Main Content
The largest of the pachycephalosaurs ("domed dinosaurs"), Pachycephalosaurus wyomingensis had an extremely thick skullcap—up to 9 inches (23 centimeters) thick. Much of the skull, as well as the dinosaur's snout, was covered by small knobs.Pachycephalosaurus wyomingensis
Image © National Geographic Society
Fast Facts
- Type:
- Prehistoric
- Diet:
- Herbivore
- Size:
- 9 ft (3 m) long; 250 lbs (115 kg)
- Protection status:
- Extinct
- Did you know?
- This species is known only by skull material—no full skeletons have ever been documented.
- Size relative to a 6-ft (2-m) man:
-
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 inches (23 centimeters) thick, and much of the skull and the snout were also covered by small bony knobs and spikes. The dinosaur's distinctive domed cranium was so stout that it sometimes survives as a fossil when the rest of the skeleton degrades.
Some scientists have postulated that Pachycephalosaurus's padded skull allowed these animals to engage in head-butting battles of dominance perhaps related to mating, much like bighorn sheep and other modern animals do. Scars on fossil remains have been interpreted as reinforcing this hypothesis, though other research is contradictory. The dinosaur's neck vertebrae might not have been strong enough to survive such collisions without breaking.
Pachycephalosaurus's dome, like the large horns and antlers of some modern animals, may have provided potential mates with a powerful visual cue of reproductive prowess.
Pachycephalosaurus probably fed on low-lying plants relatively close to the ground.
Related Galleries
Other Prehistoric Animals
Prehistoric Features
-
Bizarre Dinosaurs
A bizarre gallery of Mesozoic monsters prompts John Updike to ask: What has evolution wrought?
-
Prehistoric Time Line
National Geographic's interactive time line takes you on a 4.5-billion-year-old trip through Earth's history⎯from its Precambrian birth to the birth of Homo sapiens some 190,000 years ago.
-
Prehistoric World
Discover and explore prehistoric times with galleries, time lines, quizzes, and more.
-
Mass Extinctions
More than 90 percent of all organisms that have ever lived on Earth are extinct. Learn how millions of creatures can disappear in a geological blink of an eye—and see what might be next.
-
Photo Gallery: Permian Period
Peer into the flourishing world of the Permian, when a wealth of new animals appeared⎯before nearly all life on Earth was wiped out in a mass extinction.
This requires the latest version of Flash Player. Click here to download.Advertisement
Special Ad Section
-
Audio Slideshow
Take a photographic journey through Montana and hear Annie Griffiths Belt's narrative.
-
Adventure Videos
Check out adventure videos and go "Behind the Lens."
Shop Animals and Nature
-
Animal & Nature DVDs
Shop our store for a wide collection of animal, wildlife, and nature DVDs.
-
2010 Animal & Nature Calendars
Featuring stunning National Geographic photography, calendars make great gifts.
Blogs
-
NatGeo NewsWatch
Keep current on developments in science, nature, and cultures.
-
Dog Whisperer
Get the inside story as Cesar Millan helps problem dogs and their owners.
-
BlogWild
National Geographic explorers share tales (and photos) of their adventures.
