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Stegoceras validum

Reptilia

Taxonomy

Stegoceras validus was named by Lambe (1902). Its type specimen is NMC 515, a skull, and it is a 3D body fossil. Its type locality is Stegoceras type, Berry Creek east, GSC (NMC), which is in a Campanian terrestrial horizon in the Dinosaur Park Formation of Canada.

It was recombined as Troodon validus by Parks (1924), Gilmore (1924), Huene (1927), Hay (1930), Russell (1930), Gilmore (1931), Brown and Schlaikjer (1943) and Bohlin (1953); it was corrected as Stegoceras validum by Sues and Galton (1987), Giffin (1989), Maryanska (1990), Goodwin (1990), Olshevsky and Ford (1994), Sues (1997), Vickaryous and Ryan (1997), Eberth et al. (2001), Horner et al. (2001), Sullivan (2003), Williamson and Carr (2003), Maryanska et al. (2004), Horner et al. (2004), Ryan and Evans (2005), Currie (2005), Sullivan (2006), Sullivan and Lucas (2006), Longrich (2008), Schott et al. (2009), Butler and Sullivan (2009), Williamson et al. (2009), Butler and Zhao (2009), Lehman (2010), Longrich et al. (2010), Jasinski and Sullivan (2011), Watabe et al. (2011), Schott and Evans (2012), Mallon et al. (2015), Goodwin and Evans (2016), Schott and Evans (2017), van der Reest and Currie (2017), Evans et al. (2018), Delcourt (2018), Herne et al. (2019), Sakagami and Kawabe (2020), Dieudonné et al. (2020) and Woodruff et al. (2021).

Synonyms

Stegoceras browni was named by Wall and Galton (1979). Its type specimen is AMNH 5450, a skull, and it is not a trace fossil. Its type locality is 1 mile below Steveville (75 ft level) [AMNH], which is in a Campanian terrestrial horizon in the Dinosaur Park Formation of Canada. It is the type species of Ornatotholus.

It was recombined as Ornatotholus browni by Galton and Sues (1983), Sues and Galton (1987), Maryanska (1990), Olshevsky and Ford (1994), Sues (1997), Maryanska et al. (2004) and Currie (2005); it was considered a nomen dubium by Williamson and Carr (2003); it was synonymized subjectively with Stegoceras validum by Sullivan (2003), Goodwin et al. (2004), Ryan and Evans (2005), Williamson and Carr (2006), Sullivan and Lucas (2006), Jasinski and Sullivan (2011) and Goodwin and Evans (2016).

Synonymy list

Year	Name and author
1902	Stegoceras validus Lambe p. 68 figs. Pl. 21:1-5
1905	Stegoceras validus Lambe p. 24
1907	Stegoceras validus Hatcher et al. p. 98
1914	Stegoceras validus Brown p. 378
1915	Stegoceras validus Hennig p. 14
1918	Stegoceras validus Lambe p. 25
1924	Troodon validus Gilmore pp. 9-11
1924	Troodon validus Parks p. 383
1927	Troodon validus Huene p. 261
1930	Troodon validus Hay p. 208
1930	Troodon validus Russell p. 148
1931	Troodon validus Gilmore pp. 4-5
1943	Troodon validus Brown and Schlaikjer p. 128
1945	Stegoceras validus Sternberg p. 536
1946	Stegoceras validus Russell p. 171
1953	Troodon validus Bohlin p. 32
1964	Stegoceras validus Kuhn p. 31
1964	Stegoceras validus Russell p. 12
1964	Stegoceras validus Tatarinov p. 589
1966	Stegoceras validus Russell p. 21
1967	Stegoceras validus Charig p. 716
1971	Stegoceras validus Galton p. 45
1974	Stegoceras validus Maryańska and Osmólska p. 47
1979	Stegoceras validus Wall and Galton p. 1177
1979	Stegoceras browni Wall and Galton p. 1178 figs. 3G, 4
1980	Stegoceras validus Wolberg p. 50
1983	Ornatotholus browni Galton and Sues p. 469
1987	Ornatotholus browni Sues and Galton
1987	Stegoceras validum Sues and Galton p. 32
1988	Stegoceras validus Horner p. 314
1989	Stegoceras validum Giffin p. 528
1990	Stegoceras validum Goodwin p. 191
1990	Ornatotholus browni Maryanska p. 566
1990	Stegoceras validum Maryanska p. 566
1994	Ornatotholus browni Olshevsky and Ford p. 91
1994	Stegoceras validum Olshevsky and Ford p. 91
1997	Stegoceras validus Eberth p. 201
1997	Ornatotholus browni Sues p. 512
1997	Stegoceras validum Sues p. 512
1997	Stegoceras validum Vickaryous and Ryan p. 491
2001	Stegoceras validum Eberth et al. p. 57
2001	Stegoceras validum Horner et al. p. 10
2003	Stegoceras validum Sullivan p. 185
2003	Stegoceras validum Williamson and Carr fig. 11
2004	Stegoceras validum Horner et al. p. 461
2004	Ornatotholus browni Maryanska et al. p. 465
2004	Stegoceras validum Maryanska et al. p. 465
2005	Ornatotholus browni Currie p. 5
2005	Stegoceras validum Currie p. 6
2005	Stegoceras validum Ryan and Evans p. 319
2006	Stegoceras validum Sullivan p. 357
2006	Stegoceras validum Sullivan and Lucas p. 329
2008	Stegoceras validum Longrich p. 994
2009	Stegoceras validum Butler and Sullivan p. 29
2009	Stegoceras validum Butler and Zhao p. 66
2009	Stegoceras validum Schott et al. pp. 771-772
2009	Stegoceras validum Williamson et al. p. 291
2010	Stegoceras validum Lehman p. 788
2010	Stegoceras validum Longrich et al. p. 280
2011	Stegoceras validum Jasinski and Sullivan p. 203
2011	Stegoceras validum Watabe et al. p. 493
2012	Stegoceras validum Schott and Evans p. 903
2015	Stegoceras validum Mallon et al. p. 429
2016	Stegoceras validum Goodwin and Evans p. 6
2017	Stegoceras validum Schott and Evans p. 865
2017	Stegoceras validum van der Reest and Currie p. 919
2018	Stegoceras validum Delcourt p. 9
2018	Stegoceras validum Evans et al. p. 121
2019	Stegoceras validum Herne et al. p. 572
2020	Stegoceras validum Dieudonné et al.
2020	Stegoceras validum Sakagami and Kawabe p. 10
2021	Stegoceras validum Woodruff et al. p. 576

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Rank	Name	Author
kingdom	Animalia	()
—	Bilateria
—	Eubilateria	Ax 1987
—	Deuterostomia
phylum	Chordata	Haeckel 1874
subphylum	Vertebrata
superclass	Gnathostomata
—	Osteichthyes	()
subclass	Sarcopterygii	()
subclass	Dipnotetrapodomorpha	(Nelson 2006)
subclass	Tetrapodomorpha	()
—	Tetrapoda
—	Reptiliomorpha
—	Anthracosauria
subclass	Amphibiosauria	Kuhn 1967
—	Cotylosauria	()
—	Amniota
—	Sauropsida
class	Reptilia
subclass	Eureptilia	()

Rank	Name	Author
—	Romeriida
—	Diapsida	()
—	Archosauromorpha	(Huene 1946)
—	Crocopoda
—	Archosauriformes	Gauthier 1986
—	Eucrocopoda
—	Archosauria	()
informal	Avemetatarsalia
—	Ornithodira
—	Dinosauromorpha
—	Dinosauriformes
—	Dinosauria	()
—	Ornithischia	()
—	Genasauria
—	Cerapoda
—	Marginocephalia
—	Pachycephalosauria	()
—	Eupachycephalosauria
genus	Stegoceras
species	validum	()

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.

†Stegoceras validum Lambe 1902

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Invalid names: Ornatotholus browni Wall and Galton 1979 [synonym]

Diagnosis

Reference	Diagnosis
B. Brown and E. M. Schlaikjer 1943	A rather small species. Frontoparietal area relatively narrow and quadrangular in outline when viewed from above; low and gently arched in the immature stage, but strongly arched and deep in the adult. Prominent parieto-squamosal shelf behind the arched portion of the parietal. Frontals narrow where in contact with the nasals.
C. M. Sternberg 1945	Moderate-sized; frontoparietal mass relatively narrow and long; dome thick. well forward; frontals narrow anteriorly; parietals and squamosals forming horizontal shelf overhanging occiput; face moderately steep.
R. M. Sullivan 2003	Differs from all other pachycephalosaurs in having a pronounced parietosquamosal shelf with an incipient frontoparietal dome; nasals inflated; postorbital situated posterolaterally on the dome; ornamentation consisting of numerous minute tubercles on lateral and posterior sides of squamosals with a prominent dorsal row of up to six tubercles on each squamosal and as many as two nodes on the medial posterior projection of the parietal.
S. E. Jasinski and R. M. Sullivan 2011	Differs from Stegoceras novomexicanum in having a posterior extension of the parietal that is trapexoidal in shape; supratemporal fenestrae small, or absent, and, where open, located more laterally from the midline; squamosal sutural surface contacts splayed; robust and larger size.