Order Ornithischia dinosaur
was a dome-headed dinosaur
. It had a thick skull, a tiny brain, and large eyes. They were about 15 feet long and weighed about 950 pounds. Pachycephalosaurus had a good sense of smell. It was an herbivore
that had short forelimbs and a stiff tail.
Pachycephalosaurus lived during the late Cretaceous
period, about 76 to 65 million years ago. Pachycephalosaurs were herding dinosaurs that lived in small groups. Running was probably their main self-defense. It's domed head was probably used for attracting mates. At first, it was thought to be a defensive
mechanism, but the skull bone was found to be porous
and fragile when put under pressure. Pachycephalosaurus walked on two legs, and was not a very fast dinosaur.