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Hanssuesia sternbergi

Reptilia - Pachycephalosauridae

Taxonomy
Troodon sternbergi was named by Brown and Schlaikjer (1943). Its type specimen is NMC 8817, a skull, and it is not a trace fossil. Its type locality is southeast of Steveville (NMC), which is in a Campanian terrestrial horizon in Canada.

It was recombined as Stegoceras sternbergi by Kuhn (1964), Eberth et al. (2001), Williamson and Carr (2003), Ryan and Evans (2005) and Williamson and Carr (2006); it was synonymized subjectively with Stegoceras validum by Sues and Galton (1987), Maryanska (1990) and Maryanska et al. (2004); it was recombined as Gravitholus sternbergi by Sullivan (2000); it was recombined as Hanssuessia sternbergi by Sullivan (2003); it was recombined as Hansuessia sternbergi by Longrich (2008); it was recombined as Hanssuesia sternbergi by Sullivan (2003), Sullivan (2006), Schott et al. (2009), Longrich et al. (2010) and Mallon et al. (2015).

Synonymy list
YearName and author
1943Troodon sternbergi Brown and Schlaikjer p. 131
1964Stegoceras sternbergi Kuhn p. 31
2000Gravitholus sternbergi Sullivan p. 72A
2001Stegoceras sternbergi Eberth et al. p. 57
2003Hanssuessia sternbergi Sullivan p. 193 figs. 4-5
2003Hanssuesia sternbergi Sullivan p. 714
2003Stegoceras sternbergi Williamson and Carr
2005Stegoceras sternbergi Ryan and Evans p. 320
2006Hanssuesia sternbergi Sullivan p. 353
2006Stegoceras sternbergi Williamson and Carr p. 323
2008Hansuessia sternbergi Longrich p. 994
2009Hanssuesia sternbergi Schott et al. p. 774
2010Hanssuesia sternbergi Longrich et al. p. 280
2015Hanssuesia sternbergi Mallon et al. p. 429

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RankNameAuthor
kingdomAnimalia()
Triploblastica
Nephrozoa
Deuterostomia
phylumChordataHaeckel 1847
OlfactoresJefferies 1991
subphylumVertebrata
Gnathostomata()
Osteichthyes()
Sarcopterygii
subclassDipnotetrapodomorpha(Nelson 2006)
subclassTetrapodomorpha()
Tetrapoda()
Reptiliomorpha
Anthracosauria
Batrachosauria()
Cotylosauria()
Amniota
Sauropsida
classReptilia
subclassEureptilia()
Romeriida
Diapsida()
RankNameAuthor
Eosuchia()
Neodiapsida
SauriaGauthier 1984
Archosauromorpha(Huene 1946)
Crocopoda
ArchosauriformesGauthier 1986
Eucrocopoda
Archosauria()
informalAvemetatarsalia
Ornithodira
Dinosauromorpha
Dinosauriformes
Dinosauria()
Ornithischia()
Neornithischia()
Clypeodonta
Cerapoda
Marginocephalia
Pachycephalosauria()
familyPachycephalosauridae
genusHanssuesia
speciessternbergi()

If no rank is listed, the taxon is considered an unranked clade in modern classifications. Ranks may be repeated or presented in the wrong order because authors working on different parts of the classification may disagree about how to rank taxa.

Diagnosis
ReferenceDiagnosis
R. M. Sullivan 2003Differs from all other pachycephalosaurs in having a low, depressed parietal region of the fronto-parietal dome, anterior (frontal) and posterior (parietal) portions of the frontoparietal wide; nasal boss of frontal broad with reduced, more inflated, lateral prefrontal lobes; and parietosquamosal shelf reduced.