A newly described species of dome-headed dinosaur—a pachycephalosaur dating from around 68 million years ago—is the latest example.

Skulls of dome-headed dinosaurs are fairly common in areas of Montana that have yielded hadrosaur, Triceratops and T. rex fossils. The bowling-ball shaped pate fed speculation that they butted ...

Paleontologists have discovered two new pachycephalosaur species in North America. iStock "Pachycephalosaurs are the 'dome-headed' dinosaurs.