Pachycephalosaurus is a dinosaur that lived during the Late Cretaceous period, around 70 million years ago. It is known for its thick and domed skull, which was used for head-butting. The name Pachycephalosaurus means “thick-headed lizard.”

This dinosaur belonged to a group called the pachycephalosaurs, which were characterized by their thick skulls. Pachycephalosaurus had a long, slender body with short forelimbs and strong hind limbs for walking on two legs. It had a long tail, which was likely used for balance.

Pachycephalosaurus was an herbivorous dinosaur, meaning it only ate plants. Its teeth were small and leaf-shaped, which suggests it fed on low-growing vegetation. Pachycephalosaurus was about 15 to 20 feet long and weighed around 1,000 to 2,000 pounds.

Scientists have discovered Pachycephalosaurus fossils mainly in North America, specifically in present-day Montana, Wyoming, and South Dakota. These fossils have provided valuable information about the appearance, behavior, and evolutionary relationships of this dinosaur.