Tuesday, December 17, 2013

Giant Oviraptor Tracks from the Hell Creek

It's been known for years that there are oviraptor-like dinosaurs found in the Hell Creek Formation. We find isolated elements mostly. A pubis here, a claw there. Small snapshots into their world, but they don't answer deeper questions like how big they got, how they moved, where they lived (instead of just where their remains ended up).
Skeleton of the new Hell Creek Ovi

In 1997 Mike Triebold was scouting on private land in Harding County, SD for dinosaurs. He came across a strange looking concretion. It looked a bit like a footprint, but as we know, concretions can take on all kinds of shapes. Looking closer, there was another concretion, in the same shape nearby. Then another and another, all in a line. A small excavation was started into the nearby outcrop, and the line of concretions continued. Though the overburden was getting too deep to chase them futher, it is likely there are even more still at the site. Mike recovered the specimens and made them available for research, which will be published on shortly.

Tracks in situ. The largest are nearly 60cm (2ft) across
Excavation of tracks
The concretions have now been identified as a preserved as the trackway of a giant North American oviraptorid, much larger than the specimens that we have skeletal remains for. The trackway shows how fast the animal was moving and even what kind of muck it was trudging through. We made molds and casts of the best ones, I'm thinking it may be a great addition to our ovi display in the exhibit hall.