(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