Pachycephalosaurus means “thick headed lizard” and refers to their thick, dome shaped skull that could by 25cm thick, despite being a small(ish) dinosaur. It is a very rare dinosaur and is only known from one skull and a few pieces of its dome.
Discovery: Pachycephalosaurus was discovered in 1938
Height: The height is hard to work out without a whole skeleton but palaeontologists think it was around 2m tall (largest estimates are 4m).
Length: The estimate is about 4.5m long (upper estimates are 8m)
Weight: Maybe around 430kg.
Where it lived: North America in modern day Monatana.
When it lived: It lived about 75-65 million years ago in the Late Cretaceous.
What it ate: Scientists aren’t sure. It had very small teeth so it was likely a plant eater but may have eaten insects as well.
Weapon of choice: Its thick skull. Some palaeontologists (but not all) think it used its thick skull to protect its brain as it rammed heads with other Pachycephalosaurus. That head could be dangerous against predators as well.
Weakness: Pachycephalosaurus was quite small for a dinosaur and its brain was even smaller. We can’t be sure if it was hunted by any predators but it’s likely that it was.