Pachycephalosaurus

Pachycephalosaurus was about 4.5 metres (15 feet) long and weighed around 370 to 450 kilograms (820 to 990 pounds). That's about as long as a small car and as heavy as a large horse.23

Pachycephalosaurus was a herbivore, eating leaves, fruit, and seeds. Some scientists think it might have also eaten meat because its teeth look a bit like those of meat-eaters, but nobody knows for sure.32

Many scientists think Pachycephalosaurus used its thick dome for head-butting fights, like bighorn sheep do today. But some experts disagree and think the dome was for display, like deer antlers. It is still a mystery.32

Pachycephalosaurus lived during the Late Cretaceous period, about 69 to 66 million years ago. It was one of the last non-bird dinosaurs before the big extinction.32

Fossils of Pachycephalosaurus have been found in Montana, South Dakota, Wyoming, and Alberta. That's in North America.32

Yes, Pachycephalosaurus was a dinosaur. It was a type of pachycephalosaurid ornithischian dinosaur, which means it was a plant-eating dinosaur with bird-like hips.2

The bony dome on its skull could be up to 25 centimetres (10 inches) thick. That's about as thick as a big dictionary.24

The sources don't mention feathers on Pachycephalosaurus. So we don't know if it had feathers. It probably had scaly skin like other dinosaurs of its group.2

Maybe up to about 39 km/h (24 mph), about as fast as a fast human runner. This is an estimate from its size. It walked on two long, strong legs, so it could probably run quickly to escape predators.2

Yes, Pachycephalosaurus and Triceratops are both part of a group called Marginocephalia, which means 'head-fringed' dinosaurs. They are distant cousins.2