Thursday, July 16, 2009
Nothronychus graffami, the float and bloat Therazinosaur
Salt Lake Tribune article:
Several UMNH volunteers including me have done prep work on Nothronychus graffami. The fossil was found in deep marine sediment (the Tropic Shale) and the bones were flattened, presumably under pressure of their unusual burial. It's thought that this critter was swept to sea from near the shoreline, or died on land or in a river and the bloated carcass was washed out far offshore where it "popped" and sank. The article mentions work on a pleisiosaur near this find.
Here's a very interesting pdf with detail about the find, along with nice illustrations from the Arizona Geological Survey:
As a byproduct of my volunteer prep work, I'm now much more skeptical of what a "mounted specimen" means. Nothronychus graffami, for example, was missing its head and most of the bones were so badly deformed that no casts could be made that remotely resemble the mount that Gaston Design in Grand Junction, Colorado created. As I recall, the claws were in the best shape for casting and they're likely the least reconstructed pieces, but most of the mount would have been sculpted and not cast directly from the bones. The skull and presumed style of tooth would be scaled from specimens of related species. I doubt many visitors viewing the mount will understand the (highly) educated estimates and artistic skill that went into the recreation.