Meet Pachycephalosaurus!

See a rare and nearly complete skull of Pachycephalosaurus, a dinosaur famed for its domed head that lived around 67 million years ago. Pachycephalosaurus, whose scientific name means “thick-headed lizard,” is a popular staple of dinosaur books and documentaries. Paleoartists often depict the bipedal herbivores ramming into their rivals headfirst like modern bighorn sheep.

The fossil was found in rocks of the Hell Creek Formation, a geologic layer that records the 1.5 million years leading up to the asteroid strike that wiped out non-avian dinosaurs 66 million years ago. Over the decades, the Hell Creek Formation has yielded many sensational specimens, including the Nation’s T. rex skeleton that now resides in the museum’s Deep Time Fossil Hall.