Thread:Dinosaurus1/@comment-6025261-20180506225538/@comment-7690264-20180514160425

Chronologically Stygimoloch lived later than Pachycephalosaurus and Dracorex, however there is a Pachycephalosaurus skeleton in the upper hell creek with horns on the back of its skull suggesting that Stygimoloch was a species of Pachycephalosaurus and that the S.spinifer holotype is immature (as previously shown by Horner).