[D] Dracorex hogwartsia [Su] [jG]
Describer
Bakker, Sullivan, Porter, Larson & Saulsbury, 2006
Time
Cretaceous Late Campanian Maastrichtian
Classification
Ornithischia Genasauria Cerapoda Marginocephalia Pachycephalosauria Pachycephalosauridae
Diet
Herbivore
Fossilsite
Hell Creek Formation, South Dakota, US
Info
Pachycephalosaurus (Brown& Schlaikjer, 1943) = Tylosteus (Leidy, 1872)
Pachycephalosaurus > Pachycephalosaurus wyomingensis (Gilmore, 1931) >> Troodon wyomingensis (Gilmore, 1931) >>> Tylosteus ornatus (Leidy, 1872), Pachycephalosaurus grangeri (Brown & Schlaikjer, 1943) Pachycephalosaurus reinheimeri (Brown & Schlaikjer, 1943)
Pachycephalosaurus (Brown& Schlaikjer, 1943) > Pachycephalosaurus wyomingensis (Gilmore, 1931) > Dracorex hogwartsia [Juvenile] (Bakker, Sullivan, Porter, Larson & Saulsbury, 2006) > Stygimoloch spinifer [subadult] Galton & Sues, 1983 >> Stenotholus kohleri (Giffin, Gabriel & Johnson, 1987)
Dracorex hogwartsia (juvenile) and Stygimoloch spinifer (subadult) are reinterpreted as younger growth stages of Pachycephalosaurus wyomingensis (adult). This synonymy reduces the number of pachycephalosaurid taxa from the Upper Cretaceous of North America and demonstrates the importance of cranial ontogeny in evaluating dinosaur
diversity and taxonomy. These growth stages reflect a continuum rather than specific developmental steps defined by ‘‘known’’ terminal morphologies. (Horner JR, Goodwin MB ,2009)
Based on a nearly complete, and excellently preserved, young-adult skul, Dracorex 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.
Holotype
TCMI 2004.17.1, nearly complete skull, one lower tooth, plus first, third, eighth and ninth cervical vertebrae, nearly complete.
Etymology
After the Latin draco; “dragon” + Latin rex; “king”, a generic name inspired by the dragon-like appearance of the type skull and after fictional author J.K. Rowling\\\\\\\'s use of dragons in the \\\\\\\"Harry Potter\\\\\\\" children\\\\\\\'s book series. D. hogwartsia: Specific name after the fictional Hogwarts Academy, invention of author J.K. Rowling, the species named in honor of her contribution to children\\\\\\\'s education and the joy of exploration + -ia, a Latin noun suffix ending.
Diagnosis
Most similar to Pachycephalosaurus and Stygimoloch, particularly in the long snout, two half-rings of pyramidal spikes on the snout, and strong cheek node. Differs from Pachycephalosaurus wyomingensis and Stygimoloch spinifer in lacking a dome; differs from S. spinifer in possessing four smaller spikes, not three massive spikes, on the squamosal, and lacking a dome. Differs from all other pachycephalosaurids in the extremely large supratemporal fenestrae, with the origin of the mandibular adductor muscles expanded anteriorly onto the dorsal surface of the parietal.
Differs from the other monospecific genera (Homalocephale, Goyocephale, Wannanosaurus, and Stegoceras) with fenestrated skull tables, by having a long snout, two spike-half rings on the snout, parietal excluded from the posterior squamosal shelf, large cheek nodes, strong squamosal spike cluster on each side, generally strong accessory rugosities and longer snout.
Maximum skull length (along midline) = 412 mm; Fig. 5, height from outer condyle to head = 155 mm; height from inner condyle to head = 160 mm; and distal width = 37.5 mm. Maximum width of intercentrum (undistorted) = 55 mm; maximum length of intercentrum (undistorted) = 27 mm; and height from ventral midline of intercentrum to upper edge of postzygapophysis (undistorted) = 57 mm. Anterior width of centrum as preserved = 49 mm; anterior height of centrum as preserved = 44 mm; centrum length as preserved = 49 mm; and width across prezygapophyses as preserved (crushed) = 34 mm. Anterior width of centrum as preserved = 52 mm; anterior height of centrum as preserved = 46 mm; total height as preserved = 90 mm; width across prezygapophyses as preserved = 55 mm; G-H, anterior width of centrum as preserved = 51 mm; anterior height of centrum as preserved = 50 mm; width across prezygapophyses as preserved = 48 mm; and length from postzygapophysis to prezygapophysis as preserved = 114 mm.
Bakker, Sullivan, Porter, Larson & Saulsbury, 2006
Time
Cretaceous Late Campanian Maastrichtian
Classification
Ornithischia Genasauria Cerapoda Marginocephalia Pachycephalosauria Pachycephalosauridae
Diet
Herbivore
Fossilsite
Hell Creek Formation, South Dakota, US
Info
Pachycephalosaurus (Brown& Schlaikjer, 1943) = Tylosteus (Leidy, 1872)
Pachycephalosaurus > Pachycephalosaurus wyomingensis (Gilmore, 1931) >> Troodon wyomingensis (Gilmore, 1931) >>> Tylosteus ornatus (Leidy, 1872), Pachycephalosaurus grangeri (Brown & Schlaikjer, 1943) Pachycephalosaurus reinheimeri (Brown & Schlaikjer, 1943)
Pachycephalosaurus (Brown& Schlaikjer, 1943) > Pachycephalosaurus wyomingensis (Gilmore, 1931) > Dracorex hogwartsia [Juvenile] (Bakker, Sullivan, Porter, Larson & Saulsbury, 2006) > Stygimoloch spinifer [subadult] Galton & Sues, 1983 >> Stenotholus kohleri (Giffin, Gabriel & Johnson, 1987)
Dracorex hogwartsia (juvenile) and Stygimoloch spinifer (subadult) are reinterpreted as younger growth stages of Pachycephalosaurus wyomingensis (adult). This synonymy reduces the number of pachycephalosaurid taxa from the Upper Cretaceous of North America and demonstrates the importance of cranial ontogeny in evaluating dinosaur
diversity and taxonomy. These growth stages reflect a continuum rather than specific developmental steps defined by ‘‘known’’ terminal morphologies. (Horner JR, Goodwin MB ,2009)
Based on a nearly complete, and excellently preserved, young-adult skul, Dracorex 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.
Holotype
TCMI 2004.17.1, nearly complete skull, one lower tooth, plus first, third, eighth and ninth cervical vertebrae, nearly complete.
Etymology
After the Latin draco; “dragon” + Latin rex; “king”, a generic name inspired by the dragon-like appearance of the type skull and after fictional author J.K. Rowling\\\\\\\'s use of dragons in the \\\\\\\"Harry Potter\\\\\\\" children\\\\\\\'s book series. D. hogwartsia: Specific name after the fictional Hogwarts Academy, invention of author J.K. Rowling, the species named in honor of her contribution to children\\\\\\\'s education and the joy of exploration + -ia, a Latin noun suffix ending.
Diagnosis
Most similar to Pachycephalosaurus and Stygimoloch, particularly in the long snout, two half-rings of pyramidal spikes on the snout, and strong cheek node. Differs from Pachycephalosaurus wyomingensis and Stygimoloch spinifer in lacking a dome; differs from S. spinifer in possessing four smaller spikes, not three massive spikes, on the squamosal, and lacking a dome. Differs from all other pachycephalosaurids in the extremely large supratemporal fenestrae, with the origin of the mandibular adductor muscles expanded anteriorly onto the dorsal surface of the parietal.
Differs from the other monospecific genera (Homalocephale, Goyocephale, Wannanosaurus, and Stegoceras) with fenestrated skull tables, by having a long snout, two spike-half rings on the snout, parietal excluded from the posterior squamosal shelf, large cheek nodes, strong squamosal spike cluster on each side, generally strong accessory rugosities and longer snout.
Maximum skull length (along midline) = 412 mm; Fig. 5, height from outer condyle to head = 155 mm; height from inner condyle to head = 160 mm; and distal width = 37.5 mm. Maximum width of intercentrum (undistorted) = 55 mm; maximum length of intercentrum (undistorted) = 27 mm; and height from ventral midline of intercentrum to upper edge of postzygapophysis (undistorted) = 57 mm. Anterior width of centrum as preserved = 49 mm; anterior height of centrum as preserved = 44 mm; centrum length as preserved = 49 mm; and width across prezygapophyses as preserved (crushed) = 34 mm. Anterior width of centrum as preserved = 52 mm; anterior height of centrum as preserved = 46 mm; total height as preserved = 90 mm; width across prezygapophyses as preserved = 55 mm; G-H, anterior width of centrum as preserved = 51 mm; anterior height of centrum as preserved = 50 mm; width across prezygapophyses as preserved = 48 mm; and length from postzygapophysis to prezygapophysis as preserved = 114 mm.