ANDRZEJ KRAUZE
As a master’s student at Indiana University a few years ago, David Grossnickle became fascinated with the evolution of early mammals. His dissertation project involved comparing the skulls of modern mammals to those living when the lineage first appeared in the late Triassic, a little more than 200 million years ago, and inferring the ancient creatures’ diets based on their jaw shape. But it was while working on this project that Grossnickle came across something that puzzled him.
At the back of each side of extant mammals’ lower jaw is a bony protrusion called the angular process. “It’s found in basically all modern mammals, so I was using it in all my measurements,” Grossnickle explains. “But when I looked at the fossils, I recognized that ...
