Speaking of Life Traces…

With the much-awaited publication of my new book (Life Traces of the Georgia Coast), it’s now time to talk about it. Fortunately, I’ve had plenty of time to prepare for this part of the launching of the book, which is one advantage gained from its publication taking longer than originally anticipated. (I’m not complaining, just saying.)

A brief preview of my book, which I gave to my peers in August as a 20-minute talk at the International Congress on Ichnology meeting (Ichnia 2012) in St. Johns, Newfoundland, Canada. Please note that all subsequent talks about the book will not involve audience members to be screeched in, although folks attending my talk to the Atlanta Science Tavern event on January 26 might be tempted. (Photograph by Ruth Schowalter.)

But what’s been most exciting about this process is the overwhelmingly positive reception to my inquiries about giving talks. Amazingly, no one (so far) has said “no” when I asked if I could speak. This is a lesson for other authors who might be organizing public presentations on your own, without the financial or logistical support of a trade-book publisher: pick what you think are the right venues for speaking about your book, then ask. Until then, you never know who will agree that having you speak about your book would be a fine idea.

I am also blessed with a very good infrastructure for giving talks here in Georgia, particularly in the metro Atlanta area. Despite all of the tired jokes about banjo music – along with urging participants to accompany this music with porcine sounds  – Atlanta has a thriving scene of science and natural history enthusiasts. This intellectual richness is exemplified the Atlanta Science Tavern, which was even noticed by some out-of-town newspaper for its “Mars Landing Party” last July.

Lastly, the subject of the book is of great interest to many people in Georgia, especially those who have been to its barrier islands. More than a million visitors are estimated to visit the Georgia coast each year, with many of those driving the 4+ hours from Atlanta to get there. Of these million people, at least a few walk along a beach or marsh, or hike through a maritime forest, and see traces made by the animals that live there on the islands, prompting  them to ask, “I wonder what made that?” For those folks and more, these talks are for you.

Here’s my current schedule of appearances for the next few months, but be sure to check in once in a while on this Web site for updates. Hope to see you at one or more of these events!

Wednesday, January 23, 4:00 p.m., Emory University, Atlanta, Georgia. Talk title: Big Burrows through Ecospace and Time. This talk is part of the Department of Environmental Studies Seminar Series for the spring semester, 2013; all seminars are in Math & Sciences Building, Room N304. Free and open to the public.

Saturday, January 26, 7:00 p.m. – Atlanta Science Tavern, at Manuel’s Tavern, Atlanta, Georgia. Talk title: Exploring Tracks and Prints, Marks and Holes on Georgia’s Barrier Islands. Preregistration required, $3 suggested donation. This event is currently FULL, but you can put your name on the waiting list through the preceding link.

Tuesday, February 5, 7:00 p.m. – Georgia Center for the Book, DeKalb Public Library, Decatur, Georgia. Talk title: Life Traces of the Georgia Coast. Free and open to the public

Saturday, February 16, 5:30 p.m. – Jekyll Island Green Screen Event, Jekyll Island Convention Center, Jekyll Island, Georgia. Poster presentation (along with other presenters) summarizing some of my latest research on the Georgia barrier islands (exact title of poster to be updated later). Free and open to the public.

Sunday, February 24, 3:00 p.m. – Andalusia, home of author Flannery O’Connor, in Milledgeville, Georgia. Tentative talk title: Tracks and Traces of Flannery O’Connor’s Favorite Birds. Free and open to the public.

Sunday, March 24, 2:30 p.m. – Fernbank Museum of Natural History, Atlanta, Georgia. Tentative talk title: Tracking Exotic Mammals on the Georgia Coast. Admission fee applies if you’re not a member of the museum, but the lecture is free with admission.

P.S. Bookstores, just remember, if you invite me to speak in your store, I will bring your employees this. Consider yourselves bribed.

A Sneak Peek at a Book Jacket (with Traces)

After returning from a two-week vacation in California with my wife Ruth, we noticed a cardboard tube awaiting us at home. Intriguingly, the mystery package, which was only about 60 cm (24 in) long and 8 cm (3 in) wide, had been sent by Indiana University Press, the publisher of my new book, Life Traces of the Georgia Coast. We were a little puzzled by it, considering that it couldn’t possibly contain complimentary copies of the book. (As of this writing, I still have not held a corporeal representation of the book, hence my continuing skepticism that it is really published.) What was in this mystery tube?

Front cover and spine of my new book, Life Traces of the Georgia Coast: Revealing the Unseen Lives of Plants and Animals (Indiana University Press). The book, newly released this month, is not yet in stores, but supposedly on its way to those places and to people who were kind enough to pre-order it. But if you didn’t pre-order it, that’s OK: you can get it right here, right now.

Upon opening it, we were delighted to find that it held ten life-sized prints of the book jacket: front cover, spine, back cover, and front-back inside flaps. The cover art, done by Georgia artist Alan Campbell, looked gorgeous, and had reduced well to the 16 X 25 cm (6 X 9″) format, retaining details of traces and tracemakers, but also conveying a nice aesthetic sense. I was also amused to see the spine had the title (of course) but also said “Martin” and “Indiana.” Although I’ve lived in Georgia for more than 27 years, I was born and raised in Indiana, so it somehow seemed fitting in a circle-of-life sort of way to see this put so simply on the book.

Back cover of Life Traces of the Georgia Coast, highlighting a few of the tracemakers mentioned in the book – sea oats, sandhill crane, sand fiddler crab, and sea star – while also providing a pretty sunset view of primary dunes, beach, and subtidal environments on Sapelo Island. (P.S. I love that it says “Science” and “Nature” at the top, too.)

I had no idea what the back cover might be like until seeing these prints, but I thought it was well designed, bearing a fair representative sample of tracemakers of the Georgia barrier islands: sea oats (Uniola paniculata), a sandhill crane (Grus canadensis), sand fiddler crab (Uca pugilator), and lined sea star (Luidia clathrata), as well as a scenic view of some coastal environments. I had taken all of these photos, so it was exciting to see these arranged in such a pleasing way. My only scientifically based objection is that I would have like to see it include photos of insects, worms, amphibians, reptiles, or mammals (these and much more are covered in the book), as well as a few more tracks, trails, or burrows. Granted, I suppose they only had so much room for that 6 X 9″ space, and thus I understood how they couldn’t use this space to better represent the biodiversity of Georgia-coast tracemakers and their traces. (Oh well: guess you’ll have to read the book to learn about all that.)

Inside front and back flap material for Life Traces of the Georgia Coast, which also includes a summary of the book (written by me) and a rare photo of me (taken by Ruth Schowalter) in my natural habitat, which in this instance was on St. Catherines Island, Georgia.

I had written the summary of the book on the inside flap nearly a year ago, so it was fun to look at it with fresh eyes, almost as if someone else had written it for me. Fortunately, I banished my inner critic while reading it, and just enjoyed the sense that it likely achieved its goal, which was to tell people about the book and provoke their interest in it.

In short, this cover jacket symbolizes a next-to-last step toward the book being real in my mind. Now, like any good scientist, all I need is some independently verifiable evidence in the form of tactile data, such as a physical book in my hands. Stay tuned for that update, which I’ll be sure to share once it happens. In the meantime, many thanks to all of the staff at Indiana University Press – who I’ll mention by name next time – for their essential role in making the book happen and promoting it in this new year.

Information about the Book, from Indiana University Press

Life Traces of the Georgia Coast: Revealing the Unseen Lives of Plants and Animals, Anthony J. Martin

Have you ever wondered what left behind those prints and tracks on the seashore, or what made those marks or dug those holes in the dunes? Life Traces of the Georgia Coast is an up-close look at these traces of life and the animals and plants that made them. It tells about the how the tracemakers lived and how they interacted with their environments. This is a book about ichnology (the study of such traces), a wonderful way to learn about the behavior of organisms, living and long extinct. Life Traces presents an overview of the traces left by modern animals and plants in this biologically rich region; shows how life traces relate to the environments, natural history, and behaviors of their tracemakers; and applies that knowledge toward a better understanding of the fossilized traces that ancient life left in the geologic record. Augmented by numerous illustrations of traces made by both ancient and modern organisms, the book shows how ancient trace fossils directly relate to modern traces and tracemakers, among them, insects, grasses, crabs, shorebirds, alligators, and sea turtles. The result is an aesthetically appealing and scientifically accurate book that will serve as both a source book for scientists and for anyone interested in the natural history of the Georgia coast.

Life of the Past – Science/Paleontology

692 pp., 34 color illus., 137 b&w illus.
cloth 978-0-253-00602-8 $60.00
ebook 978-0-253-00609-7 $51.99

More information at:

http://www.iupress.indiana.edu/catalog/806767 ]http://www.iupress.indiana.edu/catalog/806767

Deconstructing an Ichnology Abstract, with Alligators

Many people from outside of the realm of academia (or is it a fiefdom?) prefer to get the latest scoops on new paleontological or geological research directly from the source, rather than just reading a press release or news article about it. As someone looking from the inside out, I’m pleased to see so many non-scientists try to probe one layer deeper with their understanding of a beloved scientific topic that interests them, and I try to encourage it through my own blogging, speaking, teaching, and other forms of outreach.

An alligator den on St. Catherines Island, (Georgia), with baby alligator and “big momma” alligator for scale. This week, I presented a poster with about these big burrows and their makers  at the Society of Vertebrate Paleontology meeting in Raleigh, North Carolina. The original field work we did for this research was reported back in March here, and now we’re ready to share more of what we found out. (Photograph by Anthony Martin.)

Unfortunately, many of the original research articles that become subjects of media attention are behind paywalls, requiring a reader to pay for access to read those articles, even if the research was publicly funded. This practice is especially common if the research is published in one of those glamorous journals that seemingly make or break academic careers in science, regardless of the lasting quality of the research. (I won’t name them directly, but let’s just say that’s the nature of science nowadays.)

So one option for these curious folks is to read abstracts from proceedings volumes of professional meetings. Abstracts, which ideally are succinct summaries highlighting the most significant findings of a given study, can thus serve as a way for the public to at least get a few insights on the latest scientific research happening in their favorite disciplines.

Want to get below the surface with this research? Oh, sorry, I was just being metaphorical. You really don’t want to go below the surface of an alligator den, which is why we mostly studied abandoned ones, mapped them, and otherwise tried to use methods that didn’t bother the alligators or otherwise have uncomfortable encounters with them.

Along those lines, the annual meeting of the Society of Vertebrate Paleontology (SVP) has been taking place this week in Raleigh, North Carolina, and it has an abstract volume associated with the meeting. Regrettably, though, the general public does not have access to these abstracts, only SVP members and people who have registered for the meeting. The Society of Vertebrate Paleontology also has a policy regarding researchers who publicly share their research results based on these abstracts, muddied by the word “embargo.” In short, this policy holds that people working for the media, which include reporters and bloggers (the latter of whom are also sometimes reporters), cannot write about and otherwise publicize research results presented at the meeting. That is, unless the researchers have given their permission to do so, or the results have been freely distributed by the researchers through a press release, blog, or other forms of outreach.

So in the spirit of the public having easier access to this primary scientific information, the following is our SVP abstract, which I presented as a poster at the meeting yesterday. The abstract is co-authored with Michael Page (Emory University), Sheldon Skaggs (Georgia Southern University), and R. Kelly Vance (also Georgia Southern University), and we worked together on the research, writing, and editing of the abstract. Because this abstract also includes a lot of scientific shorthand (charitably referred to as “jargon”), I also included a sentence-by-sentence explanation of it, in which the abstract text is in italics and my explanation is in formal typeface. So I hope you, the gentle reader, get something from this exercise in explanation, and we look forward to sharing more of this research with you as it continues to evolve and we publish it sometime next year as a peer-reviewed paper.


MARTIN, Anthony J., Emory University, Atlanta, GA, United States; PAGE, Michael, Emory University, Atlanta, GA, United States; SKAGGS, Sheldon, Georgia Southern University, Statesboro, GA, United States; VANCE, Robert K., Georgia Southern University, Statesboro, GA, United States

Large archosaur burrows are rarely interpreted from the geologic record, a circumstance that may be attributable to a lack of search images based on modern examples, rather than actual rarity.

Archosaurs make up an evolutionarily related group of vertebrates that include crocodilians (alligators and crocodiles), dinosaurs (the non-bird ones, that is), birds, and their extinct relatives. A few of the larger extinct archosaurs may have dug burrows, but paleontologists have reported very few of these, with one exception being the small Cretaceous ornithopod dinosaur Oryctodromeus cubicularis, found in its burrow with two juveniles of the same species. The authors are proposing here that this “rarity” of archosaur burrows in the fossil record might be more attributable to paleontologists not knowing what modern archosaur burrows look like. So they don’t recognize the fossil ones, leading to a perceived rarity rather than an actual one.

To test this idea, we measured, imaged, and mapped den structures of the American alligator (Alligator mississippiensis) on St. Catherines Island (Georgia, USA).

By “measured,” I mean that my colleagues and I used a low-tech instrument known as a “tape measure” to assess the width and height of an alligator den entrance. By “imaged,” we used a much more technologically complex instruments and method, called ground-penetrating radar (GPR) in combination with computers to figure out what these dens looked like below the surface. By “mapped,” I mean that we looked for alligator dens on St. Catherines Island (Georgia) and recorded their locations using a handheld GPS (global positioning system) unit, then plotted the distribution of these points to see if any patterns emerged.

St. Catherines is an undeveloped barrier island on the Georgia coast, consisting of Pleistocene and Holocene sediments.

St. Catherines Island is undeveloped in the sense that very few buildings or people live on the island year-round. It is privately owned and reserved for researchers’ uses under the direction of the St. Catherines Island Foundation. Like most of the Georgia barrier islands on the southern part of its coast, St. Catherines also has a geologically complex history. Its northwestern end is made of sediments deposited about 40,000 years ago – during the Pleistocene Epoch – whereas its southeastern end is made of much more recent sediments from the Holocene Epoch.

Alligators dug most dens along the edges of freshwater ponds in loosely consolidated Holocene or Pleistocene sand.

This sentence doesn’t need much more explanation other than to reemphasize that alligators gravitate to freshwater ecosystems to dig their dens (pictured below), not saltwater ecosystems, like salt marshes or coastal dunes.

Adult female alligators use dens to protect offspring, but burrows also aid in thermoregulation or serve as refugia for alligators during droughts and fires.

This is probably the neatest insight we gained from doing the research, is that the dens aren’t just used by big momma ‘gators for raising baby ‘gators, but also to make sure alligators of all ages are cozy during winters, stay wet during droughts, and are safe from fires. For instance, because southern Georgia has been going through a drought the past few years, some of the occupied dens we saw were in places that were high-and-dry, but the dens themselves intersected the local water table (seen in one photo above).

Some dens are evidently reused and modified by different alligators after initial construction.

This is an important point for paleontologists to know, and probably shouldn’t have been buried so far into the abstract, but we couldn’t very well put it at the beginning, either. Dens, like other homes, get used again, and probably by generations of alligators. This means that once a den is dug, stays open, and has a wetland nearby, alligators may just move into an abandoned den and modify it if needed, an alligator form of “home improvement.”

Drought conditions along the Georgia coast have exposed many abandoned dens, thus better allowing for their study while increasing researcher safety.

The drought is bad for alligators but was good for us when we did our field work, because so many dens were abandoned and exposed on dry land. This also eased any concerns we had about bothering the alligators, but especially alleviated worries we might have had about close encounters with protective parents near occupied dens. To be sure, we ran into a few of those, but not as many as we would have if conditions had been wetter.

Den entrances have half-moon cross-sections, and based on one sample (n = 20), these range from 22-115 cm wide (mean = 63 + 23 cm) and 14-55 cm high (23 + 9 cm).

I like throwing numbers into ichnology, just to remind people that this is a part of it as a science. Although our sample size is small compared to other studies of traces and trace fossils, it gives people an idea of the range of sizes of these dens, or at least their entrances. As an exercise in the imagination, think about whether you could squeeze into one of these. You know, if you were crazy enough to do such a thing.

In addition to field descriptions, we applied geographic information systems (GIS) and ground-penetrating radar (GPR) to help define the ecological context and subsurface geometry of these structures, respectively.

Computer-aided mapping methods like GIS helped us to test how alligators decided to make dens as a function of the landscape. For instance, we found most of their dens were in lower-elevation areas, which made sense when you think about water accumulating in those places. And the GPR served the dual purpose of not bothering the alligators if they were in their dens, while also keeping us away from their, um, denizens. (Sorry.)

GIS gave spatial data relatable to alligator territoriality, substrate conditions, and proximity to potential nest sites. GPR produced subsurface images of active dens, which were compared to abandoned dens for a sense of taphonomic history.

Big alligators tend to stay away from other big alligators. They also tend to burrow in sediments that don’t take too much effort for them. Female alligators also make their nests close to water bodies and dens, so their little tykes don’t have to travel so far to the water. Newer, active dens were also compared to those no longer being used to see what happens to them over time with neglect, kind of like how an old, abandoned house tends to fall apart and collapse on itself over time.

Most den entrances are southerly facing, with tunnels dipping to the northwest or northeast.

This is pretty self-explanatory, but I’ll just ask readers to think about why these dens are oriented like this.

From entrances, tunnels slope at about 10-15°, turn right or left within a meter, and lead to enlarged turn-around chambers.

Pure description here too, but by “turn-around chamber,” that means the den has enough room inside the den for a big adult alligator to go in head-first and turn around so that it’s head is right at the entrance. (See the photo of “big momma” at the top for an example of that.)

Collapsed dens in formerly ponded areas (secondary-succession maritime forests) provided further insights into subsurface forms of these structures.

Dens left high-and-dry from years ago and taken over by forests collapsed in a way that we could see the full outline of the den and measure these.

These features are: 3.1-4.6 m long; 30-40 cm deep, relatively narrow at either end (35-60 cm), and 1.2-1.6 m wide in their middles.

Dude. Those are big burrows. Dude.

Expansive areas were probable turn-around chambers, and total volumes of collapsed dens accordingly reflect maximum body sizes of their former occupants.

The bigger the den, the easier it was for a large occupant to turn around in it. And although smaller, younger alligators could have lived in these dens, some of the dens were too small to allow the really big alligators from moving into them.

One sampled area (8,100 m2), an almost dry former pond, had 30 abandoned dens, showing how multiple generations of alligators and fluctuating water levels can result in dense concentrations of alligator burrows over time.

Think of an area about the size of an American football field, and put 30 alligator dens in that area. (Now that would make for an interesting game, wouldn’t it?) These dens weren’t all made at the same time, though, and were constructed or abandoned as the pond filled or dried out, respectively.

In summary, the sheer abundance, distinctive traits, and sizes of these structures on St. Catherines and elsewhere in the Georgia barrier islands give paleontologists excellent search images for seeking similar trace fossils made by large semi-aquatic archosaurs.

That’s the big take-home message here for vertebrate paleontologists. All of the information we gathered about these alligator dens from the Georgia barrier islands, especially what they look like, can be applied to test the fossil record of archosaurs. In other words, did archosaurs actually leave lots of dens for us to find, but we just didn’t know what to look for? Hopefully we’ll find out because of this research.

Later, denning ‘gator. (Photograph by Anthony Martin, taken on St. Catherines Island, Georgia.)

(Special thanks to Ruth Schowalter for assisting with the field work, and to the St. Catherines Island Foundation for funding some of the research.)

Source of Abstract (Reference):

Martin, A.J., Page, M., Vance, R.K., and Skaggs, S. 2012. Dens of the American alligator (Alligator mississippiensis) as traces and their predictive value for finding large archosaur burrows in the geologic record. Journal of Vertebrate Paleontology, 32 [Suppl. to No. 3]: 136.