The Smithsonian’s National Museum of Natural History will display a nearly complete Pachycephalosaurus skull in its FossiLab beginning Dec. 22. Unearthed in 2024 from South Dakota’s Hell Creek Formation, the skull preserves 32 cranial bones and multiple teeth, suggesting a subadult individual. Researchers will run CT scans to study the braincase and bone positions, which may clarify how the dome developed. The museum also holds the species’ 1931 holotype dome.
Spectacular Pachycephalosaurus Skull Arrives at Smithsonian — Nearly Complete Dome on Display Dec. 22
Left lateral view of the Pachycephalosaurus skull, from the Late Cretaceous.
The Smithsonian’s National Museum of Natural History has received a remarkably well-preserved Pachycephalosaurus skull. The specimen will be on public view beginning December 22 in the museum’s FossiLab, its active specimen preparation laboratory.
“This skull is by far the most spectacular specimen of this type of dinosaur that we have at the museum,” said Matthew Carrano, a paleontologist and the museum’s Dinosauria curator. “We almost never get to see the animal’s face or the teeth or other parts of the head because they usually have broken away.”
Pachycephalosaurus is one of the most recognizable herbivorous dinosaurs from the Late Cretaceous, famous for the dense, rounded dome of bone atop its skull — a feature that gives the species its name, which means "thick-headed lizard." Although the dome is frequently depicted in books and films (including the Jurassic Park franchise) as a weapon used for head‑butting, scientists are still uncertain whether it was used for combat, display, or other purposes.
The skull was excavated in 2024 from the Hell Creek Formation in South Dakota, a site renowned for preserving a rich diversity of late Cretaceous life spanning roughly the 1.5 million years before the asteroid that triggered the Cretaceous–Paleogene extinction. Despite that diversity, Pachycephalosaurus remains are rare in Hell Creek, accounting for less than 1% of fossils recovered to date. Researchers suggest this scarcity may reflect the species' relatively modest body size — adults likely reached about 15 feet long — or the possibility that the animal occupied a limited ecological niche.
The Smithsonian specimen includes almost the entire skull and preserves 32 separate cranial bones, several of which are fused to form the characteristic dome. Numerous teeth are intact in the jaws and several replacement teeth are present as well. Based on the skull's proportions, researchers believe the individual had not yet reached full adulthood.
Carrano and colleagues plan to perform high-resolution CT scans of the skull to compare its internal structure with other specimens. "We can understand the shape and size of the brain and the position of each individual bone," Carrano explained, "which is really difficult to do when the outside looks basically like a bowling ball." These scans may shed light on how the dome and braincase developed as the animal grew.
This is not Pachycephalosaurus' first appearance at the National Museum of Natural History: the museum also holds the species' holotype dome fossil, the name-bearing specimen first described scientifically in 1931. The newly arrived skull offers both the public and researchers a rare opportunity to study a nearly complete head of this enigmatic dinosaur.
