The wide variety of modern bird behaviors – as well as the traces that result from these behaviors – continue to captivate and fascinate me. Given recent revelations of birds’ dinosaurian ancestry and the interrelationships of modern birds (an evolutionary history spanning more than 150 million years), this wonderment should be expected. Accordingly, then, the traces made by modern birds can be equally varied, and can serve as guides to the behaviors of their predecessors, especially when made by birds interacting with ecological margins (ecotones).
A mixture of tracks left by boat-tailed grackles (Quiscalus major) and American crows (Corvus brachyrhynchos) on wind ripples in the upper part of a sandy beach. So if paleontologists found something similar in the geologic record, would they be able to say more than “Looks like a bunch of birds were walking around”? That’s why we look at modern traces and their associated behaviors: to get beyond such easy (and terribly incomplete) answers. (Photograph by Anthony Martin, taken on Tybee Island; pen is about 15 cm (6 in) long.)
The most recent example I witnessed of bird tracemakers and their traces in an ecotone setting was last month on Tybee Island (Georgia). Tybee is a barrier island just east of Savannah, and one I had visited in May, when I noted burrowing wasps in the coastal dunes there. The tracemakers were boat-tailed grackles (Quiscalus major), a passerine bird (“songbird”) that people commonly see and hear along the Georgia coast. Grackles belong to to an evolutionarily related group (clade) called Icteridae, colloquially known as “blackbirds.” I frequently see grackle tracks on the upper parts of beaches and in the dunes, where they are oftentimes the most common vertebrate traces above the high tide mark on Georgia shorelines.
What was strikingly atypical this time, though, was how all of the grackles I saw making tracks were adult females. Female grackles are distinguished from males by their brown coloration, whereas the males are iridescent black, almost deep purple when viewed in the right light. Female adult grackles are also noticeably smaller than adult males, at about 70% their lengths and half their weights. Like most passerine birds, grackles have four-toed anisodactyl feet, with the “thumb” (digit I) pointing directly backwards with respect to its three forward-pointing toes (digits II-IV). Such tracks show their feet are well adapted for grasping branches in trees; yet they hang out along shorelines and nest near water bodies. I also wondered whether the tracks of this gender-sorted assemblage could be distinguished from those of the larger males, but didn’t get a chance to test this idea.
Girlfriends going out for a bite to eat by the beach: a group of boat-tailed grackles – all female adults – foraging in between the sea oats on the south end of Tybee Island. Here they were on the seaward side of the dunes, and just before sundown. (Photograph by Anthony Martin.)
Yet it wasn’t track sizes that caught my attention: it was what they were doing and the traces they were leaving. They were actively foraging, walking in between stalks of the sparsely populated sea oats (Uniola paniculata), which were barely holding down the dunes. This meant lots of slow, methodical walking with their heads down, and beaks actively snatching anything of interest. What were they finding and eating? On an over-developed island like Tybee, it could be almost anything. Grackles are notoriously omnivorous, which explains why they’ve easily adapted and thrived along the eastern coast of the U.S. despite extensive human alterations to this island and elsewhere.
Grackles in different feeding postures: two with their heads down and feet together (foreground and right), and another with her head up and left leg ahead of her right, and all after walking slowly and stopping often. With that in mind, think of the trackway patterns that would correspond with these movements and postures. (Photograph by Anthony Martin, taken on Tybee Island.)
So here’s what’s cool: these grackles were eating locally by chowing down on sea oats. That’s right, given all of the human-provided junk food they had available, they were going for the all-natural, organic, raw, and totally vegetarian option. (Tragically, it was not gluten free. But I think they were OK with that.) As a result, their tracks showed lots of short steps (diagonal walking) punctuated by “T-stops,” where they stopped to place their feet side-by side (making a “T” pattern), all of which were accented by beak traces, the last of these intersecting depressions formerly occupied by the sea-oat grains.
A close-up of the grackle from the previous photo, showing exactly why it stopped it with its feet together and put its beak down to the sand: fallen grains of sea oats. (Photograph by Anthony Martin, taken on Tybee Island.)
Another close-up of a grackle, but with sea oats in her beak. More importantly, check out the tracks behind her, the little depression where the oats laid on the sand (arrow), and the beak mark next to it that she made just before grabbing the grains. (Photograph by Anthony Martin, taken on Tybee Island.)
Boat-tailed grackle tracks that say, “I’m out looking for food, and whole grains only, please.” Note the “T-stop” pattern in the tracks and a beak impression within the trackway (center bottom) coinciding with some sea-oat grains, and a similar set of traces toward further down the trackway. (Photograph by Anthony Martin, taken on Tybee Island.)
So if you’ve read anything written by me before now, you probably know what I’m going to do next. (No, not that. But maybe next time.) I’m probably going to say, “Hey y’all, why don’t you look for traces like these next time you’re out walking along the beach?” But I’m also likely to say, “Gee, I wonder if traces like these would show up in the fossil record?” Both are important questions to keep in mind, even though the first deals with the here and now, whereas the other dives into deep time.
As a paleontologist, though, I’m all about the deep-time question. For example, when did the ancestors of grackles and other blackbirds start eating seeds from the ancestors of the sea oats, and in coastal environments? How would we know when these proto-grackles started having cereal for breakfast? If any trace fossils that look like the ones shown here do somehow got preserved, they should help connect those dots between all of the genes, bones, and other scientific evidence we use to figure out the evolution of this diverse clade of blackbirds.
Yeah, I know, it’s a body fossil. But hey, it’s the Berlin specimen of Archaeopteryx, probably the most famous body fossil in the world, so it’s OK. I was lucky enough to see it in person at the Museum für Naturkunde in Berlin early last month, and like most paleontologists who see it, I was awestruck by its 150-million-year-old beauty. Understandably, then, the evolutionary history of birds was on my mind when – three weeks later – I watched those grackles making traces on a Georgia beach. Will Archaeopteryx trace fossils ever be found? Let’s hope so, and if they do, they deserve to be as famous as this specimen. (Photograph by Anthony Martin.)
Among my favorite tracemakers of the Georgia barrier islands are birds, a fondness inspired by their great variety (more than 200 species), numbers, and diverse behaviors. But if pressed to name my absolute favorite types of bird traces, I would not hesitate to say “flying tracks.”
Tracks from a great egret (Ardea alba) on a hard-packed beach sand that say, “I just flew in, and boy are my arms tired.” Notice the offset right-left tracks, long scratch marks left by claws on the rear toes, and cohesive bits of sand pushed forward by the egret’s feet when they contacted the sand. (Photograph by Anthony Martin, taken on Jekyll Island, Georgia.)
Now, “flying tracks” may sound contradictory, as a bird in flight leaves no tracks. But for those birds for which flight is an everyday habit, they take off and land, and many of these birds do so on the ground. This fact of avian life is recorded faithfully in the sands and muds of the Georgia barrier islands, and I have often delighted in encountering such tracks made by birds from sparrows to grackles to seagulls to pelicans to great blue herons. When covering this topic in my book (Life Traces of the Georgia Coast, just in case you needed reminding), I had to restrain myself from writing too much about it. Fortunately for readers, though, I described flight traces in enough detail there that I’m confident most people will be able to spot and recognize them. The following pictorial guide, most of which I showed during a recent talk to the Atlanta Audubon Society, should also help.
Flight tracks of a small songbird (probably a species of sparrow) on coastal-dune sands, showing that it didn’t stick around very long: landing, a hop, then take-off. (Photograph by Anthony Martin, taken on Little St. Simons Island, Georgia.)
How to tell whether a bird was landing or taking off? Your first clue should be a blank area in mud or sand, which will be devoid of tracks just behind a bird trackway, or the opposite, a trackless place just beyond the last footprints. In both instances, tracks are normally paired (side-by-side). For example, here’s an entire sequence made by a common ground dove (Columbina passerina), from landing to walking to take-off.
Entire landing, walking, and take-off sequence for a common ground dove (Columbina passerina) in back-dune area. Notice how it avoided the ghost-crab burrow by walking around it just before deciding to exit the scene. (Photograph by Anthony Martin, taken on Sapelo Island, Georgia.)
Close-up of landing tracks, in which this ground dove came in from the right, then shuffled its feet to shift direction to its right. (Photograph by Anthony Martin.)
Close-up of take-off tracks, where this ground dove was walking normally, then put its feet together and did one of its typically instant take-offs. (Pro-ichnologist tip: the scratch marks to the right are ghost crab tracks, not wing impressions.) (Photograph by Anthony Martin.)
Look closer at potential flight tracks and you will see other details that tell you whether a bird was coming down to earth or bidding the ground goodbye. Landing tracks often have long impressions behind them, “skid marks” that show how the bird decelerated and controlled its fall through a combination of body positioning and calculated flapping.
For larger birds with a backwards-pointing toe (hallux) – such as herons or egrets – these tracks usually leave a lengthy scratch mark from the claw on that foot. While landing, one foot plants in front of the other – either as an offset right-left or left-right pair – and the first track normally has the longer scratch mark. Either footprint also may have some mounding of mud or sand in front of it, as the forward momentum of the bird exerted pressure against whatever medium it encountered.
Another look at those great egret landing tracks shown previously, but now probably understood a little better through the power of words combined with images. ¡Viva Comunicación de la Ciencia! (Photograph by Anthony Martin.)
Close-up of that great egret’s right track, with features showing how its foot slid across the beach surface as it slowed its descent, then stopped. (Photograph by Anthony Martin.)
In the following video of a sparrow both landing and taking off, watch how it points its rear claws toward the surface as it approaches, then make first contact, followed by the forward-pointing toes. Also notice how one foot barely precedes the other, which in its tracks would should up as a very slight offset between the two. (Warning: This video is exquisitely beautiful, and is best watched with mouth agape in wonder.)
Depending on how fast a bird came down, and taking into account lots of other factors (for example, wind direction and speed), this landing pattern could be followed by a hop, or it could just segue into a normal diagonal walking pattern. Also keep in mind that birds with small or absent halluces (plural of hallux) and full webbing between their toes – such as gulls – may just show their forward three digits skidded, leaving no claw marks in the rear part of the tracks.
Landing tracks of a laughing gull (Leucophaeus atricilla), in which it first skidded, but must have had enough forward momentum to keep it going forward with a big hop. (Photograph by Anthony Martin, taken on Sapelo Island, Georgia.)
Close-up of a different set of landing tracks from a laughing gull with nicely defined skid marks on both feet. (Photograph by Anthony Martin, taken on Sapelo Island, Georgia.)
Take-off patterns involve opposite movements, in which the feet come together, but the digits dig in and push off, leaving scratch marks from the claws and well-defined mounds of sand or mud behind the digits, instead of in front of them. They can also be quite ungainly: I’ve seen pelican and vulture trackways in which they either run or skip for five-six steps before they were aloft, with increasing distances between each successive set of tracks. But sometimes a large bird like a pelican can impress me with its tracks, showing where it successfully accomplished a sudden take-off from a standing start.
Take-off tracks of a brown pelican (Pelecanus occidentalis) in which it must have flown from a standing start. Also note the water-drop impressions in front of the tracks, indicating that the pelican had just been in the water and still had wet feathers when it took off. (Photograph by Anthony Martin, taken on Sapelo Island, Georgia.)
So given these search images, lots of birds, and blank canvases of coastal sand or mud, you should now be able to find and diagnose your own “flying tracks.” But you also don’t need to restrict your searches to beaches: these traces can be found wherever flying birds live and visit the ground.
Using such clues, could we ever apply them to recognize flying tracks from the fossil record? Why, yes indeed. And for those of you who read this fair, here’s your Easter egg. The contents of this post relate to a major scientific discovery that will be announced in a few days: you heard it here first. So look for that news to come in for a landing soon.
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.)
Aw, 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 LateCretaceous 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.
Partially 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.)
Dinosaur 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.
A 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.”
Uh 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.
Here’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.
Want 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.
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.
Authors of books are sometimes lucky enough to get people interested enough in both them and their books. Even better, these authors are sometimes invited to talk about their books to a receptive audience. Yet I’ll bet few authors get the opportunity to talk about their books with fellow book lovers while also standing on the front porch of a great American author. Even less probable is that the author of a natural history book – one related to paleontology, no less – would somehow have to relate his or her work to a deceased author best known for her Southern Gothic fiction.
It’s a sign! Upon my arrival at Andalusia Farm, the former home of Flannery O’Connor, this sign greeted me at the door, reminding me why I was there. It was fun to think that during Flannery O’Connor’s life, this is how she might have announced a lecture at her place, using a sheet of paper with words, posted on her door. (For the sake of imagination, just ignore that the notice was created and printed by person using a couple of 21st century devices.) Photograph by Anthony Martin.
This past Sunday, I was just so fortunate and challenged, having been invited to speak about my new book, Life Traces of the Georgia Coast, at Andalusia Farm, the former home of famed American writer Flannery O’Connor. Andalusia is located just north of Milledgeville, Georgia, and despite many previous trips to Milledgeville, this was my first visit to Flannery O’Connor’s former haunts. The house and grounds are in a formerly rural setting, its clay-laden driveway just off a busy highway and directly across from a chain hotel. Yet her house is still surrounded by more than 500 acres of forest, streams, and a pond; the pond is visible from the front porch of the house. These natural areas are what attracted me to coming, and provided an avenue for connecting themes of my book with this place.
A view of the main house at Andalusia Farm, where Flannery O’Connor spent more than a third of her life. Her bedroom, where much of her writing also happened, is just to the left after passing through the front porch. Photograph by Anthony Martin.
A sign telling about the recent history of Andalusia. Sadly, it does not include any mention of the Alleghanian Orogeny that contributed to the Piedmont Province there, nor does it inform visitors about the maximum extent of the Cretaceous and Eocene seaways just to the south, nor does it acknowledge the former presence and effects of the Pleistocene megafauna that used to live there. But I suppose all of that would have required a much bigger sign. Photograph by Anthony Martin.
O’Connor is much revered in the Southern U.S. and elsewhere, a loyalty that stems partly from the fact that she was indeed a terrific writer of Southern-inspired literature – consisting of short stories, novels, and essays – and partly from a wistful longing of “If only”: namely, if only she had lived longer. Born in Savannah, Georgia in 1925, she traveled to what was then called State University of Iowa (now the University of Iowa), where she earned an MFA, and soon afterwards began her illustrious writing career. In 1951, she was diagnosed with the same disease (lupus) that killed her father while he was still relatively young. She lived with this debilitating condition for the next 14 years, the last 12 of which were at Andalusia. She was only 39 years old when she died in 1964.
So how did I become a character in a Flannery O’Connor story? I blame it all on a paleobotanist friend of mine at nearby Georgia College and State University, Dr. Melanie DeVore, who suggested to me several years ago that I come to speak at Andalusia about my upcoming book. “Why?” was my first response. After all, as a long-time resident of Georgia, I was embarrassed to admit that I had read very little of O’Connor’s works until just recently. I also could not figure out how the plant and animal traces of the Georgia barrier islands could be related to a Southern author whose home was just above the fall line, between the Piedmont and Coastal Plain provinces of Georgia. Even the Cretaceous seaway from 70 million years past had not washed onto the landscape of O’Connor’s home. Thus I felt hard-pressed to come up with a way for my book to be relevant to her literary contributions and a sense of place.
Still, Melanie continued to encourage me to think about it. Admirably enough, she was trying to find ways in which natural scientists might contribute their perspectives to the considerable scholarship behind O’Connor’s works and the popular appeal of her former home. So I delved into O’Connor’s biographies, and searched for an ichnological connection between what she did and my interests. This is when I found the key, the theme that united: birds.
It turns out that O’Connor was a great lover of birds, and the thought that perhaps she had too many birds never occurred to her during her last years at Andalusia. Peafowl were her favorites for many reasons, some of which she explained ever-so-eloquently in several essays, including one of her most well-known works of non-fiction, The King of Birds. Domesticated birds also abounded on her property, including chickens, ducks, geese, and swans, all part of her avian menagerie. At one time, she evidently owned more than a hundred peafowl, a daunting number when one considers the vociferous qualities of these birds.
A peacock in a spacious enclosure just outside of Flannery O’Connor’s home, graciously displaying his tail feathers for us. See those feet? We’ll take a closer look at those soon. Photograph by Anthony Martin.
One of two peahens in the same enclosure, not nearly as resplendent and gaudy as her male companion, but still a very attractive bird. Of course, I was looking at her feet too, thinking about the tracks she would make, and how these might differ from those of the peacock. Photograph by Anthony Martin.
O’Connor’s earliest few minutes of fame were also bird-related, and established her life-long association with oddities of the South. When she was only five years old, she somehow taught a chicken to walk backwards. This feat attracted a film-reel company (Pathé News), which sent a crew from New York to Georgia to record this atypical avian mode of locomotion. The film reel, shown in theaters in 1932, also parodied O’Connor’s childhood accomplishment by reversing the film for other walking domestic animals, making these animals also appear to also walk backwards.
DO YOU REVERSE?
It’s one thing to read about Flannery O’Connor and her backwards-walking chicken, but it is another to actually see an original film about it. In the reel, she is mistakenly identified as “Mary O’Connor,” but no matter, as it was a start to her enduring fame for inventing quirky actions, plots, and characters reflecting the off-kilter cultures of her Southern environs. Incidentally, just how would you tell the difference between tracks made by a chicken moving forward or backwards? Maybe that should be the topic of a future post…
O’Connor’s link to paleontology was an oblique one, in that (as far as I know) she did not express any interest in it as a subject. Nonetheless, she was a great admirer of paleontologist, Jesuit priest, and philosopher Tielhard de Chardin, and the title of one of her anthologies, Everything That Rises Must Converge (1965), came directly from one of his writings. Also, in an “if only” moment of my own during my talk on O’Connor’s porch, I wondered what sort of fiction or essays would have come out of O’Connor had she lived long enough to learn that birds are actually living dinosaurs, and hence she had unwittingly surrounded herself with the progeny of those Mesozoic monsters.
Oh yes, my talk on O’Connor’s porch. How did that go? Fantastically. Because of the gorgeous weather that day, Craig Amason, my host and executive director of the Flannery O’Connor-Andalusia Foundation, thought that we might hold the discussion on the screened front porch, rather than inside in one of the more spacious rooms of the house. I was all for this idea, partially for its atmosphere (I mean, how cool would it be to talk about Flannery O’Connor with some of her fans on her front porch?), but also because we planned to have everyone walk on the trails with us later, looking for tracks and other traces of the animals that live there. Melanie and I had already scouted the trails in the morning and found a few surprises, so we knew that part of the program would be great fun, too: might as well get them halfway outside already by being on the porch. Fortunately, all of the dozen or so people who showed up also approved of this plan, which was helped in no small part by a heaping helping of cookies and soft drinks, enticing them to stay right there on the porch for a spell, and perhaps even relax in a rocking chair.
Dr. Bruce Gentry of Georgia College and State University, having just bought a copy of my book, opens it to take a look inside. Dr. Gentry is a scholar of Flannery O’Connor works and heads the Flannery O’Connor Studies Program at Georgia College and State University, in nearby Milledgeville.Meanwhile, I’m in the background, gesturing grandly to the delicious cookies on the table next to mewhile also introducing everyone to the topic of bird tracks and sign. Photograph by Melanie DeVore.
A sample of our front-porch chat about Flannery O’Connor and her birds, in which I point out the close resemblance between a rooster’s feet and those of a peacock. Although the peacock tracks would have been noticeable larger than those of her chickens, their overall forms would have been nearly the same, with three long thin toe-prints pointing forward, one shorter one pointing backward, and all four ending with clawmarks. Video footage by Craig Amason, exceutive director of the Andalusia-Flannery O’Connor Foundation.
A close-up of a rooster’s feet. Think about the tracks this would produce, whether walking forward or backwards. Rooster was known as “Tom” (R.I.P.), formerly owned by Carol Ruckdeschel on Cumberland Island, Georgia. Photograph by Anthony Martin.
Now compare the rooster’s feet to those of this peacock at Andalusia Farm, and you’ll see for yourself how close they are to one another in their overall form, despite the rear digits being hidden in this photo. I could not help but think that O’Connor, while seeking the pleasure of the company provided by her birds, also saw thousands of similar-looking peacock and chicken tracks every day she went outside. Photograph by Anthony Martin.
The talk itself was mercifully brief on such a fine day, with tracks and other sign awaiting us. So I simply expressed my gratitude for being there with all of us gathered in this special place, talked about Flannery O’Connor’s love of birds, and jumped into a speculative discussion of what tracks she might have seen every day on the farm. My presentation was decidedly low-tech, in which my only visual aids were paper print-outs of bird tracks and feet and a couple of my illustrations from the book, which were of bird-track categories and nests. These were supplemented by my acting out birds motions (walking, mostly), demonstrating how these behaviors would result in certain trackway patterns. One of these, much to the amusement of audience, was of a peacock doing its little circular and sideways-stepping dance, which was followed by my asking them to imagine the trackway patterns that would have resulted from such courting.
I also did a short reading from my book that introduces the topic of bird tracks, which fairly drips with admiration for the complexity of behaviors captured by such traces, thus hopefully echoing O’Connor enthusiasm for birds. Many questions were asked and observations of bird behavior offered, a give-and-take that I thoroughly enjoyed in the role of a “guide on the side” rather than a “sage on the stage” (or a “torch on the porch”). Once done, we had a short break for people to buy my book (thanks, y’all!), then walked onto a nearby trail to look at what the wild animals had left us the previous few days.
This outing was enjoyable, a bit of a treasure hunt and an eye-opening experience for many of how much animal activity is embodied by their traces in a typical Piedmont forest and its water bodies. Some of the traces I had seen earlier in the day while out scouting with Melanie, but we saw more, such as previously missed raccoon tracks and woodpecker sign. The highlights included the discovery of fresh (less than 12-hour-old) beaver tracks on one of the stream banks. This delighted several people, who told me that beavers had supposedly moved out of the area years ago, so they were pleased to know that at least one was back in the neighborhood. I was also excited to find coyote scat on the trail, which inspired earthy, amusing comparisons between the territorial markings of mammals in the wild versus those of corporate board members and academics (which, not surprisingly, are not so different in practice).
Coyotes just can’t help themselves: where we see a human footpath, they see an advertising opportunity. Here I excitedly point out an example of coyote scat, which had been strategically placed in the middle of the trail so that all other mammals would know this was her/his territory. You know, just like you might see happen in a professional meeting. Photograph by Melanie DeVore.
Fresh beaver tracks on a stream bank! This was a happy find, as it demonstrated that at least one beaver was in the area, following a nearly five-year absence of their species. These tracks show the beaver turned to its right and walked down the bank and into the water; look for the large rear-foot track to the left, and the tail dragmark in the middle. Swiss Army knife is about 6 cm (2.4 in) long. Photograph by Anthony Martin.
Once this short, ichnologically-infused hike was over, people thanked me and bid goodbye, but a few of stayed behind to take a gander at the peafowl, which were in a large enclosure just behind O’Connor’s house. One male and two females are kept there, and our timing was impeccable, as the male was in full display mode, feathers fully erect and dazzling as he strut about the grounds, while the peahens stayed in the background, mildly impressed or nonchalant. (“Oh yes, he does that all of the time,” I imagined them thinking, mildly bored.) Nevertheless, as far as we non-avian bipeds were concerned, he was indeed the king of birds.
But that’s when my ichnologist hat popped onto my head, askance from its sudden appearance. Craig had told me earlier about the peafowls making a dust bath in the confines of their enclosure, and sure enough, there it was. It matched the width, depth, and shape of dust baths I had written about in Life Traces of the Georgia Coast, only for wild turkeys. Birds make dust baths for alleviating skin parasites, in which they hunker down in them, using their wings to distribute enough fine-grained sediment on them to smother the offending lice or other arthropods. Could such traces preserve in the geologic record, whether they were made by feathered dinosaurs, birds, or mammals? How could we recognize or distinguish these from other shallow depressions? And most importantly, did Flannery O’Connor ever see such dips in the landscape, and if so, did she know their meaning?
A dust bath made by peafowls, about 50 cm (20 in) wide on its longest dimension, and looking a little less dusty after several days of intense rain the preceding week. Still, this was a cool trace to see, and conjured some imaginative thoughts about these as trace fossils. (Peafowl feces extra in the pit: no charge.) Photograph by Anthony Martin.
Another ichnologically inclined thought occurred to me while there at the enclosure, and is worthy of further experimentation. How might we tell the male (peacock) tracks from those of the female (peahen)? Take a look at the following photo, and you tell me. Anything there that might leave a distinctive mark identifying the gender of its tracemaker?
Here comes the groom! Any aspect of this tracemaker’s anatomy that might leave traces telling you he was a boy bird? Photograph by Anthony Martin.
So from this day trip to Andalusia Farm, I was awed, inspired, and ever slightly more enlightened by it all, and hoped that a small amount of the same feelings had been experienced by others who participated in this special day. Still, I was also humbled, realizing how little I still know about Flannery O’Connor, why she connected so well with birds, bird traces and behavior, or how these traces might manifest themselves to us and grace us with wisdom as recognizable trace fossils made in a distant past. Hence from my time there and into my future, I will endeavor to keep in mind the words spoken by Dr. Block, a character of O’Connor’s in The Enduring Chill from the anthology, Everything That Rises Must Converge:
“Most things are beyond me,” Block said. “I ain’t found anything yet that I thoroughly understood.”
Acknowledgements: Many thanks to: my good and long-time friend Melanie DeVore for encouraging me to visit Andalusia to share my science and sense of wonder; Craig Amason for being such a gracious host; Bruce Gentry for his continuing contributions to teaching his students about the complex and varied dimensions of Flannery O’Connor, a great American writer; the people who showed up and made for lively company; and of course the birds and their traces, which will outlive all of us, no matter the lengths of our lives.
Further Reading
Elbroch, M. and Marks, E. 2001. Bird Tracks and Sign of North America. Stackpole Books: 456 p.
Martin, A.J. 2013. Life Traces of the Georgia Coast: Revealing the Unseen Lives of Plants and Animals. Indiana University Press: 692 p.
O’Connor, F. 1955. A Good Man is Hard to Find, and Other Stories. Harcourt, Brace and Company: 265 p.
O’Connor, F. 1965. Everything That Rises Must Converge. Farrar, Straus and Giroux: 320 p.
Simpson, M. 2005. Flannery O’Connor: A Biography. Greenwood Books: 152 p.
A mixture of tracks left by boat-tailed grackles (Quiscalus major) and American crows (Corvus brachyrhynchos) on wind ripples in the upper part of a sandy beach. So if paleontologists found something similar in the geologic record, would they be able to say more than “Looks like a bunch of birds were walking around”? That’s why we look at modern traces and their associated behaviors: to get beyond such easy (and terribly incomplete) answers. (Photograph by Anthony Martin, taken on Tybee Island; pen is about 15 cm (6 in) long.)
Girlfriends going out for a bite to eat by the beach: a group of boat-tailed grackles – all female adults – foraging in between the sea oats on the south end of Tybee Island. Here they were on the seaward side of the dunes, and just before sundown. (Photograph by Anthony Martin.)
Grackles in different feeding postures: two with their heads down and feet together (foreground and right), and another with her head up and left leg ahead of her right, and all after walking slowly and stopping often. With that in mind, think of the trackway patterns that would correspond with these movements and postures. (Photograph by Anthony Martin, taken on Tybee Island.)
A close-up of the grackle from the previous photo, showing exactly why it stopped it with its feet together and put its beak down to the sand: fallen grains of sea oats. (Photograph by Anthony Martin, taken on Tybee Island.)
Another close-up of a grackle, but with sea oats in her beak. More importantly, check out the tracks behind her, the little depression where the oats laid on the sand (arrow), and the beak mark next to it that she made just before grabbing the grains. (Photograph by Anthony Martin, taken on Tybee Island.)
Yeah, I know, it’s a body fossil. But hey, it’s the Berlin specimen of Archaeopteryx, probably the most famous body fossil in the world, so it’s OK. I was lucky enough to see it in person at the Museum für Naturkunde in Berlin early last month, and like most paleontologists who see it, I was awestruck by its 150-million-year-old beauty. Understandably, then, the evolutionary history of birds was on my mind when – three weeks later – I watched those grackles making traces on a Georgia beach. Will Archaeopteryx trace fossils ever be found? Let’s hope so, and if they do, they deserve to be as famous as this specimen. (Photograph by Anthony Martin.)
