time.

A crayfish at its burrow entrance in the mudpit now in Decatur Cemetery, either defending its territory, or waving goodbye to people who study its kind and their traces. Your choice, but I know which one I’m picking.

In April, Jordi began writing about ichnology and invertebrate zoology for a more public audience through his cleverly titled blog, Infaunal Epiphany. His first entry was titled First Post, Hope Not Last!, in which he expressed a growing aspiration to connect with more than just his academic colleagues:

We scientists produce science. We scientists consume science. Most of us do that. We do our research, we publish it and other scientists read it. We are keeping all the fun for ourselves!!! It is true that there are scientists, journalists and writers who devote an effort to popularize science results. They are the ones building a bridge to society and I think it is fair to do that as many of us are investigating on public money.

Jordi wanted to share the fun of science, and in that respect, field trips with him were always a delight. These are probably what I will miss most about him, a pang that becomes particularly acute when I realize that one of our last conversations was about his some day visiting the Georgia coast to see its modern traces with me and our like-minded friends.

Lastly, in the light of his most recent life departing us, perhaps Jordi’s most poignant post on his nascent blog was Seven Reasons to Reincarnate as a Cephalopod. I won’t spoil it for anyone who hasn’t read this wonderful piece, but will just say that this post alone showcases how Jordi’s fine sense of humor blended readily with his science.

We will never know whether Jordi’s wish came true, let alone which cephalopod he might have become, or whether some element of his considerable spirit is now somehow connected to one of his beloved crustacean tracemakers or bioeroders in the past or present. But we can be assured that he will continue to live with us through his works and our memories of him. When our ichnological community meets again in his home town of Barcelona four years from now, his traces will all around us, continuing to inspire us to learn and live more.

Salud y un abrazo grande, mi amigo Jordi. Vaya con las trazas.

Correction: Someone pointed out to me that the newly elected International Ichnological Association (IIA) president is actually Alfred Uchman, not Jord. Jordi only seemed presidential to me because of his inspiring report given at Ichnia 2012 as outgoing secretary of the IIA and his agreement to host Ichnia 2016. (I am pleased to report that Alfred likewise gave an excellent speech to those gathered.) Apologies for the mistake, and thanks (as always) to anyone who points them out to me.

A Mirror Less Distant in Time

(This post is the third in a series about my recent field experiences in Newfoundland, Canada in association with the International Congress on Ichnology meeting (Ichnia 2012) in August, 2012. The first dealt with the unusualness of the Ediacaran Period and the second was about the transition from the Ediacaran to the Cambrian Period for burrowing animals.)

The Ordovician Period, a time represented by rocks from 488-443 million years ago, is an old (and I mean, really old) friend of mine. In my master’s thesis, I studied Ordovician fossils from southwestern Ohio, and for my Ph.D. dissertation, I described and interpreted Ordovician trace fossils and strata in Georgia and Tennessee. Thus for the formative years of my academic career, the Ordovician had a strong presence in my life, overshadowing most other geologically inspired opportunities in my adopted home state of Georgia.

Nice outcrop, eh? It’s composed of Lower Ordovician sedimentary rocks, formed more than 450 million years ago, and is on Bell Island, just offshore from St. Johns, Newfoundland (Canada). It’s a place I had never visited before last month, but its trace fossils took me back to Georgia. How? Guess you’ll have to read some more to find out. (Photograph by Anthony Martin.)

This Ordovician-dominated worldview contrasted with a much later focus on the present-day Georgia barrier islands. Between when I first arrived in Georgia, in 1985 through 1998, my only foray to its coast was a three-day field trip as a graduate student to Sapelo Island in 1988. Fortunately, I’ve been a more regular visitor to Sapelo and other Georgia barrier islands throughout the past 14 years or so, and my geologic perspective has accordingly traveled more than 400 million years forward to study modern plant and animal traces.

However, as I’ve embraced the present and the lessons it offers, what also happened over those years was a personal distancing from the Ordovician. This separation was unfortunate for several reasons. One is that Ordovician body and trace fossils are a mere 1.5-2 hour drive from where I live in the metropolitan Atlanta area, just south of Chattanooga, Tennessee. In contrast, the Georgia coast takes a minimum of four hours to reach by car.

Granted, northwest Georgia was part of my dissertation field area, so my leaving behind a place already prospected, poked, prodded, and otherwise inspected thoroughly more than 20 years ago is understandable and forgivable. Yet a day trip there with a colleague last spring (March 2011), along with a recent field trip to view Ordovician rocks in Newfoundland, Canada last month, reminded me of what was in my geological backyard, while also provoking new thoughts about the intersections between the Ordovician and the Georgia coast.

So what happened during those 20+ years of not studying the Ordovician rocks close to me in Georgia? Well, I gained lots more experience, went to many places with rocks and trace fossils of varying ages, and thus – I like to think – became a better ichnologist. So that leads to an imperiously pronounced statement, so please read it, take it in, and revel in its truth: Ichnology is a skill-based science.

People who study the earth sciences have an old saying, often stated during field trips to students: “The best geologist is the one who’s seen the most rocks.” The same sentiment might be applied to ichnologists. To excel as an ichnologist, it’s not your publication record (let alone impact factors of journals publishing your work), the number or size of your grants, accolades of your peers, “big-idea” review papers, erudite tomes, or any number of trappings imposed by academia that matter. What really matters in becoming a better ichnologist is how many traces you’ve seen, measured, sketched, journaled, photographed, pondered, argued over, and folded into your consciousness.

Hey, look – it’s ichnologists, trying to learn more by studying trace fossils in the field! (Photograph by Ruth Schowalter, taken on Bell Island, Newfoundland, Canada.)

Sure, peer review from your colleagues is still an important part of this learning process. Otherwise, as a tracking instructor once told me and other nascent trackers, “When you always track by yourself, you’re always right.” You don’t want to be that ichnologist who gets things wrong, then insists every other ichnologist is wrong, while also imagining that they’re teeming with jealousy over your brilliance. You know, the “they laughed at Galileo, too” fallacy.

Behold my genius! Only I can clearly see these are the tracks of an eight-legged river otter. Oh, so you think they’re from two four-legged otters, with one following the other? Dolt! Don’t you know who I am?

So am I the best ichnologist? Not just no, but hell no. The acknowledged master of ichnology is Dolf Seilacher. And the main reason I enthusiastically bestow Dr. Seilacher with a crown of back-filled and spreiten-laden burrows is because of the extraordinary amount of experience he has as an ichnologist. Granted, he’s also done all of that academic-type stuff that persuades far less-accomplished members of tenure-review committees to nod their heads with utmost seriousness and say, “Well, I suppose we can make an exception in this case.” But he also has seen, measured, sketched, journaled, photographed, pondered, argued over many, many trace fossils during his 87 years on this planet. Dolf knows traces.

Dolf Seilacher, the widely hailed master of ichnology in the world. Even when he’s wrong, he’s really good at it. (Photograph by Anthony Martin, taken in Krakow, Poland.)

So let’s go back to the Ordovician, and how it relates to Dolf and my claim about the importance of experience in ichnology. In 1997, I invited Dolf to visit Emory University as a distinguished speaker in an evolutionary biology lecture series we had then (since gone defunct, like many things at Emory). Because he had never before visited Georgia, he insisted that we also arrange a field trip for him to see some trace fossils here. So with my friend and colleague, Andy Rindsberg, we organized a day trip to an outcrop near Ringgold, Georgia to look at the Ordovician trace fossils there. Andy had done his master’s thesis on the Ordovician and Silurian trace fossils in that area, and as mentioned earlier, I had done my Ph.D. dissertation about the Ordovician rocks, in which I interpreted them mostly through an ichnological lens.

Dolf Seilacher in Georgia (USA) for the first time in November 1997, coffee in one hand and a trilobite burrow in the other. See all of those Ordovician rocks in the background? Even though he’d never been there before, he noticed trace fossils in them in less time than most of us take to read a Huffington Post headline. Gee, you think it had anything to do with his experience? (Photograph by Anthony Martin, taken near Ringgold, Georgia. And just so you know, no paleontologists were “Dolfed” in this photo.)

Andy and I knew the rocks and their trace fossils at this outcrop better than anyone in the world. Yet within five minutes of arriving at the outcrop, Dolf laid his hand on a large slab of Ordovician rock and began talking matter-of-factly about the trilobite burrows in it. Andy and I looked at each other, and said (almost simultaneously), “Trilobite burrows?”

Dolf was right. This rock and many others there were filled with circular, back-filled burrows, which were made by small trilobites that burrowed into mudflats more than 400 million years ago. During a futile attempt to disprove him the following year, Andy and I  found these burrows connected to trackways, and one even ended in a resting trace, perfectly outlining the body of a small trilobite. (Did I mention Dolf was right?)

Burrow (upper right, circular structure) connected to tracks made by little legs from a little trilobite. Trace fossils are on the bottom of a sandstone from the Upper Ordovician Sequatchie Formation of northwest Georgia. Scale in centimeters. (Photograph by Anthony Martin.)

Later on that same day, we looked more carefully at some other fossil burrows at the outcrop. These broad, banana-shaped trace fossils were ones that Andy and I had noted in our respective studies, called Trichophycus. Dolf continued his trilobite–tracemaker theme, insisting that these were also trilobite burrows. This idea was supported by scratchmarks on the burrow walls, which linked the burrows to the small legs of whichever arthropod lived in the burrows. Again, trilobites made sense as the tracemakers, and we haven’t yet found a reason why this would be wrong.

Trusted field assistant Paleontologist Barbie, pointing to a cluster of Trichophycus (interpreted as trilobite burrows) in the Sequatchie Formation of northwest Georgia. She is pointing to some scratchmarks on the burrow walls, which are preserved in natural casts of the burrows. (Photograph by Anthony Martin.)

Almost 13 years later, in March 2011, Andy and I went back to this same Ringgold outcrop to re-study the trace fossils there, done in preparation for a presentation he gave the next month at a regional Geological Society of America meeting (abstract here). He and I were surprised at how much the outcrop had changed since we last visited. Vegetation, particularly of the thorny variety, covered the ground and impeded our progress. Nonetheless, we found many excellent examples of trilobite burrows (Trichophycus), a beautiful trilobite resting trace (Rusophycus), and, for the first time for either of us, a sea-star resting trace.

Resting trace of a trilobite (Rusophycus), with a small part of its trackway leading to the trace, in the Upper Ordovician Sequatchie Formation of northwest Georgia. These trace fossils are preserved as natural casts on the bottom of a sandstone, so you’re seeing the underside of where the trilobite hunkered down more than 400 million years ago. (Photograph by Anthony Martin.)

Resting trace of a sea star (Asteriacites) in the Upper Ordovician Sequatchie Formation of northwest Georgia. This trace fossil, like that of the trilobite resting trace, is also preserved as natural casts on the bottom of a sandstone, so you’re looking underneath where the sea star moved into the mud. (Photograph by Anthony Martin.)

Our discovery of the latter two trace fossils – the trilobite and sea-star resting traces – took me from the Ordovician to the Georgia coast and back again. Throughout the late 1980s, I recall my Ph.D. advisor, Robert (“Bob”) Frey placing many of his articles in my graduate-student mailbox, all of which dealt with the traces of the modern Georgia coast. That’s odd, I thought. What did the traces of the modern Georgia coast have to do with these 440-million-year-old rocks?

In my limited worldview at the time, I did not see that the Georgia barrier islands and their traces composed a mirror, however removed by time, for looking into that Ordovician past. But eventually, given enough articles read, field work done, and trace fossils examined at these Ordovician outcrops, I slowly realized these 440-million-year-old rocks had been formed in estuaries, similar to those along the Georgia coast. When I first published an article about these rocks and their trace fossils in 1993 (link here), these strata represented the oldest known estuary deposits in the world, and some of the trace fossils could be readily compared to those on the Georgia coast. The beauty of this realization was that Frey, a master ichnologist in his own right and a contemporary of Seilacher, had allowed me to discover it for myself: he just provided the clues.

Remember that small, circular trilobite burrow with tracks connecting to it? Now compare it to the same sort of traces made by a modern beach mole crab (Albunea paretii), which left its burrow on the right, walked to the left, and is here rapidly burying itself in the sand. Scale in centimeters. (Photograph by Anthony Martin, taken on Sapelo Island, Georgia.)

Resting trace and attached trackway of a juvenile horseshoe crab (or limulid, specifically Limulus polyphemus). So think about a similarly sized trilobite making this, and what the bottom of the trace would like like, then compare it to the Ordovician trilobite resting trace fossil shown earlier. Scale in centimeters. (Photograph by Anthony Martin, taken on Sapelo Island, Georgia.)

Resting trace of a lined sea star (Luidia clathrata), with the original tracemaker just below its trace. This sea star was stuck above the high tide mark, burrowed into the underlying moist sand, but then tried to move to a better place once its spot started to dry out. Now compare this resting trace to the Ordovician trace fossil shown before. No scale, but sea star is about 8-10 cm wide. (Photograph by Anthony Martin, taken on Sapelo Island, Georgia.)

The following year and only a month ago (August 2012), Andy and I had another Ordovician learning opportunity presented to us, but this time in Newfoundland, Canada. A day trip to see Ordovician rocks and trace fossils on Bell Island, just a 30-minute ferry ride from St. Johns, Newfoundland, was a welcome break from the butt-numbing sessions of the previous two days of the Ichnia 2012 conference at Memorial University.

In our first few minutes at the outcrop and its numerous boulders – spoil piles from an iron-ore mine – we realized that one of the dislodged slabs in front of me was loaded with specimens of Trichophycus. It was a pleasant surprise to get reacquainted with this trace fossil, and in a place far away both geographically and experientially from Georgia.

Multiple specimens of Trichophycus in Lower Ordovician rocks of Newfoundland, Canada, preserved as natural casts of the burrows. See all of those scratchmarks on the burrow walls? These were also made by trilobites, but probably different ones from those in Georgia. Scale in centimeters (and that ain’t no real maple leaf.) (Photograph by Anthony Martin.)

Multiple specimens of Trichophycus in the Upper Ordovician Sequatchie Formation of Georgia, USA, also preserved as natural casts of the burrows and showing some scratchmarks on the walls. Do they look familiar to you, too? If so, welcome to the Ordovician. (Photograph by Anthony Martin.)

Here’s that trilobite resting trace (Rusophycus) from Georgia that I showed earlier. Now take a gander at the one below…

Why, that seems to be a trilobite resting trace (Rusophycus), too, but in Lower Ordovician rocks of Newfoundland. Surprise, surprise, surprise! Scale in centimeters. (Photograph by Anthony Martin.)

Suddenly, much of Andy’s and my previous experience with the Ordovician rocks of Georgia came back to us. We were, paradoxically, home, only in this instance, “home” was a time, not a place. Ichnological colleagues who had no idea Andy and I had worked with Ordovician trace fossils stared at us quizzically (and skeptically) as we excitedly discussed the burrows. But once we informed them that we had seen these trace fossils before, our experience was recognized, egos were set aside, and learning was enhanced. Funny how that works sometimes.

So with our trip to Newfoundland, we went from the alien world of the Ediacaran Period, with its trace fossils unlike anything I had seen before, to the more familiar and accommodating Ordovician Period rocks and their trace fossils. What I learned from this trip, combined with many others to Ordovician rocks elsewhere, as well as the modern sediments of the Georgia coast, was that the mirror was not so foggy after all, and that more field experiences can only further clarify these connections between life traces from the present and the not-so-distant past.

Further Reading

Buatois, L.A., Gingras, M.K., MacEachern, J., Mángano, M.G., Zonneveld, J.-P, Pemberton, S.G., Netto, R.G., and Martin, A.J. 2005. Colonization of brackish-water systems through time: Evidence from the trace-fossil record. Palaios, 20: 321-347.

Eldredge, N., 1970. Observations on burrowing behavior in Limulus polyphemus (Chelicerata, Merostomata), with implications on the functional anatomy of trilobites. American Museum Novitates, 2436: 17 p.

Fillion, D. and Pickerill, R.K. 1990. Ichnology of the Lower Ordovician Bell Island and Wabana Groups of eastern Newfoundland. Palaeontographica Canadiana, 7: 1-119.

Martin, A.J. 1993. Semiquantitative and statistical analysis of bioturbate textures, sequatchie formation (upper ordovician), Georgia and Tennessee, USA. Ichnos, 2: 117-136.

Seilacher, A. 2007. Trace Fossil Analysis. Springer, Berlin: 240 p.

Of Darwin, Earthworms, and Backyard Science

On the other hand, I sometimes think that general & popular Treatises are almost as important for the progress of science as original work.

– Charles Darwin, in a letter to Thomas Huxley, written in his home (Down House) on January 4, 1865

A combined blessing and burden that comes with travel, especially to new places, is the memory we carry of other places. The blessing part comes from the opportunity to connect previously disparate bodies of knowledge and experiences. This is always exciting for anyone who likes that sort of thing, while also satisfying purported promoters of “interdisciplinarity” (which was probably not a word until academia invented it, then pretended to reward those who practice it). On the other hand, the burden is that these thoughts of previous places can act as a veil, obscuring or overlaying our perception of novel sensations. In extreme cases, these remembrances can smother original ideas, especially if the places of our past are idealized and held as some worldly standard to which all other things must be compared.

What does this roundish stone, lying in the ground of the English countryside south of London, have to do with life traces of the Georgia coast? Good question, and if you’d like the start of an answer, please read on.

This Janus-like duality of travel occurred to me after my wife (Ruth) and I left Georgia for a few weeks of vacation in the United Kingdom, yet once there, I thought about my original home of Indiana and the barrier islands of Georgia. Ruth had never been to the U.K., and I hadn’t visited since attending an ichnology conference and field trip in Yorkshire, held in 1999. Fortunately, Ruth has a friend on the northeastern side of London who generously offered us a place to stay before we headed elsewhere. This refuge gave us a few days to learn what London had to offer us while we otherwise adjusted to cultural and temporal differences.

Among the myriad of educational opportunities in the London area is one that had been on my mind for quite a while, thanks to my writing about the Georgia coast. This was an intended visit to Down House, the former home of Charles Darwin and his family. Down House is located in a rural setting of the greater London area – Downe Village in the former parish of Kent – well southeast of Big Ben and all of the other typical touristy trappings of downtown London. Still, it can be visited via public transportation, which became doable for us Yanks once we figured out the needed connections in the intricate rail and bus system weaving throughout the London area.

From where we were staying, it took us nearly two hours to reach Down House. It was a mildly aggravating sojourn by train and bus, but made much better once we realized that driving there in London traffic with a hired car would have been far worse for both us and other people sharing the road (or sidewalk, as it may be). After our bus dropped us off in Downe Village, we saw a small sign pointing the way to Down House, and walked for  15 minutes on a quiet, country road before reaching our goal, a stroll only occasionally interrupted by brief terror induced when cars approached from the direction opposite of our expectations.

 When you step off the bus in Downe Village, this is one of the few clues that you’re near Darwin’s home, a place where scientific thought and human history changed in a big way.

A signpost in Downe Village provides a clue that Darwin has something to do with this area, although some horse named “Invicta” gets equal billing, and “St Mary the Virgin” gets bigger typeface. Still, it was nice to see Darwin’s visage there, too.

Blink and you’ll miss it: after walking about 10 minutes down the road, here’s the sign pointing the way to Down House. Personally, I thought it could use a neon fringe, or at least some DayGlo™ colors, but subdued is probably the way Darwin would have liked it.

We were also a little surprised at the subdued signage pointing us in the right direction to our goal, and I mused briefly about the homes of people who had far less impact on the advancement of human knowledge and world perspectives whose homes are accorded far more attention and adulation. (Yes, I’m looking at you, Graceland.)

The front of Down House, the home of Charles Darwin and his family from 1842 and after his death in 1882.

Down House is both modest and grand, not palatial at all, but impressive inside. Rooms on the second floor (or first floor, if you live in the U.K.) hold displays with a neatly presented synopsis of Darwin’s life and scientific findings, starting with his little boat journey in 1831-1836 through his grand synthesis of evolutionary principles. The ground floor of the house is more or less restored to the time when the Darwin family lived there, with particular attention paid to Mr. Darwin’s study, which was his main writing and experimentation room, or what modern-day scientists might call his “research space.” This is where On the Origin of Species and most other books of his were born. Infused with a purely fan-boy sort of joy, I was thrilled to be in the same place where many of his revolutionary ideas about evolution became expressed through words.

However, one item in the family living room (drawing room) intrigued me in a special way. It was a piano. This object was certainly used for the enjoyment of Darwin family members and guests, with the degree of delight of course depending on the proficiencies and musical choices of whoever played it. But then I was reminded – by the disembodied voice of Sir David Attenborough, no less – that this was not just a musical instrument, but also a scientific tool. (Disappointingly, Sir Attenborough volunteered this information in a recorded audio tour provided with admission to Down House, not through clairvoyance in a Sir Arthur Conan Doyle sense.) On this piano in the room and in the nearby Down House backyard are the places where Darwin conducted some of the earliest quantitative experiments in the behavioral ecology and neoichnology of terrestrial infauna. Or, in plain English, Darwin used this piano and a few other tools to measure and test the behavior of earthworms as tracemakers in soil.

The rear of Down House, with the two windows to the left looking into the drawing room, where the Darwin family piano is located. Unfortunately, photographs are not allowed in the interior of Down House, hence the external, voyeuristic perspective.

Darwin enthusiasts know well that the last book Darwin wrote was about a personal passion of his, the biology and behavior of earthworms. This book, titled The Formation of Vegetable Mould through the Action of Worms with Observations on Their Habits (1881), encapsulates many observations and conclusions he made from his long-term study of the oligochaete annelids that lived abundantly in the backyard and gardens of Downe House. As some biographers have noted, Darwin became quite a homebody after his years of voyaging on The Beagle, and he stayed close to Down House for much of his life after moving there in 1842. Nonetheless, this geographically restricted lifestyle did not mean he stopped inquiring about the natural world around him. On the contrary, he carried out intensive studies in and just outside of Down House, some of which dealt with earthworms, a subject that interested him for more than half of his life.

Darwin’s wonderment at worms was jump-started by something he noticed nearly thirty years after he innocuously tried to improve the soil in the pasture behind Down House. Told that he could get rid of mossy areas by laying down cinders and chalk, he obediently did so, and checked those same areas 29 years afterwards. It turned out the anomalous sediments had been buried about 18 cm (7 in) below the surface.

Darwin soon suspected this surface was newly made, formed by generations of earthworms bringing up soil over the preceding three decades. Through the technical support of his son Horace, an engineer, Darwin began to measure just how much earth an earthworm could worm. He already knew that earthworms burrowed through, consumed, and defecated sediment, which resulted in thoroughly mixed and chemically altered soils. So using his geologically inspired sense of time and rates of processes, he also rightly imagined that the daily activities of earthworms, multiplied by millions of worms and enough years, changed the very ground underneath his feet in a way so that it, well, evolved.

Ever the good scientist, though, Darwin tested this basic idea through experimentation. His assessment was accomplished through a precise measuring device invented by his son and flat, circular rocks, nicknamed wormstones, which were set out in the backyard of Down House. Based on my visual and tactile examination of the one wormstone that still lies outside of Down House, it looked like a quartz sandstone. However, out of respect for it and its ichnological and historical heritage, I did no other tests of its composition.

One of Darwin’s original “wormstones” (foreground center) placed in a pastoral setting behind Down House. Paleontologist Barbie (just behind the wormstone), who has accompanied me for much field work on the Georgia coast, helpfully provides scale.

Close-up view of wormstone, showing three metal slots set into a central ring and two rods, which provided the datum for measuring change in the wormstone’s depth over time. £10 note (with Darwin’s portrait on the right) for scale.

The experiment was elegantly simple. Using a device invented by Horace in 1870 (illustrated below, and photo here), the surface of the wormstone was measured relative to the height of the surrounding soil surface. This change in relative horizon was discerned by fitting the device on three metal slots that had been added to the edge of a central hole in the wormstone. Metal rods inserted through this same hole were connected to underlying bedrock, ensuring that these would stay stationary as worms churned the surrounding soil. Thus these rods acted as a horizontal datum through which any changes in the ground surface could be compared.

Illustration of Horace Darwin’s “wormstone measuring instrument,” with “K” pointing to where the instrument was placed to contact with the metal rods; the change with each measurement over time between this and “A” (a metal ring) would then show how much the stone had sunk downward. My source of this figure is from an online PDF by the Bromley Partnerships, Discover Darwin: An Education Resource for Key Stage Two, but its primary source is not cited there, and I could not otherwise find an attribution.

Darwin figured that the burrowing activity of earthworms underneath the stone, as well as sediment deposition at the surface as fecal castings, would result in the stone “sinking” over time, becoming buried from below. He was right. Using the wormstone and Horace’s measuring device, he calculated the approximate rate of sinking (2.2 mm/year). This was also a measure of soil deposition, which he attributed to earthworms depositing the sediment through fecal castings. Extrapolating these results further, he estimated that 7.5 to 18 tons (6.8-16.4 tonnes) of soil were moved by worms in a typical acre (0.4 hectares) of land.

Something very important to remember in Darwin’s approach to this study was that he was not just a biologist, but also an excellent geologist, taught early in his career – and later befriended – by one of the founders of modern geology, Charles Lyell. Consequently, he had a long-term view of how small, incremental changes every year added up to big changes over time. Or, to put it in Darwin’s own words (The Formation of Vegetable Mould, p. 6), when he responded to a critic claiming that earthworms were too small and weak to have any large-scale effect on their surroundings:

Here we have an instance of that inability to sum up the effects of a continually recurrent cause, which has often retarded the progress of science, as formerly in the case of geology, and more recently in that of the principle of evolution.

Darwin wasn’t just a quantitative ichnologist, but he also described and illustrated some of the traces made by earthworms, such as their burrows, aestivation chmabers, fecal pellets, and turrets made by their fecal casts. (Much later, in 2007, South American paleontologists described fossil examples of fecal pellets and aestivation chambers from Pleistocene rocks of Uruguay.) Darwin even noted the orientations and species of leaves earthworms pulled into burrows to plug these (p. 64-82), then he independently tested these results with pine needles and triangles of paper (p. 82-90)!

Illustrations of turrets made by fecal pellets of earthworms, in The Formation of Vegetable Mould through the Action of Worms with Observations on Their Habits (1881): from left to right, Figure 2 (p. 107), Figure 3 (p. 124), and Figure 4 (p. 127).

In short, Darwin, through combining his vast knowledge of biology with geological principles, had all the right stuff to make for a formidable ichnologist. Even better, he was keenly interested in the ichnological processes happening just outside his house, and didn’t feel the need to take a long boat trip to watch these processes in some far-off, exotic land. Unknowingly, he was also providing an example of how to do “backyard science” long before this term became associated with cost-effective means for introducing children to nature observation.

All of this marvelous research done by Darwin, culminating in his writing a book at Down House that ended up being one of his most popular, leads me to a bit of a mini-rant, followed by my connecting this science to my homes of Indiana and Georgia, and ending with a message of hope, if I may.

Darwin’s earthworm research epitomized the sort of long-term, DIY experimentation that seemingly only Darwin could have done, and in his day. In contrast, to show how far science has changed since his time, the current profit-oriented business model afflicting modern research universities might have demanded Darwin write a multi-million dollar (or pound) grant to conduct this study. (I suppose the piano would have been the most expensive item on the equipment list, and the wormstones the least.)

Moreover, in this hypothetical scenario, Darwin only could have written such a grant after “pre-confirming” most of his results by publishing a series of research papers. And not just by publishing these papers, but also by making sure they were in prestigious journals, most of which would require expensive subscriptions to read, ensuring that only a small handful of people would read about his work. (A book written for a popular audience? Please.) Had Darwin been a young man, the completion of a 30-year-long study also would have depended on whether he was granted tenure early on. This likely would have been decided by people with little or no expertise in geological processes, earthworms, and bioturbation, but who could certainly count grant revenue and compare journal impact factors.

Fortunately, though, Darwin was independently wealthy, well established as a senior scientist, and never had to worry about tenure or other such trivial matters. Instead, he could just focus on studying his much beloved worms, then think of how to share his vast knowledge of them with a broader audience. Darwin never used the word “ichnology” in his writings, let alone “neoichnology,” and he wrote a book on this topic for natural-history enthusiasts, rather than through a series of research papers published in inaccessible journals. Nonetheless, in his own way, he surely advanced the popularization of ichnology through his slow, deliberate, careful, and imaginative methods, which he combined with a desire to communicate these results to all who were interested.

How does all of this link with Indiana and Georgia? Well, Darwin’s “backyard science” reminded me of how I, like many naturalists of a certain generation, grew up learning about nature through what was in my own backyard. Today I have no doubt that my fascination with the behavior and ecology of insects, plants, and yes, earthworms in my Indiana backyard all contributed to a subsequent desire to do science outside as an adult. To satisfy this urge, I later picked geology as my main subject of study, but also took advantage of my biological leanings by concentrating on ichnology in graduate school. My living in Georgia since 1985 and other serendipitous events then eventually led to my writing a book about traces of the Georgia barrier islands (being published through Indiana University Press). In one chapter of this book, when I introduce earthworms as tracemakers, I made sure to write at least a few pages about Mr. Darwin and his experiments with earthworms. So although Darwin never traveled to Indiana or the Georgia coast, I carried my boyhood and adult experiences of both places in my mind to his former home.

Now here’s the hopeful message (not to be confused with a “hopeful monster“). Lots of field-oriented scientists spend much of their time outside for their research, and many require only modest amounts of money for their studies. So what they have begun to do is side-step the reigning corporate mentality influencing so-called “big science” at universities, while also making active attempts to better connect their research with more people than their academic peers. Through organized efforts like The SciFund Challenge and other crowd-sourcing methods, scientists are seeking small personal donations from the public, allowing them to better focus on their research, rather than spending much time, energy, and angst in writing massive research grants that have little chance of being funded. Thus much like earthworm castings, these  donations add up over time and provide rich, fertile ground for conducting basic science. (OK, maybe not the best metaphor, but you get the point.)

Another facet of this research is the stated commitment of scientists to report their research progress through blogs, then publish their peer-reviewed results in open access journals, which provide articles free for anyone with an Internet connection and curiosity in a scientific subject. All of this means that small investigations with big implications – like Darwin’s study on earthworms – are more likely to happen, and are better assured of reaching a public eager to learn about these sciences, while giving the opportunity for people to witness the direct benefits of their investments.

So how does the Darwin family piano relate to his study of earthworms? Do the southeastern U.S., earthworms, and Darwin’s study of their behavior somehow intersect? In answer to the first question, it’s interesting, and in answer to the second, yes. But an explanation of both will have to wait until next time.

In the meantime, if you go out for a walk later today, pay attention to the ground beneath you, and think of how it reflects an ichnological landscape, a result of collective traces made by those “lowly” earthworms, and how Charles Darwin clearly explained this fact in 1881. For me, it was an honor to stand in the same area where Darwin made his measurements, used his humble instruments, and applied his fine mind; this despite my later realization that I was standing on a new ground surface relative to where Darwin stood. After all, 130 years has passed since his death, meaning the ground had been recycled by descendants of the same earthworms he watched with his appreciative and discerning eyes. All of which makes for a different kind of descent with modification, one that instead reflects an ichnological perspective well articulated and appreciated by Darwin.

Darwin’s “sandwalk,” a walking route behind Down House he often took to help with his thinking, and a visible trace today of Darwin’s legacy as one of the first popularizers of ichnology.

Further Reading

Darwin, C. 1881. The Formation of Vegetable Mould through the Action of Worms with Observations on Their Habits. John Murray, London: 326 p. (A scan of the original book, converted to a PDF document, is here.]

Pemberton, S. George and Robert W. Frey. 1990. Darwin on worms: the advent of experimental neoichnology. Ichnos, 1: 65-71. (Text for article here.)

Quammen, D. 2006. The Reluctant Mr. Darwin: An Intimate Portrait of Charles Darwin and the Making of His Theory of Evolution. W.W. Norton, New York: 304 p.

Verde, M., Ubilla, M., Jiménez, J.J., and Genise, J.F. 2006. A new earthworm trace fossil from paleosols: aestivation chambers from the Late Pleistocene Sopas Formation of Uruguay. Palaeogeography, Palaeoclimatology, Palaeoecology, 243: 339-347.



Gopher Tortoises, Making Deep and Meaningful Burrows

As I wrote this post, I was flying from Atlanta, Georgia to Minneapolis, Minnesota to attend the annual meeting of the Geological Society of America (GSA), where I’ll be with about 7-8,000 geoscientists from across and outside of the U.S. Why am I not doing something else, such as field work on the Georgia coast? Well, other than to learn the latest of what’s happening in the world of geology, seeing old friends, and meeting new ones, I’m here to share new scientific knowledge coming out of the Georgia coast with my fellow geologists and paleontologists. The subject of the presentation I will give tomorrow – Tuesday, October 11 – is about the wondrous burrows of a humble-looking, slow-moving, and seemingly lethargic reptile that actually is an ichnological force of nature: the gopher tortoise (Gopherus polyphemus).

A gopher tortoise in captivity, but living a safe and happy life at the 4-H Tidelands Nature Center on Jekyll Island, Georgia. Although it may not look like a big deal, it is a very impressive tracemaker, deserving the rapt attention of geologists and paleontologists. (Photograph taken by Anthony Martin.)

So you’re probably wondering why geologists and paleontologists should hear about gopher tortoises from me. It’s a good question, because I’m not a biologist, and these animals are famous for their very important role in ecosystems. Specifically, they are well known as keystone species in the sandy soils of longleaf pine-wiregrass communities of the southeastern U.S. Just like the keystone to a building, once you remove gopher tortoises from their ecosystems, a lot of other species disappear with it. Surprisingly, their ecological worth all revolves around their burrows.

And oh, what marvelous and grandiose burrows they make! The lengthiest of their measured burrows approach 14 meters (45 feet) long and as much as 6 meters (20 feet) vertically below the ground surface. These burrows commonly twist to the right or left on their way down, which probably helps protect its tortoise occupant against predators, while maintaining a constant temperature and humidity in the burrow. With so much digging, of course, a lot of sand has to be excavated, so the locations of their burrows are easily spotted by looking for piles of sand in the middle of a grassy field or in a longleaf-pine forest. For female tortoises, these sand piles also serve as nesting sites, where they bury their eggs to incubate.

Satellite view of gopher-tortoise burrows on St. Catherines Island, Georgia. Nearly all of the white spots you see in the photo – indicated by the yellow arrows – are the sand piles (aprons) outside of their burrows. Look closely, and you can see some of the trails worn down by tortoises traveling between burrows. Yes, these are animal traces you can see from space! (Original image from the U.S. Geological Survey and Google Earth, taken in May 2008.)

Close-up view of a sand apron outside of a gopher-tortoise burrow entrance. The large amount of sand tells you that this must be a very deep burrow. Field notebook is about 15 cm (6 in) long. (Photograph taken by Anthony Martin on St. Catherines Island, Georgia.)

In cross-section, their burrows have flat bottoms and rounded tops, similar to a tortoise body. Burrow widths varies with the length of the tortoise, as it needs to be wide enough for the tortoise to turn around in the burrow. So this means a 30-cm (12 in) wide burrow can accommodate a tortoise of that length or less. The powerful front limbs of tortoises are specially adapted for digging, ending in flat, spade-like feet with stout claws. Burrow walls are compacted by the hard shell of the tortoise as it moves up and down the burrow. These burrows descend steeply, at angles of 20-40°, which means they have to be good climbers to get out of their deep burrows.

Down-tunnel view of a gopher-tortoise burrow, with the light at the end of that tunnel not  from an oncoming train, but reflected morning sunlight on the tunnel wall at one of its turns. (Photograph by Anthony Martin, taken on St. Catherines Island, Georgia.)

Now think about a tunnel that’s about 10 m (33 ft) long and 30 cm (12 in) wide, and how much space that represents underneath the ground, and you’ll see what I mean about the vital role of these burrows ecologically, geologically, and (most importantly) ichnologically. In terms of ecology, about 200-300 species of invertebrate and vertebrate animals cohabit these burrows (whether a gopher tortoise is in it or not), including the longest snake in North America, the eastern indigo snake (Drymarchon couperi), the secretive gopher frog (Rana capito), the Florida mouse (Podomys floridanus), and a bunch of different insects. At least a few of the insects and the Florida mice make their own burrows, thus adding their little homes to the main burrow, like small anterooms to a big mansion.

Idealized conceptual sketch showing a cut-away view through a gopher-tortoise burrow with many additional burrows made by other animal species. Note especially the short horizontal tunnels near the burrow top, which would have been made by hatchling tortoises, and the vertical shafts that connect to these, which would have been made by Florida mice. (Illustration by Anthony Martin.)

So now you can see why this ichnologist (that would be me) became rather enamored with these burrows. For one thing, they have great preservation potential in the fossil record. A  general rule in ichnology for the preservation of burrows is “deeper is better,” in that burrows that go to great depths are less likely to be eroded by surface weathering and erosion, and more likely to be fossilized. Secondly, we know that vertebrate animals in the geologic past also made big burrows, such as synapsids and even small dinosaurs. I’ve done research on the few dinosaur burrows interpreted from the geologic record, and am especially interested in how such large burrows might compare with similar burrows made by modern animals, such as gopher tortoises.

But how to study these burrows without digging them out and leaving the tortoises undisturbed? Fortunately, two colleagues of mine at Georgia Southern University – Sheldon Skaggs and Robert (Kelly) Vance – came up with an elegant solution, which was to use ground-penetrating radar, also known by its acronym of GPR. This method uses a portable unit to transmit microwaves underground (don’t worry, not these aren’t intense enough to cook the tortoises), which reflect off surfaces with different qualities, especially the curved, compacted surfaces of burrow walls. Computers then process and render these reflections into three-dimensional images that more-or-less represent the forms and geometries of the burrows.

Sure enough, we tried out this technique on gopher-tortoise burrows on St. Catherines Island of the Georgia coast in January and July this year. Although we can’t share all of our results just yet, we did successfully make three-dimensional images of the burrows, all without us having to burrow ourselves, or bother the tortoises by becoming homewreckers. Veronica Greco, a wildlife biologist on St. Catherines Island who has studied the behavior and breeding of the tortoises, also helped us to better understand the biology of these reptiles.

Although it looks like Sheldon (center) is mowing the lawn and I’m (right) just supervising, he’s actually pushing a portable ground-penetrating radar (GPR) unit over a field that has some gopher-tortoise burrows in it, while I walk alongside to look at the reflection profiles. Kelly (background) is no doubt monitoring our every move, but is also recording our location. (Photograph by Ruth Schowalter, taken on St. Catherines Island, Georgia.)

My talk at the GSA meeting will be about how we used GPR to study the burrows in a non-invasive way, and how our results might be applied to studying similar burrows in the fossil record. After the meeting is over, we plan to summarize our results in a research article, which we’ll submit to a journal later this year for peer review.

Unfortunately, gopher tortoises are endangered because of huge losses in acreage of longleaf-pine forests in the southeastern U.S. during the past 200 years or so. Knowing this makes our study of their burrows even more meaningful, for if these wonderful tracemakers go extinct in the near future, we will not have the chance to study them and their burrows. In this sense then, only geologists and paleontologists who know about their ichnology through studies like ours will be able to study their burrows, which would be a sad thing indeed. Let’s hope they survive and thrive, and we can continue to learn more about these superb burrowing animals and their traces.

(P.S. Many thanks to the St. Catherines Island Foundation for their support of our research!)

Further Reading

Aresco, M.J., 1999. Habitat structures associated with juvenile gopher tortoise burrows on pine plantations in Alabama. Chelonian Conservation and Biology, 3: 507-509.

Doonan, T.J., and Stout, I.J., 1994. Effects of gopher tortoise (Gopherus polyphemus) body size on burrow structure. American Midland Naturalist, 131: 273-280.

Epperson, D.M., and Heise, C.D., 2003. Nesting and hatchling ecology of gopher tortoises (Gopherus polyphemus) in southern Mississippi. Journal of Herpetology, 37: 315-324.

Guyer, C., and Hermann, S.M. 1997. Patterns of size and longevity for gopher tortoise burrows: implications for the longleaf pine-wiregrass ecosystem. Bulletin of the Ecological Society of America, 78: 254.

Jackson, D.R. and Milstrey, E.R. 1989. The fauna of gopher tortoise burrows. In Diemer, J.E. (editor), Proceedings of the Gopher Tortoise Relocation Symposium, State of Florida, Game and Freshwater Fish Commission, Tallahassee, Florida: 86-98.

Jones, C.A., and Franz, R. 1990. Use of gopher tortoise burrows by Florida mice (Podomys floridanus) in Putnam County, Florida. Florida Field Naturalist, 18: 45-68.

Lips, K.R. 1991. Vertebrates associated with tortoise (Gopherus polyphemus) burrows in four habitats in south central Florida. Journal of Herpetology, 25: 477-481.

Martin, A.J., Skaggs, S.A., Vance, R.K., and Greco, V. 2011. Ground-penetrating radar investigation of gopher-tortoise burrows: refining the characterization of modern vertebrate burrows and associated commensal traces. Geological Society of America Abstracts with Programs, 43(5): 381.

Varricchio, D.J., Martin, A.J., and Katsura, Y. 2007. First trace and body fossil evidence of a burrowing, denning dinosaur. Proceedings of the Royal Society of London, B, 274: 1361-1368.

Witz, B.W., and Wilson, D.S., and Palmer, M.D. 1991. Distribution of Gopherus polyphemus and its vertebrate symbionts in three burrow categories. American Midland Naturalist, 126: 152-158.

Why Study Traces in Georgia? A Celebration of the Familiar

For those of us who live in Georgia, we either forget or don’t know about the ecological and geological specialness of this part of the U.S. For example, my undergraduate students here in Atlanta often talk dreamily about their desire to visit the Amazon River basin, Costa Rica, Kenya, Australia, or other places far removed from Georgia, beguiled as they are by the exotic “other” qualities of those places with their biota and landscapes. On the other hand, almost none of these students have been to the Okefenokee Swamp, the Blue Ridge Mountains, the Cumberland Plateau, the long-leaf pine forests of Ichauway, or the Georgia barrier islands, unless my colleagues or I have taken them there on field trips. Yet these places, especially those with freshwater ecosystems, collectively hold a biodiversity nearly matching that of the Amazon River basin, an evolutionary consequence of the long geologic history of the Appalachian Mountains.

To be fair, I have likewise found myself succumbing to such place-based deflection and lack of appreciation for what is more-or-less in my backyard. In 2001, I realized that I had been to Brazil (three times) more often than Fernbank Forest (two times), even though Fernbank was only a five-minute bicycle ride from home in Decatur, Georgia. This imbalance was soon corrected, though, and many visits later, I learned to appreciate how this old-growth southern Appalachian forest in the middle of metropolitan Atlanta is a gem of biodiversity, every native species of plant and animal a facet testifying to their long evolutionary histories. Still, I wonder why we often ignore what is nearby, even if it is extraordinary?

Related to this quandary is one of the most common questions I encountered from friends, family, and colleagues while writing my book – Life Traces of the Georgia Coast – which was, “Why are you, a paleontologist and geologist, writing about the traces of modern plants and animals in Georgia?” This is a legitimate inquiry, but my answer surprises most people. I tell them that my main reason for staying here in Georgia to study the tracks, trails, burrows, nests, and other traces of its barrier islands is because these traces and their islands are world-class and world-famous. This high quality is directly linked to the biodiversity of the Georgia barrier islands, but also their unique geological histories compared to other barrier-island systems. Furthermore, these islands have inspired more than a few major scientific discoveries related to modern ecology and geology, some of which, made nearly 50 years ago, are still applicable to diagnosing the fossil record and the earth’s geologic history. In short, the Georgia barrier islands and their traces also reflect a legacy recognized by scientists far outside the confines of Georgia.

How so? I’ll explain in upcoming posts, and hope to demonstrate how the marvelous ecosystems of the Georgia coast and its geological processes are the proverbial gift that keeps on giving, continually helping us to better understanding the earth’s geologic past. Now that’s special!

Burrows at dawn: a partial view of the thousands of ghost-shrimp burrows dotting a Georgia beach at low tide, their entrances looking like tiny volcanoes. What makes these burrows so important, scientifically speaking, and why are they something that would cause scientists from outside of Georgia to travel and see in person? Photo by Anthony Martin and taken on Sapelo Island, Georgia.