Diving Down Under in the Cretaceous Sea

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.

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

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.

A Trace Fossil by Any Other Name

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?

Who Made the Three-Toed Dinosaur Track?

In paleontology, occasionally a scientific hypothesis rules for several decades or more and enters the public realm, becoming part of popular lore. Nonetheless, science is always changing, which means that what we took for granted as a “true” story can be upended in a way that surprises everyone, perhaps even the paleontologists doing the revising. Such is the situation with the “giant-stalking-theropod-dinosaur-causing-a-dinosaur-stampede” story of the Lark Quarry dinosaur tracksite in Queensland (Australia). This tale has been reigning for more than 30 years and is known worldwide by paleontologists and laypeople alike, but now faces a makeover in the light of new evidence.

Here are some dinosaur tracks from Queensland, Australia. The dinosaurs that made them had three toes on their rear feet, and walked only on those two feet (bipedally). So were these from theropod dinosaurs or ornithopod dinosaurs? Don’t know? Then I guess you’ll have to read more, won’t you? Display is at the Museum of Tropical Queensland in Townsville, Queensland (Australia). Note the stylish sunglasses (lower right) for scale.

The Case of the Mistaken Dinosaur

Like all stories in paleontology, that of Lark Quarry – a world-famous dinosaur tracksite in Queensland, Australia - starts in the geologic past; in this instance, during the Cretaceous Period, about 98 million years ago. The cast of this tale consisted of about 150 dinosaurs, played by:

• One species of a large herbivorous dinosaur (an ornithopod), who was a mere bit actor, making a cameo appearance before the main act.

• Two species of small dinosaurs – one a theropod and the other an ornithopod – who made up most of the cast; and

• The star of the show, a tyrannosaur-sized theropod, who made a grand entrance toward its climatic finish.

The story is filled with dramatic flourishes, of a tranquil scene shattered by brutal carnivory, and of a quiet Cretaceous lakeshore becoming a killing ground. The former lakeshore, though, left no bodies, only tracks. So we have to reconstruct what happened there by using the oldest science known to humankind, ichnology: the study of modern and fossil traces.

A small sample of the 3,300 dinosaur tracks of Lark Quarry in Queensland, Australia, showing evidence for three species of dinosaurs that either walked or ran along a Cretaceous lakeshore 98 million years ago. Who made these tracks,  what behaviors do they represent, and how were the trackmakers’s behaviors related to one another? That is the mystery – and now the controversy - of Lark Quarry.

The Mystery of Lark Quarry

One of the most famous dinosaur tracksites in the world – Lark Quarry Conservation Park in central Queensland – is protected from the elements of the Australian outback by a beautiful, spacious, and environmentally friendly building. But how comfortable would it be to spend a night there, alone with the dinosaur tracks? I was about to find out, having been accidentally locked in, and just after the departure of the last tour of the day.

Lark Quarry has gorgeous dinosaur tracks, and lots of them. But would you sleep with them?

The Australian Age of Dinosaurs is Now

What is happening right now in Australia with dinosaurs is akin to another time and place on the other side of the world: the 19^th century and the American West. 

Cretaceous Worlds of Queensland, Part V: Fossil Lives in Downtown Winton

After spending a night in the paleontologically delightful town of Hughenden, my wife and paleo-companion Ruth and I were off to Winton, about 215 km to the southwest.

I had visited Winton once before in 2007, but for only a day and night. Nonetheless, the trip there was so memorable (and why is another story), I had vowed to come back, and was eager for Ruth to visit it with me. Based on my all-too-short foray, I reckoned its combination of paleontology, bush poetry, cowboy culture, ample beer, and welcoming folks would be a winning blend for both of us. So we were prepared to stay a while to better soak up the unique flavors of this place.

We arrived in town early afternoon on Wednesday, June 30 2010, just after the start of the antipodal winter on a gorgeous blue-sky day, and promptly checked into the North Gregory Hotel. I had also stayed at the North Gregory during my previous trip, the main reason being that this was the site of where Waltzing Matilda was first performed in public, in 1895. Was this the original hotel, you ask? Well, no, and neither was its previous incarnation: three fires had wiped out three earlier hotels, including the original one. Hence the designation of this as the “site” where Waltzing Matilda was played. Place is important, as is memory.

The North Gregory Hotel, site of classic songs, fires, beers, paleontology, and other essential facts of life in the outback of Queensland, Australia. Photo is from Rita’s Outback Guide.

With only a few hours of sunlight left, we had a decision to make about our afternoon in Winton: Australian culture or Australian fossils? Our typical eclectic (or is it hedonistic?) attitude of “having our cake and eating it too” held sway, though, so we did both.

First we walked across the street to the Waltzing Matilda Centre, which claims that it is “the only centre devoted to a single song.” (I have little doubt that this assertion is correct, so you should likewise feel no urge to use “The Google” on “the Internets” to find out whether it is true.). The display there does indeed supply a thorough history of the composer Banjo Patterson and how Australia’s most famous song originated (like many songwriters, he was trying to impress a sheila). But Ruth was most impressed with a separate art gallery in the centre, which featured Australian-themed art from local artists.

The beauty of a small town like Winton is that we just had to walk back across the street to sate our thirst for paleontological knowledge. (Also beautiful was that beer could be had on both sides of the street.) The historic Corfield and Fitzmaurice Building, which used to be the town’s general store, is where you go to see fossils in downtown Winton. To see the largest dinosaur bones in Australia, which are coming out of the ground near there, you have to drive a little ways (about 15 km) east of town to the Australian Age of Dinosaurs, and to see a world-class dinosaur tracksite (Lark Quarry), you have to drive a lot more (about 100 km) to the south of Winton. (Do you think that’s enough foreshadowing of the next two blog entries?)

Dinosaurs, the North Gregory Hotel, and a bar! Winton has it all, including an abundant supply of XXXX. No, it’s not what you might first think, but as the Australian joke goes, “It’s how you spell ‘beer’ in Queensland.”

Despite what looked like a small place from the outside, we were impressed with what awaited us inside, all for just a small entrance fee: a nice collection of local fossils (many Cretaceous), and a locally produced diorama that recreated an event from the Cretaceous Period, 95 million years previously, recorded in the aforementioned dinosaur tracksite south of town.

“Excuse me! Pardon me! We really must be going!” There’s something about a large theropod walking through your neighborhood that invokes a bit of anxiety in a wee dinosaur.

The diorama in the Corfield and Fiztmaurice Building represents a labor of love, depicting in dramatic detail the interpreted scenario of the Lark Quarry tracksite. In it, the artisans reproduced the probable environment (a muddy lakeshore), a few representative dinosaurs that made the tracks – including one very imposing (and rather portly) theropod – and a bunch of dinosaur tracks, looking as if they were made yesterday, when actually they were made sometime in the past few years.

Dinosaur tracks, recreated in downtown Winton and representing tracks from a large number of small dinosaurs, with the real thing (a dinosaur tracksite) about 100 km south of town. I wonder why most of those tracks are heading in the same direction?

The diorama even include a bit of speculation (as far as I know) that one of the small ornithopod-dinosaur trackmakers slipped and fell into the mud, leaving it vulnerable to victimization, whereupon the large theropod set upon it in a most rapacious way. In other words, it got eaten.

Bloody hell – all me mates left me here in the mud for that theropod! (Too late, this small ornithopod discovers that there’s no mateship in the Cretaceous.)

Other than the diorama were fossils, and perhaps the most impressive is a sauropod femur in a display case, which I recall belongs to the sauropod dinosaur nicknamed “Elliott.” This prodigious bone was set alongside the femur of an adult bull (Bos taurus, male version). Considering the cowboy culture of the area, this made for a brilliant contrast, easily understood by nearly any visitor educated in bovine anatomy.

That’s not a femur.

That’s a femur!

But there was much more than dinosaurs here for a paleo-enthusiast to marvel. How about fossil plants? There were some of those, and as a great two-for-one special that pleased this ichnologist very much, a Cretaceous fossil leaf had a leaf mine preserved in it, where a larval insect burrowed below the leaf cuticle as it chowed down on some yummy mesoglea. How cool is that? These sorts of trace fossils can lend to insights about the original ecosystems in which the dinosaurs lived.

It’s a body fossil (a deciduous-tree leaf) and it’s a trace fossil (the leaf mine in the leaf, indicated by the arrow), coming from Cretaceous rocks of Queensland.

Some trace fossils on display that were not from the Cretaceous, but much more recent (I suspected Pleistocene) were labeled as “Sea Wasp Eggs. Leftopius duponti. Loc. S. Aus.” Yet they looked very much like some insect trace fossils I had seen from Argentina, like beetle pupal cases. So I took this picture and looked up the name later (yes, using “The Google” on “The Internets”), and was gratified to see that they were indeed pupal chambers, they are interpreted as the works of the Pleistocene weevil Leptopius duponti, and they have been reported from South Australia and northern Queensland.

“Sea-wasp nests”? No on all of those words, but they’re still very interesting trace fossils. These were made by Pleistocene weevil larvae, and found in South Australia and northern Queensland.

And even though dinosaurs were the paleontological stars of this exhibit, I was pleasantly surprised to see the skeleton of an old (but not quite a fossil) northern hairy nosed wombat (Lasiorhinus krefftii) on display, nicknamed the “Winton Wombat.” This wombat became famous within the Australian paleontological community when its bones were found in between some sauropod dinosaur bones at a dinosaur dig site near Winton.

The “Winton Wombat,” a northern hairy nosed wombat that burrowed down next to some dinosaur bones and died in its burrow just so it would confuse some paleontologists a few thousand years later. Cheeky bugger.

Was this a creationist dream come true, where modern mammals and dinosaurs lived at the same time, then were mixed together by a Noachian flood just before burial? Well, as we like to say in the southern U.S.: “Not just no, but hell no!” Here’s a really simple explanation, in three parts: (1) wombats are very good at burrowing; (2) this wombat burrowed down to the level of some 95-million-year-old dinosaur bones near the surface (which, as a matter of fact, is where they are found today); and (3) the wombat died in its burrow. Or, a miracle occurred. Your pick.

So what was next on our quest for furthering our paleontological education in the Winton area? How about a visit to the most exciting recent development in Queensland paleontology, the Australian Age of Dinosaurs Centre? See you there next week!

The theropod track on the sign would not lie: when you’re in Winton, you’re on Australia’s Dinosaur Trail.

Luck, Preparation, and Opportunity: Part II

"You won't find anything."

This assurance came from Tom Rich as he drove, and me as his sole passenger on a quick trip to the Victoria coast. At his invitation, we were traveling together to Flat Rocks, the Dinosaur Dreaming dig site near Inverloch, Victoria. It was late February 2006 and the last weekend of the dig season there. It was a privilege for me to witness the closing of yet another successful field season and meet some of the people associated with Dinosaur Dreaming. But at the same time I was entering an intellectual unknown.

Dinosaur Dreaming, February 2006

I had been in Australia for less than three weeks, on a sabbatical from Emory University for the first time in 16 years. The primary reason for my being there was to work with Patricia (Pat) Vickers-Rich on a geoscience-education project, but I was open to any other opportunities that might arise. So when Tom asked me if I would like to come with him to the coast, I emphatically said “yes,” albeit with a blend of awe, excitement, and trepidation. The last of these feelings stemmed from my being in a new place, with new people, and new rocks (an example of how “old” becomes “new” in geology). The still-healing fractured tibia in my right leg, the result of a biking accident only a month before, also reminded me to take it slowly, and I had brought a walking stick with me to help with traversing the flat platform of rock. (Yes, the person who first named “Flat Rocks” must have had a lack of imagination that day.)

Flat Rocks, near Inverloch, Victoria.

Tom’s pessimistic statement came in response to my observing that in 14 years of work at the Flat Rocks site, a source of some major paleontological discoveries, no trace fossils had been detected, yet I expressed hope that I would find some there. His pessimism, though, was based on what was known then. The only trace fossil described from Early Cretaceous rocks both east and west of Melbourne was a single, small dinosaur track from the Otway Group, in rocks dated at about 106 million years ago and from Knowledge Creek. Pat and Tom found this track in 1980, during their only time to Knowledge Creek, a place they swore they would never visit again because of its remoteness and difficult access.

No fossil burrows, not even those of invertebrate animals – such as insects or crayfish – had been reported from kilometers of expansive Cretaceous outcrops. Invertebrate trace fossils, especially burrows, are normally the most common trace fossils in any given sedimentary rock sequence, and I thought it was unusual that none had been described after more than 100 years of geological research in this area.

Fortunately for both of us, Tom was wrong. I found two isolated large theropod dinosaur tracks the first day, the first such tracks discovered from this site, then found fossil crayfish burrows the day after that.

Fossil crayfish burrows at Flat Rocks, Strzelecki Group, 115-120 million years old. Burrows were filled with a differently colored sand while the surrounding sediment was still soft, and both sediments later cemented to form sandstones. Photo scale = 10 cm (4 inches).

I promptly celebrated this discovery by sitting on them.

Me sitting on Cretaceous fossil crayfish burrows: photo by Gerry Kool.

Although the dinosaur tracks were nice to find, I actually was more excited about the second day’s discoveries, for reasons explained later. The fossil crayfish burrows led to a paper that took nearly two years to write and publish, but one that was well worth it for its contributing to the solution of a 130-year-old evolutionary puzzle first posed by famed evolutionary scientist Thomas Huxley.

This new knowledge thus alerted future dig crews to start looking for more trace fossils, and especially dinosaur tracks. Sure enough, the next year, in February 2007, an undergraduate student, Tyler Lamb, found a third large theropod track, only 5 meters (16 feet) from the dig site.

Large theropod dinosaur track, preserved as a sandstone fill of an originally concave feature, and weathered out in bold relief. Yup, same photo scale as in the previous picture.

The humbling realization for everyone after this find was that hundreds of volunteers and professional paleontologists had walked across this track for nearly 15 years, unknowingly putting their feet on the same spot where a dinosaur had stepped 120 million years earlier. Hence my own luck, preparation, and opportunities enabled others to make their own discoveries, using the same winning combination of fortune, knowing what to look for, and circumstance.

Tomorrow, Tom and I leave together for Inverloch and will walk over the same rocks, more than four years ago, with both of us expecting to be surprised by what we find. The next post should be about our progress, but also be looking for one that explains why the fossil crayfish burrows were more important to science than the dinosaur tracks, and how these were connected to Mr. Huxley.