d 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 garnere