A rare dinosaur skull will soon go on display at the Smithsonian's National Museum of Natural History, but the fossil will not be on view for long.
The near-complete skull of a Pachycephalosaurus, a dome-headed herbivore from the Cretaceous Period around 67 million years ago, was found in 2024 in the Hell Creek Formation in South Dakota, Matthew Carrano, research geologist and curator of dinosauria at the National Museum of Natural History, told ABC News.
The fossil represents the dinosaurs that were living in the last 1.5 million years before an asteroid struck and caused them to go extinct, Carrano said.
The skull is significant because there aren't many of these types of dinosaurs that have been found, Carrano said. Its bones account for less than 1% of the dinosaur fossils found in the formation, according to the Smithsonian.
There are only about three such fossils in the world, Carrano said in a video posted to Instagram. They would have lived at the same time as Tyrannosaurus rex, of which ten times more fossils have been found.
"People have been looking in this part of the country in these rocks for fossils for more than 100 years," he told ABC News.
The skull is also close to complete, containing many bones that researchers have never seen before still connected in their original position, Carrano said.
"It's really just a very beautiful fossil, but also really, really informative for us on the scientific side," he said.
Pachycephalosaurus are bipedal dinosaurs known for their recognizable heads, which almost look like half a bowling ball, Carrano said. The top of its head could measure from anywhere between 6 and 9 inches of solid bone, he added.
There may not be as many fossils of Pachycephalosaurus because they were relatively much smaller than its contemporaries, such as T. rex, Carrano said.
"They just tend to survive less well than something that is 40 feet long," he said. "...Time is not kind to animal remains."
Its name is derived from Greek words that translate to "thick-headed lizard."
The skull measures about 3 feet long and likely belonged to a Pachycephalosaurus that was not yet fully grown, likely about 15 to 20 feet tall, Carrano said.
It will be on display at the fossil lab at the National Museum of Natural History in Washington, D.C., from Dec. 22 to 28. It was purchased by philanthropists Eric and Wendy Schmidt and donated to the museum, according to the Smithsonian.
"When we see an ancient fossil like this one, we are confronted with the story of our planet's past and can consider how humans fit into Earth's geologic history in a profoundly different way," Wendy Schmidt said in a statement.
Visitors will be able to get close to the display glass to inspect the fossil closely, Carrano said. The animal's delicate tooth structure, which it used to chomp on plants, is "beautifully preserved," he said.
"It's a nice space where we actually work on fossils in front of the public," Carrano said.
Paleontologists will soon perform a CT scan to allow access to internal structures within the animal's brain cavity beneath its thick skull, according to the Smithsonian.
While Pachycephalosaurus fossils are not found frequently, Carrano is hopeful that more will be discovered in the coming years.
"There's a lot of interest right now for paleontologists to try to understand more about these dinosaurs," he said.