Wannanosaurus yansiensis. Chinese pachycephalosaur. A very early or basal version of the later pachycephalosaurs, this dinosaur is known from very little physical evidence. The type specimen is actually not much more than a head, a partial leg, and one piece of backbone. The head is fragmented as well, but does tell us quite a bit about the animal. The general consensus is of course that this is certainly a pachycephalosaur, just a very early basal one. Additionally, it is a very small animal by all indications and both robust and thin femurs have been associated with the animal. Most of its teeth, it is thought, have been identified and related to other members of the family. However, when all is said and done there is very little evidence of this dinosaur that has been recovered and accordingly there is a good amount of speculation that has gone into designing the image of the living animal. It is assumed that they engaged in some uniquely pachycephalosaurian behaviors such as headbutting or at the very least feats of strength, shoving matches, with their heads.