New artwork IV: Tyrannosaurus rex maxilla

For quite a while I've wanted to draw a theropod maxilla. They're pretty neat looking elements, and tyrannosaurid maxillae at that are pretty rugose, and have some interesting textures. I did this drawing once I got back from New York earlier in the month. I'm very happy with this piece, and it isn't very big - maybe 8" wide.
Here's a quiz: what's important about this specimen? The specimen # is UCMP 118742.