Pachycephalosaurus wyomingensis was the largest of the pachycephalosaurids—"thick-headed dinosaurs"—which featured extremely thick skullcaps. The top of a Pachycephalosaurus skull could be 9 ...

Partway down the list of household dinosaur names, you may know the pachycephalosaurus. Even if you don’t recognize that formality, the dome-shaped head of this creature is notorious, much thanks to ...

What I was looking at was the smallest Pachycephalosaurus ever found. The bones of the young Pachycephalosaurus next to a cast of “Dracorex” in the ROM collections. Photo by Brian Switek.

To test this idea, the team cut open bones and skull fragments from Dracorex, Pachycephalosaurus and Stygimoloch to see how old the dinosaurs had been when they died. “It’s real easy to tell ...

Late last year paleontologists Jack Horner and Mark Goodwin made waves by proposing that what had previously been thought to be two distinct genera of "bone-headed" dinosaurs—Stygimoloch and ...