By Laura Geggel, Senior Writer | November 9, 2016 01:56pm ET
The discovery of a pair of fossilized skulls from dome-headed dinosaurs is shedding light on how these bizarre creatures called pachycephalosaurs evolved, researchers say.
Both of the skulls are relatively complete. One, discovered in the Kaiparowits Formation of Utah, dates to about 76.5 million years ago. The other, found in the Kirtland Formation of New Mexico, is about 73.5 million years old, the researchers said.
The location of these skulls — in the southern Mountain states — indicates that pachycephalosaurids may have diversified in the south before they moved north and gave rise to the pachycephalosaur known as Stegoceras, said study lead researcher David Evans, an associate professor in the Department of Ecology and Evolutionary Biology at the University of Toronto.