The Great Cretaceous Walk

The Great Cretaceous Walk Takes a Rest

2011-09-30T15:46:00.000-04:00

About six weeks ago, I shared the happy news of our discovering dinosaur tracks at Milanesia Beach, Victoria, which turned out to be the largest collection of polardinosaur tracks known in the Southern Hemisphere. Those tracks were found duringthe month-long excursion (May-June 2010) along the Victoria coast that inspiredthe start of this blog. And although we found heaps more trace fossils, thetracks constituted out most important scientific find. So even though we have abut more science to do, this is as good of a time as any with this blog to say,“Catch you later” and make a transition both geographical and temporal.

The Great Cretaceous Walkhas been very, very good to me. But it’s time to take a pause in all of thewalking and talking about the Cretaceous of Australia, and look closer to home (Georgia)and at this time in the present (otherwise known as “now”). Photo by Tom Rich, and taken onMay 28, 2011 (Day 2) of our month-long field survey of the Cretaceous tracefossils of Victoria.

As loyal readers probably know, I live most of the year in Georgia (the one in the USA, not the "other" Georgia), and have been herefor about 25 years. But ever since 2006, when my wife Ruth and I lived for 3-4 months in Melbourne, Victoria, I’ve been back to Australia almost every year,normally staying for 4-8 weeks each time. Most of those visits have involvedgoing to Victoria for paleontology or teaching Emory University students in Queensland, but Ruth and I have also managed to visit everystate and territory in Australia, with all-too-brief glimpses of Cretaceousrocks and fossils in Queensland and Western Australia. To be sure, we adoreAustralia and its fascinating natural history, and it now feels like our adoptedhome.

Ruth and me, at the end of a typical day of paleontological field work in Australia. Well, OK, I'll admit the truth: neither one of us had a horse. Photo from cutprintreview.com.

Part of this blog, then, has been a big, juicy, love letterwritten to Australia. Granted, loving Australia is easy ‘cause it’s beautiful, given its fantastic Cretaceous rocks, natural scenery, geologic history,body fossils, trace fossils, people, and (of course) good beer. But as often happens with long-distance relationships,it’s lately been superseded by what’s closer to home.

I'm going to miss seeing tasty outcrops of Cretaceous rocks - like these - on the Victoria coast...

...and gorgeous, dramatic vistas like this. I can't believe I almost got paid to do this.

But you know what I'll miss the most about doing field work on the Victoria coast? All of the signs warning me of my impending doom.

Speaking of signs, I just want to point out that nobody, and I mean nobody, pays attention to following the rules more than Tom.

What could be so distracting that it would cause me to cast anichnological gaze elsewhere? Well, what many of you may not know is that whilewriting The Great Cretaceous Walk –which started in May 2009 – I was also writing a book about the modern tracesof plants and animals of the Georgia barrier islands.

This is one of thebrazen, shameless hussies keeping me from thinking about Australia: St.Catherines (Island), Georgia (USA). Not to mention her sisters Sapelo,Cumberland, Jekyll, Ossabaw, and Wassaw. How could any ichnologist resist theirsiren calls to study their copious modern traces?

Remember the saying, "Variety is the spice of life"? Compare and contrast the previous photo with this one, taken while doing field work on the Victoria coast, and you'll get a taste of the curry I've been experiencing the past few years from doing field work in both Australia and Georgia.

My book, titled Life Traces of the Georgia Coast (Indiana University Press), is now in pre-production, meaning that it couldcome out later this year, but more likely will be publicly available the firsthalf of 2012. It’s going to be a bloody big book, coming in at an estimated 600pages long and with more than 130 figures, the latter consisting mostly of my photos andillustrations. It will also have color plates depicting some of thetracemakers, none of which are in Australia: alligators, armadillos, greatblue herons, vultures, moon snails, horseshoe crabs, and many more speciesnative to the southeastern U.S.

Best of all for paleo-philes, though, this bookdoesn’t just dwell in modern times, but looks at how these modern traces can becompared to similar-looking trace fossils in the geologic record, helping us tobetter interpret trilobite burrows, dinosaur tracks, and other suchvestiges of past life.

Tracks of a great blue heron (Ardea herodias) in a beach sand on St. Catherines Island, Georgia, providing a nice analogue for thin-toed dinosaur tracks that might have been preserved in similar sandy deposits from the geologic past.

Thin-toed theropod dinosaur tracks, preserved in former riverbank sands from 105 million years ago, at Milanesia Beach, Victoria (Australia). See what I mean about comparing modern and fossil traces?

Because of this book and its impending publication, I’vebeen shifting my creative energies away from the Cretaceous rocks of Australiaand more toward what is right here, right now in Georgia. I even began another blog, lazily given the same titleas the book (Life Traces of the Georgia Coast). Thus for me to continue trying to write The Great Cretaceous Walk while also devoting thoughts, energy, andwords to a new blog that deals with subjects that are literally closer to home woulddilute both, pleasing no one.

A map showing our route one day (June 10, 2010) along the Victoria coast near Apollo Bay, when I turned on my GPS unit at the start and turned it off at the end of the field day. Just look for the little blue dots, which recorded my position throughout the day. Yes indeed, that was a lot of walking, but it was worth it for all of those luscious trace fossils we saw along the way.

But before saying “bye for now” on this blog, I thought itwould be best to talk about you, gentle reader. For example, of everything mentionedhere, what topics did you find the most interesting? Unlike a lot of other blogs– such as those about funny cats, being a mommy in a first-world country, ormommies in first-world countries who have funny cats (no, I’m not linking them)– this one had two primary and connected goals: to educate and entertain.

So I’llbet a lot of readers came to it with the expectation that they might become alittle more educated about the paleontology of Australia. But hopefully theyalso found it happily humorous, or were surprised to see a science site suffused with a surfeit of surly suppositions, or an alarming amalgam of alliterations. (But never palindromes, unless youfind yourself in Glenelg. In words, alas, drown I.)

Anyway, asof today – September 30 (Eastern U.S. time zone) – here are the top five posts,based on your page views:

1. Clancy,Matilda, and Banjo: Australian Dinosaurs, Living Large

2. WhoMade the Three-Toed Dinosaur Track?

3. DivingDown Under in the Cretaceous Sea

4. WhyDinosaur Tracks Matter

5. TheDinosaur Tracks of Western Australia May Go Extinct

Four ofthose five posts had the ever-magical word “dinosaur” in the title, so it’s notexactly shocking to discover these at or near the top of the chart. Which made#3 (DivingDown Under in the Cretaceous Sea) all the more pleasing to see performso well. What’s really amazing is that it’s about gastroliths (stomach stones) and their function in sea-dwelling Cretaceouscritters! (Granted, these were some pretty neat critters, too.)

Similarly, the post that justbarely came in #6 (Kronosaurus: The King (or Queen) of the Queensland Sea) was alsogratifying, and I was glad to provide more public awareness about one ofAustralia’s most spectacular - but underappreciated - marine predators of all time (also mentioned here and here).

I also hope that my posting of #5 on the list (TheDinosaur Tracks of Western Australia May Go Extinct) made a very small difference in decisions made aboutbestowing National Heritage status to areas with dinosaur tracksites along thecoast of Western Australia. As I write this, paleontologists are surveying some of the tracksites there to assess theirscientific value in light of proposed development along the coast.

Just put the word "dinosaur" in something's name, and suddenly people start paying attention to it. You know, like Dinosaur Cove, Victoria, where I'm pictured here with Ruth and Tom Rich. Photo by Greg Denney, one of the world's greatest dinosaur trackers. (Hey, I'm just quoting.)

Somethingelse I was very pleased to see from reader statistics was how many people from awide range of countries were checking out the blog. For instance, here are thetop-ten nations represented by you, the readers:

1. UnitedStates

2. Australia

3. UnitedKingdom

4. Canada

5. Germany

6. Italy

7. Russia

8. France

9. Brazil

10. NewZealand

Sure, I wasnot surprised to see that a blog written by an American in passable AmericanEnglish (with occasional forays into Australian “Strine”) would be read mostly by Americans, who also have thedecided advantage of a 300+ million population and an overabundance ofcomputers and free wireless connections.

Yet what wasmost gladdening for me – and impressive – is how enthusiastically Australianstook to reading what this Yank had to say about their country and its fossils.Despite Australia having only about 8% of the population of the U.S. andnot-so-free wireless (once causing me to even walk into a much-loathed Maccas to avail myself of its complimentaryInternet connection) 17% of all pageviews over the past year-and-a-half originated from Australia! That’s bloody marvelous, and makes me feel good about givingsomething back to the wonderful people of Oz after you put up with me for somany visits. Good on ya, mates!

But I wasalso warmed to know that people in Uruguay, Qatar, Indonesia, Slovakia, Malaysia,the Philippines, and many other countries set their eyes on my words andphotos. Thank you all, and I hope you learned something.

Will The Great Cretaceous Walk ever make acomeback? Yes, but in two very different ways. More conventionally, I’ll still writeand publish an occasional post, especially if some really cool fossildiscoveries come out of the Cretaceous rocks of Australia. This is highlylikely, especially considering the exciting research continuing in theCretaceous of Victoria, Queensland, and Western Australia.

But the mainway you’ll again read about “Way Back Then Down Under” will be as a book,probably with the following title and subtitle:

TheGreat Cretaceous Walk: Adventures and Misadventures of an AmericanPaleontologist in Australia

(Wait a minute, thatsounds familiar.)

Why write abook? Well, thanks to this blog, much of it has already been written, so it’sactually low-hanging fruit for someone who likes to write books. But ratherthan simply recycling old posts – which would be deadly dull – a book presentsan exciting opportunity to give readers more details, more experiences, and morestories about the Cretaceous worlds of Australia. I also expect that thesestories will be greatly improved through the loving attention of a good editorand a little bit of peer review.

For example, almost all of what you read in myprevious 50 posts was self-edited, which is not the best way to guarantee high-qualitywork. I mean, in one post, I misspelled Kylie Minogue’s name, for crissake. (For that mistake alone, I should be flogged. Preferably by Kylieherself.) My point is, for all of the blather and boasting thetechno-literati are making about the joys of self-publishing through the new “e-book revolution,” there is nosubstitute for professional guidance in improving a book and making it a moresatisfying experience for the author and readers.

Who willpublish The Great Cretaceous Walk,and when? I don’t know the answer to either question, as I’ll have to puttogether a semi-coherent proposal, find a likely publisher, send the proposal, thenkeep fingers, toes, and other appendages crossed while waiting tofind out whether it’s accepted (or not). If not the first time, then try, tryagain.

Regardless, I'm confident that it will get published some day, as thestories of Australia past, made clearer through the fossils discovered todayand the people who find them, are just too beguiling to be ignored. Once thebook is published, even more of the world will walk with me as they learn aboutthe unique and fascinating Cretaceous lands, skies, and seas of Australia.

Until then, Igive you all an Aussie salute, ta muchly, and cheers.

Paleontologists' tracks on a sandy beach of Victoria, heading to and from a Cretaceous outcrop, made during The Great Cretaceous Walk last year. Will these traces outlast the lives of the paleontologists? No, they were washed away with the next tide. But at least I took a picture.

Hard to believe I hadn't yet linked to anything from one of the greatest "on the road" movies ever made in Australia, Priscilla: Queen of the Desert. Spoiler: Priscilla was the bus. And my last piece of advice for everyone? No more bloody Abba!

Discovering the Dinosaur Tracks of Milanesia Beach

2011-08-14T19:19:00.000-04:00

(In my previous entry, I described the start of a day in the field – June 14, 2010 – at Milanesia Beach, Victoria (Australia), just hours before Tom Rich, Greg Denney and I discovered the largest assemblage of polar dinosaur tracks in the Southern Hemisphere. In that entry, I also pointed out how few dinosaur tracks had been documented in Victoria before then, which also meant very few polar dinosaur tracks had been found in the Southern Hemisphere. This background gave some context on why this find is a big deal, paleontologically speaking. So, would you like to want to learn how these tracks were discovered? Then read on.)

As Tom Rich, Greg Denney, and I walked down Milanesia Beach the morning of June 14 2010, my thoughts were about the dearth of dinosaur tracks found thus far in Victoria, Australia. Geological research of these Cretaceous-age rocks had been going on for more than 100 years, and paleontological studies there had been particularly intense during the past 30 years. Yet during that time, only four definite dinosaur tracks had been discovered in all of the extensive Cretaceous outcrops of coastal Victoria. Moreover, all of these were individual prints, with no dinosaur trackways showing at least two sequential steps. The previous three weeks of field work Tom and I had done along the coast seemed to bear out this notion that dinosaur tracks were rare here, even scarcer than their bones.

Nonetheless, I also tried to shake a premonition, experienced only a half hour after arriving at Milanesia Beach, that we might find dinosaur tracks there. Rest assured, this hunch was not inspired by séances, Ouija boards, psychic-pet hotlines, or any other forms of necromancy. Instead, it was based on our seeing the physical sedimentary structures and small invertebrate trace fossils (burrows) that told me we were looking at the former deposits of river floodplains. These environments would have been perfect for preserving dinosaur tracks. Regardless, I reminded myself to just be a cold, clear-headed, objective scientist: you know, a pessimist.

A few more of the dinosaur tracks of Milanesia Beach, Victoria (Australia). Three size categories were there: small, medium and large, all made by three-toed theropod dinosaurs. Greg Denney found the ones shown here, which he discovered by recognizing how this rock matched another one with dinosaur tracks that I had found just a few hours before. Please buy him an adult beverage next time you see him, slap him on the back, and say, “Good on ya, mate!”

Just to dissipate these inward distractions, I decided to look intently at more of the small invertebrate burrows in the outcrop along Milanesia Beach. At this point, Greg abandoned me, and I didn’t blame him. He walked ahead to join Tom, who was already several hundred meters east of us, searching for bones, teeth, or other bodily remains of fossil vertebrates.

Meanwhile, I took some more photographs and measurements of the burrows we had only found 20 minutes before. Once that was done, I ambled leisurely, scanning both the outcrop and large boulders strewn across the beach. While walking, I carefully picked where my feet landed, having learned the hard way that these rocks often had nearly invisible slippery surfaces caused by slimy algal overgrowths. I had already fallen a few times during more than a hundred kilometers of walking along the Victoria coast, and did not want to add another bruise, bump, or scrape to my three-week-old collection.

Walk this way, but be careful. The boulders of Milanesia Beach and other rocky shorelines of the Victoria coast, aided by their algal friends, can become hazardous when prospecting for fossils.

To this day, I don’t know why, but one large, rectangular block of rock among dozens along the shoreline compelled me to stop and take a moment to stare at it. All I can imagine now is that this sensation stemmed from more than ten years of tracking animals in the sands and muds of the Georgia barrier islands and other places in the world, a collective experience that led to a subliminal recognition of something real, something worth noticing on the periphery of my vision. I looked to my left, then down at the top surface of the boulder.

There was a small, three-fold impression, looking vaguely like the middle three fingers of a human hand. It was close enough to touch, so I did. My own three middle digits molded to the indentations, confirming what my eyes had seen but not quite believed. It was a small dinosaur track.

After a quick inhalation of breath and almost trembling, I dared to look at the rest of the rock, scanning from left to right. More patterns of three came into focus, one after another, each identified faster than the previous one. Within about 5-10 seconds, I realized the bumpy surface was loaded with dinosaur tracks. Instead of shouting “Eureka!” or some similarly noble and dignified sentiment, I whispered a much shorter synonym of the phrase, “Hallowed excrement!”

The slab of rock that made me ready to buy a slab of beer to celebrate. It has at least 16 dinosaur tracks on it, although some are so shallow that you can’t see them very easily in the first photo (top), and at least two are only represented by paired clawmarks. With a little bit of digital enhancement, though, you can then see some of the fainter ones (middle image), and I later mapped track locations (bottom). That map is now a testable hypothesis, and potentially could be disproved or otherwise modified in the future by me or someone else. That’s science, folks.

One of footprints – a chicken-sized one, only about 7 cm (2.8 in) long – was close to the edge of the slab. With my heart beating faster, I then did something I almost never do with modern tracks, which was to backtrack. I shifted my focus behind the track nearest me to see if any similar preceded it. Sure enough, there was another one of the same size, aligned with the previous one. Halted briefly by disbelief, I backtracked one more time. Another track was exactly where it should be, at a distance nearly identical to the space between the other two, although slightly off the line of travel. One, two, three steps in sequence, showing a slight rightward turn. A preserved motion from more than 100 million years ago, made by a small theropod dinosaur on a river floodplain during a polar summer. It the first known dinosaur trackway in all of southern Australia, and the first polar-dinosaur trackway from the Southern Hemisphere.

The first known dinosaur trackway from southern Australia, made by a chook-sized theropod dinosaur, about 105 million years ago and probably during a polar summer. While walking, it decided to turn slightly to the right. At first I speculated it did this because it moved around an irregularity in its landscape caused by two overlapping dinosaur tracks on its right. That idea didn’t make it through peer review, though. Again, that’s science, folks. Scale = 13 cm (5 in) long.

But there was no time to celebrate. I needed to get to work and do something that went beyond mere discovery. I looked more closely, and felt the rock surface to augment what my eyes told me. Following this, I began sketching what was there and marking locations of the tracks, using graph paper in my geological field notebook to make a scaled drawing that served as a “track map.” Unlike taking photographs, drawing forced me to look at the rock and its fossil tracks repeatedly, carefully, and critically, a time-honored observational technique I teach to my students.

This method soon paid off, for within about 10 minutes, I found a few more tracks, subtle ones that either consisted of very faint toe impressions or were missing parts. For instance, two tracks were only evident as paired marks made by sharp claws from two toes. A quick, initial count yielded about 14 tracks, all showing three or fewer toes. The surface itself only had an area of about 0.7 m² (7.5 ft²), so it held a lot of information in a small space. This was a busy little piece of real estate during the Early Cretaceous.

A small indulgence in 21^st century technology that was necessary, though, was to use a handheld GPS unit to determine the location of this rock. With this, it quickly determined the latitude-longitude coordinates of where I was standing. These were saved as a waypoint but also written in my notebook, just in case the GPS unit somehow ended up in the seawater that just happened to be crashing in waves behind me.

My staying in one spot for nearly 45 minutes and writing in a notebook provoked some curiosity in Greg, who left Tom and came back down the beach to see what was holding my attention. He was all smiles as he walked up to where I was seated, which was on another boulder in front of the track-bearing slab.

“What’d you find?” he asked cheerfully.

I grinned back, gestured toward the slab surface, and said with a mixture of pride and awe, “Dinosaur tracks.”

Greg’s jaw dropped, and he briefly looked like a stunned mullet as his eyes took in what was there. In silence, I thoroughly enjoyed watching him re-discover each dinosaur footprint, a wonderful moment to share with a field compatriot. Once he regained his voice, he exclaimed, “Wow, this is fantastic!” Yes, it was.

Putting my scientist hat back on (covering up the stylish paleontologist hat), I then decided to test some of these preliminary results. I asked Greg, a non-paleontologist but a skilled observer, to point to everything he thought was a dinosaur track. Within a few minutes of studying the surface, he quickly identified nearly every one I had detected, with only a few misses. “Nice job!” I told him, and we then went over his test results, just like I would with any eager and talented student of mine.

Tom soon joined us. Like Greg, he also wondered what had held our interest so raptly, and he asked the same question: “What’d you find?” My reply to him, though, was slightly different, as I got a little professorial and answered his question with a question: “What do you think is there?”

Tom coolly looked at the rock surface, bringing to bear more than 40 years of paleontological experience, with more than 30 of those years spent studying the Cretaceous rocks and fossils of Victoria. A moment passed, then he pointed to the best-preserved dinosaur track, and said matter-of-factly, “Looks like a dinosaur track.”

I smiled. “Yes, it is. See any others?”

One by one, he pointed to each track, and like Greg, found nearly every one I had identified. This was a great example of a little scientific principle called repeatability: that is, a scientist should be able have her or his results repeated independently by other scientists.

But I wasn’t through with Tom, and asked him to take a close look at the little, chicken-sized track nearest me. “Anything special about it?”

That stumped Tom. “Help me out. What am I supposed to see?”

“Look behind it. See anything like it?”

He quickly put his finger on the small track preceding the one nearest me.

“Good. Anything behind that one?”

“That one,” he said, putting his finger on another identically small-sized track.

I smiled again, something I was doing a lot of that day. “It’s a trackway,” I shared, letting understated brevity speak for its importance.

When that little bit of information sunk in, Tom allowed himself the indulgence of a very small, almost Mona Lisa-like smile. I had already pointed out the trackway to Greg, but he kept silent as he enjoyably watched Tom go through much of the same interrogation he had just experienced. After all, it’s always better to watch someone else take a test than to take one yourself.

So with this affirmation from my field partners spurring me on, I resumed with taking measurements and writing notes, then took some photographs. Greg helped with the data collection, acting as a scribe with my field notebook as I measured lengths, widths, and depths of the footprints with digital calipers. As we did this, I could tell Tom’s mind had gone somewhere other than gathering data about the dinosaur tracks. At some point, he asked to borrow my tape measure, and he immediately went about measuring the length, width, and thickness of the slab. He sat down, wrote in his notebook, and then revealed what he was thinking.

“Greg, do you think we could get a front-end loader down here to take this up?”

I was surprised by Tom’s question, but shouldn’t have been. As an ichnologist, I’ve never been much of a collector. My work normally consists of describing, measuring, and photographing trace fossils, recording their locality information, then bidding adieu, sometimes never seeing them again. After all, I don’t have a museum with storage space or research labs at my disposal, let alone collection managers and the means for collecting large, heavy rocks. On the other hand, Tom has all of these amenities available to him, along with a collecting permit. Why did he have a collecting permit? We were actually in Great Otway National Park, which meant that no fossils could be taken without the written permission of the Australian government.

Thus Tom had made a perfectly valid inquiry. He wasn’t planning to let this big hunk of rock stay here on Milanesia Beach, but instead was already plotting how to put it in Museum Victoria. His scribbling consisted of back-of-the-envelope calculations of the approximate length, width, and height measurements, which yielded volume, which was then multiplied by density of the rock – sandstone interbedded with siltstone, which was about 2.7 g/cc, or more than 2.5 times the density of water. This yielded an estimated weight of about 700 kg (1,500 lbs) for the rock in front of us.

Amazingly, nearly a year later, in early June 2011, Tom, with the help of Pat Vickers-Rich, their daughter Leaellyn Rich, Greg Denney, David Pickering (Museum Victoria), and personnel from Parks Victoria succeeded in carrying out his quixotic goal of transporting this block of rock with dinosaur tracks safely off the beach. It and the other block containing dinosaur tracks from the same site were then transported and deposited in Museum Victoria in Melbourne, where they are now stored for future reference and further study.

Tom measuring the first block of dinosaur tracks on Milanesia Beach, plotting how to bring ‘em back alive, er, well, you know what I mean. Photo stolen brazenly from Dinosaur Dreaming.

In this video (produced by Museum Victoria), Tom explains the scientific significance of the Milanesia Beach dinosaur tracks, although he’s giving this explanation from the relative comfort of a storage room at the museum in Melbourne. Watch further, and you’ll see both Tom and Greg helping with the recovery of both blocks containing the dinosaur tracks, which were put on a small front-loader and carried up the trail from the beach.

Oh, right. There was a second block of dinosaur tracks. Greg discovered that one. With that, he handily provided yet another reason why academic paleontologists are extremely dependent on non-academic folks to make significant contributions to our science. Greg’s discovery was also a lesson in hubris for me. I was so giddy (and more than a little prideful) about finding the first block, I didn’t bother to look around to see if any more like it were nearby.

Greg did. So while I was self-satisfyingly writing field notes about the tracks on the first block, and imagining future fame (perhaps even an appearance on The Colbert Report), he was looking at every nearby boulder. Suddenly, at some point he started acting like a larrikin, and ran around the beach looking for a piece of driftwood. Within a few seconds, he found a 2” X 4” board (you’d be surprised at what washes up on some of these beaches), and quickly placed one end under a boulder less than 2 m (6.5 ft) away from where I sat. Clearly inspired by Archimedes, he started to flip the rock by using the board as a lever.

“Greg, what are you doing?”, I asked, as Tom and I watched him with slightly alarmed curiosity.

“This rock is the same as that one!” he shouted gleefully.

As if watching a tennis match, Tom and I swiveled our heads back-and-forth between the slab with the dinosaur tracks and the one Greg was attempting to turn over. He was right: they matched perfectly, although this one was upside-down, with its uppermost surface hidden from view. Realizing that Greg had, indeed, not turned into a galah, we ran over to help, and got the block turned over.

On its top surface were more dinosaur tracks. I pulled out a small brush from my field vest and cleaned off the distracting modern beach sand on its surface, and we then stared at the lithified sand from a 105-million year-old floodplain. Sure enough, some of this Cretaceous sand had been molded into the three-toed shapes of dinosaur feet. So only three hours beforehand, when we first descended onto Milanesia Beach, only two confirmed dinosaur tracks had been found in the Eumeralla Formation of western Victoria. Now we had 24. You could say we were having a good day.

The second block of dinosaur tracks from Milanesia Beach, minutes after Greg Denney discovered it. It has at least eight tracks on it, probably all of them from theropods, and its layering and rock types perfectly match those of the first block with dinosaur tracks I had found three hours before. With this slab, the number of dinosaur tracks discovered at Milanesia Beach went up about 50%, and our respect for Greg went up immeasurably.

About a week later, Greg Denney demonstrates how he found the second slab and its dinosaur tracks at Milanesia Beach by using a lever to move weighty rocks. Here he is assisted by my wife Ruth, who had just arrived in Australia a few days before (but looking completely unaffected by jet-lag).

Greg’s method for finding the tracks was both simple and brilliant. He had noticed the thickness of the first block, its thinly interbedded sandstones and siltstones, and a gray siltstone a little more than halfway down its thickness, looking much like a different ingredient in an otherwise monochrome layer cake. He then glanced around to see if any other boulders shared those traits, and matched one of them with the one in front of me. Seeing that the gray siltstone bed was less than halfway down its thickness, he correctly surmised that it was wrong-side-up, and intuited that the dinosaur tracks could be on its top surface. He was right.

Photo of me studying the dinosaur tracks from the block I found on Milanesia Beach; the block Greg Denney found is in the foreground. Look for the gray band of siltstone in both blocks, which along with the little detail about dinosaur tracks being on their top surfaces shows they were originally part of the same bed. Photo by Ruth Schowalter, taken a week after the initial discovery

Again, there was little time to celebrate, as it was now mid-afternoon on a near-winter day. This meant we were soon going to lose our sunlight, and we still had a long uphill hike ahead of us back to the car park. Tom quickly measured the second slab’s dimensions and figured out its weight. He reckoned it was about 400 kg, smaller than the first one, but still too massive for any (or all) of us to haul up the trail.

I hurriedly photographed the overall surface, conscious of how our light would soon disappear, and started sketching the forms and locations of the tracks on the surface. I also noted any similarities or differences between these newly found tracks and the ones found a few hours earlier. One of the last items on the agenda was to take a few video clips of me talking about the dinosaur tracks, which I knew later could be edited into a informative video. Looking at these clips later brought a smile to my face, because I was trying to be informative and objective, but also couldn't help but show how thrilled I was with what had happened.

A short video that tells about the dinosaur-track discovery at Milanesia Beach that went out with the press release about the peer-reviewed article. The initial video footage was taken by Greg Denney the same afternoon he and I found the two slabs with their dinosaur tracks. That and other footage taken by me and Ruth Schowalter were then edited and produced by Carol Clark of Emory University.

Greg again assisted me in recording measurements, as I used the digital calipers to gather data on the dinosaur tracks from this second block (number of toes, length, width, depth, and so on), and he wrote down the numbers in my field notebook as I read them aloud. Only then did I take close-up photographs of individual tracks with a photo scale next to each, documenting their dimensions and other details.

Much later, back in the comfort of my office at Emory University in Atlanta,Georgia, I re-measured the tracks from photographs to double-check these results, just in case I had misspoken or Greg had miswritten that afternoon. Because I did not know whether I would ever see these tracks again – notwithstanding Tom’s relentless plotting to acquire them – I was being extra careful about making sure the results could be repeated, checked by others, and otherwise pass peer review in the future.

As the sunlight faded, we decided we had enough for now, and vowed to come back the next week to better assess the geological context of the tracks, study and photograph them once more, and figure out how to recover them from this high-energy, wave-filled place.

Our tracks connecting with the dinosaur tracks of Milanesia Beach on the walk home at the end of the day, June 14, 2010.

Milanesia Beach had been very good to us that day, and as we all slogged up the steep trail, we were filled with smiles and excitement. The three of us did indeed come back the next week, along with geologist Mike Hall and my wife Ruth Schowalter. Once the tracks were relocated, I recorded more measurements and descriptions, while the others did a reconnaissance of the local geology.

We knew that some more science had to be done before we could share our finds with the rest of the world, which was that peer-review thing scientists like to talk about. Nonetheless, we were confident that day would come.

Sure enough, exactly one year later – on June 14, 2011 – my coauthors and I - Tom Rich, Pat Vickers-Rich, Mike Hall, and Gonzalo-Vazquez Prokopec - received the good news that our scientific article had been accepted for publication in the journal Alcheringa. Our peers had confirmed what we knew that day one year before: we had just discovered the best assemblage of polar dinosaur tracks in the Southern Hemisphere, the first dinosaur trackway from the southern part of Australia, and extended the geographic range of dinosaur finds in Victoria.

And although these tracks were only a drop in the proverbial bucket when it comes to paleontological discoveries, they help to affirm the most important point about the fossil record: it gets better every day.

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(This entry is dedicated to the memory of my nephew, Thomas Schowalter, 1995-2011, who loved animals and nature. This story is for you.)

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Peer-Reviewed Article

Martin, A.J., Rich, T.H., Hall, M., Vickers-Rich, P., and Vazquez-Prokopec, G., 2011, A polar dinosaur-track assemblage from the Eumeralla Formation (Albian), Victoria, Australia. Alcheringa: An Australasian Journal of Palaeontology. DOI:10.1080/03115518.2011.597564

News Stories, Blog Links

Escience Commons (Emory University): Polar Dinosaur Tracks Open New Trail to the Past

Museum Victoria: First Victorian Dinosaur Trackway

Dinosaur Dreaming: Our Dinosaur Tracks

Cosmos Magazine: Rare Dinosaur Footprints Found in Victoria

Smithsonian Magazine: Victoria’s First Dinosaur Trackway

El Mundo: Hallan huellas de dinosaurios polares australiano

WIRED: Huge Group of Polar Dinosaur Tracks Discovered in Australia

Livescience.com: Tiny Dinosaurs Left Footprints On Ancient South Pole

Daily Mail (U.K.): The Wonderful Lizards of Oz: Over 20 Three-Toed Dinosaur Tracks Found on Australian Coast

Australian Geographic: Polar dinosaur trackways found inVictoria

The Dinosaur Tracks of Milanesia Beach: Part I

2011-08-09T10:30:00.000-04:00

Because of the sparse and uneven record of dinosaurs in Australia, their fossil footprints are more valuable here than anywhere else on Earth.

- Thomas H. Rich and Patricia Vickers-Rich, A Century of Australian Dinosaurs (2003).

The Preamble

Dinosaur tracks are hard to find. This humbling realization struck me during the third week of a month-long field excursion in May-June 2010, while doing field work along the craggy coast of Victoria, Australia. Why was I there, engaging in such an apparently fruitless quest? Paleontologist Tom Rich of Museum Victoria had invited me to look for trace fossils made by dinosaurs and other Cretaceous animals that might be preserved in the rocks of Victoria. Yet as was often the case with looking for fossils of any kind, there were no guarantees of success. He and I had already searched more than a hundred kilometers of coastal cliffs and platforms east of Melbourne, and were then working our way through sites west of there.

Here are four three-toed dinosaur track,s preserved on a block of sandstone at Milanesia Beach, Victoria (Australia). They’re faint, but there – look closely for all four. These tracks were probably made by small theropods on a river floodplain during a polar summer about 105 million years ago, when Australia was close to the South Pole. On June 14, 2010, I discovered the block that contained these tracks, and a few hours later, Greg Denney found another block with more tracks. This is a big deal, as they represent the greatest number of polar dinosaur tracks found in any one place in the Southern Hemisphere. It’s enough to make you want to do a happy dance. Scale bar in photo (lower left) = 10 cm (4 in).

So a bit of stubbornness underpinned our visit to Milanesia Beach, located in southwestern Victoria, Australia. Milanesia Beach is about a three-hour drive from the big city of Melbourne, but is a relatively isolated place. A testament to its relative inaccessibility is that, despite its possessing a beautiful beach, framed by dramatic seacliffs, the people who normally see it are not swimmers, surfers, or sunbathers, but hikers. Moreover, it is only a brief waypoint for these recreationalists as they otherwise enjoy the gorgeous scenery of one of the most famous walking routes in Australia, The Great Ocean Walk.

On Monday, June 14, 2010, we were not visiting Milanesia Beach to hike and enjoy the bucolic countryside. Instead, Tom Rich, local guide Greg Denney (of nearby Apollo Bay) and I were there to look for fossils in that area that area dating back to about 105 million years ago. The landscape was certainly very different back then; it was a time when Australia was close to the South Pole, and dinosaurs walked across broad floodplains of rivers that coursed through its circumpolar valleys.

Milanesia Beach was a new place for me, and it might as well have been new for Tom, as he had not visited it in more than 20 years. His main reason for looking at its rocks was for fossil bones, especially those of dinosaurs or mammals. My purpose, however, was different. I am an ichnologist, and was there to look for trace fossils, vestiges of life that would most often consist of burrows and trails made by invertebrate animals, like insects, crustaceans, or worms. Tom had invited me to come to Victoria to fulfill this purpose, which was to find as many trace fossils as possible. If we were really lucky that day, though, these rocks might also reveal trace fossils of vertebrates, such as the burrows or tracks of mammals, dinosaurs, or other back-boned animals. Unfortunately, during the preceding three weeks of field work, I had only found a few invertebrate trace fossils and no vertebrate trace fossils. We seemed more than due for a big break.

It was a fine day, denoted by crisp morning temperatures and overcast conditions, but with no signs of the antipodal winter thunderstorms – accompanied by rain, gusting winds, and powerful waves – that had kept us off the coastal outcrops for much of the previous week. Earlier that morning, Tom and I drove from where we were staying in Apollo Bay, picked up Greg at his home along the way, and parked our field vehicle near a trailhead, about 2 kilometers upslope from the beach. The walk down to the outcrops, punctuated by muddy, slippery patches, promised a vertically challenging slog later in the day, just when we would be most spent from our explorations below.

The sign at the trailhead (top) along the Great Ocean Walk telling us the distance to Milanesia Beach. Annoyingly enough, it said absolutely nothing about uphills and downhills along the way. But we were gratified that none of us had brought along bicycles, dogs, cats, tents, fires, or any combination of those items.

Within about 15 minutes down or up this trail, you get some great views, including this first glimpse of Milanesia Beach the morning of the dinosaur-track discovery. It’s a beautiful place with beautiful trace fossils. Now if only it had a pub at the trailhead, it’d be perfect.

Greg, who had joined us for our scouting rocks of the Lower Cretaceous Eumeralla Formation composing the dramatic cliffs near Apollo Bay, had a long-standing relationship with Tom as a field assistant and friend. He had grown up in the area and had the good fortune of living next to one of the most famous dinosaur sites in Australia, Dinosaur Cove. In the 1980s, Greg and his father (David Denney) assisted Tom, Pat Vickers-Rich, and a crew of volunteers with some of the most technically difficult conditions any dinosaur dig site should ever have to endure, detailed by Tom and Pat in the book Dinosaurs of Darkness (2000, Indiana University Press). In our more recent venture in June 2010, Greg had quickly proved a valuable asset in our field endeavors, suggesting roads and parking spots for our field vehicle, and advising on safe access points for outcrops via trails leading from wherever we parked.

Here’s a brief interview I conducted with Greg Denney about his and his father’s (David Denney's) role in the recovery of dinosaurs at Dinosaur Cove. Fittingly, this interview was done at Dinosaur Cove, and the day before we discovered the dinosaur tracks at Milanesia Beach, only 9 km (5.5 mi) west of there.

Greg had also become my ichnological apprentice during our previous week together in the field, and was now quite good at spotting small fossil invertebrate burrows in Cretaceous outcrops. I would have liked to take credit for his rapid ichnological success because of my extraordinary teaching abilities, but (less delusionally) I instead chalked it up to his spending much of his life outdoors. After all, he had already trained his eyes to pick up small details in his natural surroundings, such as wallaby tracks, echidna dig marks, and kangaroo poo. These skills also had not been sullied by the constant distractions of “big-city life,” a challenge I face every day when not in the field and living at home in the metropolitan area of Atlanta, Georgia (USA).

The 30-minute trip promised by the trailhead sign next to the parking area was surprisingly accurate, considering how carefully we placed our feet while walking down the steep, winding track. Toward the bottom of the trail, we also had to cross a small stream teeming with freshwater leeches. Other than these blood-sucking parasites, it was no big deal, and all three of us had been through far worse. At the bottom of the trail, we were greeted by an upside-down sign bearing the usual warnings about all of the potential forms of mayhem and death that awaited us if we proceeded.

An upside-down trail sign at Milanesia Beach, which was either auspicious or cheeky, depending on perspective. (Naturally, I choose “cheeky.”) Note all of the graphic admonitions of impending doom if you bother to go on from that point, none of which we heeded.

On the more level ground of Milanesia Beach, two choices faced us in our fossil explorations. Either go to the outcrop on our immediate right with only beach sand in front of it, or to a more modest outcrop on our left, with our path complicated by numerous blocks of rock that had fallen from cliff-faces above. We looked briefly at the closest part of the outcrop to the right, but these rocks seemed too coarse-grained to have many discernible trace fossils. Fine-grained sandstones or siltstones are much better for preserving identifiable invertebrate burrows or vertebrate tracks. Thus we chose to go left, a decision that was helped by high waves already lapping against the outcrop on our right.

A view over our shoulders after exiting the trail onto Milanesia Beach, showing a coarse-grained sandstone without any trace fossils. In other words, boring. What was exciting, though, was getting a glimpse of the Milanesia Beach fishing hut (arrow), which apparently has its own Facebook fan page. (You didn’t believe me, did you?)

While walking parallel to the shoreline, we quickly went from a sandy beach to rocky shore. Some of the blocks of rock we passed were much smaller and rounded than others, providing indirect clues of their relative time on the beach. For example, the surf had shaped the smaller and more rounded rocks for a longer time than the bigger ones, and the larger blocks retained angular corners from their more recent breakage off nearby cliff faces. Normally in a talus field like this, I would just stroll across it and not spend much energy looking at each stone for its paleontological value. Nonetheless, I did glance at them, albeit more out of a sense of self-preservation while making sure I stepped in all the right places and didn’t slip on any slimy algal films.

Meanwhile, we stopped occasionally to scan the rocks in the vertical outcrops, as well as the larger angular blocks scattered across the upper part of the shore. The several-meter-high vertical exposures of layered shale, sandstone, and conglomerate were at the top of the beach, marking where the sea had eroded these sedimentary strata. The surf crashed behind us, causing us to shout to one another as we pointed out anything of geological interest. We also warily watched the sea for any rogue waves or elevation of the tide that might catch us by surprise. Field work along the Victoria coast is treacherous enough to encourage a healthy paranoia in its practitioners, and that day was no different.

Cretaceous outcrop to the left, ocean waves to the east on Milanesia Beach. You might say we were stuck between rock and a wet place. Tom is walking in front, Greg is just behind him, and I was lollygagging behind, which later turned out to be a good thing. You can even see how my footprints (left) show where I looked at the outcrop, then backtracked to get a better overall view.

In retrospect, we were fortunate to have the winter solstice approaching that time of the year, which meant the sun would begin to set close to 5:00 p.m., thus urging us to use our time judiciously. Sure enough, within less than 10 minutes of our arriving, Greg and I started finding trace fossils – invertebrate burrows – in fine-grained sandstones and siltstones exposed in the outcrop. One type of burrow was a stubby vertical cylinder. Another was a thin, reddish J- or U-shaped structure; both were formerly open tubes that had been filled with sand very soon after they were made, more than 100 million years ago. Each burrow form was abundant in the thin strata.

Wow, look – invertebrate trace fossils! Two types were at Milanesia Beach, identifiable by size, color, orientation, and other features. The first (top) are sand-filled burrows that are mostly horizontal, but with some short vertical shafts. These sometimes have an internal structure that show their tracemakers – probably insect larvae – packed their burrows with sand behind it as they moved forward. The second (middle) are thin J- or U-shaped burrows, also filled with sand, but colored red by hematite (iron oxide). Sometimes the “U” form manifests as a “J” if only part of the burrow is exposed, but the tops will show a pairing of tubes (bottom) that reveal their true “U’s”. Such burrows may have been made by larval insects, such as dipterans.

These little trace fossils invoked an excitement in me that cannot be described with words, but I’ll try anyway. Such burrows are sensitive indicators about the ecology of this area 105 million years ago, and typical of what you might see in a modern river floodplain. For instance, some insect larvae will dig burrows in the sediment under very shallow water or on the surfaces of emergent sand bars. The presence of these burrows alone was scientifically important, and when put in the context of having been formed in a polar environment, they were doubly significant.

You see, insects and other invertebrates in polar environments can’t burrow into frozen sediment. Rather, they wait until late spring or summer to make their domiciles or brooding burrows, after the uppermost layers of sediments have thawed out, or once new, soft surfaces have been formed by sediment deposited by spring run-off. Moreover, the physical sedimentary structures associated with the trace fossils, consisting of ripple marks and cross-bedding, also indicated a healthy flow of water, which would have more likely formed during a polar spring or summer following snow melts.

Along those lines, I had published a paper in 2009 about physical sedimentary structures, invertebrate burrows, and vertebrate tracks associated with a point bar in the Colville River, on the North Slope of Alaska. Hence the rocks in front of us, when combined with what I had learned from that Alaskan point bar a few years beforehand, almost acted like a time machine. The Cretaceous rocks of Australia and the modern sediments of Alaska could be compared as polar ecosystems, even though they were separated by more than 100 million years and thousands of kilometers.

Poverty Bar, a point bar of the Colville River on the North Slope of Alaska, which during the summer holds heaps of insect, nematode, and vertebrate traces. This makes for a nice modern analogue when looking at sedimentary rocks formed in Cretaceous polar environments of Australia. Why yes, those are grizzly bear tracks just to the left of mine, which is why you won’t hear me whinging about freshwater leeches in Victoria. By the way, those are Cretaceous rocks (partially covered by vegetation) in the background, which contain dinosaur bones and tracks from other Cretaceous polar environments. But that's another story.

Yet another justification for my growing elation was that these burrows closely resembled trace fossils I had seen in rocks at another place - Knowledge Creek- which was just a few kilometers east of us. Knowledge Creek is the place where the only well-documented dinosaur track was discovered from the Eumeralla Formation. In 1980 – a little more than 30 years before he, Greg, and I stepped foot on Milanesia Beach together – Tom and Pat found this track, which was probably made by a small ornithopod dinosaur.

The only previously documented dinosaur track from the Lower Cretaceous Otway Group, probably made by a small ornithopod dinosaur, and discovered in 1980 by Tom Rich and Pat Vickers-Rich at Knowledge Creek, only 2 km (1.2 mi) east of Milanesia Beach. It’s in Museum Victoria in Melbourne, and a rare example of a dinosaur track from Victoria. Or, should I say, was.

Although I had visited Knowledge Creek three times in recent years (2006, 2007, and 2009), I had not found any other definite dinosaur tracks there. Nonetheless, I was lucky enough to have discovered possible dinosaur burrows, and invertebrate trace fossils nearly identical to the ones we were seeing that morning at Milanesia Beach. Similar sedimentary rocks and trace fossils at Knowledge Creek and Milanesia Beach implied similar environments produced these rocks. So perhaps the conditions at both places were conducive to dinosaurs walking across floodplain surfaces, allowing their tracks to get preserved well enough that they would be identified some day.

After photographing and noting the locations of these trace fossils, Greg and I continued down the eastern extent of the beach. Tom, on the other hand, had already gone well ahead of us to look for bones. I think he was glad that Greg was helping with my ichnological investigations, which allowed him to concentrate more on finding the bones of dinosaurs or other vertebrates. In his previous scouting of Milanesia Beach with others of his body-fossil-hunting ilk more than 20 years before, they had not found any skeletal material. Thus they had since written it off as a place to look for such fossils. Nonetheless, he also knew that during that elapsed time, rockfalls and weathered surfaces might have revealed previously hidden body parts, new to human eyes.

Excited about the invertebrate burrows and their host rocks, I turned to Greg as we sauntered down the beach, and said casually, “Now all we have to do is find some of those other things we’ve been looking for. But I won’t say what, because I don’t want to jinx it!” Greg grinned and said, “Righto, say no more!” Somehow he knew I was talking about dinosaur tracks. In our previous forays, I had mentioned these trace fossils as something we should be looking for at every turn.

What was the reason for such vigilance? Well, up until that day, only four well-defined dinosaur tracks had been found in all of the Cretaceous rocks of Victoria, a part of Australia only slightly less in area than California. The first track, found by Tom and Pat at Knowledge Creek, was only about 10 cm (4 in) wide and long. Tom and Pat were doubly lucky that day: once for finding the track, and twice for having the right tools to collect it. Using a hammer and chisel, they carved it out of the rock and hiked out of the site. The latter task was so difficult, they vowed never to return.

Upon their return to Melbourne, they immediately placed the specimen in the Museum Victoria fossil collection. This track later became the template for thousands of reproductions used for science education in Victoria, and photographs of it appeared in many popular-outreach articles and books. Hence it became iconic. For many people, and for more than 25 years, this was the dinosaur track from the Cretaceous of Victoria.

Attentive readers who are also well versed in arithmetic are now waiting for the other three shoes to drop, so to speak, and I’m glad to oblige. In 1989, another isolated dinosaur track was found during a fossil-hunting group led by Tom Rich. Discovered at a place called Skenes Creek, more than 30 km (19 mi) east of Knowledge Creek, but bearing rocks of the same age as those at Knowledge Creek, Dinosaur Cove, and Milanesia Beach. This specimen was also a small ornithopod track, nearly identical to the one from Knowledge Creek. The field crew had a rock saw with them, so they neatly cut the surrounding rock into an easily transportable square slab, and likewise took it to Museum Victoria. Once there, it received a catalog number and sat in a drawer for the next 21 years. I saw it in its museum drawer in May 2010 – only three weeks before our sojourn to Milanesia Beach – and verified it as the second dinosaur track reported from the Eumeralla Formation. However, it still has not been formally described in the scientific literature. (Note to all: I got dibs.)

This space left intentionally blank, but some day will be filled with a photo of the second ornithopod track from the Eumeralla Formation, found in 1989 at Skenes Creek, Victoria, and relegated to a museum drawer for more than 20 years. Ignored no longer, I should be describing it in the upcoming year and will compare it directly to the track from Knowledge Creek.

The other two dinosaur tracks from Victoria were both made by large theropods and are east of Melbourne, at the Dinosaur Dreaming dig site in the geologically older rocks (115-120 million years old) of the Strzelecki Group. I found one in 2006 (not pictured here, because it’s not very pretty), then a dig-site volunteer, Tyler Lamb, found a nicely defined one in 2007, only about 5 meters from the main dig site.

A single dinosaur track from the Strzelecki Group, made by a large theropod dinosaur, and only the fourth definite dinosaur track from Victoria. The track is about 35 cm (14 in) long, which when multiplied by 4.0 gives the approximate hip height of the dinosaur: 1.4 m (4 ft. 7 in). That’s eating size, as in, it would have been big enough to have eaten us, had it been interested in consuming slightly fatty bipedal mammals.

So there you go: four definite dinosaur tracks from all of the Cretaceous of Victoria, after more than 100 years of paleontological research in those rocks. The two tracks from 105-million-year-old rocks west of Melbourne – Knowledge Creek and Skenes Creek – were attributable to small ornithopod dinosaurs. Large-sized theropods likely made the two 115-million-year old tracks in rocks east of Melbourne.

An abundance of dinosaur bones found during the past 30+ years in this part of Australia, though, indicate a more diverse fauna should be there, and these dinosaurs should have been leaving tracks during the springs and summers in between harsh polar winters. Moreover, in most places where dinosaurs used to live, dinosaur tracks tend to be more abundant than their bones. Frustratingly enough, the situation in the Cretaceous rocks of Victoria was just the opposite. Paleontologists deal with gaps in the fossil record all of the time, but this was a big one for the fossil record of polar dinosaurs in Australia.

Fortunately, that gap was about to get filled. How? That's the subject of my next entry, coming soon.

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Further reading:

Polar Dinosaur Tracks Open New Trail to Past, by Carol Clark: Emory University news release, Aug. 9, 2011

Martin, A.J., Rich, T.H., Hall, M., Vickers-Rich, P., and Vazquez-Prokopec, G., 2011, A polar dinosaur-track assemblage from the Eumeralla Formation (Albian), Victoria, Australia. Alcheringa: An Australasian Journal of Palaeontology. DOI:10.1080/03115518.2011.597564

Cruising the Cretaceous of Queensland: Student Edition

2011-07-18T15:46:00.000-04:00

Earlier this month – July 4-8, 2011 – was my third time to see the wondrous Cretaceous fossils of Queensland, Australia. But it was my first with university students in tow to share in that paleontologically inspired excitement. Our trip together to outback Queensland was during the third week of a five-week program for Emory University students taking a study-abroad program in Australia, taught by me and my good friend (and oh yeah, colleague) Steve Henderson from Oxford College of Emory. We did this trip to give them a taste of what life was like in the modern-day outback and 100 million years ago during the Cretaceous Period, when theropod dinosaurs like Australovenator wintonensis (“Banjo”) likely chowed down on hapless ornithopod dinosaurs, and the whopping pliosaur Kronosaurus queenlandicus was ruling the inland seaway that covered much of the area we saw during our trip.

Paleontological innocents abroad, about to get acquainted with the past lives of outback Queensland. And who could resist posing with a life-sized recreation of the large ornithopod dinosaur Muttaburrasaurus langdoni, located in Hughenden, Queensland? Well, OK, I told them their grades depended on it, so they quickly got into the spirit of things.

Our trip was a bit frenzied, involving more than 2,500 km of driving (fortunately all of it handled by B.J., perhaps the greatest bus driver in the history of Australia), and it was done over the course of just five days, but still provided for a most excellent learning experience. Here is a brief synopsis of what happened and what we learned.

Day 1: Monday, July 4 – We started our trip in Townsville, Queensland, which is the home of James Cook University and site for the classroom work we do in the first and last two weeks of the program. The plan was to drive to Winton, Queensland that day, with a stop en route in Hughenden, which is about halfway to Winton. As loyal readers may recall (or not), Hughenden has the Flinders Discovery Centre, which has a mounted replica skeleton of Muttaburrasaurus and many plant, invertebrate, and vertebrate fossils local to the Cretaceous rocks of that area, as well as a smattering of exotic fossils, such as those all of the way from the U.S. This plan worked brilliantly – which is to say, it worked – as we were able to see heaps of fossils in Hughenden while also getting a much-needed lunch break during the six-hour trip from Townsville to Winton.

A few Emory students, admiring a replica of Muttaburrasaurus at the Flinders Discovery Centre in Hughenden. I could swear one of them said, “It looked much bigger on TV.”

Later that same afternoon, we made it into Winton with time to spare for a visit to the Fitzmaurice and Corfield Building. This building, with its unassuming and decidedly non-paleontological name, actually holds a very nice collection of Cretaceous fossils, including one of the better representative samples of fossil plants from the Winton Formation. Its main claim to fame, though, is its life-sized diorama depicting some epic dinosaurian panic inspired by the Lark Quarry dinosaur tracksite, a mere 110 km (68 km) to the south of where we were gawking.

Why run away when you can draw? A dedicated student attempts to render the dramatic diorama of a massive, rampaging theropod dinosaur and a host of fleeing small theropod and ornithopods, viewable at the Fitzmaurice and Corfield Building in downtown Winton.

Lots of real fossils – plants, invertebrates, vertebrates, and (best of all) trace fossils in the display cabinets at the Fitzmaurice and Corfield Building in Winton also made us stop, look, and listen.

Day 2: Tuesday, July 5, 2011 – After staying for the first of two nights in Winton, we got off to an early start in the morning to the Australian Age of Dinosaurs (AAOD) Centre. Here we were treated to a tour of the facilities by Trish (“Tricky”) Sloan, who, with her extensive paleontological knowledge delivered with good-natured aplomb, informed and entertained us about the dinosaurs that had been found near there recently, such as huge titanosaurs, namely Wintonotitan (“Clancy”) and Diamantinasaurus (“Matilda), as well as the baddest of the bad of Australian theropods, Australovenator ("Banjo"). Trish also let us in on a few recent fossil discoveries that will gain the AAOD even more attention from the paleontological community and general public in the next few years (nope, I ain’t telling).

Look at the bones! The Australian Age of Dinosaurs Centre (AAOD) has enough dinosaurs to study for a long, long time. And what do they do anyway? They keep finding more. Do you blame them?

Trish “Tricky” Sloan of the AAOD shows everyone the right way to prepare a dinosaur bone, using the latest tools of the trade, while also making allusions to dental hygiene that elicited a few winces of painful remembrance.

The students were also wowed by a look at the preparation lab, the sizes of some of the bones being prepared, and getting to hold a real dinosaur bone or two. A surprise appearance by David Elliott – who co-founded the AAOD with his wife Judy Elliott –topped off a great morning for everyone. Actually, it was just a surprise for the students, because I asked David to stop by to meet them, and he graciously agreed. (I owe that bloke a slab or two.)

Of course, you can’t go to Winton without visiting the Waltzing Matilda Centre, so we did just that immediately after the AAOD tour so that everyone could learn about the story behind the unofficial national anthem of Australia. What was unexpected about this visit, though, was that one of my students alerted me to a few small dinosaur tracks and other Cretaceous fossils on display in a room containing old medical equipment. Despite two previous visits to their facility, I never knew about this little collection, literally tucked away in a corner. The Waltzing Matilda Centre also has a small replica of the Lark Quarry dinosaur tracksite rendered in cement outside and in the back, which meant that even a “cultural stop” in our study-abroad curriculum kept referring back to paleontology.

Real dinosaur tracks on display at, of all places, the Waltzing Matilda Centre, alongside old medical equipment. Here’s where I would normally make some witty analogy about doctors and dinosaurs, but I’ll leave that up to you.

Fake dinosaur tracks in concrete at the Waltzing Matilda Centre, but based on real dinosaur tracks not too far from Winton. I think the chain was to prevent people from adding their tracks to those of the dinosaurs, which has been known to happen.

This just goes to show you that it is nearly impossible to avoid bumping up against the rich fossil record of central Queensland and its effect on the people of the area. This point was emphasized even more so that evening when we went to dinner at The Australian Hotel in Winton, and the owner, upon hearing I was a paleontologist, went into a back room and brought out a very nice specimen of a theropod dinosaur track for us to study and admire. This impromptu consultation could not have better demonstrated to our students how deeply paleontology has been integrated into the culture of outback Queensland.

A paleontologist walks into a bar, and the bartender brings him a dinosaur track. Sorry, that no joke: it’s all part of being in Winton. Yes, a beer in one hand and a dinosaur track in the other is indeed a dream come true for me. My life is now complete. (Note also how Steve is looking enviously at both items.)

Wait, I didn’t tell you what we did after the Waltzing Matilda Centre, which was make our way 110 km (68 mi) south of Winton to one of the most famous dinosaur tracksites in the world, Lark Quarry. I’ve written about this tracksite several times before (here, here, and here), so I won’t rehash why it’s so revered.

You have to really want to see the Lark Quarry dinosaur tracksite (which we did), and it was worth every kilometer of travel along that mostly unsealed road while dodging sheep, cows, and ‘roos.

And as a testament to the enduring (and growing) popularity of this tracksite in the public imagination, a big, boisterous crowd on a regularly scheduled tour preceded us. Fortunately, a trail outside of the Lark Quarry Conservation Building beckoned and gave us an opportunity to learn about the geology and geomorphology of this desert region. So Steve, an expert teacher of desert geology in the field, gifted us with a lecture on that topic and engaged in discussion with the students about the landforms around us and how they originated. For example, most erosion in this arid environment was, paradoxically enough, a result of running water, caused by flash flooding from infrequent rainstorms and torrential runoff.

Learning geology in what used to be called, before The Computer Age, “the field,” “outdoors,” or simply “outside” (I know, how retro) on the Spinifex Trail outside of the Lark Quarry Conservation Building, south of Winton, Queensland. This quaint approach to education mostly worked, although judging from the photo, most of our students still need some help in lengthening their attention spans. To be fair, I’m sure they were still puzzling over the meaning and implications of "swagmen," "tucker bags," and "jumbucks" learned earlier that day at the Waltzing Matilda Centre.

After a walk on the trail, it was time to see the tracksite, which we had all to ourselves as the last tour group of the day. Our guide, Vern, told the students the “old” (traditional) story about how a group of more than 100 small dinosaurs – ornithopods and theropods – were startled by the approach of a much larger theropod dinosaur, triggering a stampede nearly 100 million years ago that was recorded by their tracks in the then-soft lakeshore sediments. The students were also awed by this place (at least, I think they were), and one told me later how he suddenly realized, while staring at the tracks, “Wait a minute. There were dinosaurs right here!” Those are the “ah-ha!” moments teachers of paleontology live for, and again demonstrates how trace fossils, like, totally rule.

Students lining up along the walkway overseeing the thousands of dinosaur tracks preserved at Lark Quarry. Don’t worry, I made sure all of the students got out OK, because it would be very embarrassing to get accidentally locked in.

Paleontologist Barbie makes a special guest appearance at Lark Quarry to see the tracksite, and helpfully explains that Wintonopus is an ichnogenus and Wintonopus latomorum is an ichnospecies, both of which are based on a distinctive and recurring form of a dinosaur track preserved here, and not of its inferred trackmaker, which was likely a large ornithopod dinosaur. Need to learn more about the basis of naming trace fossils? Well, you came to the right place. And just in case you’re also intrigued with Paleontologist Barbie, a photo album of her recent adventures in Australia are here.

Day 3: July 6, 2011 – Sadly, we said goodbye to Winton on Wednesday morning, but were off to take a dip in the Cretaceous seaway. And there’s no better place to see the fossil evidence for this seaway than at Kronosaurus Korner in Richmond, Queensland. Richmond is about a four-hour drive from Winton if you want to stay on paved roads (which we did), and was well worth the effort, as we saw a great variety of Cretaceous marine fossils there.

Even better, we had a guided tour by Paul Stumkat, who wears a lot of hats at Kronosaurus Korner: fossil preparator, paleontologist, and paleo-artist. Like Trish Sloan at the AAOD Centre, he was an extraordinary fount of knowledge for our students, and what I originally thought would be a one-hour tour became two-and-a-half times as long. (This was a good thing.) Paul not only led us through the regular exhibits of pliosaurs and other plesiosaurs, ichthyosaurs, turtles, fish, ammonites, and much, much more, he also took us into their fossil-preparation lab and a storage shed, the latter of which held a very large and newly discovered Cretaceous fish.

The students get to view an actual fossil specimen of the giant pliosaur Kronosaurus queenlandicus, after seeing a life-sized recreation of one only two weeks before in the Museum of Tropical Queensland. Paul Stumkat (left) of Kronosaurus Korner regaled us with tales of fossils found and yet to be found in the Cretaceous rocks around Richmond.

Day 4: July 7, 2011 – The previous night, we got into Charters Towers to get a little bit of sleep before our next leg of the trip, got up early in the morning, and headed north to the Undara Lava Tubes, which are just south of Ravenshoe, Queensland. Although formed in the mere Pleistocene (190,000 years before now), these geologic features are very spectacular, and, after all, we were also teaching environmental geology along with paleontology as part of the study-abroad program. Thus it was an entirely justifiable part of the trip while also being on our way to the coast.

One of the many lava tubes at Undara National Park, with our students wading through its moist interior. This is where some psychoanalyst might make a remark about the symbolism of descending into a long, dark, tunnel, no doubt while riding a train and smoking cigars. Fortunately, we instead talked about hot magma, subduction, and orogenies.

Lava tubes are formed when the outside part of a basaltic lava cools quickly, but the liquid hot magma continues to flow underneath that hardened crust, leaving a huge, hollow tunnel. Basaltic lava has low viscosity – owing to its high temperature (about 1,200° C) and low silica content, among other factors – and in this instance, the lava flowed a long ways: just more than 160 km (> 100 mi) from the central volcano. Because Steve and I had never been there, nor seen lava tubes like these, our group was folded into a guided tour, which was excellent. The students even became immersed in their subject by, well, immersing themselves. The walkway into one of the tubes was partially underwater, so we ventured undaunted into wetness and darkness. A good time was had by all.

That night (our last of the trip) we spent in Ravenshoe, which began with Steve and me making sure we celebrated our lava-tube-filled day with dinner and an adult beverage at Tully Falls Hotel, the highest pub in Queensland. Later, Steve and I joined a spirited discussion with the students at the pub hotel (where we stayed overnight). Much to our delight, the students were earnestly proposing and debating a wide range of topics – paleontological, geological, biological, environmental, and otherwise. It was almost as if they were behaving like real paleontologists or geologists. We felt like proud parents, only with the decided advantage of not having to pay for their college tuition.

Day 5: July 8, 2011 – Our last full day of the field trip, in which we went from Ravenshoe to Mission Beach and back “home” to Townsville, involved more environmental geology and a little bit of ecology, but with a surprise paleontological twist. In the morning, we witnessed the southern edge of the Daintree rainforest, a World Heritage site noted for its incredible biodiversity, and a brief stop at a roadside overlook along the way gave us a taste of what was there. Our main goal for the day, though, was to see how Cyclone Yasi, a Category 5 tropical storm, had affected the coastal region near there when it made landfall in Queensland on February 3, 2011.

Once we arrived at the coast, we went to the visitor’s center in Innisfail, a place that had been also hit hard by Cyclone Larry in 2006. While there, I asked one of the employees about how the cassowaries (specifically, the southern cassowary, Casuarius casuarius) had fared since the most recent cyclone, knowing that many of their fruit trees – which they depended on for food – had been knocked out of commission. She then gave us a great tip about a nearby area (Etty Bay, just north of Mission Beach) that had easy-to-see cassowaries.

Why did the cassowary cross the road? None of your bloody business, mate. (P.S. I really love these birds.)

Knowing that this might be a once-in-a-lifetime opportunity to our students to see live cassowaries outside of a zoo, we headed to Etty Bay. Sure enough, there they were, walking around in the open, in an uncomfortable coexistence with people on holiday at the beach. Why was this uncomfortable (at least, to me)? Because the southern cassowary is one of the few birds capable of severely injuring or killing humans (although this reputation is mostly a bum rap, as they’re nowhere near as dangerous as dihydrogen oxide).

Nonetheless, before exiting the vehicle, Steve and I made sure that all of the students were well versed in “cassowary safety” by giving them the following tips:

• Do not feed them, no matter how much they may beg, whimper, or threaten.
• Do not approach them in any way, whether aggressively, whimsically, or with an ironic, post-modern perspective.

• Do not put your arm around them to pose for pictures, especially while wearing silly hats.

• Do not attempt to place a saddle on them or otherwise attempt to ride them.

• Do not, by any means, make fun of their secondary flightlessness. (This really makes them mad.)

A few students, distracted by a beautiful beach at Etty Bay, Queensland, temporarily forgot that a large modern theropod dinosaur was sitting just behind them, while others watch warily. No worries, they all steered clear of one another, and no harm was done by either humans or dinosaurs.

Fortunately for our students (and the cassowaries), the former heeded our warnings and kept respectful distances from these potentially dangerous birds. Why were these avian theropods hanging out by the beach, other than for the pleasant atmosphere? Evidently people had been feeding them, so they were now habituated to human food and presence, which is ultimately not good for the cassowaries.

Meanwhile, I was in ichnological heaven, because these big birds were making abundant and exquisitely detailed three-toed footprints on the beach sands. These tracks are absolutely wonderful modern analogues for three-toed dinosaur tracks, especially those made by theropod dinosaurs. It also served as a very nice example of how cassowaries are wide-ranging in their habitats. Normally viewed as “forest birds,” cassowaries play an essential ecological role in the rainforests of tropical Queensland, eating a wide variety of fruits and dispersing seeds through their excrement (colloquially known as “poo”).

Gorgeous tridactyl (three-toed) tracks of an adult southern cassowary on beach sands of Etty Bay, looking much like the tracks of a non-avian theropod from the fossil record.

Close-up of a cassowary track, showing all three toes, claw marks, and skin impressions. The smallest of the three toes is digit II, the middle one with the “killing claw” is digit III, and the remaining one on the outside is digit IV. This one is from the cassowary’s left foot.

Thus it was very satisfying for me (in a contrarian sort of way) to see cassowaries also leaving so many of their traces in intertidal environments, too. This seeming anomaly provided for a nice point of discussion with the students later, when Steve and I later lectured (on the beach, of course) about coastal geology and the interactions of animals from nearby forest ecosystems with coastal environments. I also asked them, “Where did we see tracks like these just two days ago?”, and we were very happy to hear them all say, “Lark Quarry!” In other words, they easily made the connection between these modern avian dinosaur tracks and Cretaceous non-avian dinosaur tracks, both of which they were able to view directly in Queensland, Australia only days apart from one another.

From there on, we only had a few stops along the way back to Townsville, and the trip was officially over that night as we drove into the city. I bade everyone farewell, and wished them luck for the last two weeks of the program, with Steve in charge. The next day, I left for Melbourne and Museum Victoria for a few days of research.

With the end of this trip, though, let us hope that its sights, sounds, and other sensations of the Cretaceous and other times of Queensland, Australia will continue in our imaginations for our collective lifetimes. After all, this is why we do study-abroad programs: to broaden ourselves. Cheers, mates!

Many thanks to: Steve Henderson; Justine Garcia (our illustrious graduate teaching assistant); our willing students, Emily, Hank, Jenna, Iris, Jordan, Giacomo, James, Ally, Meredith; Paleontologist Barbie; and especially the Cretaceous fossils and modern fauna and flora of Australia, because we could not have done this trip without you.

Teaching the Past, Cretaceous and Other Times

2011-07-03T02:59:00.000-04:00

It’s a safe generalization to say that academic paleontologists devote much of their time and energy to educating non-paleontologists about the wonders of past lives. This lofty goal might be accomplished in an official capacity as a university professor or a museum researcher, or unofficially through public speaking, publishing popular-outreach books, or – to be totally modern, hip, and self-referential – writing a blog. In this instance, I am mixing official and unofficial duties by sharing a few of my experiences with teaching paleontology to undergraduate students at my university (Emory) during a study-abroad program in Queensland, Australia.

A happy group of American university students, which is as they should be, because they are in Queensland, Australia learning about its paleontology. Little do they know their state of fossil-induced bliss is about to be interrupted by a lurking Early Cretaceous pliosaur, Kronosaurus, inexplicably occupying an aerial environment and in the present. (I’ve been trying to tell them all along that some things are worse than a failing grade.) Photo taken by me at the Museum of Tropical Queensland in Townsville.

This Emory study-abroad program has been around on-and-off since 2006, but this year’s is the first where I’ve had the opportunity to teach paleontology as its featured attraction. The two courses we are teaching concurrently in the program are environmental geology and paleoecology, the latter course advertised under the rather swishy title, “Ecosystems through Time.” Because I am also a geologist and have taught environmental geology many times (not to be too much of a tall poppy about it), it has been both fun and challenging to retrofit that course to better emphasize all of the fantastic case studies in Australia pertinent to this subject. Think about it, but not for too long. Shoreline processes and cyclones in an island-continent-nation that has most of its population living in big cities along the coast, soon to be affected more so by accelerated sea-level rise? Check. Catastrophic flooding that takes away precious lives and wipes out expensive property? Check. Earth resources that, once exploited through mining, set off all sorts of environmental problems and controversies? Check. Indigenous perspectives and how those views synch perfectly with modern ecological thinking, that is, what affects the landscape also affects the Great Barrier Reef? Check, check, and check.

A plume of sediment caused by flooding in Queensland in January 2011, on its way to the Great Barrier Reef, an example of how the terrestrial and marine environments are connected in Australia, and why environmental geology is a good means for exploring this concept. Photo from EarthSky.

And as yet another example of why plate tectonics rules our lives (whether we like it or not), we talked about how a Chilean volcanic eruption and its andesitic ash cloud drifting across the Pacific Ocean disrupted flights into and out of southern Australia during the past several weeks, overlapping with the start of this program. So scratch what I said earlier about how “challenging” it has been to incorporate Australia examples, as it was all too easy. Australia is all about geology and how its affects people’s lives here.

But what about paleontology, you ask? Perhaps an attentive reader (that is, all of you) noticed I used the plural pronoun “we” when describing who is teaching the program, and I am fortunate to be accompanied by my friend and paleontological-geological-educational colleague, Stephen Henderson in this program. The way we arranged the program is that I teach both classes (environmental geology in the morning, paleoecology in the afternoon) in a classroom setting the first two weeks.

This is not my colleague Steve Henderson, although it could be, depending on his mood. It’s actually a wonderfully rendered large theropod dinosaur, made so that it appears to be bursting out of the Museum of Tropical Queensland in Townsville, Queensland. As if a huge predatory dinosaur is not enough for some people to get a clue, there’s a sign warning everyone to stay out of the garden, too.

After Steve arrives in Australia (which he already did, two days ago), we will co-teach the third week on an Outback field trip with the students (more on that later). At the end of that five-day trip, I wave goodbye, and Steve teaches the last two weeks of the program. That’s five weeks total for the students, held together (like duct tape, only better) by our graduate teaching assistant, Justine Garcia, who is here for the entire duration of the program and lives on the James Cook University campus in Townsville, Queensland with the students. So the students are getting paleontology for the full five weeks they are here in Australia. Best of all, they have an intensive exposure to this topic in the middle of the program, in which we give them both barrels, chock-a-block with paleontological musings and insights inspired by real fossils from Australia.

Wow, real Cretaceous fossils from Australia! These are what you hold up when someone questions what paleontologists know about the life of the ancient past. Specimens in the Flinders Discovery Centre of Hughenden, Queensland, which my students will get to see tomorrow.

And oh what fossils Australia has! Just in the first two weeks of the program, we read and discussed articles about: the world-famous Ediacaran fossil assemblage of South Australia; the evidence (thus far) for the early evolution of four-limbed vertebrates (otherwise known as tetrapods) in Australia; the well-known dinosaurs, crayfish, and other biota of the formerly polar environments of Victoria, Australia; the world-famous Riversleigh fossil assemblage from western Queensland; and the newly discovered Pleistocene megafauna tracksite from western Victoria, recording the movements of the largest marsupials that ever lived.

Megafaunal tracks from the Volcanic Plains of western Victoria, made by the largest marsupials known – diprotodontids – during the Pleistocene Epoch. These and other mammal tracks were described and interpreted in a recent paper titled “A Diverse Pleistocene Marsupial Trackway Assemblage from the Victorian Volcanic Plains, Australia” by Stephen Carey and many others (2011), Quaternary Science Reviews, v. 30, p. 591-610. And my students learned about this just this past week while we were in Australia.

This next week, our field trip into the outback will then focus on the Cretaceous of Queensland, with fossils of both the terrestrial and marine realms of that time. Loyal readers can now live vicariously through our students, as they learn about the past lives of the area around Winton, the Cretaceous Lark Quarry tracksite, the newly documented (and totally cool) Cretaceous dinosaurs of this area; the Cretaceous marine invertebrates (ammonites, belmnites, and bivalves, oh my!) and marine reptiles (ichthyosaurs, plesiosaurs, and turtles, oh my!) of the former inland sea that covered this part of Australia about 100 million years ago.

So I feel very privileged to share that educational experience for the first time with our students this next week. It’s not all about the discoveries we make as paleontologists – you know, the ones that result in headlines, invitations to talk shows, and dancing with Hollywood stars (OK I made up that last one, but it could happen). Instead, it’s about those inward discoveries others can make with us paleontologists as they learn about what preceded us on and in the earth’s land, sea, and sky. Welcome to the Cretaceous of Australia, my students, and may you love it as much as I do.

One of my favorite dinosaur recreations, which is of an unspecific hypsilophodontid dinosaur, a common inhabitant of the formerly polar Cretaceous environments of Victoria, Australia. Display in the Museum of Tropical Queensland, Townsville, Queensland, and me (wearing Ray Troll t-shirt, of course) for scale.

The Dinosaur Tracks of Western Australia May Go Extinct

2011-06-12T11:33:00.000-04:00

You really have to want to visit Broome and nearby environs in the Kimberly region of Western Australia, because it’s a long ways from nearly everywhere else in the world. Even of the Australians I’ve met, relatively few have been there, despite Broome’s beautiful beaches, camel rides on those beaches, a wonderful open-air theater (the oldest In Australia), pearling history, longtime connections to Asian culture, small-town feel, and charming locals. Oh, and its dinosaur tracks, which of course was one of the reasons why I was motivated to go there with my wife Ruth in 2009.

Anyone up for some “ichnotourism”? At low tide near Broome (Western Australia), you can see some of the biggest dinosaur tracks in the world, made by sauropods about 130 million years ago. Or, you could put a gas-processing plant on top of them and build a port, which will generate absolutely no ichnotourism, stuff up the local environments, and if anything drive people away from the area. Hmm, tough choice: (A) short-term profits benefiting a few people and causing lots of collateral damage, vs. (B) preserving a world-famous natural resource, coastal environments, and cultural heritage that will continue to give back tourism dollars to the local community in perpetuity. Not to bias you, but I’m going with (B). (BTW, lovely wife Ruth for scale.)

It was May 2009 when we decided to go to Broome for a week-long vacation after field work had been completed on the Victoria coast. We had been looking for trace fossils in the Cretaceous rocks east and west of Melbourne, Victoria and had done a final field check for a paper I had just written, reporting the oldest known dinosaur burrows interpreted from the fossil record. As mentioned earlier, there were many touristic incentives for us to go to Broome, but a major factor in our decision to visit was its dinosaur tracks, which can be easily viewed by the public.

Broome had been on my list of places to visit in Australia ever since I had seen a talk in 2002 by Australian dinosaur ichnologist Tony Thulborn. Thulborn’s talk was at the International Palaeontological Congress meeting, held in Sydney that year, a meeting that gave me a great reason for the first of many visits to Australia. His presentation had the deliberately provocative title, “Giant Tracks in the Broome Sandstone (Lower Cretaceous) of Western Australia.”

The summary (abstract) of his talk also promised to provide evidence that these dinosaur tracks were the largest known, which by default made them the largest tracks made by any animals in the history of the earth. It was quite a claim, but he backed it up with photographs and careful measurements, the latter indicating tracks that were nearly 2 meters (6.6 ft) wide! At the end of his talk, he then justifiably bragged, “Mine’s the biggest!” (He assured us he was only talking about the tracks.)

I made a point of seeking out Dr. Thulborn afterwards to discuss his results, partially as an ichno-groupie, but also wanting to introduce myself as someone who was interested in coming back to Australia, perhaps to study trace fossils with him or someone else there. (The studying trace fossils part actually happened, but with other people, and it turned out just fine.) We had a nice, too-short chat about the tracks and fossil tracks in general, shook hands, and I haven't seen him since. Oh well.

Even more unfortunate, the research on the tracks seemed to halt after 2002, which I understood through the paleontological grapevine (or “bush telegraph”) was related to a large number of complicated reasons, summarized simply as “life.” A reality is that not everything in science gets done, and sometimes that includes really important, high-profile discoveries that involve the “D” word. No, not that “D” – I’m talking about dinosaurs.

In 2009, seven years after meeting Dr. Thulborn, I still remembered his talk and its photos of the spectacular dinosaur tracks near Broome, and knew I still wanted to go there. So I suggested to my faithful field companion, Ruth, that we might consider a trip to Broome after finishing field work in Victoria that year. As mentioned earlier, Broome had plenty of couple-oriented activities other than looking at more Cretaceous rocks. But I must admit that I would not have argued so persuasively about traveling across two continents and an ocean – Melbourne to Broome, then Broome to the eastern U.S. afterwards – if it had not been for the dinosaur tracks there. There really aren’t many places in Australia where you can see such tracks, and in an easily accessible (and free) public place. In contrast, Lark Quarry, the world-class tracksite near Winton in Queensland, charges admission (although it’s worth every penny), and Victoria has very few dinosaur tracks. (Well, OK, scratch that last statement. And you should buy these guys beers next time you see them.)

Naturally, we went and had a great time in Broome for the week we were there, with one of the highlights our seeing the dinosaur tracks there. The tracks are just west of town and along the coast, so we hired a rental car for the day and drove to a parking lot next to the best-known public site for the tracks, Minyirr-Gantheaume Point. You can’t just there go whenever you feel like it, though, but you need to read local tide charts ahead of time, as the tracks could be under meters of water when you arrive. And I do mean meters, because Broome and that area of Western Australia has some of the highest tide ranges of anywhere in the world, close to 10 m (or 33 feet, for you metric-phobic Yanks out there). So we had timed our visit for both low tide and sunset, which also afforded low-angle light that helped to accentuate the tracks.

Beautiful exposures of the Lower Cretaceous Broome Sandstone at Minyirr-Gantheaume Point, just west of Broome, Western Australia. Notice how the rocks above are red and white, whereas the rocks below look a little green around the gills? That’s the part submerged with every flood tide, meaning you’ll need snorkeling gear if you want to see dinosaur tracks then.

Minyirr-Gantheaume Point has a nicely done information kiosk just above the rocky marine platform containing the dinosaur tracks, with attractive signs telling visitors about both the tracks and their connections to the indigenous people of the area, the Rubibi. You see, tracks both modern and fossil, as well as their representation as iconography, comprise a key part of the spirituality and heritage of indigenous people in Australia, thus playing an integral role in the longest continuous human culture on earth. In this instance, the tracks reflect part of a Dreamtime story and songline, in which a Lawmaker named Marella (“Emu Man”) left three-toed tracks along his route. This reference to three-toed tracks is no doubt linked to those of theropod-dinosaur tracks in the area, but also may have been influenced by modern emu tracks, which closely resemble the theropod tracks in size and form. These sorts of connections between ancient legends of indigenous people and fossils are also common with in North America, but had at least 30,000 years longer to develop in Australia.

Several actual-sized molds of a typical three-toed theropod track are set in concrete at the kiosk, and part of the display states how at least nine types of dinosaur tracks have been discovered from the area. This area along the coast, much of it bearing dinosaur tracks, is also called the Lurujarri Heritage Trail, and is about 80 km (50 mi) long, reaching from just south of Broome to the north as part of an incomparably scenic area of Western Australia, sometimes simply called the Kimberley. Not coincidentally, this trail has thousands of dinosaur tracks throughout much of it, which has led some paleontologists (including Thulborn) to state that it might be one of the richest sources for dinosaur tracks in the world. Supposedly at least 16 types of dinosaur tracks (ichnospecies) have been identified from this assemblage, but they haven't been studied well enough to say exactly what dinosaurs made all of these. Astonishingly, only six dinosaur bones of any age have been found in all of Western Australia, so their presence fills in a considerable gap in the fossil record of dinosaurs in this part of the world, while also demonstrating yet again why dinosaur tracks matter.

Dinosaur “tracks” that are actually modern human traces, where the cast of a theropod dinosaur track was used to make artificial ones in concrete. I’m assuming these are based on a real track from the Broome area, but alas, further information was lacking. Shoe size: 8 1/2 (mens).

Of course, we weren’t just satisfied with an information kiosk and faux tracks, so we descended onto the rocky shoreline to look for the real things. We had read that the best ones are visible in the lowest part of the intertidal range, giving us a starting point in our search, but we also looked at what might be exposed in cross sections of the strata along the way. It was a very nice task, as the variegated sandstone beds were seemingly illuminated from within by the setting sun, making for lovely scenery.

Outcrop of the Lower Cretaceous Broome Sandstone, looking good near sunset along Minyirr-Gantheaume Point near Broome.

Sure enough, we found places where the normally flattish layers of sandstone looked like they had been punched downward and warped into unusual forms. These were likely dinosaur tracks in cross-section, very similar to ones I had seen in Jurassic and Cretaceous rocks of the western U.S. Sometimes such odd structures, when recognized as coming from dinosaurs, are nicknamed “brontosaur bulges.” The hypothesis for these features is that they were formed by compression of soft sandy layers by the feet of multi-ton dinosaurs, such as sauropods, that through their great weight deformed sediment well below where their feet actually touched the original surface.

So-called “brontosaur bulges” seen in cross-section, probably caused by sauropod dinosaurs when they stepped on soft sand about 130 million years ago, but they also could have been from large ornithopods, stegosaurs, or other weighty dinosaurs.

Further down we went, until at the water’s edge we spotted the large, three-toed tracks. Their narrow toes, sharp clawmarks, and narrower widths compared to lengths meant they were probably theropod tracks. The theropod tracks, most of which were 25-30 cm long, show this area had relatively large predatory dinosaurs in this area of Australia during the Early Cretaceous. Using a little formula for figuring out the approximate sizes of the trackmakers – 4.0 X footprint length = hip height – these theropods had hip heights of about 1.0-1.2 m (3.3-4 ft), which made them much larger than, say, Velociraptor, but smaller than Allosaurus.

Theropod tracks at low tide, preserved in the Broome Sandstone. Looks like at least one trackway is there, with the theropod heading toward Ruth, probably because she's modeling the latest in paleontological footwear.

A theropod track at low tide in the Broome Sandstone, with my left foot (25 cm long) next to it for scale. You know, there’s something about seeing the real thing that’s so much better than those phony ones by the car park.

A pan of an area bearing some theropod tracks at Minyirr-Gantheaume Point and a brief paleontological explanation by Yours Truly.

More tracks were just to the north along the shoreline, but not of theropods. These were more akin to those Dr. Thulborn had mentioned in his talk seven years previously. These huge depressions were very likely sauropod tracks, some of them about a meter wide. Although these didn’t show any good definition of toes (thus they were probably undertracks), their overall size and shape were very similar to those of undoubted sauropod tracks I had seen in Late Jurassic rocks of Utah and Colorado. In some places, these depressions aligned, indicating apparent trackways, and a few showed a double–register where the rear foot (pes) overlapped the front foot (manus) as these sauropods walked slowly through this area about 130 million years ago.

Double-register or indirect register (right), where the rear foot of a sauropod stepped onto the track made by the preceding front foot of the same side. Yes, that's another probable sauropod track just to the left. Wow, sure are a lot of dinosaur tracks in this area. Reckon it and the shoreline north of Broome deserve National Heritage status?

This is your lucky day: yet another video explanation of the dinosaur tracks at Broome, but about the sauropod tracks. Sorry for it not having a cheery (or cheeky) soundtrack, too, but at least you get to see a brief cameo appearance by Ruth.

OK, that’s the nice, warm, fuzzy part: privileged American tourists travel far to see dinosaur tracks in Western Australia, have a good time, go home, and share their adventure with friends, students, sworn mortal enemies, and indifferent strangers. Then why the inflammatory and gloomy headline to this story?

Well it turns out that a liquefied-natural-gas (LNG) processing plant, accompanied by a port and other major development, is being planned for James Price Point, about 60 km (35 mi) north of Broome and part of the 80-km long coastline holding the dinosaur tracks. The plant would be the joint effort of a number of energy companies, including Shell and BP. (Gee, what's the worst that could happen?) Anyway, the plan has recently received a lot of attention from environmental and indigenous-rights activists (see links at the end of this post), and seems that most people are not very happy about it. Also, according to Tony Thulborn (remember him?) in a long, detailed online comment to a recent news story in Nature, this is probably the worst place possible to put the plant because of how it will adversely affect (that’s lawyer-speak for “destroy”) the dinosaur tracks in that area.

But this isn’t just a matter of direct destruction of the tracks, which will certainly happen in the immediate vicinity of the plant. Scientifically invaluable trace fossils north and south of the plant also could be buried under thick layers of sand, meaning that paleontologists won’t be able to study them. You mean, the people behind the gas-processing plant are actually going to hire trucks to carry in heaps of sand and dump them onto the dinosaur tracks, just to tick off those crazy scientists and environmentalists? (Cue Mr. Burns laughing diabolically in the background.)

No, it’s a matter of shoreline dynamics at play, and how we humans can alter these factors once we change a shoreline, however little or big. The port will host large tankers, which in turn will require breakwaters, groins, and other modifications to the shoreline. How the sand will be moved by longshore drift, tides, or storms then comprise a big question mark. Although, on the plus side, more sand in some places along the shore might hide the tracks and thus better preserve them. But there’s no way to know which ones will win the “longshore lottery,” so to speak.

So what can you do to help make sure these 130 million-year-old tracks are around a few more years so that scientists can study them, tourists can see them, and an important part of indigenous cultural history is kept alive? Write to the following bloke and tell him (politely, using the word “please” as much as possible) that you would like this area to have National Heritage status. Then it will be less vulnerable to development, and more likely to change in a slower and more geologically appropriate way.

The Honourable Tony Burke, MP

Minister for the Environment

PO Box 6022

House of Representatives

Parliament House

Canberra ACT 2600

E-mail: Tony.burke.mp@aph.gov.au

The decision about whether this area will get National Heritage status will be made by June 30, so do your best to make your voice heard before then. As one of the signs said at Minyirr-Gantheaume Point: “Please look after our country. If you do, this country will look after you.”

Sunset on Cable Beach near Broome, Western Australia. Is the sun setting on the dinosaur tracks of Western Australia, too? Yes, but let's hope it does literally, and not metaphorically.

And today's appropriate song for ending this post is Return to Country, by Kerrianne Cox, who is from Western Australia and working with other activists to oppose the LNG plant at James Price Point. The reverie interrupting the song and slide show doesn't quite work for me, although I agree with the sentiment, especially the exquisite Cretaceous rocks in that part of Australia.

Pertinent Links

Summary by the ABC of dinosaur tracks in Australia, but with emphasis on the Western Australia ones.

Dinosaur footprints threatened by natural gas project

Scientific American article (republished from Nature)

Save The Kimberly

Gas hub 'would destroy dinosaur prints

PRI story, “Dinosaurs Walked Here,” including audio interview (MP3) with Dr. Steve Salibsury, paleontologist at University of Queensland:

Pindanpost (blog) with lots of links about the story

Kronosaurus: The King (or Queen) of the Queensland Sea

2011-04-29T10:31:00.000-04:00

Life was good during the Early Cretaceous – about 110 million years ago – in what would some day become Queensland, Australia. That is, life was good for whatever was making tucker out of whatever else was alive at that time. In that sense, then, when it came to the Cretaceous seaway that covered much of inland Australia then, few animals enjoyed life more than the giant marine reptile Kronosaurus queenlandicus.

Fancy a dive in the Cretaceous sea of Queensland? You’d have a lot more to worry about than running into a box jellyfish, blue-winged octopus, or great white shark, mate, like a bloody huge Kronosaurus. Artwork is on a tapestry (batik?) in Kronosaurus Korner, Richmond, Queensland, and the presumed artist is Paul Stumkat, who’s also the curator and fossil preparator there. (When you do paleontology in central Queensland, you have to wear a lot of hats.)

Last July 2010, while on a paleontological drive-about (not to be confused with a walkabout) in central Queensland with my wife Ruth, we ended up in the small town of Richmond. Our stopping in Richmond was not random, as I had visited there in 2007 and was thoroughly impressed with the alliteratively (and illiteratively) named fossil museum there, Kronosaurus Korner. So we were visiting to see this facility and its paleontological displays, including the remains of the enormous Cretaceous predator that inspired the museum’s name.

And just who, er, I mean, what was Kronosaurus? It is classified as a pliosaur, and pliosaurs were an evolutionarily related group of marine reptiles that lived during the latter part of the Mesozoic Era, from about 200 to 90 million years ago. Although pliosaurs chronologically overlapped with dinosaurs, they were separated by habitats, as dinosaurs were mere land-dwellers and pliosaurs probably never willingly left the ocean. Pliosaurs shared a common ancestor with another group of marine reptiles – plesiosaurs – but differed from those by having large skulls relative to their total body lengths and short necks. Both groups, though, had flippered limbs that were well adapted for swimming.

Why have a large skull? Normally this trait has nothing to do with holding a bigger brain, but rather for supporting the ability to bite through anything that might be in your environment. Kronosaurus was a great example of a big-time biter, having dozens of 25-cm (10-in) long pointy teeth and a skull about ¼ of its body length. How long was that? Its adult body lengths are estimated to have been about 8-10 m (26-33 ft), although that has been the subject of controversy, as explained later.

Here’s a small piece of a Kronosaurus skull (above) compared to the full-sized skull of a much-feared modern aquatic reptile of Australia, the estuarine crocodile (Crocodylus porosus), also known as “salties” for their occasional sea-faring ways. I don’t know about you, but I would rather take my chances with a “salty” instead of a “Krony.” Display at Kronosaurus Korner, Richmond, Queensland.

As can be surmised from its species name, Kronosaurus queenlandicus hails from Queensland. The type specimen was found in 1899 near the town of Hughenden, consisting of just a lower jawbone (mandible) with a few teeth. Paleontologist Heber Longman named it in 1901, although at first he thought it was an ichthyosaur. Like many scientists, though, he later corrected this mistake. (We scientists are funny about that: it’s almost as if science has self-correction built in as part of its process.) In the 1920s, station owner Ralph Thomas found the most famous specimen of Kronosaurus on his ranch (Army Downs) north of Richmond. He told a fossil-hunting team from Harvard University about it, and they decided to collect the specimen so it could be studied.

Only thing was, this specimen was really big (we’re talking “Tyrannosaurus big”), and its bones were still encased in sandstone, which meant that taking it out and transporting it would not be easy. So it was broken into 86 pieces, with some of fragmentation accomplished by dynamite, strategically placed by a field assistant nicknamed “The Maniac” (no, I am not making that up). In 1932, all 4-5 tonnes of rock containing the bones were shipped back to the U.S., and the bones have stayed there ever since.

Yes, this sort of Yankee paleo-imperialism still rankles with people I talked with in Queensland, with which I agree, considering how taking a fossil too away from its place of origin can reduce our understanding of it. Fortunately for Australians who don’t feel like traveling to the eastern U.S. to see their pliosaur, more specimens have been found since, and these have stayed in Australia, including several at Kronosaurus Korner (appropriate, that).

A partial skeleton of Kronosaurus showing the lower outline of its skull, preceding part of a front limb and a few of its vertebrae, namely the neck (cervical) and back (dorsal). Specimen on display at Kronosaurus Korner, Richmond, Queensland.

Moving the specimen to the U.S. did not mean it would be seen by the public in all of its pointy-toothy glory any time soon, though. Extraction of the skeleton took 27 years, and it was not revealed to the public at the Harvard Museum of Comparative Zoology until 1959. The detailed story of this ordeal, as well as the genius of its preparation and mounting by James Jensen, Sr. (“Dinosaur Jim”) is told by his son, James Jensen, Jr. here.

A classic photo of the classic specimen of Kronosaurus, originally from Queensland, Australia, but now on display at the Museum of Comparative Zoology (Harvard University), with the mysterious Lady in Red for scale. Little does she know that this specimen is wearing the fossil equivalent of lifts. Wish I could credit the photographer, but I understand it's originally from a postcard, and the digital image comes from always-excellent Oceans of Kansas web site.

Tragically, I have not seen this specimen of Kronsaurus, which happens to be much closer to my home (Atlanta, Georgia USA) than central Queensland. The skeleton, displayed beautifully in the Museum of Comparative Zoology at Harvard (Cambridge, Massachusetts), is only about a two-hour flight from Atlanta, so perhaps I should make a trip to see it sometime. (Mental note: Start going to major natural-history museums in the eastern U.S.)

The odd thing is, the original skeleton was nowhere near as complete as the mounted version might imply. Evidently, too many vertebrae were added to its back, making it about 13 meters (42 feet) long, and enough plaster was added to the mount that it gained the facetious nickname of “Plasterosaurus.” So now paleontologists think that Kronosaurus might have been “only” 8-10 meters (26-33 feet) long. But hey, what are a few meters among friends when you’re a Cretaceous pliosaur?

Another partial skeleton of Kronosaurus giving more of a sense of its total length: partial skull in front extending back to its tail (caudal) vertebrae, with a few paddled limbs thrown in for good measure. My lovely wife Ruth is serving as a scale in the back, fulfilling the cliché about geologists (and paleontologists) that their only photos of people are as scale. Incidentally, she’s 1.8 m (5.8 ft) tall.

Is Kronosaurus found only in Australia? One fossil says “no.” A geologically older species of Kronosaurus – Kronosaurus boyacensis – was discovered in 1992 in Cretaceous rocks of northern Columbia, a place far away from both Queensland and Massachusetts. Nevertheless, when you’re a large marine reptile during a time of very high sea level (which the Cretaceous had), you and your relatives could get around. So they did.

OK, I know what you’re thinking. (No, not that, although you’re close.) You’re wondering, “But wait: aren’t you an ichnologist? What are you doing talking about some big marine reptile and its body fossils?” Well, here’s Example #1,243 why trace fossils kick butt yet again (and I never get tired of reminding everyone of that fact). For a long time, paleontologists didn’t know what Kronosaurus ate, but trace fossils helped to provide some answers.

At first, large shelled cephalopods – ammonites and nautiloids – were proposed as the most likely candidates for Kronosaurus fodder. This hypothesis made sense because of: (1) the co-occurrence of many large nautiloid and ammonite fossils in the same Cretaceous deposits holding the remains of Kronosaurus; and (2) its massive size and banana-sized teeth implied that these were used for crunching hard-shelled or hard-boned animals, of which nautiloids and ammonites certainly qualified.

Mmmm…Cretaceous calamari [drooling sounds]. Otherwise known as nautiloids (above) and ammonites (below) to marine biologists, paleontologists, or anyone else who loves cephalopods. Specimens on display at Kronosaurus Korner.

But there are two problems with that hypothesis. Thus far, no nautiloids or ammonites have been found as stomach contents in Kronosaurus, and no shells of either animal have been found with toothmarks matching the dental records of Kronosaurus. The first of those two facts is excusable, considering how few specimens of this enormous pliosaur have been found, let along ones with their gut regions intact. The second fact, though, is tougher to explain as an absence of evidence. Cephalopods in general (including squid) are very abundant as body fossils in the Cretaceous marine deposits of Queensland. So you would think someone would have found one or more examples that had been punctured by a Kronosaurus. So far, not yet.

Did any other Cretaceous reptiles munch on these molluscans? Yes, but not in Australia, and not by Kronosaurus. This behavior has been documented through trace fossils in Cretaceous marine deposits of North America for paleoecologically analogous marine reptiles, the awesome mosasaurs. These toothmarks show up as circular punch-marks on ammonite shells, which also line up in a way that they correspond with the tooth row of a mosasaur.

These holes in an ammonite shell were either made by small gastropods (limpets) or are toothmarks from a mosasaur. I don't have to tell you which hypothesis is sexier, but science tends to go for "brainy." Which, of course, is the sexiest. Regardless, I'm going with the biting hypothesis. So these marks in a Late Cretaceous nautiloid shell from the U.S. are credited to a mosasaur teaching its young to kill. In this scenario, the big ones (AT) are from the adult and the small ones (JT) are from the juvenile. Figure from: Kauffman, E. (2004), Mosasaur predation on Upper Cretaceous nautiloids and ammonites from the United States Pacific Coast, Palaios, v. 19, p. 96-100.

However, one prominent ichnologist – Dolf Seilacher – disagreed with this hypothesis and argued that these traces also may have been scars made by limpets, which are gastropods that like to attach to hard substrates, like shells. This set off a bit of a scientific tussle, as the “pro-biters” took on Seilacher and other “pro-attachers” who agreed with his hypothesis. No one was disputing that these ammonites had a bunch of big holes and some animal caused them, but the explanations for these features were so radically different from one another, it was worth a good argument.

The last I’ve heard, though, is that the “pro-biters” have regained some favor, as they described a few ammonite specimens showing fracture patterns consistent with biting by an animal with massive and powerful jaws. One paleontologist (Erle Kauffman) even interpreted repeated biting as possible evidence of an adult mosasaur teaching its young how to kill ammonites. How cool is that? It’s ichno-cool.

Speaking of ichno-cool, trace fossils provide a clue that Kronosaurus may have been at least biting (if not eating) other large marine reptiles swimming in the same Cretaceous seaway. The skull of an Australian elasmosaur (a type of plesiosaur), Woolungasaurus glendowerensis, has some marks on its skull consistent with crushing by large teeth. Could it have been from Kronosaurus? Maybe, but a few more specimens showing more clear evidence would be nice. Of course, that hasn’t stopped some paleo-artists from depicting Kronosaurus victimizing Woolungasaurus.

Skull of the Early Cretaceous elasmosaur Woolungasaurus glendowerensis that had the misfortune of putting its head inside the head of another animal with really big teeth (like a Kronosaurus); look at the puncture mark (arrow). Specimen on display in the Museum of Tropical Queensland.

Unfortunately, as far as I can find from my (admittedly non-exhaustive) literature reviews, this idea of “Kronosaurus skull-crushing fury” has not been tested rigorously yet, and certainly not as much as the “mosasaur chomping ammonite” hypothesis. One trace fossil that would really help would be a massive coprolite. Size alone would tie it to Kronosaurus, and the contents would tell us directly just what went through its gut (or at least the gut of one such animal). Other coprolites attributed to marine reptiles have been recognized from the same Cretaceous deposits (some of which were on display at Kronosaurus Korner), so I hold out hope that someone, some day, will find an enormous pile of fossil sea-dung.

So if Kronosaurus were around today, what would it eat? It probably would go for large fish – maybe even sharks – and take a bite out of the soft parts of an occasional sea turtle or marine mammals. I can’t help but think that the pack-hunting orcas would turn the tables and make short work of one, though. Nonetheless, I have some photographic evidence suggesting other potential prey, especially if a Kronosaurus came up onto land:

Bloody hell! Don’t drive right into its mouth, mate! And here you thought veering around ‘roos and staying awake were the worst hazards of driving a lorry in the Queensland outback.

Too much plastic in the world’s oceans? Here’s one solution: bring back Kronosaurus to get rid of your rubbish!

Anyway, all of this goes to show us that, despite our knowing about its presence in the Cretaceous seas of Australia for more than a hundred years, we still have a lot more to learn about this magnificent marine reptile. May Kronosaurus queenlandicus stay alive in our paleontological thoughts, and my best ichno-wishes that trace fossils will somehow tell us more about how it lived.

I just can’t get enough of this beautiful, inspirational song – From Little Things, Big Things Grow, by Kev Carmody – and was delighted to know that two of my favorite Australian singers - Sara Storer and Archie Roach - had covered it. It’s not about Kronosaurus, but about peaceful change, which pretty much cover paleontology and a lot else in life.

Keeping Track of Fossil Tracks

2011-03-30T06:58:00.000-04:00

The fossil thieves drove their sport ute into the Western Australia outback in the middle of the night, confident that no one would see them. Just to make sure, though, they turned off their headlights the last kilometer before their destination, using moonlight to keep their tires on the unsealed road. Once at the site, they used torches (flashlights) to search the ground, and quickly found what they were seeking. They pulled out a portable rock saw from of the back of the vehicle and cut through the 120-million-year old sandstone, the abrasive sound masked by nearby waves crashing during high tide. The sandstone bed was thick, but split evenly along its bedding plane so the thieves were able to use a lever bar to pry up each square. These blocks were heaved onto the truck bed; blankets were used to cushion them below and cover them above. The perpetrators got into the truck and sped away from the site, well before the first rays of the morning sun revealed the newly made and oddly square holes in the rock. They had just taken some of the few stegosaur tracks known from the geologic record, and they had stolen these from aboriginal tribal land. It was both a crime against the state and a grave insult to the people who regarded these tracks as part of their heritage.

Nice dinosaur track you got there. It’d be a shame if something happened to it. Track is from a large theropod dinosaur, preserved in Early Cretaceous sandstone of Western Australia. Please don’t take it, legally or otherwise.

The preceding scenario is partially fictionalized, but based on an incident that actually happened in Western Australia in 1996. Paleontologists had been negotiating with indigenous elders to study the tracks, which had been considered as part of their Dreamtime stories; hence this was a sacred site for thousands of years before Europeans and others arrived in that area. The stegosaur tracks were recognized by the paleontologists in 1991, and were similarly regarded as “sacred objects” by these scientists in their own way, but for their scientific value.

So what was the big deal about these tracks, and in a paleontological sense? Stegosaurs were at that time unknown from Australia, with not a scrap of bone indicating their former presence on that continent, despite their abundance in Mesozoic rocks of North America, Asia, and Africa. Even now, 15 years after the tracks were stolen, no one has yet identified a stegosaur body fossil from anywhere in Australia. Even more significant, stegosaur tracks are apparently much more rare in the geologic record worldwide than their skeletal parts. A few have been reported from Europe (Poland, the U.K., and Portugal), and Africa, but only two from North America. This situation – the opposite for most trace fossils, which normally outnumber body fossils – also means that the Australian stegosaur tracks would have contributed to a better understanding of how stegosaurs walked or otherwise behaved in this part of the world during the Mesozoic Era.

Trying to find stegosaur tracks? You’re better off looking for their bones, especially in North America. But you may have your work cut out for you (pun intended) in Australia. Specimen is of Stegosaurus stenops and is in the Carnegie Museum of Natural History.

The Australian paleontologists, once they recognized what they probably had, agreed to limit their time studying the tracks. Of course, they also would not collect these tracks for a museum because of their spiritual importance. Besides, any extraction of them would damage the rock that had held these tracks for millions of years and, in the eyes of the elders, would change their Dreamtime.

Once permission was gained to study the tracks, though, word somehow got out about them, and a terrible thing happened. Professional fossil collectors, looking to sell the tracks to a buyer, went to the site and cut out the tracks with a rock saw. Amazingly, one of these tracks was eventually recovered and a suspect arrested. Nonetheless, no one knows what happened to all of the tracks, although they presumably ended up in private hands of a wealthy fossil collector. What is known, though, is that the trust between the indigenous people and the paleontologists was violated, perhaps irreparably. Worst of all for science, unless miraculously recovered, the stegosaur tracks will never be described or interpreted. (As an aside, I hope that the people who did this will get a visit from a Wandjina some day.)

G’Day! Heard you stole some sacred objects from our Dreamtime. Bad move, mate. Who’s your daddy? (Artwork by Ruth Schowalter (a.k.a. Hallelujah Truth.)

Nonetheless, this incident also relates to a thought I’ve wrestled with in recent years. (No, not about the premature cancellation of the TV series Farscape: everyone knows that was wrong.) However heretical it might seem for an academic paleontologist to say, I sometimes disagree with the sentiment that all fossil specimens belong in a museum. In my opinion – which, like most opinions, is actually never humble – some trace fossils, such as dinosaur tracks and other vertebrate tracks, are better left where they were found. Why? Because our knowledge about them will not always be enhanced by taking them away from their places of origin. This is especially the case if we know these trace fossils were recognized by local indigenous people and became part of their cultural heritage.

For example, while once on a field trip organized by academic paleontologists, we visited a site that used to have fossil vertebrate tracks. Notice I said, “used to have.” As we walked up to the former location of the tracks, I was shocked to find out they had been collected by other academic paleontologists, instead of being left in the context of their original ancient environments. Even more vexing, the tracks had been lying next to Native American petroglyphs that depicted tracks looking very similar to the fossil ones (maybe coincidental, but probably not). The petroglyphs had been made by indigenous people living in that same area more than a thousand years beforehand. Thus the separation of the fossil vertebrate tracks from the petroglyphs resulted a greater loss of context, but this time cultural.

I expressed my dismay to the field-trip leader by asking, “What are they [the tracks] doing at [name of prestigious institution]?” The bemused and condescending response was, “That’s where they belong!” (You know, like the Indiana Jones line, “It belongs in a museum!”) This was followed by some semi-serious joking about how they wanted to collect the petroglyphs too, but archaeologists studying the site insisted against it. (And they would have gotten away with it too, if it weren’t for those meddling kids, er, I mean, archaeologists.) All of this was legal, done with proper permits, through well-known institutions, and was carried out by credentialed individuals through their respective (and respected) institutions. Yet I found it unsettling.

Native American depiction of a three-toed track in the western U.S., pecked into a Mesozoic sandstone. Was it representing the nearby track of a theropod dinosaur, or of a modern bird? Probably of a bird, because of the little dot at the bottom, representing a backward-facing thumb (hallux). But wouldn’t it be nice to be able to compare them directly with theropod dinosaur tracks in the same area?

Guess what: you can! This Middle Jurassic theropod dinosaur track is at the Red Gulch Dinosaur tracksite in Wyoming (USA), and only a few hundred meters away from Native American petroglyphs. By the way, it, hundreds of other dinosaur tracks, and the Native American petroglyphs are under U.S. federal protection. So don’t even think about it.

Yes, I know how the collection of fossil specimens by a museum helps to preserve these in perpetuity, and make them available to researchers for future generations. Plus I totally understand paleontologists taking body fossils away from a field site so these can be carefully extracted in a lab and made ready for detailed study. But I wonder whether it is worth taking away trace fossils related to the heritage of living people. We now know that fossils, including fossil tracks, probably inspired many spiritually oriented stories in indigenous cultures. In such instances where such connections can be demonstrated, perhaps it’s better to leave fossils – especially trace fossils, which often need no further preparation to be studied – where they lie.

What’s the alternative to collecting for scientists who want to make these specimens available for others to study: you know, that peer-review thing we scientists claim we like so much? One word: lasers. That is, laser scanning is now providing a way to make three-dimensional computer-generated images of fossil tracks that can be studied, shared, and archived like real tracks. The tracks can still be kept in the field, with their localities kept confidential so only qualified researchers should gain access to them. But laser scans will also insure that if the tracks weather, are damaged, or stolen, paleontologists still have a means to evaluate the information they hold for generations to come.

It’s not sharks with laser beams on their heads, but it’s pretty close from a media-hype perspective: dinosaur tracks and lasers, in which the lasers are used to scan and make images of the tracks. Image from Photonics, Inc., based on a study led by Marco Avanzini of geology department the Museo Tridentino di Scienze Naturali (Italy).

For paleontologists who do not have ready access to laser scanners (let me check – nope, no lasers here), old-fashioned molding and casting can also be a way to create a reasonable replica of a fossil track. Of course, experienced people should be the ones to apply this technique to avoid damaging the tracks, but it also does not always have to be done by professional paleontologists. Replicas of fossil tracks can be made by non-professional paleontologists and sold as substitutes for the real thing, while still being appreciated for their beauty and scientific worth.

Is it real? Yes, it’s real. Oh, you mean, is it a real dinosaur track? No, but it’s a real replica of a theropod dinosaur track, which was probably from the Early Jurassic of North America. After all, I’m not studying it, just admiring it. And as a colored resin cast, I can hang it on a wall and not worry about it crashing to the ground and destroying a vestige of the geologic past. Gorgeous photo by Ty Butler of Tylight™.

Regardless of whether fossil dinosaur tracks in Western Australia are stolen, or fossil tracks elsewhere are legally (and well intentionally) collected, science can still be done on future finds of fossil tracks by seeking other ways of knowing them. These ways can still result in our knowing what animals made them and why, while also being aware that the beliefs of living descendants of indigenous people can be respected without unnecessary intrusion. This is what our current Western culture calls a “win-win scenario,” but I like to think it of it as honoring one another during our short time together here on this 4.6 billion-year-old earth. To quote the late American writer Kurt Vonnegut:

"Hello babies. Welcome to Earth. It's hot in the summer and cold in the winter. It's round and wet and crowded. On the outside, babies, you've got a hundred years here. There's only one rule that I know of, babies - "G*d damn it, you've got to be kind."

One of my favorite Australian bands, Yothu Yindi, with a short introduction by the lead singer - Mandawuy Yunupingu - about our relationship to the earth. And if you don’t like my preaching, that’s fine. There are lots of blogs out there about funny cats that really need reading.

Fossil Collectors and Academic Paleontologists: Grudge Match, Love Fest, or a Little of Both?

2011-03-07T07:26:00.000-05:00

In July of 2010, while in the small outback-Queensland (Australia) town of Boulia – mentioned in a previous entry – I was reminded through one simple question about a huge cultural and communicative gap dividing many people otherwise connected through their mutual love of fossils. The question, posed to me by Dick Suter, an extraordinary fossil collector who lives in Boulia, was: “Do you have a Ph.D.?” I have heard this question before in both the U.S. and Australia, and it is almost never asked out of curiosity, but to pick a fight. This time was no different, as I sensed his inquiry was tinged with antagonism. I braced myself, and said, “Yes.”

Here I am, having a cordial conversation with fossil collector Dick Suter (right) of Boulia (Queensland, Australia) at the Stone House Museum. He was a great guy and had lots of paleontological experiences to share during our visit with him, for which we were grateful. Just don’t tell him you’re a paleontologist and have a Ph.D. Photo by Ruth Schowalter.

Sure enough, he launched into a tirade about academic paleontologists, which is not worth repeating here. After all, I've heard variations on this theme in the U.S. from a few fossil collectors who felt likewise about people of my ilk. So instead I will emphasize that he was otherwise a very nice bloke who took much of his time to personally show my wife Ruth and me what fossils he had collected in the past few years, and which ones he was extracting from Cretaceous rocks in his own “fossil prep lab.” He also told us some stories of his discoveries, which were considerable, colorful, and memorable. What is most impressive about Mr. Suter – 74 years young - is that he works as a volunteer. As far as I know, he does not sell or trade fossils, so he is not trying to profit from all of his hard work. I’ll also bet he bought all of his equipment for his fossil-prep lab by using his own money. Further complicating matters (by making you like him more, that is), he does the right thing by contacting academic paleontologists about his potentially important finds.

Cretaceous marine reptiles are Mr. Suter’s forte – ichthyosaurs, plesiosaurs, and sea turtles – but he is particularly good at finding ichthyosaurs. A few he had on display at the Stone House Museum were stunning specimens, including one of the few in this part of the world (that I knew of) with evidence for live birth in ichthyosaurs. Wish I could say more about it, but I don’t know if these fossils are being described by academic paleontologists, and do not want to compromise any peer-reviewed study of them.

Which introduces one of the challenges of fossil collectors (most without Ph.D.’s) and academics paleontologists (consisting of university professors and museum professionals, most of whom have Ph.D.’s) working together. How to reconcile the idealistic rules of paleontological inquiry with the realistic concerns of people on the ground (literally) who are out there finding many of the fossils that need to be studied?

In truth, the success stories of fossil collectors and academics working together are actually more common than the not-so-successful ones. There are some fantastic examples – most recently, here – of where fossil collectors and other non-academic folks have been invaluable for finding, recovering, contacting academic paleontologists, and actively participating in the study of important discoveries. Indeed, Australia has some of the finest examples of this, especially in Victoria and Queensland, where people without Ph.D.’s and formal educational training in paleontology have found numerous scientifically significant Cretaceous fossils.

On a more personal level, I have examples to share of where trace fossils were first found by fossil collectors (not me), which later led to some real science happening. Here you go, mates:

Fossil amphibian (temnospondyl) tracks from 310 million years ago, found by amateur fossil collectors of the Alabama Paleontological Society, in Alabama (USA). Specimens described in a peer-reviewed publication by Martin and Pyenson (2005).

Ediacaran fossils initially identified as trace fossils, later shown to be body fossils, from 550-million-year old rocks in North Carolina (USA), found by an amateur fossil collector. Specimen described in a peer-reviewed publication by Tacker, Martin, Weaver, and Lawver (2010).

Fossil fish trail in Eocene-age (50 million-year-old) rocks, made by the bottom-feeding fish Notogoneus osculus, and found by a professional fossil collector in Wyoming (USA), but donated to the U.S. National Park Service at Fossil Butte National Monument. Specimen described in a peer-reviewed publication by Martin, Vasquez-Prokopec, and Page (2010).

What also happens, though, is that such “good news” stories are sometimes ignored in favor of tabloid-like fare that emphasizes personal conflict over science, a siren-like call of sensationalism that can even slither into respected science journals. This reporting of strife (whilst also ignoring cooperation) has a long history, harkening back to the days of the late 19^th century with American paleontologists Edwin Cope and Othniel Marsh. Nevertheless, media bias aside, I know for sure that some fossil collectors are regarded with venomous disdain by a few academic paleontologists, and the feeling is reciprocated on the part of a few fossil collectors. What’s up with that – can’t we all just get along?

Speaking as an insider privy to some rather heated conversations on this topic, I can say that part of the contempt for fossil collectors coming from academic paleontologists stems from their adherence to an ethical stance, and one I also support, incidentally. Scientifically important fossils should not become mere economic commodities that end up in private hands, akin to, say, Barbie dolls. (As the proud owner of a Paleontologist Barbie doll, though, I can understand the zeal of some collectors.) In fact, the Society of Vertebrate Paleontology has an ethical pledge taken by all of its members to not be involved in the sale of vertebrate fossils for non-scientific and non-archival purposes. For proper study – so that results can be repeated and tested (you know, what scientists are supposed to do) – fossils typically need to be held in perpetuity by an academic or otherwise accredited institution. Or, as fictional archaeologist Indiana Jones once famously said, “It belongs in a museum!”

As mentioned earlier, this tension between fossil collectors and academic paleontologists is nothing new, having been around for about 200 years and going back to the early 19^th century of Europe. For example, Mary Anning (1799-1847) of Lyme Regis in the U.K., discovered beautiful specimens of Jurassic ichthyosaurs in her local environs, much like Dick Suter finds Cretaceous ichthyosaurs in Australia today. Sadly, Anning received little credit for her discoveries at the time, while wealthy collectors and academic paleontologists profited handsomely from her finds. Only belatedly has she received her due for her contributions to paleontology, with several biographies (here and here, for example), historical accounts (here and here), and even a commercially successful novel (Remarkable Creatures, 2010, by Tracy Chevalier) that tell of her astonishing life. Granted, Anning was also ignored because of British chauvinism and class-based snobbery: she was poor, female, unmarried, and uneducated, a socially lethal combination in the U.K. at the time. Was she aware of this lack of respect and recognition? Oh, yes. She once wrote, "The world has used me so unkindly, I fear it has made me suspicious of everyone."

Along those lines, last year I had a rather unpleasant encounter with a fossil collector in the U.S. who felt the same way as Anning, only this person’s distrust was accented by aggressive hostility. I was with two other academic paleontologists (yes, they had Ph.D.’s too), and we were shown a “pterosaur beak mark” in a rock this person had collected. It was an extraordinary claim, thus requiring extraordinary evidence. Yet all three of us recognized the fossil as the external mold of a clam (also known as a “bivalve” to those Ph.D. types). Did I wish it were a trace fossil of a pterosaur feeding? Not just yes, but hell yes! But we couldn’t just wish it were so.

Look, a trackway made by an 8-legged river otter in Yellowstone National Park in the U.S.! Isn’t that amazing? It must be an extremely rare genetic mutation that caused this phenomenon. What? You think those tracks were made by two normal otters, each with four legs, and one was following the other? Why should I listen to you, when I obviously have so much more experience tracking animals than you with your fancy-pants Ph.D.?! Face it: You can’t handle the truth!

So one of us spoke, and not unkindly. All three of us academic paleontologists teach undergraduate non-science majors at our respective schools. Accordingly, we have learned through years of classroom experience how to correct misconceptions as part of educating, as well as let people down in a way that does not crush their hopes and dreams. (Well, except when we assign final grades.)

But the collector, instead of listening to an explanation of why his/her find was a bivalve impression, reddened, quivered briefly, and exploded. This collector berated us for our over-education, which had obviously blinded us to any other possible explanations for what was in front of us; accused one of us of spreading vicious rumors about this collector on the Internet (needless to say, but I have to say it anyway, my colleague had not done such a thing); then smugly asserted how his/her considerable field experience was worth far more than our paltry ivory-tower opinions, especially because none of us had ever visited his/her field site.

Gee, which fossil collector you think I’m more likely to work with in the future: Mr. Suter, who had a few bad things to say about academic paleontologists (some of which may actually been justified, and none of which was personally directed at me); or He/She Who Shall Not be Named? First guess doesn’t count.

But here’s what interesting about this collector’s braggadocio and verbal bullying (in a Chinese curse sort of way): he/she actually had a point about our never having been to his/her site. And this is an advantage that fossil collectors will always have over academic paleontologists, which the latter do not like to admit: the collectors see heaps more rocks and fossils than we do, and sometimes all year round. We academics, on the other hand, are limited to seeing natural outcrops of rocks for a few months a year (if we’re really lucky), or not at all.

For example, while I spend my time doing the following:

• Writing these blog entries (admittedly, this is more fun than most work);

• Teaching classes at my university;

• Grading assignments, exams, and papers from those classes;

• Reading and answering student e-mails;

• Meeting with students for advising and counseling;

• Writing recommendation letters for these same students (not to mention former students); and

• Attending departmental meetings, committee meetings, college-faculty meetings, and, of course, other meetings.

What do you think amateur paleontologists are doing in the meantime? That’s right: they’re in the field, looking for (and finding) fossils, which they often bring back to their own fossil-preparation facilities to extract them, and thus learn even more about what they have discovered. So who do you think has more direct, hands-on experience with the nitty-gritty-dirty of paleontology, them or me? (Was that a rhetorical question?)

A rare photo of me in the field, walking along the coast of Victoria, Australia, looking at Cretaceous rocks, which was great! (Hmmm, that would make a great name for a blog.) A less-rare photo of my daily life would show me in front of a laptop computer in a cluttered office, on a university campus in an urban setting, underlain by metamorphic and igneous bedrock, and more than a two-hour drive from any trace fossils. In other words, tragedy. Photo by Tom Rich (who has a Ph.D., and is an academic paleontologist - poor bloke).

The point here is not to play some game in relativism, as in “Aren’t we both amazingly accomplished and clever in our own special ways, while also having our jerky moments with one another?” Instead, it is to provide a peek into how the different approaches of fossil collectors and academic paleontologists with relation to their beloved subjects – fossils – and their respective cultures can sometimes lead to misunderstandings, miscommunications, and mistrust, thus missing out on the mysteries.

So next time at The Great Cretaceous Walk, we’ll talk about something that really matters – trace fossils – and how these fossils fit into some of the continuing cooperation, conflict, or other ways fossil collectors and academic paleontologists relate to one another, somehow resulting in science and other ways of learning along the way.

Australian band Midnight Oil, performing perhaps their most well-known song, Beds Are Burning (1987). My two reasons for featuring this video: (1) it’s a great song, with a theme of reconciliation (fossil collectors and academic paleontologists: group hug!); and (2) to watch former Australian Minister for Environment, Heritage and the Arts, Peter Garrett, dance like a larrikin.

Dreaming of Dinosaur Dreaming

2011-02-24T10:49:00.001-05:00

Humans like to celebrate anniversaries during their lifetimes in fives and tens, which I like to think is a direct reflection of a much longer evolutionary heritage. For instance, why fives and tens, and not, say, threes or sevens? Look at your hands and feet, count your fingers and toes, and see what totals you get for each appendage (yakuza excluded). These numbers are a result of our having descended from synapsids (“mammal-like reptiles”) that likewise had five digits on each end of four limbs. In fact, all mammals are synapsids, and the last common ancestor synapsids shared with dinosaurs and other egg-laying reptiles was more than 300 million years ago. Humans and most other mammals don’t lay eggs (albeit, some placental mammals like to hatch from eggs), but a few still do – monotremes, such as platypuses and echindnas – thus demonstrating a lingering trait of this reptilian ancestry.

So it was this week that I was reminded of a five-year anniversary, the evolutionary history of mammals, and our long-lost connection to dinosaurs, thoughts that all coincided as they were triggered by remembering the Dinosaur Dreaming dig site in Victoria, Australia.

No, these people are not incarcerated and carrying out their sentences by cracking rocks all day in the summer sun. They actually are: volunteers at the annual Dinosaur Dreaming dig site in coastal Victoria, Australia; looking for fossils of Cretaceous dinosaurs, mammals, turtles, and other animals; and very much enjoy doing this. Really.

In early February of 2006 (yes, five years ago), I traveled to Melbourne, Australia for a four-month sabbatical from my teaching position at Emory University, the first (and perhaps last) I had been granted. Before leaving, my stated goal was to work on a science-education project with Patricia (“Pat”) Vickers-Rich, a paleontologist and professor at Monash University, as well as the director of the Monash Science Education Centre. (Let’s just say Pat wears a lot of hats, all of which look quite stylish and are completely appropriate for each given occasion.)

Within the first week of my residency at Monash, Pat’s husband – paleontologist Tom Rich of the Museum of Victoria (mentioned in earlier entries of The Great Cretaceous Walk) – invited me to visit the Dinosaur Dreaming site with him for the final weekend of the 2006 dig season. The site, which is only about a two-hour drive from Melbourne, had been investigated and excavated for Mesozoic vertebrate fossils since 1994, but for only a month once every year, typically in February, toward the end of the Australian summer. I was thrilled to be invited to this paleontologically significant place, and I enthusiastically accepted Tom’s generous offer.

Tom Rich’s bumper sticker was only telling part of the story: he does indeed brake for dinosaurs, but he comes to a full stop, gets out of the car, and stays a few days for Cretaceous mammals.

I remember that day very clearly, and probably will for the 10^th, 15^th, 20^th, and 25^th anniversaries (No guarantees after that last one, though.) During the otherwise uneventful drive to Inverloch, Victoria, I excitedly talked with Tom about the paleontology that had been done in this area, and occasionally took in the rolling green hills and gorgeous blue skies of the Victoria countryside. Once we caught our first brief look of the tan-brown cliffs of the coast, I smiled: it was my first sighting of the Cretaceous rocks of Australia. Little did I know then how many of those rocks I would see in the next five years (especially in 2010), and how much I would scrutinize and beseech them to reveal their ichnological secrets. But that’s the problem with predicting the future: you just don’t know it until it happens, and even when it is happening, you still might not connect it to the past.

My first up-close view of the tasty Cretaceous outcrops at Flat Rocks, near Inverloch, Victoria. The people are part of the dig crew in February 2006, and they were pumping seawater out of the man-made depression going into the bone-bearing layer of rock, a daily ritual during the dig season. For those of you from the southeastern U.S., note the lack of kudzu and other vegetation covering the rocks, a distinct advantage in prospecting for trace fossils. But then you have to deal with the tides. Oh well. If it isn't one thing, it's another. It's always something.

The Dinosaur Dreaming dig site is also referred to as Flat Rocks, an informal name applied by people to this small area of the coast. Unimaginatively (or appropriately), it was given that name because of the broad, flat platform, formed by beds of Cretaceous sandstones and conglomerates that dip gently to the east and are planed off by marine erosion. Oh, did I mention this dig site is drowned by high tides twice every 24 hours? The bone-bearing bed that attracts so much attention from the volunteers happens to be in the intertidal zone on the marine platform, so dig crews can only break up the hard rock to look for bones during low tides. This odd circumstance certainly goes against the stereotype of dinosaur dig sites taking place in dusty deserts, but the crews that work here do not concern themselves with conditions elsewhere, and have dealt with their situation admirably.

If you want to get more bones from the Dinosaur Dreaming bone bed, you either have to drain it after each high tide, or hand out snorkel masks to everyone. They opt for the former, and I don’t blame them.

The bone bed extends up above the shore at Flat Rocks and is in the main cliff-face, marked by Tom Rich's foot here, but unfortunately is not as productive as the part that's underwater much of the time. Go figure. And no, I have nothing to say about Tom's fashion choices in headgear, although I personally would have gone with a teal keffiyeh, rather than basic red.

Because of these high tides, and to make maximum use of the time when volunteers are at the site, they haul back heaps of rocks to a rental house, which serves as “home” for most crew members, even if only for a week or two. What do they do then – drink slabs of beer and tell tales of what bones they found? If only. Instead, they sit down to break up the rock into sugar-cube sizes, looking for small, fractured bits of dinosaur bones or teeth, or the rare (but much celebrated) mammal jaw. Regardless of whether it belongs to a dinosaur, mammal, or other vertebrate, a “bone of the day” is often declared, though, and at the time I visited, this was announced on a bulletin board outside the house.

Why was everyone feeling the Dinosaur Dreaming blues? Is it because of the several hundred kilograms of rocks that need to be fractured into tiny bits while searching for elusive fossils?

The news you need to know each day for the Dinosaur Dreaming dig site. As you can see, the “bone of the day” on February 25, 2006 was a turtle skull. Not surprising, as the site manager was (and still is) Lesley Kool, and she loves turtles. (Incidentally, she is the inspiration for the name of Koolasuchus – the youngest known temnospondyl amphibian in the geologic record, coming from the Cretaceous of Australia.) My favorite notice on the bulletin board? The notice about the PARTY.

After a beautiful little mammal mandible was found from the Dinosaur Dreaming site in 1997, followed by more mammal jaws and teeth in ensuing years, people associated with the site began joking that the locality should be nicknamed “Mammal Dreaming.” Tom Rich, originally a paleo-mammalogist in his interests and training, thus fulfilled his long-held dream of studying Cretaceous mammals in Victoria.

Logo for the Dinosaur Dreaming t-shirt in 2007, showing a typical Australian irrelevance for what were arguably the most scientifically important fossils to come out of Flat Rocks. But, you have to admit, it’s pretty darned funny, right up there with the recent depiction of a "Thunder Thighs" sauropod (Brontomerus) punting a Utahraptor.

These finds were indeed rather important, including jaw bones and teeth of the oldest known placental mammals (Ausktribosphenos nyktos, Bishops whitmorei) and monotreme mammals (Teinolophos trusleri) in Australia, but they are exceedingly tiny (mere millimeters long), requiring much processing of rock, sharp eyesight, and the right search images. In short, this dig site requires some commuting, draining, breaking, squinting, sweating, swearing, and lots of other active verbs that only overlap in a few ways (mostly the swearing) with, say, most dinosaur dig sites in the western U.S.

Going back to February 2006, I must confess that I was awestruck at the opportunity to visit Dinosaur Dreaming and meet the people involved with it: a fanboy, you might say, one who had read Dinosaurs of Darkness from cover to cover and knew all of the names of the people associated with the Victoria dinosaur prospecting and digs over the years (including the legendary Dinosaur Cove). Indeed, I had to ask someone there to pinch me to make sure I wasn’t dreaming. (Which actually did not go over as well as I expected.)

Anyway, I had a few agenda items in mind that fine February weekend, all of them ichnological. For example, were there any fossil invertebrate burrows preserved in the sandstones and conglomerates? If so, these could be used for discerning the original sedimentary environments entombing the bones. Were there any tracks of the same animals whose bones had been washed into a stream 115 million years ago, such as those of dinosaurs, birds, or mammals, showing that they also lived in the area where parts of their dead bodies rested? How did any trace fossils I might find relate to the original environments of this place, when it was snogging with Antarctica and located at about 75° latitude south?

What happened that weekend in a paleontological- and ichnological-discovery sense has already been covered in previous entries (here, for example), and I won’t say, “and the rest was history” (because that would be a cliché, which I avoid like the plague). There are other memories showing why it was an extraordinary weekend, some comical, others magical, such as when:

• One of the long-time volunteers – Mary Walters, who I had just met – and I sped along a dark road in the Victoria countryside searching with the car’s headlights for my field boots, accidentally left on the top of Tom Rich’s Land Rover and unnoticed by him as he drove off. During our madcap excursion, we found one boot and two socks: the other boot was never found. (It was OK, though, as Gerry Kool gave me a pair of “Blunnies” (Blundstones) the next day to wear. And I still have them.)

• During my first day of scouting for trace fossils, I couldn’t help but notice a small snake, surely venomous (this was Australia, mate) that wriggled desperately on a sandy area of the beach, trapped at the base of the cliff. I had no idea how it got there, but it needed to go somewhere else. I managed to coerce it into my field hat, carried it to a vegetated drainage several tens of meters away, and released it. Intrigued by this ominous experience, I walked back to the spot where it had been flailing. Just above there was a fossil invertebrate burrow, the first I had found at the site. Thanks, snake.

• Mike Cleeland, longtime volunteer and an extraordinary fossil finder, sang at the “closing ceremony” for the 2006 dig season that certainly fit with the theme of Dinosaur Dreaming: To Dream the Impossible Dream. (I only wish he had done My Way, but somehow blending the Frank Sinatra and Sid Vicious versions). This song was preceded by the sudden appearance of a mother brush-tailed possum, carrying her babies on her back as she walked along the top of a wooden fence, as a dog barked energetically at them in the adjoining yard: placental and marsupials meeting in the present, with fossils of their relatives locked inside nearby Cretaceous rocks.

• Awards that followed Mike’s entertainment, some of which employed numerous inside jokes that no doubt multiplied exponentially during the dig. The camaraderie was palpable and warm. I could see how this event happens every year: it’s not really so much about the science, but the people.

The close of the 2006 Dinosaur Dreaming dig, celebrated with awards, stories, thanks, music, and adult beverages. From right to left: Wendy White, Lesley Kool, John Wilkins, a wayward dingo (cleverly disguised as David Pickering, even down to the beer in his paw/hand), Mary Walters, and Tom Rich. Note the photo bomb in the lower left, done by a cane toad: cheeky buggers.

Five years ago, this was a start of a new chapter that introduced me to a group of colleagues and friends in a place far away from where I sit now in Georgia, USA. So when I see pictures of Flat Rocks and the antics (and oh yes, fossils) of the 2011 Dinosaur Dreaming dig, including people I not only know but am quite fond of (in a burly, mateship sort of way), I smile and remember that time five years ago, and imagine years of science and friendship extending well into the future, bound together by the remains of Cretaceous lives.

One of the first sights of my visit to Flat Rocks in February 2006, the banner for Dinosaur Dreaming. It's still going up at the same spot every February, hopefully for as long as the bones reveal themselves. Want to volunteer for future digs? Just let them know.

In closing for this time, an emotionally moving and beautiful song (From Little Things, Big Things Grow) performed live by Australian musicians Kev Carmody, Paul Kelly, and John Butler. The song is actually about indigenous land rights in Australia, but its refrain applies to just about anything in life, including Cretaceous mammal jaws, trace fossils, and small snakes that point the way to trace fossils for visiting Yank ichnologists.

Of Min Min Lights and Ichthyosaurs

2011-02-16T06:03:00.000-05:00

As loyal readers know from previous entries, following field work in Victoria, my wife Ruth and I went on a paleontologically themed “drive-about” (as opposed to walkabout) in western Queensland last July 2010. We started in Townsville, and went west from there (after all, going east would have put us in the Coral Sea). We then paused for a fun day and night in Hughenden, followed by three glorious days and nights in Winton. Where to go next for a married couple in pursuit of more knowledge about fossils and their role in inspiring the human imagination in Australia? Well, how about Boulia?

An artistic recreation of Cretaceous ichthyosaurs frolicking like dolphins at the Stone House Museum in Boulia, Queensland (Australia), thus providing a good example of how convergent evolution influences art: mural by Rona Thoragood (1997). For more about intersections between paleontology and art in outback Queensland, check out Ruth Schowalter’s (Hallelujah Truth’s) musings here and here.

We knew almost nothing about Boulia before visiting it, other than brief descriptions in tourist brochures we had picked up in Townsville, Hughenden, and Winton. But in every one of these was a blurb about the Stone House Museum and “Dinosaur” Dick Suter, an amateur fossil collector who had put together an educational display of Cretaceous fossils from around those parts. Knowing the area around Boulia was in the middle of the former Cretaceous seaway, we figured that the museum would have plenty of items to slake our continuing thirst for learning about Australian life from 100 million years past.

After bidding a sad goodbye to Winton, it was about a four-hour drive on one-lane roads for much of the way to Boulia. On entering town, we noted that, though small, it was bigger than most outback-Queensland towns we had seen, some of which have names on a map solely because of a single pub hotel just off the road. Boulia likewise had a pub hotel, which ably met our budgetary and adult-refreshment needs. A petrol station, only a short walk from the hotel, had meals and snacks, and our sitting down for supper on its open-air porch provided an all-too brief tourist-eye view of the relaxed pace of life in Boulia.

But before that, we went to Boulia’s year-round and non-paleontological claim to fame: a place devoted to telling tales about the legendary Min Min Lights, fittingly called the Min Min Light Encounter Centre. Sara Collins – in charge of promoting tourism in Boulia – was there at the center and served as an all-around lovely person for welcoming newcomers, Yanks included. She successfully persuaded us to go experience their display, and we were not disappointed, as it involved entertaining animatronics, sound effects, storytelling, a rotating room (really), and of course, lots of lighting effects. It was what would happen if The Muppets ever worked with Steven Spielberg. (Which, actually, they did, but they really need to get together more often.)

What are the Min Min Lights? They are disembodied, moving, and multi-colored lights, either real or imagined, that appear in the night sky in this part of the outback. Interestingly, the story of the Min Min Lights reminded me of the Marfa Lights, reported near the small town of Marfa in west Texas (USA) since the 1950s. The best scientific explanation for such recurring phenomena throughout the world is that they represent Fata Morgana (which, incidentally, would also be a great name for a rock band, a James Bond villain, or both). A Fata Morgana is a mirage caused by atmospheric distortions and reflections of light that form at the interfaces between air masses with different temperatures. Or something like that: I'm a paleontologist, not a physicist.

Entering Boulia, Queensland at dusk, a ghostly windmill looms in the distance, and wait – what’s that? It’s either the Min Min Lights, or the headlights of a “sport ute:” whichever you prefer to believe.

The next morning, we checked out of the hotel and went straight to the Stone House Museum at its opening time. And there outside it was “Dinosaur” Dick Suter himself: 74 years old, but filled with the proverbial vim and vigor. Because we were his first visitors for the day, he devoted a good amount of time to educating us about the fossils there before other tourists drifted in later that morning. Most of the fossils were in a one-room building behind the eponymous Stone House (which dealt more with human stuff, thus did not hold my interest for very long). This little house had an eye-catching sign for any paleontologically inclined folks:

It’s a sign! But it’s not the Min Min Lights. Instead, it’s a straightforward and entirely truthful advertisement about the Cretaceous marine-reptile fossils within the small house on the grounds of the Stone House Museum. Oh, and there’s lots more than “just” marine reptile fossils, too!

This area of the world is well known for its Cretaceous marine reptiles, so I was not surprised to see that these were most prominently mentioned. Dick Suter has previously told people that none of these animals were dinosaurs, so his nickname of “’Dinosaur’ Dick” is a bit of a misnomer in that respect. It really should be “’Ichthyosaur’ Dick,” despite its lack of alliteration, or “’Ichthyosaur-Elasmosaur’ Dick,” or “’Ichthyosaur-Elasmosaur-Chelonian’ Dick,” or…OK, I’ll stop. The point is, he finds lots of fossils in the area around Boulia, none of which are dinosaurs.

What did he have? Yes, bones of the aforementioned ichthyosaurs, elasmosaurs, and chelonians (the last also called "turtles" to most people) were indeed there, as well as fossil fish (including some beautifully preserved fish heads), ammonites, and a wide variety of invertebrate fossils other than ammonites. As an ichnologist, though, I was pleased to see two types of trace fossils there: gastroliths (pictured twice before in this blog – here and here) and a supposed turtle coprolite. Coprolites, which are fossil feces (yes, they fossilize, but please do not experiment with this at home), are always tricky trace fossils to correctly distinguish from, say, a mass of rock that just happens to look like a pile of excrement. But the one he had on display probably was a coprolite, based on its form, content, and association with probable poopmakers, er, I mean, tracemakers. I just wish the contents could be examined in more detail to test this suppository theory further.

A coprolite identified as belonging to a Cretaceous turtle at the Stone House Museum in Boulia, Queensland, in which the rock was broken open to reveal a part and counterpart of the coprolite. Note what looks like either shell or bone fragments in a compacted, slightly rounded mass, which constitutes not-bad evidence supporting this object as a coprolite. But where exactly was it collected? Which geologic formation is it from? Is the specimen archived with a museum number and other information about its discovery? And how do we know it came out of a turtle bum?

Some possible tracemakers for coprolites in the same Early Cretaceous deposits: sea turtles, identified as Notochelone costata. How would we be able to make a good, testable hypothesis that would link these turtles with supposed turtle coprolites? Think about it, but not too much, because it’s actually not that complicated.

Other than the trace fossils (and oh yeah, the marine reptiles, ammonites, and other body fossils), Ruth and I were most impressed with the colorful paleo-art adorning the interior walls of the house. These murals were painted by Rona Thoragood in 1997, and they were lovely. I particularly liked the following one because of its color, composition, and attempt to show the major players in the original ecosystems from the Cretaceous Period.

Artist’s depiction of the Early Cretaceous seaway that covered much of what is now called Queensland, Australia about 100 million years ago. Shown in the ocean are: pterosaurs flying overhead; a large, long-necked plesiosaur (center), a short-necked plesiosaur - perhaps a pliosaur (right); ammonites (below center); teleost (bony) fish; a colorful coral reef; and a sea turtle swimming over the reef, evoking comparisons to the Great Barrier Reef. Note to creationists: the wall air-conditioning unit in the middle of the mural was not extant during the Cretaceous.

After our visit, we left Boulia and the former Cretaceous seaway for our next destination, the considerably larger town of Mt. Isa. As we departed, we were left with lasting memories of the bountiful and beautiful fossils of this land, as well as the beguiling Min Min Lights that still illuminate our imaginations.

Wait, did you think I was saying goodbye? That the Great Cretaceous Walk is going to stop walking? As if. In next week’s entry, I will sort out a few lingering thoughts provoked by our visit to Boulia that concern the somewhat uneasy relationships between academic paleontologists (people like me) and amateur paleontologists (people like Dick Suter, who greatly outnumber the academics).

But for now, I’ll leave you with Australian country-music performers Sara Storer and John Williamson, singing Raining on the Plains, which much of the Queensland outback experienced in a big way with the recent passage of Cyclone Yasi. (And please do note the all-too-important appearance of upraised and soon-to-be-emptied beer glasses at 0:54 and 1:45.)

Diving Down Under in the Cretaceous Sea

2011-02-09T06:43:00.000-05:00

Cyclone Yasi - the massive tropical storm that hit Queensland, Australia last week – was a Category 5 hurricane, with winds well in excess of 250 km/hr (> 150 mph) at one point. Once it reached that place where the land meets the sea, it smashed a large area from Cairns to Townsville, its eye passing over Mission Beach, then Tully, places I have visited twice with study-abroad students from Emory University. The cyclone continued inland, bringing high winds and heaps of rain to communities inland that normally stay dry: Hughenden, Winton, Richmond, Boulia, and Mt. Isa. As expected, entire beaches vanished, coastal forests were torn apart, and property damage was excessive. Fortunately, though, very few people were injured, a direct result of excellent emergency preparedness by the Australian people and government.

The path of Cyclone Yasi (top), compared to a paleogeographic map of Cretaceous Queensland (bottom). Sometimes the sea comes back to visit, however briefly and horrifically. Cyclone track map is from Wikipedia Commons, and paleogeographic map was in the Museum of Tropical Queensland, Townsville, Australia, a place that was hit hard by Yasi just last week.

So how does Cyclone Yasi relate to the Cretaceous of Queensland? These storms help to remind us that the direct influence of the modern sea on the former site of a Cretaceous seaway is only a hurricane away. Thus the shells, bones, and trace fossils of lives 100 million years past are soaked anew with marine-spawned waters, an elemental circle that has repeated many times, long after ammonites and plesiosaurs cruised through the open waters that covered what we now call Queensland.

So let’s go back to that seaway for several moments. In a previous entry, I introduced my gentle readers to some of the trace fossils of that Cretaceous sea, gastroliths, otherwise known as “stomach stones.”

For Mesozoic vertebrates, gastroliths are normally apparent as localized accumulations of rounded gravel, pebbles, or cobbles in the skeletons of dinosaurs and marine reptiles. However, in Mesozoic vertebrates that lived on land exclusively - like dinosaurs – the existence of gastroliths has been a subject of remarkable controversy. At least one paleontologist has even derisively referred to gastroliths as “gastromyths,” which I, as the founder of The Church of Ichnology, would consider sacrilege if applied to real ones.

“Those aren’t trace fossils – they’re just a bunch of rocks!” Blasphemy! I cast thee out of the Church of Ichnology! No more beer for you! Photo is of gastroliths recovered from a Cretaceous elasmosaur by “Dinosaur Dick” Suter and are on display in Boulia, Queensland, Australia.

Other paleontologists have even started to question long-supposed gastroliths in sauropod dinosaurs; nevertheless, these trace fossils are now getting recognized more often in ornithopods and theropods. Their presence in theropods, though, is unsurprising, considering how many of their living relatives (birds) also use gastroliths.

So why all of the disagreement about gastroliths in the fossil record? It has to do with distinguishing localized collections of rounded rocks that might have accumulated in a skeleton well after an animal died, versus those that were in its body before it died. Sure, skepticism is warranted when the sedimentary strata surrounding fossil skeletons also contain lots of rounded rocks that look just like the ones found inside a skeleton. But other explanations tend to whither on the vine when these stones occur only in the abdominal region of a skeleton. For example, fossil marine reptiles – like plesiosaurs – are oftentimes encased in fine-grained sedimentary rock – like shale or sandstone – with nary a pebble in sight. This means that an accumulation of pebbles inside a vertebrate animal is probably not an accident.

Recreation of the Cretaceous plesiosaur (more specifically, elasmosaur) Woolungasaurus glendowerensis, swimming through the Museum of Tropical Queensland in Townsville, Australia.

When you find a cluster of stones that look like these, they’re inside the rib cage of a Mesozoic marine reptile, and you don’t see any other such stones in the rock surrounding the skeleton, it’s probably OK to identify these as gastroliths. But why are they there? Read on. (Gastroliths at Kronosaurus Korner, Richmond, Queensland, Australia.)

Aside from debating which dinosaurs had gastroliths or not, everyone seems to agree that these rocks assisted in digestion in these animals. When enfolded in a muscular gizzard, a bunch of silica-rich stones would have helped to mechanically grind down tough-to-digest food, rather than relying just on stomach acids or enzymes. But the presence of concentrated masses of rounded rocks in non-dinosaurian vertebrates, such as Mesozoic marine reptiles, caused a little bit of pause in paleontologists before they also identified these as gastroliths. The hesitation felt by paleontologists was not so much about “what,” but more about “why,” as in “Why did marine reptiles swallow rocks?” Digestion was not considered as the sole reason, because these animals only ate seafood, most of which should not have required as much grinding as tough plants, insects, or other terrestrial foodstuff.

As a result of one idea discarded, an alternative one proposed by paleontologists was that these rocks somehow contributed to buoyancy control. For example, everyone who has done SCUBA diving knows that weight belts need to be used in combination with a buoyancy compensator (BC) vest. This human-based analogy, however imperfect, helps us to think about how these reptiles – some of which were multi-tonne animals – moved vertically within a watery environment to find food, mate, give birth, go up to the surface to breathe, and otherwise conduct marine-reptile business. To float, they had to ingest air at the surface, and to sink, they had to exhale, all of which was aided by coordinated movements of the fins and tail.

So let’s just look at some large, modern, air-breathing marine vertebrates for an example of how this is done, and the mystery will be solved, right? In fact, whales would be perfect, right? Well, no. Turns out gastroliths are absent in cetaceans (whales, dolphins, and porpoises); instead, these animals have other adaptations that allow them to easily move up and down in the water column, yet don’t require them to swallow anything other than food. Sea turtles are a bust, too: not one modern or fossil sea turtle had been found with gastroliths. Turned out the only modern marine vertebrates that have gastroliths are some pinnipeds (seals, sea lions and walruses) and crocodilians (alligators and crocodiles). So because crocodilians are reptiles, let’s focus on those, and specifically we’ll take a look at estuarine crocodiles (Crocodylus porous) of Australia, which are affectionately known as “salties” because of their tolerance of marine salinity.

An estuarine crocodile (“salty”) in a tank at the Alice Springs Reptile Centre (Northern Territory, Australia), showing excellent buoyancy control as it hangs out on the bottom, whilst readily evoking thoughts of large marine reptiles in the Cretaceous. For perfectly rational reasons, I did not check to see whether it had any gastroliths.

The “rocks must help with buoyancy control” idea, though, took a hit with a 2003 study that showed that gastroliths make up far too little weight compared to the body weight of a crocodilian (Alligator mississippiensis): only about 1-2%. This means they have little effect on a crocodile just moving up and down in the water. So this hypothesis got tweaked a bit: maybe these were used not so much as ballast for diving, but for stabilizing while swimming. Instead of weight belts, then, think of the tiny weights placed on tires to balance them on a car, which help the tires to rotate more evenly.

OK, time for the thesis-antithesis-synthesis approach. How about, gastroliths were used for both buoyancy control (balance more than ballast) and helping to digest food. Maybe we may have a winner! (At least, for now. We scientists have this peculiar habit of changing our minds about hypotheses once we get new evidence.) Two Cretaceous elasmosaurs from Queensland, described in 2005, not only had gastroliths, they also unexpectedly contained stomach contents (fossilized, of course), which included bits of clams, snails, crustaceans, and other invertebrates that lived on the ocean bottom. This evidence was a big surprise, because paleontologists had always assumed elasmosaurs only ate fish, and never thought of them as bottom feeders. You reckon some rocks in your stomach would help to grind down those hard-shelled critters and make them easier to digest? (Hopefully you said “yes,” otherwise stop reading this right now, and go back to watching CSI.)

So now we have a new hypothesis for gastroliths in marine reptiles, which is a variation on a previous one, but also combines another one given previously for these trace fossils. In summary, the more things change, the more they stay the same, unless they change, then they’re not exactly the same, especially if they only changed a little bit.

Famed Australian singer-songwriter Kasey Chambers (and oh yeah, Shane Nicholson), perform Rattlin’ Bones, singing of “…smoke not rising, fuel not burning, the sun not shining, late-night sorrow scratching at a door”; and “dragging stones until buried beneath the ground, with dust and bones.” Lyrics that evoke Cyclone Yasi and gastroliths in Cretaceous plesiosaurs, respectively. Best wishes to all in Queensland affected by Yasi.

Further Reading on Gastroliths

Cerda, I.A. 2008. Gastroliths in an ornithopod dinosaur. Acta Palaeontologica Polonica, v. 53, p. 351-355.

Drehmer, C.J., and de Oliveira, L.R. 2003. Occurrence of gastroliths in South American sea lions (Otaria byronia) from southern Brazil. LAJAM, v. 2, 123-126.

Henderson, D.M. 2003. Effects of stomach stones on the buoyancy and equilibrium of a floating crocodilian: a computational analysis. Canadian Journal of Zoology, v. 81, p. 1346-1357.

McHenry, C.R., Cook, A.G., and Wroe, S. 2005. Bottom-feeding plesiosaurs. Science, v. 310, p. 75.

Taylor, M.A. 1993. Stomach stones for feeding or buoyancy? The occurrence and function of gastroliths in marine tetrapods. Philosophical Transactions: Biological Sciences, v. 341, p. 163-175.

Wings, O. 2007. A review of gastrolith function with implications for fossil vertebrates and a revised classification. Acta Palaeontologica Polonica, v. 52, p. 1–16.

Why Eat a Rock? Gastroliths (‘Stomach Stones’) as Trace Fossils

2011-01-30T11:42:00.000-05:00

During the past 30 years or so, trace fossils – such as tracks, burrows, nests, toothmarks, coprolites (fossil feces), and so on – have been steadily gaining more respect and recognition in paleontology. I would like to think this is a direct result of my dedicated “ichnoevangelism,” in which I have attempted to convert The Great Unwashed who fail to see the paleontological truth inherent to trace fossils, but the world of paleontology is much bigger than the Church of Ichnology (so far). Nonetheless, despite this overall increase in enlightenment, one type of trace fossil still causes some recalcitrant non-believers to turn gazes elsewhere and ignore their scientific worth. Those would be gastroliths, otherwise known as “stomach stones.”

Gastroliths extracted from the interior of a Cretaceous elasmosaur (a large, long-necked marine reptile) in central Queensland, Australia. Specimens are at the Stonehouse Museum and collected by “Dinosaur” Dick Suter in Boulia, Queensland. I know, they just look like a bunch of rocks, not trace fossils. Please read on, and prepare to learn.

I was reminded of this ichnological inequity while traveling in Queensland, Australia this past July (2010), noting three modest displays of these enigmatic trace fossils. One was in the tiny town of Boulia, another in the much bigger town of Mt. Isa, and the third in the tiny-but-still-bigger-than Boulia town of Richmond. The gastroliths in Boulia and Richmond had been directly associated with the skeletal remains of elasmosaurs, marine reptiles that lived during the Cretaceous Period (about 100 million years ago) in this part of Australia. The gastroliths seen in Mt. Isa, though, were in the gut region of a dromornithid skeleton. Dromornithids were large flightless birds – distantly related to ducks and flamingoes – that lived during the latter part of the Cenozoic Era, from about 25 million to only about 40,000 years ago.

Gastroliths associated with the gut region of a fossil dromornithid. Specimens on display in the Riversleigh Fossil Centre in Mt. Isa, Queensland.

Outside of Australia, gastroliths have been found in a few species of dinosaurs, too. So why were these gastroliths present in Mesozoic marine reptiles, dinosaurs, and Cenozoic land birds?

Oh wait, sorry about that: I never explained the term “gastroliths,” other than to say they were “stomach stones.” That’s not very helpful, so I’ll back up and get more basic. Gastroliths are rounded rocks that, for whatever reason, end up in an animal’s digestive tract. Why would an animal swallow a rock? Two reasons come to mind:

(1) Accidental ingestion, in which a rock that was too close to some food and went along for the ride. (This is how we get some of our beloved pets to take pills they otherwise would never find appetizing.) In dinosaurs and ancient birds, some paleontologists have also proposed that they (the rocks, not the paleontologists) might have been inadvertently consumed while carried in mouths during nest building.

(2) Deliberate ingestion, in which an animal knowingly (instinctively) sees a delectable rock and swallows it, for reasons that will be further explained soon.

Determining which of these two scenarios happened with a fossil animal is a matter of numbers, as in, how many stones are preserved in the gut region of a fossil animal. Odds are that accidental ingestions should be unusual events, considering the low nutritional value of most rocks (not to mention their lack of fiber), as well as the potential for choking on them, which would negatively impact future reproductive success. As in, when you’re dead, you don’t get to pass on your genes, and choking uncontrollably probably isn’t sexy enough to attract many mates, either. (But if it works for you, hey, knock yourself out – literally.)

This means that gastroliths should be absent or rare in animals that did not intentionally eat them. Then again, a high concentration of rocks in a relatively small area within the main body cavity of a skeleton implies that these were repeatedly swallowed for good reason. This circumstance also implies that this seemingly odd behavior actually was not so strange and provided some adaptive advantage to that animal.

OK, so what are the benefits of purposefully swallowing rounded rocks? To answer this, paleontologists turn to our good friend uniformitarianism (or its less syllabic synonym, actualism), in which modern animals teach us about gastroliths and how these animals use them. For example, we can easily observe chickens (chooks), budgerigars (budgies – not to be confused with budgie smugglers) and other small birds seeking out grit, pebbles, and other small stones and swallowing these. Much larger flightless birds, like emus and ostriches, do the same, and accordingly pick a wider size range of stones. This practice is linked to aiding digestion; the gastroliths lodge in the muscular crop or gizzard of a bird’s digestive tract and are then used to grind down any tough-to-digest food that passes through the same place.

American crow (Corvus brachyrhynchos) picking out some pebbles and swallowing them, presumably to help it digest some food. Footage taken in Vancouver, British Columbia, which is in some country just north of most of the continental U.S. (Sorry, I’m American, hence my lack of geographical knowledge.)

As yet another example of how modern birds are theropod dinosaurs, several theropods from the Jurassic and Cretaceous Periods – Lourinhanosaurus, Caudipteryx, Nqwebasaurus, Sinornithomimus, and others - have beautifully preserved masses of gastroliths in their gut regions. Strict carnivores tend not to need gastroliths, though, so their presence in these theropod dinosaurs points toward their probably having had a more varied diet as insectivores, omnivores, or even herbivores.

Gastroliths in the gut region of the small theropod Caudipteryx zoui, with an overall view (top, arrow pointing to gastroliths) and a close-up of the gastroliths concentrated in its abdominal region (bottom). Replica (cast) on display in the Carnegie Museum of Natural History in Pittsburgh, Pennsylvania.

Gastroliths have been interpreted in other types of dinosaurs, including a few ornithopods, sauropods, and ceratopsians, but are rare enough that they must not have been needed in most dinosaur species. Dinosaur paleontologists also acknowledge the possibility that larger carnivorous theropods might have secondarily ingested some gastroliths by eating a gastrolith-bearing animal. But as far as I know, this idea has not yet been convincingly supported as a genuine evidence-based hypothesis.

Animals also had to be discriminating about what rocks they gulped down. For example, what if a sauropod spotted a rounded cobble of limestone and thought (as much as a sauropod could think), “Wow, that’ll help grind my food!,” and gobbled it down. Well, limestone is composed of CaCO₃ (calcium carbonate), which is present either as the minerals calcite or aragonite. A simple test for these minerals, conducted in introductory geology labs worldwide, is to simply apply a drop or two of diluted acid to a rock suspected of being a limestone. If the rock fizzes like a sparkling Shiraz, then it’s definitely limestone: the acid is liberating the CO₂ in the CaCO₃, and the bubbles you see are composed of that gas.

Chemical reaction caused by adding dilute hydrochloric acid (HCl) to calcite. Gee, I wonder how a limestone cobble – composed of calcite – might have fared after a few minutes in an acidic gastrointestinal tract?

So now imagine the acidity of a typical sauropod stomach, which might have had a pH of < 3 (on a scale of 1 to 14, with 1 being the most acidic). What do you think would have happened if a limestone cobble slid down into such a gut environment? Yes, that’s right: the Mesozoic equivalent of Alka Seltzer. Other than for self-medication (rather unlikely), I just can’t see how eating limestone would have benefited a sauropod or any other dinosaur, because the rock would have dissolved too quickly to be used in a gastric mill.

And sure enough, most undoubted gastroliths are rocks composed of silica-rich minerals (chert, quartzite, quartz sandstone), which are more chemically stable than calcium-bearing minerals and resist chemical weathering from most acids. The bigger of such rocks also tend to be rounded: sharp corners would have had a tough time going down a gullet, or been painful enough to discourage doing something like that again, even on a dare. (“Come on, mate – bet you can’t swallow that big, spikey rock!”)

What modern animals – other than birds – have gastroliths? Perhaps surprisingly, some crocodilians have gastroliths, which also help with digestion, but further serve as ballast for buoyancy control when swimming. In the wonderful world of invertebrates, freshwater crayfish (also known generically as yabbies in Australia) have gastroliths, too. However, these are radically different in purpose compared to gastroliths in vertebrates, as they are secreted directly by crayfish and are related to maintaining a proper balance of calcium in their bodies.

What’s great about gastroliths as trace fossils is that we now know a lot more about them and their functions in some modern animals and dinosaurs because of intensive research on this topic in the past 10 years or so. Nevertheless, their scientific importance as trace fossils in marine reptiles from the Mesozoic Era – particularly in some Cretaceous plesiosaurs of Australia – is only just now being recognized. So that will be the subject of the next entry: their probable uses in big sea-faring reptiles 100 million years ago in Australia.

More great examples of Cretaceous gastroliths at the alliteratively (albeit illiterally) named Kronosaurus Korner in Richmond, Queensland (Australia). Notice the chunk of an elasmosaur rib just above these, showing how they likely were inside the elasmosaur. I wonder why?

In closing, as we reflect on the ichnological importance of gastroliths, I leave you with a song by Australia’s most famous balladeer, John Williamson, dedicated to the most beloved of gastrolith-using large flightless birds in Australia, the emu (Dromaius novaehollandiae).

Old Man Emu, written and performed by John Williamson, along with a visual tour of some of Australia’s most iconic terrestrial animals. Now if only someone would do a version that included Mesozoic animals of Australia…

A Trace Fossil by Any Other Name

2011-01-19T23:03:00.005-05:00

Seemingly everyone – but especially five-year-olds – can enthusiastically rattle off the genus or species name of their favorite dinosaur or other prehistoric animal. “Tyrannosaurus rex!” “Triceratops!” “Dimetrodon!” But I will bet a six-pack of my favorite adult beverage that 99% of people – kids and adults alike - cannot name a single trace fossil in the same way. And even if they did, could you imagine anyone applying the same vigor and gusto reserved for body fossils as they shout out the names of trace fossils? “Ophiomorpha nodosa!” “Eubrontes! “Celliforma!”

Wow, look! It’s Thalassinoides in Early Cretaceous rocks of Victoria, Australia! I absolutely love that trace fossil! Wait, come back – where are you going? Was it something I said?

You mean to say those words mean nothing to you? (And if they do, you’re either an ichnologist, or you cheated by using “The Google” on “The Internets.”) Well, just for contrast, think way back to when you read the genus or species names of the fossil animals just mentioned and the images those triggered.

With the Late Cretaceous Tyrannosaurus rex, you probably thought of a 7-8 tonne, bipedal carnivorous theropod dinosaur, with a huge head filled with giant, recurved teeth, ridiculously puny arms holding only two claws on each hand, and perhaps performing a noble deed, like eating a lawyer off a toilet (and thus doing its part to deter needless litigation).

Triceratops horridus, also from the Late Cretaceous Period, is a heavy-set herbivorous quadrupedal ceratopsian dinosaur with beak-like mouth, an enormous bony head shield, and three intimidating horns pointing forward from that head shield, a dinosaur that would never be confused with Torosaurus (oh wait, it is).

Dimetrodon, which had a bunch of species placed under that genus, is probably the most famous non-dinosaurian animal confused for a dinosaur. However, this sharp-toothed quadrupedal synapsid reptile from the Permian Period, which preceded dinosaurs by about 35-40 million years, is always associated with its “sailback,” formed by long neural spines.

The point here is that people who know nearly nothing about paleontology – but have seen these names corresponding with certain images – later can’t help but associate the distinctive features of these fossils with their names. This generality confirms one of the main reasons why we name things in the first place: so we can remember them. The second big reason why we name things is to communicate about them. Names are a sort of shorthand we use to make sure we’re talking about the same thing. Hence biologists and paleontologists alike use genus and species names in taxonomy, which is the science of classifying life.

So it makes sense that ichnologists have adopted a similar process of naming trace fossils, imaginatively called ichnotaxonomy. Think that’s outlandish? Wait, it gets better. They even use ichnogenus and ichnospecies names. Now, you might think that’s pretty cheeky of ichnologists, considering how trace fossils are not the actual or altered remains of ancient organisms, but of their behaviors. Nonetheless, the naming of trace fossils is supposed to serve exactly the same purpose as regular biological taxonomy, which is to remember trace fossils and communicate about them.

For example, if someone cries out “Ophiomorpha nodosa!” during a moment of wild, unbridled passion, ichnologists are supposed to think of a 1-5 centimeter wide, knobby-walled, tubular structure with a branching geometry. (Or, at least we try really hard to think of that.) Likewise, during a cocktail party, someone may casually mention Eubrontes – not to be confused with the Bronte sisters or Brontesaurus – which should conjure up an image of a 35-40 cm long tri-radiate structure, with pinching-and-swelling along the length of each radiating part before these taper to claw-like points, either expressed as a natural cast or a depression on a sedimentary rock surface. The use of Celliforma in a song lyric (as in, “She tried to Celliforma love, but I ain’t buying none today”) no doubt should inspire an ichnologist to dream of 2-3 cm long ovoid chamber-like structures, rounded at one end and flattened on the other.

The trace fossil Ophiomorpha nodosa from Pleistocene rocks of the Bahamas. These rocks are only about 125,000 years old though, so they’re barely considered as trace fossils, but they’ll do for this example.

The trace fossil Eubrontes (ichnospecies uncertain) from Early Jurassic rocks of the Connecticut River Valley of Massachusetts (USA) at the Pratt Museum, Amherst College.

Several specimens of the trace fossil Celliforma germanica from Late Cretaceous rocks of Patagonia, Argentina, on display in the Museo Paleontológico Egidio Feruglio, in Trelew, Argentina.

Notice what I didn’t do, which was to say these were “burrows,” “tracks,” or “nests” (respectively), because those would have been interpretations. I also didn’t say what animals made them because – you guessed it – that would have been an interpretation, too. Ichnogenus and ichnospecies are ideally descriptive, because in paleontology, good descriptions can last forever, but interpretations are always subject to change.

Not all ichnologists heed such conservatism, though, and sometimes ichnogenus and ichnospecies names are just plain dumb. Why yes indeed, I am talking about Hondichnus, an ichnogenus given that moniker because the person who named it thought this trace fossil resembled a motorcycle-track pattern. (Sorry, I refuse to link to the reference for this, but if you really must know, it can found through various search engines by using that name.) Not surprisingly, no one else has used that ichnogenus since its invention, hence demonstrating what the rest of the ichnological community thought of it. As a result, sometimes trace fossil names seem to die quiet, ignoble deaths, but once they’re in the literature, they can be resurrected.

So what does this all of this ichnotaxonomy talk have to do with entries from the last three weeks (here, here, and here), which were about the Early Cretaceous dinosaur tracks of Lark Quarry in Queensland, Australia? In 1979, Australian paleontologists Tony Thulborn and Mary Wade identified the big, three-toed dinosaur tracks at the site as the ichnogenus Tyrannosauropus, which as an ichnogenus had been named by another paleontologist in 1971. As can be discerned from such a name, this ichnogenus was allied with large theropod dinosaurs, such as tyrannosaurs. This meant that any subsequent identification of a three-toed fossil dinosaur track as “Tyrannosauropus” also implied that a large theropod made it. Furthermore, the repeated use of this name, especially when referring to the large tracks at Lark Quarry, meant people became less likely to think about any alternative hypotheses for their makers, such as dinosaurs other than large theropods.

Fortunately, science tends to encourage a little bit of questioning the status quo. But it still took about 30 years before two other paleontologists – Anthony Romilio and Stephen Salisbury from the University of Queensland – realized these three-toed tracks likely had been misidentified. Instead, these probably belong to the ichnogenus and ichnospecies Amblydactylus gethingi, not Tyrannosauropus. What’s significant about this is that Amblydactylus gethingi is a fossil track associated with large ornithopod dinosaurs, an interpretation based on the overall form of the tracks and how closely these match known ornithopod feet of the same size.

Amblydactylus gethingi, though, was originally defined from dinosaur tracks in Early Cretaceous rocks of Alberta, Canada, thus aptly showing how different species of ornithopod dinosaurs living in Australia and Canada at about the same time could have made very similar tracks. In this instance, ichnotaxonomy would be extremely useful for overcoming an otherwise huge language barrier between Australian and Canadian ichnologists, and their utterance of the words “Amblydactylus gethingi” would allay any confusion provoked by a rapid exchange of “G’Days” and “Eh’s.”

Comparison between the foot bones of the large Early Cretaceous ornithopod dinosaur Muttaburrasaurus langondi of Australia and the Early Cretaceous ichnospecies Amblydactylus gethingi, outlined in purple (the preferred color of the enemy). But the track was previously identified as Tyrannosauropus and interpreted as made by a large theropod dinosaur. Do you see where this line of reasoning is going? Illustration modified very slightly (colorized) from Figure 7 of Romilio and Salisbury, Cretaceous Research, in press.

Anyway, Thulborn and Wade also proposed two new ichnogenera and ichnospecies for the two smaller and much more abundant tracks at Lark Quarry: Wintonopus latomorum – which were made by some emu-sized ornithopods – and Skartopus australis – which were made by chicken-sized theropods. As mentioned in my previous post, we know the approximate sizes of the trackmakers based on their footprint lengths; these were multiplied by 4.0, which give us the hip heights of the dinosaurs. The small theropods were 13-22 cm (5-9 in) at the hip, whereas the small ornithopods had hip heights up to 150 cm (5 ft), and the “Big Guy’s” (or “Gal’s”) hip height was about 2.5 m (8.3 m).

The three ichnogenera of tracks at Lark Quarry, all in one photo: “Tyrannosauropus” (T), which is now identified as Amblydactylus gethingi; Wintonopus (W); and Skartopus (S).

Well, that is yet another piece of evidence that resulted in a dinosaur assumed to be more like Hugh Jackman to suddenly transmogrify into Dame Edna Everage. A hip height of 2.5 meters just happens to match the hip height of Muttaburrasaurus langdoni, which is a large ornithopod known from body fossils in rocks of about the same age as the Lark Quarry rocks, from about 98 million years ago.

A life-sized reconstruction of the large Early Cretaceous ornithopod dinosaur Muttaburrasaurus langdoni in Hughenden, Queensland, with me underneath it for scale. Just out of view in the background is a closed pub. Oh what a terrible place, is a pub with no beer. Photo by Ruth Schowalter.

Remember the opening scene of the Lark Quarry story, in which a large ornithopod plods onto the Early Cretaceous lakeshore? An ornithopod about half the size of Muttaburrasaurus left tracks on part of the exposed surface at Lark Quarry before the arrival of the smaller dinosaurs. Although I don’t know whether ichnogenus or ichnospecies names were applied to those tracks, they may have represented a missed opportunity, as they could have been compared to the 11 “Tyrannosauropus” tracks to test for differences. After all, juveniles, subadults, and adults of the same species of ornithopod could have made footprints that, 100 million years later, would have been given three different names by ichnologists, erroneously leading some to think that perhaps three different species of dinosaurs made them. This is the continuing challenge of ichnotaxonomy: how to separate descriptions from interpretations when making names.

So to make a long story mercifully just a tiny bit shorter, here’s a summary of what is still accepted about the Lark Quarry “dinosaur stampede” story:

• A sizeable ornithopod dinosaur walked onto the lakeshore.

• A stampede later took place on that same lakeshore, involving more than 150 dinosaurs.

• The stampeding dinosaurs were comprised of two species of small dinosaurs, one a theropod and the other an ornithopod.

• These dinosaurs ran at high speed and in the same direction.

• A large dinosaur walked onto the scene from the same direction in which they ran. In other words, the small dinosaurs ran directly toward the big one.

So even though the “giant predator scaring the small dinosaurs” story is now in doubt, the most pertinent question one can still ask about Lark Quarry is that posed by Thulborn and Wade in 1979:

Persuasive circumstantial evidence leads us to conclude that they represent a stampede - that is, a wild, unreasoning and panic-stricken rush to escape the threat of danger. What could have caused such presumed panic?

Just as an anecdotal and speculative explanation, I have watched flocks of small shorebirds flee/fly as a group and move toward and then around me when I approach them on foot, even though predation is not my intent. After all, my 1.65 m (5 ft. 6 in) height must seem rather intimidating to such tiny animals. As a result, I also can’t help but imagine how a small, chook-sized dinosaur would have likewise tried to avoid being underfoot when a 3-5 tonne herbivore arrived on the scene, if for no other reason than to avoid being squashed. So you might say, they were running flat out to avoid being flattening.

The moral of Lark Quarry is that dinosaur tracks still matter, as do names. But perhaps the most important lesson of all, is that naming something should never stop learning about what is being named.

Australian country-singing legend Slim Dusty, singing a lament to the absence of adult beverages in a public bar in his most famous song, In the first version, it’s all sadness and sorrow, but nothing is done other than to whinge about it. The second song is a response to the first, in which “true blue” Aussies decide they’re going to do something to remedy this situation. How does this relate to ichnotaxonomy and the Lark Quarry dinosaur tracks? I’m not really sure, but I think it has to do with variations on a main theme, as well as an excuse to mention beer.