The first time paleontologist Robert Bakker examined a small one-of-a-kind dinosaur skull at, the Cleveland Museum of Natural History, something about it puzzled him. And while he couldn’t quite put his finger on what that something was, he was fairly sure it was not the skull of a gorgosaurus as its label indicated. So Bakker, adjunct curator of paleontology at the University of Colorado, Boulder, did what he always does— he began to draw, using a pencil to record each and every trivial bump, groove, and jut of what he affectionately had nicknamed the “Cleveland critter.”
After several sketches, Bakker’s hunch proved correct. His diagrams clearly showed that anatomically, the critter’s skull had several variations from that of other, larger gorgosaur skulls. As it turned out, the Cleveland skull was not that of a gorgosaur, but of an entirely different and as-yet unidentified genus of dinosaur: a nanotyrannad lancensis or...