[N] 2006 Dracorex hogwartsia
Bakker, R.T., Sullivan, R.M., Porter, V., LArson, P. and Saulsbury, S.J. (2006) Dracorex hogwartsia n. gen., n. sp., a spiked, flat-headed pachycephalosaurid dinosaur from the Upper Cretaceous Hell Creek Formation of South Dakota. in Lucas, S. G. and Sullivan, R.M., eds., 2006, Late Cretaceous vertebrates from the Western Interior. New Mexico Museum of Natural History and Science Bulletin 35. pp. 331-346
The pachycephalosaurid Dracorex hogwartsia, n. gen., n., sp., is a new pachycephalosaurin based on a nearly complete, and excellently preserved, young-adult skull from the Upper Cretaceous Hell Creek Formation (Lancian) of South Dakota.
D. hogwartsia shows an unexpected mix of truly very primitive and very advanced features: no dome; wide open supratemporal fenestrae; large, spiked nodes on the squamosals; nodes of various shapes and sizes covering the skull including the cheek and snout; and a very long snout and tooth row. The so-called “primitive” nature of the skull (i.e., the well-developed supratemporal fenestrae and discernable peripheral skull elements: anterior + posterior supraorbitals and postorbitals 1 + 2, suggest that these features are present as the result of paedomorphosis. Consequently, all previous phylogenetic analyses are considered inadequate. At least three pachycephalosaurins co-existed in the Lancian - Dracorex, Pachycephalosaurus and Stygimoloch. Strong sexualsocial selection probably generated the morphological diversity in skull shapes of these Late Cretaceous pachycephalosaurids.