Thursday, June 17, 2010

Dinosaurs Down Underground: Part II

(I am now in Melbourne for a brief respite from the field, which will likely commence on Sunday, weather permitting. So in lieu of a field report, the following is the second in a three-part series about the development of the scientific hypothesis of “burrowing dinosaurs,” based on fossil evidence from Montana (USA) and Victoria in Australia.)

A general principle in paleontology is that the least accessible places often have the most important fossils. In the case of burrowing dinosaurs, this was true in both hemispheres. In the Northern Hemisphere, the place was in western Montana (USA), south of the small town of Lima, and in the Southern Hemisphere, it was in Victoria, Australia at a hard-to-reach and auspiciously dubbed location called Knowledge Creek.

During a 2005 field season in western Montana, a field crew associated with Montana State University (MSU), including paleontologist Yoshi Katsura of the Gifu Prefecture Museum (Japan), were prospecting a Cretaceous formation for dinosaurs or any other fossils that might reveal themselves. One day, he spotted a few dinosaur bones sticking out of the formation.

Yoshi Katsura, dinosaur hunter and discoverer of the first known burrowing dinosaur, Oryctodromeus cubicularis. With rock hammer ready for action, he looks straight out of either an Akira Kurosawa or a Quintin Tarintino film (and if the latter, let’s hope it’s not Kill Bill 3).

The prolific science-fiction writer Isaac Asimov once remarked, “The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!' but 'That's funny…’” Accordingly, while the crew set to excavating the skeleton, paleontologist David (Dave) Varricchio of MSU experienced one of those “that’s funny” moment. As he described the sedimentary rock surrounding the dinosaur bones, he noticed how it defined an odd but distinctive structure.

Later in that summer of 2005, Dave e-mailed me a photo of the structure, but with minimal information, all the better for preventing any biases on my part. After I looked at it for a while, I wrote back to him with an analysis and concluded, “Looks like a burrow to me. What did you have in it – a crocodile?” When he told me it was a dinosaur, I started doing a Snoopy dance. This was potentially a major discovery: the first known burrowing dinosaur from the geologic record!

The dinosaur was also a small ornithopod. Dave had long suspected that some small ornithopods in Montana were likely candidates for underground lifestyles, a hunch he readily admitted was based on little information. But now he had some evidence to start testing it, so that it was more than a feeling.

A few months later, Dave flew me out to Bozeman, Montana (Well, actually, he didn’t fly me out himself – it’s not like he’s a pilot, too – but he did pay for my plane ticket.) From there, we went together to the site and excavated the soft sedimentary rock around the structure from which the dinosaur came.

Dave Varricchio of MSU, paleontologist and performance artist, rehearsing a set piece in which he digs out the remains of a dinosaur burrow, which in and of itself was dug out by the dinosaur. Yet, the burrow was defined through hollowness before being filled by geologic processes between those excavations. Iterative, yet composed of opposites; diachronous, yet connected through a continuum. Very post-modern, with elements of surrealism. Discuss amongst yourselves.

When we finished, we stood back to look at the structure. It was a natural cast of the burrow, set in white sandstone, and was originally a descending, spiraled tunnel (right turn, followed by a left turn) with an enlarged chamber at the end. This must have been the living room. There was, however, no sign of the bathroom, which must have been outside the burrow, probably with the dinosaurian equivalent of a crescent moon marking it.

View of the purported burrow of the Cretaceous dinosaur Oryctodromeus, with arrows pointing to smaller burrows of other animals cheeky enough to live undergound with a dinosaur. What, I didn’t talk about this yet? Please do read further, then.

The original tunnel was just wide enough to admit the adult, a tight fit that also shows up in burrows made by a lot of modern burrowing critters, like armadillos and coyotes. Before we started digging, I also predicted that the big burrow should have smaller burrows coming off the main tunnel made by other animals that lived in the same burrow, such as insects and mammals. (This sort of interspecies cohabitation is probably illegal in most of Georgia and all of Alabama. Except if the animals are kinfolk, of course.) Nevertheless, it is very common in modern gopher tortoise burrows, which can have as many as 300 species of animals sharing any given burrow with a tortoise.

Sure enough, we found a cluster of small, pencil-like burrows on the upper corner of the big burrow, and a larger, banana-sized burrow on the lower corner. These additional bits of evidence made it even more likely that what we were looking at was the former home for the dinosaur and other critters that found this underground haven a safe, stable place to hang out.

The evidence got better once the specimen was prepared at the Museum of the Rockies. The dinosaur clearly showed anatomical traits suited for digging. Need more evidence? The adult dinosaur had two partially grown offspring of the same species in the burrow with it. This dinosaur was not only a digger, but a denner that took care of its young. It also demonstrated that this dinosaur might have faced the same problem as modern human parents, such as getting their kids out of the house.

Starting in the first half of 2006, Dave, Yoshi, and I wrote a paper that summarized our results and sent it in for peer review. But we were then surprised to experience several rejections. (I won’t say which journals rejected it, but will just say how that’s the nature of science). With a little more persistence, we finally did get it through peer review and into print in the journal Proceedings of the Royal Society of London, B in March 2007. The publication of the paper garnered a little bit of media attention, although it was understandably buried under the far more important bit of news that Britney Spears was coming out of rehab (again).

Nonetheless, the news stories were nice for public education about the paper. The paper also led to our eventually winning an award for Best Paleontology Paper in 2007 from a Spanish foundation, Fundación Conjunto Paleontológico de Teruel-Dinópolis. Best of all, it inspired a very cool work of art, done by Georgia visionary artist, Ruth Truth (aka, Ruth Schowalter).

Mother Earth, Mother Dinosaur (2007), by Ruth Truth, and photographed by Ty Butler. (Full disclosure: I have slept with this artist, while also being married to her. Yes, I know: how retro.)

Art and science combined then, as this artwork graced the cover of a public-outreach book we wrote for and published through the Fundación Conjunto Paleontológico de Teruel-Dinópolis, titled El Dinosaurio que Excavó su Madriguera [The Dinosaur that Dug Its Burrow]. This book was translated into Spanish from our American English, and was aimed at Spanish teenagers to interest them in science.

The cover of El Dinosaurio que Excavó su Madriguera [The Dinosaur that Dug Its Burrow], published through the Fundación Conjunto Paleontológico de Teruel-Dinópolis in December 2009.

So what does any of this have to do with Australia and dinosaurs there? Ah, that is the subject of Dinosaurs Down Underground: Part III. (And not to worry, it will be nothing like Rocky III, Rambo III, and especially Crocodile Dundee III.) Next stop, Knowledge Creek, Victoria!

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