National Museum of Natural History
Meet Pachycephalosaurus!
December 22, 2025 – December 28, 2025
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.
The recently acquired skull of the dome-headed dinosaur Pachycephalosaurus. USNM PAL 803273, Department of Paleobiology, Smithsonian Institution. Gift of Eric and Wendy Schmidt. Photo by James D. Tiller and Phillip R. Lee.
