Bone heads

 Pachycephalosaurus

At 8 meters long, this was a dino not to be messed with.

Pachycephalosaurus was the largest Pachycephalosaur.

Dracorex

Dracorex means dragon king.

It ate plants.

Stygimoloch

At 4 meters long, this dinosaur was half the size of the Pachycephalosaurus.

It has appeared in the film Jurassic World: Fallen Kingdom.