Talk about thick-headed! One of the more unusual looking dinosaurs, the Pachycephalosaurus had a 10-inch thick helmet-like skull.

Fun Facts

  • Pachycephalosaurus wyomingensis lived during the Late Cretaceous, 70 to 66 million years ago, in what is now the western U.S., including Montana, South Dakota, and Wyoming (hence the genus name).
  • This animal would have shared its environment with Anklyosaurus, Dracorex, Triceratops, and Tyrannosaurus, among others.
  • It was the largest known member of the pachycephaloaurid family and its name means “Thick Head Lizard.”
  • Scientists have never found more than a skull of this creature, but they have a pretty good idea of what it looked like from studying closely relatives. They believe it was a biped (walked on its back legs), which short arms and a thick, stiff tail.
  • Scientists do know from looking at the skull that it had good eyesight, a beaked mouth, a small brain, and knobby, little bones on the top of its head.

Questions and Answers

Question: What’s up with the helmet head?

Answer: Scientists initially believed Pachycephalosaurus used its head to fight opponents. Later, scientists believed that perhaps it was just for show. New findings of Pachycephalosaurus skulls with healed over wounds support the idea that it used its tough noggin for fighting.

Learn More

See more images of this unusual dinosaur.