Pachycephalosaurus and no, that is not the longest dinosaur name (the longest is Micropachycephalosaurus) but it is a well known creature ,this movie star features in Jurassic World and The Lost World.
The “thick-headed lizard” could grow 4.5 metres long and weighed around 450kg, with a skull 25cm thick, it really earned the name! It was the largest in the Pachycephalosaurid dinosaurs, with it’s short neck and short arms and was probably not that fast. Many people think that the spiky dome on it’s head was used for ramming into rival males or predators but, more evidence is presenting itself that suggest they swung their heads at each other or didn’t do it at all. Instead they may have used it as decoration, but that is unlikely, this is just a question to be answered later but by the power of palaeontology we shall find the truth!!!