Looking for Traces in an Ordovician Sea

It might seem a bit strange to consider traveling back 450 million years as a “homecoming.” But geologists time travel often enough to qualify as Time Lord apprentices, regardless of whether we are traveling by phone booth, car, or on foot. What creates this situation is how geologists may experience much of their training, teaching, or research interests in rocks of a certain age, gaining a certain comfort level when dealing with the earth of that time.

Cincinnatian-Outcrop-2“Hey everyone, let’s go to the Ordovician!” “Sounds good to me. Road trip!” You can do this when you live in a place with abundant, fantastically preserved, and freely available fossils. Which incidentally describes the area around Cincinnati, Ohio. (Photo by Anthony Martin.)

For me, my most recent homecoming was to the Ordovician Period, a geologic time span of about 488-444 million years ago. As a geologic period, its life and marine environments are represented quite well by the world-class fossil-bearing limestones and shales in and around the area of Cincinnati, Ohio. This is where I gained my formative training as a paleontologist, as I studied Ordovician rocks and fossils in the area while working on an M.S. degree in geology at Miami University in the mid-1980s. (Incidentally, Miami was a university before Florida was a state, and the rocks around it are much older than any in Florida, too. As a matter of pride, then, I like to inform people that I went to the “real” Miami.)

So last month I was lucky enough to participate in two field trips and a paleontology mini-conference in the region of Cincinnati, Ohio, which felt very much like a homecoming. The field trips and conference were co-sponsored by: the myFOSSIL Project, an NSF-funded initiative working to unite avocational (“amateur”) fossil collectors with professional paleontologists while enhancing STEM (Science Technology Engineering and Math) through the science of paleontology; The Dry Dredgers, a fossil-collecting club founded in 1942 (!) in Cincinnati, and consisting of some of the most knowledgeable and enthusiastic collectors I’ve met anywhere; the Cincinnati Museum Center, which hosted the conference and keynote talk (more on that soon); and the Paleontological Society, which was ably represented at the mini-conference by their current president, past president, and other officers and members.

Cincinnati-Musum-CenterExterior of the Cincinnati Museum Center, which helped to host the Paleontology Mini-Conference, houses a fantastic collection of Ordovician-age fossils, and served as the venue for a keynote talk given by Yours Truly. The museum building originated as the Cincinnati Union Terminal in 1933 and was later converted into the museum in 1990. It’s a very neat place for both its art-deco architecture and its displays, and every visit to the Cincinnati area should include it. Right after having some Skyline Chili and Graeters Ice Cream, that is. (Photo by Anthony Martin.)

Already I’ve listed many reasons for being there, but the main incentive was as the keynote speaker for the mini-conference, an invitation I received and gratefully accepted late last year. For that, I gave a public lecture at the Cincinnati Museum Center on a Friday night, and on the topic of my most recent book, Dinosaurs Without Bones (2014). I had my usual fun time with the lecture, the audience had a variety of thoughtful questions for me to answer and otherwise discuss, and I happily did a book signing afterwards. We were then given a tour of the museum, which has world-class Ordovician fossils in it and much more.

Sound great? It was. But the real highlight of my journey was seeing the Ordovician rocks and fossils in the area. Hence I had to participate in the pre-meeting and post-meeting field trips to various roadcuts in Kentucky, Indiana, and Ohio while there. As an ichnologist, I was was also keenly interested in revisiting the trace fossils in these rocks, which I had not seen in a long time (by human standards). Accordingly then, the following photos show some of the people and outcrops we visited, but really focus on the coolest trace fossils I saw, accompanied by my attempts to explain each.

Many thanks to everyone who made the 2016 Cincinnati Paleontology Mini-Conference happen, and much appreciation for taking me back “home” to the Ordovician.

Dry-Dredgers-Carl-BrettThe pre-meeting field trip and part of the post-meeting trip benefited from the presence of the indefatigable Dr. Carl Brett from the University of Cincinnati. I am continually awed by both his knowledge of the Ordovician rocks and fossils and his unrestrained enthusiasm for sharing this knowledge. Even better, he loves trace fossils, which officially makes him my new best friend. (Photo by Anthony Martin.)

Cincinnatian-Outcrop-1Roadcuts like these, all chock full of Ordovician body fossils and trace fossils, make me and other paleontological connoisseurs very happy. (Photo by Anthony Martin.)

Rusophycus-CincinnatianCarl Brett found these gorgeous trilobite resting traces at the very first outcrop, which at first made me a little jealous, but I got over it quickly enough after staring at these beauties for a few minutes. These were probably made by a species of Flexicalymene, which burrowed down into a firm mud below, possibly to hide from predators but also as shelter from other problems above. Later, silt and fine sand filled in the depressions, making these natural casts. Be sure to look for the little trilobite tracks, too.

Small-Cruziana-CincinnatianHow about the cutest trace fossil I saw? Here’s a tiny trilobite burrow I found on the bottom of a siltstone bed (my thumb is pointing to it). The dual pathways mark where its little legs pushed down and into the sediment below it; it have been made by a juvenile or full-sized adult that just happened to be really small. It is again preserved as a natural cast, so you’re looking at the bottom of the bed. (Photo by Anthony Martin.)

Palaeophycus-CincinnatianMost of these trace fossils are compressed and intersecting horizontal burrows, which are  visible because they are filled with a different sediment than the surrounding rock. Notice smaller-diameter and more complicated burrow system to the right, which apparently was made first, as the other burrows cut across it. Both were likely feeding burrows made by worm-like animals. (Photo by Anthony Martin.)

Diplocraterion-Palaeophycus-CincinnatianAt least four different types of trace fossils are on this slab: the little “pockmarks” that also show some branching; the lined burrow toward the top of the slab (eroded so that it looks like a snail trail); the long, discrete burrow just above the scale, and the “dumbell” one on the lower right. Applying the principle of cross-cutting relations, can you work out the sequence of which burrow came first, second, third, and last? All were likely made by wormy critters and are feeding burrows, although the “dumbell” burrow also served as a home, as we’re looking at the top of a U-shaped burrow. More on that with the next photo… (Photo by Anthony Martin.)

Diplocraterion-CincinnatianThe trace fossils on this surface are similar to that of the previous one, but has a lot more “dumbells,” which represent U-shaped burrows that were originally tubular, with the critter – maybe a worm, maybe a crustacean – having its head close to one opening and its rear end close to the other. To visualize these burrows in three dimensions, make a “U” with your thumb and forefinger, turn it so you are looking at the tips of your fingers, and imagined a line of collapsed sediment between the two limbs of the “U.” (Photo by Anthony Martin.)

Diplocraterion-Spreite-CincinnatianThese are bottom expressions of the U-shaped burrows, but omitting the tubes. The curved lines inside the linear parts show where the maker of the U-shaped burrow moved its burrow up or down in response to what was happening on the surface. A little confused by that? You’re not alone, and welcome to my world. (Photo by Anthony Martin.)

Diplocraterion-Cross-Section-CincinnatianHere are partial vertical sections of two U-shaped burrows, with the one on the left also displaying the internal structure made by animal as it moved its burrow up or down, depending on whether it had sediment dumped on top of its burrow (move up!) or the top was eroded (move down!). I think this one went down, but can’t say for sure without seeing the burrow bottom, which is not preserved here. (Photo by Anthony Martin.)

Chondrities-CincinnatianThis branching burrow, which if reconstructed in three dimensions would look like an upside-down bush, was made by an animal (or several with their burrows overlapping) feeding on the sediment. The branches are from repeated probing into the surrounding sediment, then withdrawing, then probing again. (Photo by Anthony Martin.)

Dry-Dredgers-1What other trace fossils are in these outcrops of Ordovician limestones and shales? Too many for these people to see them all and study, but clearly they don’t care. And that’s a good thing. (Photo by Anthony Martin.)

Groovy Trace Fossils at the SVP

After an undramatic (but still tiring) trip from Atlanta, Georgia to Berlin, Germany, I’m happy to be attending the Society of Vertebrate Paleontology annual meeting (SVP) in Berlin. The meeting – with talks, posters, and various social events – officially begins today (Wednesday, November 5) and continues through Saturday, November 9, but like all good paleontology meetings, it also has field trips before and afterwards.

Aside from my being with more than a thousand other paleontologists, exchanging information about the latest research, and enjoying good German beer while learning about this research (all of these are connected, I assure you), one of the main reasons why I am so far from Georgia is to present some of my research, too. It’s very much in the preliminary stages, but my coauthors and I thought it would be good to put this work out for other paleontologists to examine, poke, prod, and otherwise leave their impressions on it before we present it in a formal, peer-reviewed paper. I’ll be providing pictures and words expressing our work in a poster session today.

Groovy-Trace-Fossils-Cedar-Mountain-FormationSeries of small grooves in an Early Cretaceous (about 100 million-year-old) sandstone in Arches National Park, Utah (USA). Notice how they make radiating patterns, too. Do you wonder what made these trace fossils? If so, join the club. My coauthors and I take a semi-educated guess, which is just below for your reading pleasure. (Photograph by Anthony Martin, taken in June 2012; scale in centimeters.)

The following abstract summarizes the work, but the preceding picture might help, as does this one-sentence summary at the start of the poster:

Linear grooves in Early Cretaceous sandstone beds of the Early Cretaceous (Aptian-Albian) Cedar Mountain Formation are likely feeding trace fossils made by a beaked vertebrate, such as a pterosaur or bird.


MARTIN, Anthony J., Emory University, Atlanta, GA, USA, 30322; KIRKLAND, James I., Utah Geological Survey, Salt Lake City, UT, USA; MILNER, Andrew R.C., St George Dinosaur Discovery Site at Johnson Farm, St. George, UT, USA; SANTUCCI, Vincent L., National Park Service, Washington, DC, USA.


Abundant linear grooves on sandstone bedding planes of the Ruby Ranch Member of the Cedar Mountain Formation (Lower Cretaceous) in Arches National Park (Utah, USA) are interpreted as feeding traces made by a beaked vertebrate, such as a bird or pterosaur. These grooves have regular lengths (15.7 ± 2.0 mm), widths (3.4 ± 0.3 mm), and depths (1.5 ± 0.7 mm; n = 30), indicating a common origin related to the behavior and anatomy of their tracemakers. The trace fossils are either: solitary, bundled together as parallel groups of 4-8 grooves, or form semi-circular to circular patterns of 35-70. Bundles forming arc-like patterns are 13-15 cm wide. Grooves are on the same surface with runzelmarken, invertebrate trails, tridactyl theropod tracks, and a didactyl dromaeosaurid track. Forms and patterns of these features do not correspond to any known inorganic structures or invertebrate traces, nor traces made by fish. Thus they are considered as trace fossils made by either birds or pterosaurs. Runzelmarken and laminations imply that algal films bound sedimentary surfaces and helped to preserve these trace fossils and their associated theropod tracks. Hence the grooves may have been grazing traces, in which tracemakers gouged just underneath and parallel to algal films by using hard body parts, such as beaks. If so, beaks would have been 3-4 mm wide and groove lengths would have been linked to beak length and neck movement. The diameter of the semicircular and circular patterns suggests that the tracemakers were relatively small vertebrates. Arc-like patterns of clustered grooves could have been made by the tracemaker standing in one spot or shifting laterally to systematically mine the surface. However, no pes tracks were observed in direct association with these grooves. Hence the traces also may have been formed.

Many thanks to my coauthors – Jim Kirkland, Andrew Milner, and Vincent Santucci – for their help on this research, which hopefully will get a little bit of the attention it deserves here in Berlin. Stay tuned this week for more ichnologically related posts, which I’ll try to write and publish in between all of the aforementioned enjoyable exchanges and German beer.

Tracing the Two Medicine

Field scientists have to get into the field. If they don’t, they get cranky, narrow-minded, and – worse of all – feel like frauds. What’s the cure for this malady? Getting into the field.

Tony-in-the-FieldSee that smile? That’s a field scientist, who is out standing in his field. (Photograph by Paul Germano.)

This is the first summer since 2008 in which I did not have to edit or write a book. From 2008 to 2012, I was writing and editing Life Traces of the Georgia Coast (2013, 692 pages), and from 2012-2013, my literary efforts were devoted to Dinosaurs Without Bones (2014, 460 pages) So with these two books behind me and none in the making now, along with three merciful months off from my “day job” of being a college professor, I had few excuses for not getting outside to see some rocks and fossils this summer.

So it was with much joy when my long-time friend and fellow paleontologist David (Dave) Varricchio asked me earlier this year if I’d be interested in coming out to Montana to do some field work with him this summer. Even better, I’d get to do paleontological field work with him in the Late Cretaceous Two Medicine Formation (~75 million years old) at “Egg Mountain,” a paleontologically classic area near Choteau, Montana. I said yes, have been here for a week now, and it’s been glorious.

Egg-Mountain-Digging-2 To look for traces, sometimes you have make your own traces. Here’s this summer’s Montana State University field crew excavating at Egg Mountain, where they’re looking for dinosaur bones and eggs, while also cataloging trace fossils like insect cocoons and burrows. If you’re looking for Dr. Varricchio, he’s the one in the middle with the jackhammer. (Photograph by Anthony Martin.)

The main reason why the field site is called “Egg Mountain” is because it and other places in the area are where the first known dinosaur nests in North America were discovered by Jack Horner and Bob Makela in the late 1970s and early 1980s. They further uncovered evidence that at least one dinosaur here – the large hadrosaur Maiasaura peeblesorum – had extended parental care, taking care of its young in their nests well after hatching.

Later in the 1990s, Dave and his colleagues showed that the small theropod Troodon formosus made rimmed ground nests and arranged it eggs carefully in these nests. This combination of body fossils (bones and eggs) and trace fossils (nests and egg arranging) changed many of our views of dinosaurs, rendering their behaviors much less like reptiles and more like birds.

Maiasaura-Nesting-Site Sometimes I hear paleontology referred to as a “historical science,” but it also has its own human history. This marker and several others in the field area mark where some of that history was made, with the discovery of the first known dinosaur nests in North America. (Photograph by Anthony Martin.)

Two-Medicine-Formation-OutcropI love waking up to the Two Medicine Formation in the morning. And there’s no shortage of trace fossils to discover in it with each waking day. (Photograph by Anthony Martin.)

Hadrosaur-Track-Two-MedicineA natural sandstone cast of an adult hadrosaur, weathered out of the surrounding softer mudstone that – in the absence of bones – serves as a visual reminder of who lived in this area. (Photograph by Anthony Martin.)

I had been to this site three times before – 2000, 2008, 2009 – but each of those were short visits, the longest lasting only a week. This time, I would get to stay for as long as three weeks, which allows for plenty of time to better document the invertebrate and vertebrate trace fossils here. So far, I’ve only published one paper with Dave based on previous work in the Two Medicine Formation, which was on some of the insect trace fossils near the nest sites. These trace fossils gave valuable clues about how these insects lived, and in the same ecosystems as the nesting dinosaurs, which I’ll happily cover in detail in my next blog post.

Fossil-Cocoons-MontanaInsect burrow with pupal chamber (left) and two insect cocoons, one of which has a “hatching window” where the adult insect left the cocoon. Look closely and you’ll see the original silk-weave pattern still on the cocoons, which are preserved as finely crystallized calcite. (Photograph by Anthony Martin.)

So with one week of field work done, I’m happy to report that plenty of trace fossils have revealed themselves to us, and I have every expectation that more will be found in the next two weeks. And this, boys and girls, is why I am a field scientist and paleontologist: to experience that joy of discovery that happens in the same places where the plants and animals of their ecosystems breathed and died 75 million years ago. Field work never fails to take me back in time, to when those animals behaved in ways that left their traces for us recent arrivals on this earth to appreciate with wonder.

Fun-With-Field-Work-MontanaThis is my office for the next two weeks. Not bad, huh? I could get used to this, and plan to. (Photograph taken by my camera, which was set on an automatic timer.)

(For another introduction to this field work, here’s a blog post done cooperatively with my wife Ruth, who will be joining me here at the field site in just a few days.)

Life Traces of a Master: A Tribute to Dolf Seilacher (Part III)

(This is the third of a three-part series honoring the memory of paleontologist-ichnologist-teacher-artist Dolf Seilacher, who died on April 26, 2014. Part I of the series is here and Part II is here.)

After Dolf’s only trip to Georgia in 1997, I saw and talked with him a few more times, conversations that sometimes involved rocks and trace fossils in the field, but sometimes not. These times and places were in 2003 (Switzerland), 2004 (Argentina), 2006 (the far-off land of Philadelphia), and 2008 (Krakow, Poland).

Plenty of other ichnologists from around the world attended these meetings, too. Many of them I now consider as long-time friends, in which we get back for regular reunions to talk and argue about trace fossils, discussions that are normally accompanied by ritualistic consumption of significant volumes of libations. Almost always in such conversations, though, someone mentions the name “Dolf.” This then leads to animated discussions of his articles, remembrances of personal encounters with him (which usually involve some sort of strongly worded disagreement about a scientific idea), or telling stories about field trips, where Dolf noticed something extraordinary that everyone else had missed. In other words, even when Dolf wasn’t there, he was still present.

Seilacher-Ichnia-ArgentinaIf invited to speak at a gathering of ichnologists, Dolf Seilacher was never shy about saying “yes.” Here he addresses participants of the 1st International Ichnological Congress (Ichnia), held in Trelew, Argentina in 2004. (Photograph by Anthony Martin.)

As opposed to his trip to Georgia in 1997, the 2003 meeting in Switzerland was more-or-less in Dolf’s backyard, a short trip from his home in Tübingen, Germany. This was the International Ichnofabric Workshop, a biannual meeting of ichnologists that’s been taking place since the 1990s in various trace-fossil-rich places throughout the world. I love these meetings because of their balance between time spent blabbing in conference rooms and time spent in the field, looking at trace fossils: typically three days inside, three days outside. Now that’s what I call “fair and balanced.”

Dolf-Roland-IIW-BaselHow would you like to have your “Dolfing“? Inside or…

Dolf-Field-Switzerland…outside? (Both photographs taken by Anthony Martin in July 2003, Switzerland.)

Many of the trace fossils we encountered on the field-trip portion of the workshop were originally from deep-marine environments, made 30-50 million years ago by invertebrate animals that lived in on ocean-floor sediments hundreds or perhaps thousands of meters below the surface. Later, when the Alps were uplifted by colliding plates, this oceanic-continental mashing transported the trace fossils, resulting in seemingly anomalous signs of life from a deep seafloor, but in alpine settings. Dolf was one of the world’s experts on deep-sea traces, and among the few ichnologists to have taken a submersible ride (DSV Alvin) to more than 3,500 m (11,500 ft) down, highlighted in the IMAX film Volcanoes of the Deep Sea (2003). So it was no surprise when our first encounters with these trace fossils in the field prompted him to share his considerable knowledge about them.

Although Volcanoes of the Deep Sea is a fine documentary film in its entirety, for now just watch the first three minutes here to see Dolf in the field, looking for deep-sea trace fossils and talking about his mistress, who he met on his honeymoon. (Spoiler alert: His “mistress” is a trace fossil, and a complicated one, named Paleodictyon.)

Seilacher-SpirorapheDolf was clearly excited about sharing what he knew about the deep-sea trace fossils during our Ichnofabric Workshop in Switzerland. And he knew a lot. (Photograph taken by Anthony Martin in July 2003, Switzerland.)

The 2004 meeting in Argentina was a big deal for ichnologists, as this marked the first International Ichnological Congress, more briefly called Ichnia. More than a hundred ichnologists of varied interests, backgrounds, and nationalities gathered in Patagonia, Argentina, first for a glorious four-day field trip based out of Comodora Rivadavia, then for the congress itself in Trelew. Dolf joined us for the latter, and people who delivered talks in the sessions soon realized they were not going to leave the stage until Dolf asked them a question or made a comment about their work. At the time, he was 79 years old, but clearly was not ready to slow down teaching all of us.

Bromley-Pemberton-Seilacher-IchniaA rare circumstance: three of the most significant ichnologists in the world leaving fresh and contemporaneous footprints in the same habitat. From left to right is Richard Bromley (Denmark), George Pemberton (Canada), and Dolf, who was accepting an award from the organizers of this Ichnia. Jorge Genise’s hands (left) for scale. (Photograph by Anthony Martin, taken in Trelew, Argentina in April 2004).

The 2006 meeting in Philadelphia was significant, as this was for a symposium in honor of Dolf’s long and successful career. Organized as a session within the Geological Society of America meeting, it attracted so many ichnologists that the symposium lasted the entire day. In our talk, Andy Rindsberg (mentioned in my last post) and I decided we would cover one of Dolf’s favorite topics, the traces made by animals when they stop, nicknamed “resting traces.” In planning our talk, we knew Dolf would appreciate some good-natured poking fun at his expense. So we decided to lampoon both his authority in our field and his penchant for smoking good cigars through the following two slides (shown here side-by-side).

Freud-Seilacher-CigarTwo slides shown in succession at the Seilacher symposium, held in the 2006 Geological Society of America meeting in Philadelphia, Pennsylvania. Translation on the right is “Sometimes a resting trace is just a resting trace,” and I think you can figure out the one on the left now. I don’t know the photo credit for Dr. Freud, but the one on the right was taken by Andy Rindsberg at the Seilachers’ home in Tubingen, Germany in 2006.

It was a success. Dolf was sitting in the front row while I gave my talk, and I’ll never forget his delighted smile when he saw the image of Sigmund Freud dissolve into his, with an almost perfectly mirrored pose.

The last time I saw Dolf was in Krakow, Poland, and at the second Ichnia meeting in 2008. His presence was doubly appreciated by all of us, as Jagiellonian University was also hosting – at the same time – Dolf’s pride and joy, the Fossil Art exhibit.

Fossil-Art-Sign-KrakowIt’s a sign! Advertising the exhibit Fossil Art, that is. In this instance, the venue was at Jagiellonian University in Krakow, Poland, and in 2008. (Photograph by Anthony Martin.)

However, it was at this meeting where Dolf showed us a side we had almost never seen, but one that was completely appropriate for where we were. Alfred Uchman, the meeting organizer (and one of the world’s experts on deep-sea trace fossils), had asked Dolf to speak at the opening of the meeting on an ichnologically themed topic of his choosing. I don’t remember the main topic of his presentation, and the reason why for my faulty memory is because of what happened first.

Dolf began his talk with a deeply heartfelt and remorseful apology. In an awareness of both history and place, he told us how the grand room in which we were seated was where, in 1939, Jagiellonian University officials had handed over control of this esteemed institution – one of the oldest universities in the world and the intellectual home of Copernicus – to invading forces of Nazi Germany. Dolf, as a German citizen, a World-War II veteran who fought on the side of the Nazis, and who shared a first name with a certain genocidal dictator from Germany, expressed his shame and regret about what had happened in that place and then. I looked around the room and recall sensing the surprise we all felt at his  expression of regret, but also its poignancy and sense of redemption. He then went on and delivered his scientific talk, but it had become one overshadowed by our realization of how horrific histories and inquisitive inquiries are shared facets of our humanity.

Then there was Fossil Art. I remember seeing the first iteration of this traveling display in Germany in 1994, then elsewhere. This exhibit consists of life-sized reproductions (epoxy resin casts) of rock slabs, most of which held gorgeously intricate and intriguing trace fossils, but some with body fossils and physical sedimentary structures, such as ripples and mudcracks. At this meeting, we were privileged enough to get a guided tour of the exhibit by Dolf himself, who gave an introduction to its purpose as a way of engaging our minds and senses with beautiful patterns in rocks, many of which were made by animals from millions of years ago.

Seilacher-Fossil-Art-2Seilacher-Fossil-Art-1Dolf Seialcher introducing Fossil Art to a gathering of ichnologists at Ichnia 2008 in Krakow, Poland. (Photographs by Anthony Martin.)

Many of these reproductions received fanciful titles, such as The Trilobite Circus of Penha Garcia and Witch Broomings, and are mounted like works of art, with carefully arranged lighting accentuating their features. These “slabs” also have Dolf’s written explanations in placards next to them, describing and interpreting their geological significance, but also marveling at their beauty. Is it art, or is it science? Yes. Anyway, I’ll just let these images speak for this masterful blending of natural, aesthetic beauty and scientific information.

Cambrian-Beach-Party-Fossil-ArtCambrian Beach Party II, representing trace fossils made by large slug-like animals on a beach about 500 million years ago. (Photograph by Anthony Martin, taken in Krakow, Poland in 2008.)

Trilobite-Circus-Fossil-ArtThe Trilobite Circus of Penha Garcia, a collection of exquisitely preserved trilobite burrows from Portugal, preserved as natural casts. (Photograph by Anthony Martin, taken in Krakow, Poland in 2008.)

Trilobite-Pirouettes-Fossil-ArtTrilobite Pirouettes, more natural casts of trilobite burrows, but showing looping and stopping (“resting”) behaviors. (Photograph by Anthony Martin, taken in Krakow, Poland in 2008.)

More ichnology meetings took place since then: the third Ichnia meeting in Newfoundland, Canada (2012), and the most recent International Ichnofabric Workshop in Çannakale, Turkey (2013). Dolf did not physically attend either meeting, which did not surprise anyone, as he was in his late 80s, and we were starting to hear stories about his failing health. Nevertheless, a day never passed without his name coming up in conversation. So although most of us had not seen him since 2008, his ideas, personality, and methods seemed permanently attached to us, akin to some of the fossils he had studied.

Now that Dolf is gone and we are left with his considerable life traces, what would be  the best way for all of us to remember him? I suggest we do it through the flattery of imitation.

We are living in a time when science is very popular, even in the U.S., evident from TV shows like Cosmos and Your Inner Fish, as well as many clear and wonderfully written  science books. A few people have even declared that we’ve entered a “golden age” of science communication. Yet basic scientific research is also under assault from anti-science political forces, ones that insist on alternative realities where opinions are given equal (or superior) weight when compared to factual evidence. Moreover, mainstream academia is currently undergoing an administratively led collapse from within, as U.S. universities move more toward a corporate model that places higher profits over discoveries, knowledge, and teaching.

Still, through Dolf Seilacher’s life and accomplishments as a scientist, teacher, and artist, he showed a way to side-step the current chaos. Through his practices, he demonstrated how nearly all of us can do science and make discoveries every day by simply using our senses, pencils, paper, and intellects. Just to be clear, this is not a call to Neo-Luddism, in which we abandon our precious iPads and laser scanners while chanting incantations honoring our pre-technological ancestors. Instead, it is one that asks us to rediscover these basic skills – observing, drawing, and imagination – for conducting science, discovering, learning, and passing on new-found insights to future generations. In short: be more like Dolf.

Danke und Auf Wiedersehen, Dolf, for the gifts you gave us, traces that will continue long after you have become part of the earth and life you so loved studying.


Seilacher, A. 2007. Trace Fossil Analysis. Springer, Berlin: 226 p.

Seilacher, A. 1997, 2008. Fossil Art. (Two versions of this book were published, one through the Royal Tyrell Museum of Palaeontology in 1997, which was 64 page long; the other was through CBM Publishing in Laasby, Denmark, and was 101 pages long. The latter book can be purchased here.)

‘Dinosaurs Without Bones’ Leaves Its First Marks

Life Traces of the Georgia Coast was published just a little more than a year ago, which as far as authoring goes, seems like yesterday. (Well, unless you’re James Patterson.) Yet as of now, it’s now my second-most recent book.

Dinosaurs-Without-Bones-BookHey, look: it’s a book. How about that? (Photograph by the person whose name is on the cover.)

So I’m proud to announce today is the official launch date of my latest book, Dinosaurs Without Bones: Dinosaur Lives Revealed by Their Trace Fossils (Pegasus Books). What’s it about? Yeah, I know, the main title implies the existence of invertebrate or incorporeal dinosaurs. But the subtitle makes clear that it’s all about the fossil record of dinosaurs apart from just their bones: tracks, nests, burrows, toothmarks, gastroliths, feces, and much more. It’s not only the first comprehensive book written about dinosaur trace fossils, it’s my first overt attempt at popular-science writing in book form. How was it for me? Great fun, and I hope readers feel the same about it.

In a sure sign that authoring might be addictive, I started writing Dinosaurs Without Bones before the publication of Life Traces of the Georgia Coast. The latter book took nearly four years to complete, from proposal to holding that rather hefty volume in my hands. In contrast, I wrote and illustrated Dinosaurs Without Bones in just a little over a year, starting in the summer of 2012 and finishing in December 2013.

This marsupial-like gestation for Dinosaurs Without Bones can be attributed to several fortunate factors coming together, such as my having written two editions of a college textbook on dinosaurs (Introduction to the Study of Dinosaurs, 2001, 2006), writing about dinosaur trace fossils in a 2010-2011 blog (The Great Cretaceous Walk, now defunct), having the fresh experience of writing Life Traces of the Georgia Coast, and the freedom to write with a popular audience in mind. Write? Right.

Although today seems like a firm starting point for its availability to readers, it’s actually been in an incremental “soft launch” during the past few weeks. For example, my publisher made it available for sale by Charis Books in Atlanta, Georgia when I gave a talk to the Atlanta Science Tavern at their annual Darwin Day Dinner on February 9. Other people have told me via Facebook, Twitter, and in person that their pre-ordered copies had already arrived last week. Then just last week, I had a bit of a coming-out party for the book at the annual Science Online 2014 meeting, where it was among the featured new science books, which were all given away in a raffle to lucky meeting participants.

Dinosaurs-Without-Bones-Book-Paleontologist-BarbieMy colleague Paleontologist Barbie, happily posing next to Dinosaurs Without Bones during its first big public viewing at the Science Online 2014 meeting last week in Raleigh, North Carolina. (Photograph by the author again. Unfortunately, Paleontologist Barbie’s arms, much like those of a tyrannosaur, are too short for her to do a selfie.)

I know what you’re thinking: Where can I buy this book? (Your second most likely question is: Does it mention cats? The answer is yes, several times.) If you do get the book and read it, please let me know what you think of it, either via Twitter (@Ichnologist), its Facebook site, e-mail, or most retro of all, in person. Here’s a list of suggested means for acquisition:

  • Your local independent bookstore. Tell the owner I sent you.
  • Order it directly from Pegasus Books here.
  • Order it from Powell’s Books here.
  • Order it from Barnes and Noble here.
  • Order it from that online business that’s trying really hard to make all of those other just-mentioned businesses go extinct. (And I ain’t naming it, because that gives it more power.)

Thanks, hope you like it, and happy tracks, trails, nests, and burrows to you.

 Pertinent Bibliography

Martin, Anthony J. 2014. Dinosaurs Without Bones: Dinosaur Lives Revealed by Their Trace Fossils. Pegasus Books, New York: 460 p.

2013 International Ichnofabric Workshop: Çanakkale, Turkey

After a week of traveling and “touristing” in Turkey with my wife Ruth, which included a 16+ hour overnight bus ride from Goreme to Çanakkale (thus proving that “bus lag” is a real thing), it is now time to learn some ichnology. Every two years, ichnologists from around the world – normally 30-40 people hailing from 10-15 countries – gather for the 2013 International Ichnofabric Workshop which consists of six days of talks, field trips, and congenially conducted arguments about trace fossils, traces, and ichnology in general. The workshop, which I mentioned in the next-to-last chapter of my book (Life Traces of the Georgia Coast) is typically held in some beautiful place with lots of trace fossils and beer nearby (and not necessarily in that order of priority). This time is taking place in Çannakale – located on the western side of Turkey, across from Gallipoli.IIW-2013-Banner[Darth Vader voice] The ichnologists are here: I can sense them. Ichnologists, such as this one (who, incidentally, owes me money) are emerging from their burrows everywhere – much like periodical cicadas – to discuss ichnology here in Çanakkale, Turkey. (Photograph by Ruth Schowalter.)

Based on the program, most of the talks will be about marine invertebrate trace fossils and their uses in interpreting ancient animal behavior and their environments, although a few will also talk about how ichnofabrics – the sum effect of tracemakers on a given substrate, such as sediment or rock – can be applied to learning more about environmental change and evolution. You know, that weighty stuff we natural scientists crave doing.

Goreme-Ichnofabric-1So what the heck is an “ichnofabric”? Here’s an example provided by a paving stone in Goreme, Turkey, in which the people who placed it there thought, “Gee, this rock has some cool looking fabrics in it,” (although they likely thought that in Turkish.). But they probably did not know these fabrics were the result of trace fossils made on a sea bottom by marine invertebrate animals millions of years ago. (Photograph by Anthony Martin.)

So for those people who are not able to attend – most of the world, in other words – I will do my best to provide a regular report on what we are doing and learning here. For this, you can come back to this blog every few days, or for more instant gratification, you can follow me on Twitter (@Ichnologist), which I will use for quick assessments of the events as they’re happening. For those of you familiar with how the Twitterverse works, I and other ichnologists should be using the hashtag #Ichnofab2013 to denote the workshop. Teşekkür eridim!

The Ichnology of Jurassic Park

All paleontologists remember their first time. Mine was in 1993, during a hot, steamy summer in Atlanta, Georgia. I had just spent the previous month camping in wilderness areas of Wyoming, so coming back to a big city with all of its urban temptations meant I was weak and susceptible to seeking out unusual sources of pleasure. Although I was not quite ready to be taken for such an exhilarating ride, it was an experience I’d never forget. Afterwards, once I had recovered enough to be able think about it, I wanted to do it again.

I am, of course, talking about seeing the film Jurassic Park on a movie screen. Sure, this movie has been around long enough (20 years) that nearly every paleontologist has also watched it on a TV, computer, or mobile device. But there is something about seeing dinosaurs – which, let’s face it, are most famous for their size – shown big. The initial glimpse of a Brachiosaurus munching on the tops of tall trees, a herd of Paralophosaurus ringing a glistening lake, an ill Triceratops dwarfing its human caretakers, the grand entrance of the Tyrannosaurus: all of these “actors” were meant to be seen large, and fill us with awe. It worked. Plot, acting, and science aside, Jurassic Park was, and probably still is, the best movie made for conveying what it would feel like for us humans, separated by a minimum of 65 million years, to see real, living dinosaurs.

“It’s, it’s a dinosaur.” That pretty much said it all in 1993, and still does. But what traces were being made by this Brachiosaurus as it strolled through its all-you-can-eat salad bar, known to you and me as a “landscape”? Please read on.

In 1993, though, I did not have an appreciation for some of the smaller details included in this film, and how my research specialty of ichnology – the study of traces, like tracks, burrows, and nests – was reflected throughout it. What dinosaur traces were included in the movie, and how were these traces used to serve or advance the plot? I also wondered how 20 years of field experience and scholarly research in ichnology might have changed my perceptions of it since that first viewing.

So with the re-release of Jurassic Park in 3-D last week, I decided it was time to view it from an ichnological perspective and share these thoughts with others. After all, my next book, Dinosaurs Without Bones (Pegasus Press), is about dinosaur trace fossils, and written for a popular audience. Also, in between the movie’s first release and now, I wrote two editions of a college textbook on dinosaurs (Introduction to the Study of Dinosaurs). Thus I went to the theater well justified in watching Jurassic Park once more, to see for myself how dinosaur traces were portrayed in the most well-loved of all dinosaur movies. And oh yes, for the fun.

For the sake of simplicity, I’ve divided these traces into two categories: those viewers could directly observe in the film, and others that could be inferred from the dinosaurs’ behaviors. Wherever possible, I also connect traces shown in the movie to research done on dinosaur trace fossils during the last 20 years, giving a broad sense of how far dinosaur ichnology has progressed since 1993.

(Ichnologist’s note: Even though all of the live dinosaurs in the movie were set in the 1990s, the study of their modern traces still qualifies as neoichnology. In contrast, any reference I make to actual dinosaur trace fossils is paleoichnology. Just so you know.)

Dinosaur Traces in Jurassic Park

Velociraptor hatchling traces. Jurassic Park shows two different but complementary examples of hatchling traces for “Velociraptor.” (I will call this dinosaur Velociraptor throughout this post, but as most dino-philes know, the director, Steven Spielberg, scaled up the Late Cretaceous Velociraptor to maximize its frightfulness. Hence it is actually more like the Early Cretaceous Deinonychus or Utahraptor.)

One is an egg-emergence trace, which is the hole left in an eggshell where a dinosaur broke out of its egg. In this scene, a cooing Velociraptor hatchling pokes its cute little nose out of its egg. (This nose, if everything worked out for it, would some day would be warmed by fresh human viscera.) We first witness this tracemaking in the Jurassic Park laboratory toward the start of the film, the same day most of the protagonists arrive on the island (Isla Nublar). As far as I know, such trace fossils have not been interpreted from the fossil record, or if they have, they have not been referred to as trace fossils: which they should be.

The next day, after dinosaur paleontologist Alan Grant and his two companions – Lex and Tim Murphy – were sufficiently terrified (and enthralled) by various dinosaur encounters out in the park, they come across a Velociraptor nest. The nest has about 15-20 broken eggs, and the fracture patterns of the eggshells provide clear evidence of hatching. But these traces also had tiny, two-toed tracks leading away from them. The tracks, with two toes studded by digital pads, were typical for deinonychosaurs. However, unlike nearly every theropod track I’ve seen, these tracks lacked claw marks at their ends. (Tsk, tsk, says this nitpicking ichnologist.)

Baby-Velociraptor-Traces-JPAw, look at the cute little Velociraptor tracks and hatched eggs. Don’t these traces just make you want to say, “Who’s the cutest little predator in the world?” Still from Jurassic Park (1993), taken from www.anyclip.com.

Even though these tracks were flashed on the screen for only a few seconds, what’s really cool is how they convey three important pieces of information. One is that the Velociraptor chicks hatched after the torrential rainstorm of the previous night, and thus only mere hours before our wandering heroes saw their traces. Second, the tracks demonstrate that the hatchlings were not altricial, but ready to move and leave the nest immediately, presumably without parental care. Third, Dr. Grant realizes that these successfully fertilized and hatched eggs mean the “female-only” genetic fail-safe plan for the dinosaurs just got disproved. In other words, these traces mattered.

One point about that nest: as far as I could tell from, this Velociraptor mother did not make a rimmed structure to protect the eggs, such as those made by another Late Cretaceous theropod, Troodon, or Late Cretaceous sauropods in Argentina. Instead, the eggs were laid out in the open, like some ground-nesting shorebirds might do. In contrast, the Jurassic Park sequels featured Velociraptor nests that were much more overt as traces, such as a rimmed nest seen in Jurassic Park III.

Troodon-Rim-NestPartially preserved rimmed nest structure of Troodon, a Late Cretaceous theropod that lived in what we now call Montana. The rim has eroded quite a bit since its discovery in the mid-1990s; the Troodon egg clutch was in the area of the foreground before its extraction. (Photograph by Anthony Martin; scale in centimeters.)

Triceratops feces. “That is one big pile of sh*t,” observes Dr. Ian Malcolm, the “chaotician” (mathematician) who supplies both pessimism and comic relief throughout the movie. In this scene, where the main protagonists attend to an under-the-weather Triceratops, two impressive piles of fecal material inspire Dr. Ellie Satler, a paleobotanist, to figure out whether or not the ceratopsian had eaten any toxic plants.

Somehow I suspect this scene was meant as a metaphor for what most paleontologists have to do in their day jobs in order to do any paleontology at all.

Still, when added together, this amount of still-moist waste was far too voluminous to have been from one or two depositional events: I mean, this dinosaur was sick, but not that much. As a result, park personnel must have been responsible for making these dung heaps from several days worthy of Triceratops contributions. (Strictly speaking, then, these heaps were composite traces.) If so, this would have been a rather unenviable job, but maybe they were better paid than Dennis Nedry, the disgruntled computer programmer who later provided ample fodder for Dilophosaurus.

Unfortunately, fossil Triceratops feces (coprolites) are thus far unknown from the geologic record. What is exciting, though, is that several excellent studies have been done by Dr. Karen Chin on Late Cretaceous hadrosaur coprolites. These coprolites, like the fictionalized Triceratops feces, contain lots of plant material, telling us much about what these hadrosaurs ate 75 million years ago. They also tell us what ate the feces or grazed on them, which were dung beetles and snails, respectively. (Indeed, I now wonder if Isla Nubar had a severe shortage of dung beetles, which might explain how those Triceratops feces got piled higher and deeper.)

Two-Medicine-CoproliteDinosaur coprolite – probably from a large hadrosaur, such as Maisaura – and filled with wood fragments, accompanied by special bonus trace fossils: dung beetle burrows! Specimen from the Two Medicine Formation (Late Cretaceous, Montana) as part of a Museum of the Rockies traveling exhibit at Fernbank Museum of Natural History. (Photograph by Anthony Martin, taken in 2001 and scanned from a 35-mm slide; scale in centimeters.)

• Tyrannosaurus tracks. Probably the most memorable scene in Jurassic Park is the grand entrance of the Tyrannosaurus, whose approach is first detected by “impact tremors” transmitted in cups of water on the dashboard of a jeep. Following this first bout of terror and the arrival of Ellie Sattler and big-game hunter Robert Muldoon, Malcolm, convalescing in the back of a jeep, looks down at a three-toed Tyrannosaurus track. The track, filled with water from the rain, communicates a warning as it vibrates from the footfalls of the approaching giant theropod. This repeats the previous image of the trembling water in the cup, but is made doubly dreadful by happening in a freshly made footprint of the same animal causing the tremors.

So what was by far the most exciting moment in the movie for me, ichnologically speaking? The Tyrannosaurus making a track, in which mud pushes up and out to the sides of its right foot, observed at 2:38 in the following video clip. Just watch:

This was already a great scene for all of its action, suspense, and lawyer eating. But check out that track-making!

Only a few fossil tracks have been attributed to Tyrannosaurus or other tyrannosaurids, mostly for being the right size (really big) and geologic age (Late Cretaceous). One was discovered in New Mexico in 1983, but wasn’t reported in a scientific journal until the year after Jurassic Park came out. More than a decade passed before another was found in Montana in 2007 and reported in 2008. Tragically, both were isolated tracks, and a Tyrannosaurus trackway, with two or more consecutive steps, has not yet been found. If so, it would make for a pretty darned nice find. So please do let the world know if you find one.

Large-Theropod-Track-CretaceousA large and well-preserved three-toed theropod track from the Early Cretaceous Glen Rose Formation of Texas, made about 95 million years ago. Although this track was more likely made by Acrocanthosaurus, rather than Tyrannosaurus rex, you can be assured that this theropod, like all living things, was a distant relative of T. rex. (Photograph taken by Anthony Martin; scale in centimeters.)

• Velociraptor tracks (adults). These tracks, shown only for a few seconds, are outside of the Velociraptor enclosure after the power was shut down. Muldoon, accompanied by Sattler, spots the footprints, and he wordlessly identifies them. (His expression also tells the audience that Sattler and he are going to be in deeper doo-doo than the Triceratops piles.) The twisted and broken bars of the enclosure provide additional traces affirming the conclusion that these ‘raptors are on the loose. All of these traces are shown only minutes before Muldoon utters his meme-inspiring last words, “Clever girl.”

Tracking-Velociraptors-JPUh oh: Velociraptor tracks, and these don’t look like they’re from hatchlings. Good thing Muldoon is a big-game hunter, who’s skilled at tracking and predicting Velociraptor behavior based on their tracks. But too bad his hypothesis was falsified in such an unpleasant way, but I suppose he could have picked kinder reviewers. Still from Jurassic Park (1993), taken from www.anyclip.com.

Deinonychosaur-Track-UtahHere’s what a real deinonychosaur track looks like. This one, from the Early Cretaceous of Utah, is a right foot impression, and is just slightly smaller than the adult tracks depicted in Jurassic Park. Notice the digits are thinner and end with sharp clawmarks, too. (Photograph by Anthony Martin; scale in centimeters.)

• Bioerosion of fossil dinosaur bones by modern dinosaurs. Toward the end of the film, the main human heroes – Grant, Sattler, Murphy, and Murphy (which sounds like a law firm, but we know how T. rex feels about those) – are confronted by a Velociraptor pack in the Jurassic Park visitor center. During their attempts to flee the ‘raptors, both species end up disarticulating and breaking some of the mounted dinosaur skeletons in the atrium of the visitor center. Their actions were thus a form of bioerosion, in which the fractured dinosaur bones are traces of their activities. Alternatively, the bones may have been artificial casts, in which case their breakage would have constituted bioerosion of modern substrates.

This bioerosion is made more complicated when the Tyrannosaurus rex (who everyone agrees is the ultimate protangonist of the movie) enters the atrium and, among other antics, smashes a skeleton of itself with a recently crunched Velociraptor. As a result, the jumbled assemblage of bones at the end is attributable to three separate, interacting tracemakers: four humans (two adult, two juvenile), two Velociraptors (both adults), and one Tyrannosaurus (adult). What should be noted, though, is that if the Velociraptor was already dead when flung by the Tyrannosaurus, then the broken skeleton is a trace of the Tyrannosaurus, not the Velociraptor. In other words, the Velociraptor body was just being used as a tool.

Bioerosion in action, as a result of Velociraptor and human interactions. Also, at 2:45: T. rex smash!

Dinosaur Trace-Making Behaviors in Jurassic Park

• Brachiosaurus tracks, browsing traces. When Drs. Grant and Sattler experience their first jaw-dropping glimpse of a Brachiosaurus, they watch it rear up on its hind feet, and come down hard on front feet. Considering that a Brachiosaurus this size might have weighed at least 30 tonnes, it surely would have left deep tracks in both the front and rear from the increased stresses imparted by these actions. Also, its cropping the tops of trees would have caused some easily visible gaps in the canopies of forests on Isla Nubar.

• Theropod toothmarks. Part of the fun of Jurassic Park was indulging in our worst nightmares about these non-avian theropods frequently sampling human flesh. Assuming that the theropod teeth in each instance penetrated skin and muscle and contacted bone, toothmarks would have included the following: (1) Tyrannosaurus toothmarks on goat, human, and Velociraptor bones; and (2) Velociraptor and Dilophosaurus toothmarks on human bones.

• Triceratops resting trace. When the paleontologists and others visit the ailing Triceratops, it was lying on its right side. I couldn’t help but think that if Triceratops or any other large ceratopsian dinosaur ever reclined like that, and in the right type of sediment, it would have left a gorgeous body impression. This scene also reminded me of bison traces I’ve seen in Yellowstone National Park, in which bisons roll onto their sides for a dust bath, leaving outlines of their bodies. Did dinosaurs – especially the feathered ones – ever take dust baths, and leave similar body impressions? We don’t know yet, but such trace fossils are something to look for.

• Dinosaur stampede. One of the most astonishing computer-generated effects of Jurassic Park, and one that was especially effective in 3-D, was of a dinosaur stampede. In this scene, a flock of Gallimus run toward and around Grant, Murphy, and Murphy, just before the ambush-hunting Tyrannosaurus rex slaughters one of them (the Gallimus, that is). I’ve written about this scene before, connecting it to a dinosaur tracksite in Queensland, Australia that has more than 3,000 tracks preserved. Although the site was originally interpreted as the only evidence of a dinosaur stampede, the tracks were recently reinterpreted as swim tracks. I’ll write about this topic at length in my upcoming book, so for now, I ain’t saying nothing more.

Run away, run away!

• Tyrannosaurus drag mark. After the Tyrannosaurus rex decides that a measly goat was just an appetizer and begins seeking out the nearest available mammals for nomming purposes, at some point it overturns and begins pushing an SUV, which still has Lex and Tim Murphy trapped underneath it. Its flipping the SUV with its head certainly would have left a substantial mark on the muddy ground, a trace that then would have been connected to a semi-circular dragmark (clockwise oriented), and with tracks directly adjacent to these traces. Her tracks also may have been deeper in their fronts because of her head being down as she pushed, reflecting a shift in her weight distribution. However, I should again remind everyone that just like with the dead Velociraptor used for bioerosion by this same T. rex later in the film, the SUV is not making the trace. It is only a tool being used by the tyrannosaur, which is the real tracemaker.

• Tyrannosaurus running trackway – This pulse-quickening chase scene, in which the T. rex pursues a jeep driven by Muldoon and with Malcolm and Sattler as passengers, very likely would have caused a wonderful sequence of tracks. These tracks would have shown increasing stride lengths from a standing start to full-speed run, and each successive track would have registered external and internal structures consistent with this acceleration. Even better, the tracks would have cross-cut the jeep tire-tracks at some points, demonstrating to a later observer that the tyrannosaur was very likely following the jeep. (The demolition of a low-hanging tree branch by the T. rex during the chase also counts as some bioerosion along the way.) Some convincing studies have been done since showing that an adult Tyrannosaurus could not have moved as fast as the one in Jurassic Park, but it still could have caught most running humans. And just to repeat what I said earlier, it’d be really nice for someone to find a T. rex trackway, which would give us more direct evidence of how these massive theropods moved.

• Velociraptor scratch marks and other traces. This time, while watching the harrowing and claustrophobic scene in which a pair of Velociraptors hunt the Murphy siblings in a kitchen, I started thinking about the traces they might have left. Did their claws leave scratch marks on the door handles and kitchen counters? Did they indent the steel counters when they jumped up on these surfaces? A broken window is also shown as a trace of their smashing through glass once they became frustrated with a locked door.

OK, enough of the fanciful ichnology. What about other dinosaurs and their traces? Well, it turns out that Jurassic Park saved the real, living dinosaurs for the very end of the movie. These were five brown pelicans (Pelecanus occidentalis), flying in formation as Grant, Sattler, and their companions leave Isla Nubar in a helicopter. For Grant, this is a poignant moment, as he is likely reflecting on how dinosaurs were still with us today as birds. With that thought, I will say “amen,” and add that dinosaur traces – tracks, nests, feces, bite marks, and all – are still here with us, too, and don’t require special glasses to see them in three dimensions. Thanks for that reminder, Jurassic Park.

Pelican-Tracks-SapeloWant to see some modern dinosaur traces? Here are tracks of a brown pelican, made in wet sand while it was loafing on a beach at low tide on Sapelo Island, Georgia. To see more modern dinosaur traces, just go outside, and you’ll find them wherever birds are found. (Photograph by Anthony Martin; scale in centimeters.)

Further Reading

Chiappe, L.M., Schmitt, J.G., Jackson, F., Dingus, L., and Grellet-Tinner, G. 2004. Nest structure for sauropods: sedimentary criteria for recognition of dinosaur nesting traces. Palaios, 19: 89–95.

Chin, K. 2007. The paleobiological implications of herbivorous dinosaur coprolites from the Upper Cretaceous Two Medicine Formation of Montana: why eat wood? Palaios, 22: 554-566.

Chin, K., and Gill, B.D. 1996. Dinosaurs, dung beetles, and conifers: participants in a Cretaceous food web. Palaios, 11: 280-285.

Elbroch, M., and Marks, E. 2001. Bird Tracks and Sign of North America. Stackpole Books, Mechanicsburg, Pennsylvania.

Erickson, G. M., Van Kirk, S. D., Su, J., Levenston, M. E., Caler, W. E., & Carter, D. R. 1996. Bite force estimation for Tyrannosaurus rex from tooth-marked bones. Nature, 382: 706–708.

Gignac, P.M., Makovicky, P.J., Erickson, G.M., and Walsh, R.P. 2010. A description of Deinonychus antirrhopus bite marks and estimates of bite force using tooth indentation simulations. Journal of Vertebrate Paleontology, 30: 1169-1177.

Hutchinson, J.R., and Garcia, M. 2002. Tyrannosaurus was not a fast runner. Nature, 415: 1018-1021.

Jacobsen, A.R. 1998. Feeding behaviour of carnivorous dinosaurs as determined by tooth marks on dinosaur bones. Historical Biology, 13: 17-26.

Lockley, M.G., and Hunt, A.P. 1994. A track of the giant theropod dinosaur Tyrannosaurus from close to the Cretaceous/Tertiary Boundary, northern New Mexico. Ichnos, 3: 213-218.

Manning, P.L., Ott, C., and Falkingham, P.L. 2008. A probable tyrannosaurid track from the Hell Creek Formation (Upper Cretaceous), Montana, United States. Palaios, 23: 645-647.

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

Romilio, A., and Salisbury, S.W. 2011. A reassessment of large theropod dinosaur tracks from the mid-Cretaceous (late Albian–Cenomanian) Winton Formation of Lark Quarry, central-western Queensland, Australia: a case for mistaken identity. Cretaceous Research, 32: 135-142.

Romilio, A., Tucker, R., Salisbury, S. 2013. Reevaluation of the Lake Quarry dinosaur tracksite (late Albian-Cenomanian Winton Formation, central-western Queensland, Australia): no longer a stampede? Journal of Vertebrate Paleontology. 33: 1, 102-120.

Sellers, W.I., and Manning, P.L. (July 2007). Estimating dinosaur maximum running speeds using evolutionary robotics. Proceedings of the Royal Society of London, B, 274: 2711-2716.

Thulborn, R.A., and Wade, M., 1979. Dinosaur stampede in the Cretaceous of Queensland. Lethaia, 12: 275-279.

Varricchio, D.J., Jackson, F. and Trueman, C.N. 1999. A nesting trace with eggs for the Cretaceous theropod dinosaur Troodon formosus. Journal of Vertebrate Paleontology, 19: 91-100.


Different Coastlines, Same Traces, and Time

This past week, I visited North Carolina for varied reasons, but all related to paleontology and geology. First, I gave a well-attended evening lecture about polar dinosaurs, graciously invited and hosted by the Department of Geography and Geology at the University of North Carolina-Wilmington (UNCW). Later in the week, I presented a poster at the Society of Vertebrate Paleontology (SVP) meeting in Raleigh (covered last week here), while also taking in a couple of days of talks, posters, and enjoyably catching up with paleo-friends while meeting neo-friends. Regrettably, I had to leave the meeting early, but with good reason, which was for a field trip to look at fossils in a Pleistocene outcrop near Wilmington with faculty and students from UNCW. Overall, it was a fulfilling week, teeming with paleontological and social variety.

This pithy summary, though, omits lots of details (and if it didn’t, then it wouldn’t be pithy). But one item worth explaining a bit more here was a brief trip to Wrightsville Beach, which is a barrier island was just east of Wilmington. Dr. Doug Gamble, a geography professor in the UNCW Department of Geography and Geology, offered to take me there just before my talk, which I eagerly accepted. Considering all of the field work I had done on the Georgia barrier islands to the south of there, and that I would be teaching a course on barrier islands next semester, going to this beach was an opportunity to learn more about the similarities and differences between Georgia and North Carolina beaches.

Panorama of Wrightsville Beach on the coast of North Carolina, replete with human locomotion traces and dwelling structures. These features make it very different from most beaches in Georgia. But what about other traces? Don’t you just love rhetorical questions? Including this one? (Photograph by Anthony Martin.)

Many North Carolina beaches are famous (or infamous) as examples of what can go wrong with unrestrained development of barrier islands. Many such case studies have been explored through the research, writings, and activism of geologist Dr. Orrin Pilkey of Duke University, as well as other coastal geologists who have looked at the effects of human alterations of these habitats. Wrightsville Beach is such a barrier-island beach, having  been heavily modified by human activities during the past 150 years or so. When comparing it in my mind to the Georgia barrier islands, it most resembled Tybee Island, which is also next to a relatively large city (Savannah), easily accessible by a bridge, and developed as a sort of “vacation destination” for people who like beaches, but also want them to have all of the amenities of the places they left behind. Otherwise, it held little resemblance to the mostly uninhabited and undeveloped beaches I prefer to peruse on the Georgia barrier islands.

After driving over the bridge to the island, we walked onto the beach in several places, and I began looking for traces. At first there was little to see, which was a direct result of there being too much to see. Because it was a pleasant day and we were visiting in the afternoon, much of the beach had been heavily trampled by humans, with more than a few of these people aided in their bioturbation by canine companions. Obvious restructuring of the beach included a jetty at the north end that combined a concrete wall and boulders, and pilings of concrete blocks at the south end. Dunes were modest, low-profile, and capped by sparse stands of sea oats (Uniola paniculata), and behind these were hotels, condominiums, and houses, all chock-a-block. It would be too strong to say this beach was alien to me, let alone post-apocalyptic, but it did seem like an altered reality compared to my experiences in Georgia.

A jetty at Wrightsville Beach (North Carolina) composed of concrete and rocks, intended to preserve sand on the beach, which it is doing here, but also results in an imbalanced distribution of sand along it. Note the abundant human and canine tracks on the right, shouting out any other animal traces that might have been in the sand. (Photograph by Anthony Martin.)

Another view of the jetty at Wrightsville Beach, sharply contrasting sand deposition and erosion on either side of it. (Photograph by Anthony Martin.)

A pile of broken concrete being used as rip-rap at the south end of Wrightsville Beach in an attempt to slow erosion there. Or something. (Photograph by Anthony Martin.)

Only with more walking toward the south end of the beach did we see less of an overwhelming human-dog ichnoassemblage and start noticing signs of the native fauna. With this, I became comforted by the familiar. These traces included some I had seen many times on Georgia beaches, including: the soda-straw-like burrows of parchment worms (Onuphis microcephala); the volcano-like sand mounds and chocolate-sprinkle-like feces of callianassid shrimp (either Biffarius biformis and Callichirus major); the soft-serve-ice-cream-like fecal mound of acorn worms (Balanoglossus aurantiactus); and the hole-in-the-ground-like burrows of ghost crabs (Ocypode quadrata). (OK, so I ran out of metaphors.) Seagull tracks abounded as well, lending more of a dinosaurian flavor to the trace assemblage.

Two burrows of parchment worms (Onuphis microcephala) on Wrightsville Beach, exposed by a little bit of erosion, with tiny fecal pellets at their bases. Scale in millimeters. (Photograph by Anthony Martin.)

Burrow aperture and fecal pellets of a ghost shrimp (either Biffarius biformis or Callichirus major) on Wrightsville Beach. Scale in millimeters again. (Photograph by Anthony Martin.)

Fecal casting of an acorn worm, and probably that of a golden acorn worm (Balanoglossus aurantiactus) on Wriightsville Beach. One end of its burrow is underneath this pile, and that would be its anal end, which is sensibly located in a different place from its oral end. And I think you know the scale by now. (Photograph by Anthony Martin.)

Ghost crab (Ocypode quadrata) burrow and tracks, out of the intertidal zone and more into the dunes on Wrightsville Beach. (Photograph by Anthony Martin.)

These traces thus showed us that this North Carolina beach, one majorly changed by humankind during the past 150 years, actually was more biodiverse than one might think at first glance. In my mind, then, it became just a bit more wild through these signs of life hinting at what laid beneath our feet.

At this point, I could depress everyone by listing what traces and biota were not there, but that’s not the point, so I won’t. In a more progressive sense, what traces we saw represented traces of hope, of life hanging on despite environmental change, living almost invisibly beneath our feet. So as human development continues on beaches like these, and sea level rises through the rest of this century, I felt assured of their being survivors of this change, and of their traces outlasting our humanity. The trace fossils of the future are now, and recording our effects on the life that makes these traces. How many will wink out with our species, and how many of their marks will outlast us?

An intergenerational stroll – a grandmother and grandson? – alongside the pier on Wrightsville Beach in North Carolina. Did she have memories of this beach in her childhood? How do these compare to what she sees there now? What memories will this child have of it in the future, especially as the sea continues to rise? If these memories are not recorded, what will be left behind? (Photograph by Anthony Martin.)

Further Reading

Pilkey, O., and Fraser, M.E. 2005. A Celebration of the World’s Barrier Islands. Columbia University Press, New York: 309 p.

Thieler, E.R., Pilkey, O., Cleary, W.J., and Schwab, W.C. 2001. Modern sedimentation on the shoreface and inner continental shelf at Wrightsville Beach, North Carolina, U.S.A. Journal of Sedimentary Research, 71: 958-970.

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.



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.