PBDB Taxon

Basic info	Taxonomic history	Classification	Included Taxa
Morphology	Ecology and taphonomy	External Literature Search	Age range and collections

Stegoceras validum

Osteichthyes

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 is the type species of Stegoceras.

It was recombined as Troodon validus by Parks (1924), Gilmore (1924), Huene (1927), Hay (1930), Russell (1930), Gilmore (1931), Brown and Schlaikjer (1943), 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), Woodruff et al. (2021), Dyer et al. (2023), Wick and Lehman (2024).

Synonyms

Gravitholus albertae was named by Wall and Galton (1979). Its type specimen is RTMP 72.27.1, a skull, and it is a 3D body fossil. Its type locality is Jenner Ferry, which is in a Campanian terrestrial horizon in the Oldman Formation of Canada.

It was considered a nomen dubium by Sullivan (2003), Williamson and Carr (2003); it was considered a nomen dubium by Sullivan (2006); it was synonymized subjectively with Stegoceras validum by Dyer et al. (2023).
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 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), 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), Goodwin and Evans (2016), Dyer et al. (2023), Wick and Lehman (2024).
Troodon sternbergi was named by Brown and Schlaikjer (1943). Its type specimen is NMC 8817, a skull, and it is a 3D body 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 Sternberg (1945), Kuhn (1964), Charig (1967), Eberth et al. (2001), Williamson and Carr (2003), Ryan and Evans (2005), Williamson and Carr (2006); it was recombined as Gravitholus sternbergi by Sullivan (2000); it was recombined as Hanssuesia sternbergi by Sullivan (2003), Sullivan (2006), Schott et al. (2009), Longrich et al. (2010), Schott and Evans (2012), Mallon et al. (2015), Schott and Evans (2017), Woodruff et al. (2021); it was recombined as Hanssuessia sternbergi by Sullivan (2003); it was recombined as Hansuessia sternbergi by Longrich (2008); it was synonymized subjectively with Stegoceras validum by Sues and Galton (1987), Maryanska (1990), Maryanska et al. (2004), Dyer et al. (2023).

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
1943	Troodon sternbergi Brown and Schlaikjer p. 131
1945	Stegoceras validus Sternberg p. 536
1945	Stegoceras sternbergi Sternberg p. 537
1946	Stegoceras validus Russell p. 171
1953	Troodon validus Bohlin p. 32
1964	Stegoceras sternbergi Kuhn p. 31
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 sternbergi Charig p. 716
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
1979	Gravitholus albertae Wall and Galton p. 1181 figs. 3E-F, 4J
1980	Gravitholus albertae Currie pp. 29-30
1980	Stegoceras validus Wolberg p. 50
1983	Ornatotholus browni Galton and Sues p. 469
1987	Ornatotholus browni Sues and Galton
1987	Gravitholus albertae Sues and Galton p. 28
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	Gravitholus albertae Maryanska p. 566
1990	Ornatotholus browni Maryanska p. 566
1990	Stegoceras validum Maryanska p. 566
1994	Gravitholus albertae Olshevsky and Ford p. 91
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
2000	Gravitholus sternbergi Sullivan p. 72A
2001	Stegoceras sternbergi Eberth et al. p. 57
2001	Stegoceras validum Eberth et al. p. 57
2001	Stegoceras validum Horner et al. p. 10
2003	Stegoceras validum Sullivan p. 185
2003	Hanssuessia sternbergi Sullivan p. 193 figs. 4-5
2003	Hanssuesia sternbergi Sullivan p. 714
2003	Stegoceras sternbergi Williamson and Carr
2003	Stegoceras validum Williamson and Carr fig. 11
2004	Stegoceras validum Horner et al. p. 461
2004	Gravitholus albertae Maryanska et al. p. 465
2004	Ornatotholus browni Maryanska et al. p. 465
2004	Stegoceras validum Maryanska et al. p. 465
2005	Gravitholus albertae Currie p. 5
2005	Ornatotholus browni Currie p. 5
2005	Stegoceras validum Currie p. 6
2005	Stegoceras validum Ryan and Evans p. 319
2005	Stegoceras sternbergi Ryan and Evans p. 320
2006	Hanssuesia sternbergi Sullivan p. 353
2006	Stegoceras validum Sullivan p. 357
2006	Stegoceras validum Sullivan and Lucas p. 329
2006	Stegoceras sternbergi Williamson and Carr p. 323
2008	Hansuessia sternbergi Longrich p. 994
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	Hanssuesia sternbergi Schott et al. p. 774
2009	Stegoceras validum Williamson et al. p. 291
2010	Gravitholus albertae Lehman p. 788
2010	Stegoceras validum Lehman p. 788
2010	Gravitholus albertae Longrich et al.
2010	Hanssuesia sternbergi Longrich et al. p. 280
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
2012	Hanssuesia sternbergi Schott and Evans p. 912
2015	Hanssuesia sternbergi Mallon et al. p. 429
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	Hanssuesia sternbergi Schott and Evans p. 868
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
2021	Hanssuesia sternbergi Woodruff et al. p. 580
2023	Stegoceras validum Dyer et al. pp. 75-76
2024	Stegoceras validum Wick and Lehman p. 90

Is something missing? Join the Paleobiology Database and enter the data

Rank	Name	Author
kingdom	Animalia	()
—	Bilateria
—	Eubilateria	Ax 1987
—	Deuterostomia
phylum	Chordata	Haeckel 1874
subphylum	Vertebrata
superclass	Gnathostomata
class	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

show all | hide all

Invalid names: Gravitholus albertae Wall and Galton 1979 [synonym], Stegoceras browni Wall and Galton 1979 [synonym], Troodon sternbergi Brown and Schlaikjer 1943 [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 (Hanssuesia sternbergi)	Differs 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.
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.
A. D. Dyer et al. 2023	Modified from Schott et al. (2011). A medium-sized pachycephalosaurid differing from all other pachycephalosaurians, where known, by possessing six or more nodes in the primary parietosquamosal node row, a row of small, keel-shaped nodes on lateral margins of postorbitals and squamosal, numerous minute tubercles on lateral and posterior sides of the postorbitals and squamosals, no ventrolateral corner node on the posterior surface of the squamosals, no nasal ornamentation, a greatly reduced maxillary-premaxillary diastema, and a pubic peduncle of the ilium that is mediolaterally compressed and platelike. Differs from all other domed pachycephalosaurians (except possibly Colepiocephale lambei), where known, in possessing a parietosquamosal shelf (may be fully incorporated into the dome in mature individuals), as opposed to the dome extending to the posterior margin of the skull. The palpebral and prefrontal are not incorporated into the dome, as in Acrotholus audeti, Pachycephalosaurus wyomingensis, Prenocephale prenes, and Sphaerotholus spp.

Measurements

No measurements are available

Composition:

hydroxyapatiteo

Entire body:

yesg

Adult length:

10 to < 100o

Adult width:

1.0 to < 10o

Adult height:

1.0 to < 10o

Architecture:

compact or denseo

Ontogeny:

accretion, modification of partso

Grouping:

gregariouso

Environment:

terrestrialo

Locomotion:

actively mobileo

Life habit:

ground dwellingo

Diet:

herbivoreo

Reproduction:

oviparouso

Dispersal:

direct/internalo

Dispersal 2:

mobileo

Created:

2005-08-25 05:49:46

Modified:

2005-08-25 07:49:46

Source: g = genus, o = order

References: Peczkis 1995, Marsh 1875, Kiessling 2004

Age range: Middle Campanian or 83.60000 to 72.20000 Ma

Collections (31 total)

Time interval	Ma	Country or state	Original ID and collection number
Campanian	83.6 - 72.2	Canada (Alberta)	Psalisauridae indet. (64647 64657 64662) Stegoceras sp. (64661) Stegoceras validus (64646 64652 64658 64660) Troodon sternbergi (64648 64656) Troodon validus (64659 64663 64665)
Late/Upper Campanian	83.6 - 72.2	USA (New Mexico)	Stegoceras validum (76714)
Late/Upper Campanian	83.6 - 72.2	Canada (Alberta)	Ornatotholus browni (47629 48619) Stegoceras validum (230768) Stegoceras validus (48618 type locality: 60876) Stygimoloch sp. (76752) Troodon validus (53976 59107)
Middle Campanian	83.6 - 72.2	Canada (Alberta)	Gravitholus albertae (72144)
Middle Campanian - Late/Upper Campanian	83.6 - 72.2	USA (Montana)	Ornatotholus browni (50829) Stegoceras validum (14470 14491 50825 50826 50827 61452) Stegoceras validus (14446)