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Stegoceras

Reptilia

Taxonomy
Stegoceras was named by Lambe (1902). It is not extant.

It was synonymized subjectively with Troodon by Gilmore (1924) and Hay (1930).

It was assigned to Reptilia by Huene (1909); to Acanthopholididae by Nopcsa (1915); to Psalisauridae by Lambe (1918); to Ceratopsidae by Lambe (1902), Lambe (1905), Hatcher et al. (1907), Lambe (1911), Hennig (1915) and Huene (1927); to Acanthopholidae by Nopcsa (1923), Nopcsa (1928) and Nopcsa (1928); to Pachycephalosauroidea by Zhao (1983); to Pachycephalosauria by Maryanska and Osmólska (1985); to Tholocephalidae by Sereno (1986); to Eupachycephalosauria by Dieudonné et al. (2020); and to Pachycephalosauridae by Sternberg (1945), Romer (1956), Parsch (1963), Tatarinov (1964), Kuhn (1964), Romer (1966), Charig (1967), Russell and Chamney (1967), Swinton (1970), Maryańska and Osmólska (1974), Thulborn (1974), Galton (1974), Dong (1978), Wall and Galton (1979), Wolberg (1980), Molnar (1980), Rage (1981), Sues and Galton (1982), Dodson (1983), Russell (1984), Clemens (1986), Sues and Galton (1987), Carroll (1988), Maryanska (1990), Goodwin (1990), Olshevsky and Ford (1994), Sues (1997), Eberth (1997), Sereno (1997), Sereno (1998), Sereno (1999), Sereno (2000), Eberth et al. (2001), Sullivan (2003), Williamson and Carr (2003), Maryanska et al. (2004), Ryan and Evans (2005), Sullivan (2006), Williamson and Carr (2006), Sullivan and Lucas (2006), Longrich (2008), Butler et al. (2008), Schott et al. (2009), Jasinski and Sullivan (2011), Jasinski (2015) and Woodruff et al. (2021).

Synonymy list
YearName and author
1902Stegoceras Lambe p. 68
1905Stegoceras Lambe p. 49
1907Stegoceras Hatcher et al. p. 97
1909Stegoceras Huene p. 18
1911Stegoceras Lambe p. 9
1915Stegoceras Hennig p. 14
1915Stegoceras Nopcsa p. 13
1918Stegoceras Lambe p. 32
1923Stegoceras Nopcsa p. 198
1927Stegoceras Huene p. 261
1928Stegoceras Nopcsa p. 73
1945Stegoceras Sternberg pp. 535-6
1956Stegoceras Romer p. 632
1963Stegoceras Parsch p. 8
1964Stegoceras Kuhn p. 31
1964Stegoceras Tatarinov p. 589
1966Stegoceras Romer p. 370
1967Stegoceras Charig p. 716
1967Stegoceras Russell and Chamney p. 11
1970Stegoceras Swinton p. 231
1974Stegoceras Galton p. 1064 fig. 6
1974Stegoceras Maryańska and Osmólska p. 47
1974Stegoceras Thulborn p. 173
1978Stegoceras Dong p. 227
1979Stegoceras Wall and Galton p. 1179
1980Stegoceras Molnar p. 138
1980Stegoceras Wolberg p. 50
1981Stegoceras Rage p. 68
1982Stegoceras Sues and Galton p. 188
1983Stegoceras Dodson p. 95
1983Ornatotholus Galton and Sues p. 469
1983Stegoceras Zhao p. 304
1984Ornatotholus Russell p. 25
1984Stegoceras Russell p. 25
1985Stegoceras Maryanska and Osmólska p. 141
1986Ornatotholus Clemens p. 80
1986Stegoceras Clemens p. 80
1986Stegoceras Sereno
1987Ornatotholus Sues and Galton
1987Stegoceras Sues and Galton
1988Ornatotholus Carroll
1988Stegoceras Carroll
1990Stegoceras Goodwin p. 191
1990Ornatotholus Maryanska p. 566
1990Stegoceras Maryanska p. 566
1994Ornatotholus Olshevsky and Ford p. 91
1994Stegoceras Olshevsky and Ford p. 91
1997Stegoceras Eberth p. 201
1997Stegoceras Sereno p. 443
1997Ornatotholus Sues p. 512
1997Stegoceras Sues p. 512
1998Stegoceras Sereno p. 62
1999Stegoceras Sereno p. 2138 fig. 2
2000Stegoceras Sereno p. 482
2000Ornatotholus Sereno p. 497 fig. 25.8
2001Stegoceras Eberth et al. p. 57
2003Stegoceras Sullivan p. 185
2003Hanssuessia Sullivan p. 193
2003Stegoceras Williamson and Carr fig. 11
2004Ornatotholus Maryanska et al. p. 465
2004Stegoceras Maryanska et al. p. 465
2005Stegoceras Ryan and Evans p. 317
2006Stegoceras Sullivan p. 357
2006Stegoceras Sullivan and Lucas p. 329
2006Stegoceras Williamson and Carr p. 323
2008Stegoceras Butler et al. p. 8
2008Hansuessia Longrich p. 994
2008Stegoceras Longrich p. 994
2009Stegoceras Schott et al. p. 781 fig. 8
2011Stegoceras Jasinski and Sullivan p. 215
2015Stegoceras Jasinski p. 79
2020Stegoceras Dieudonné et al.
2021Stegoceras Woodruff et al. p. 588 fig. 14

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RankNameAuthor
kingdomAnimalia()
Bilateria
EubilateriaAx 1987
Deuterostomia
phylumChordataHaeckel 1874
subphylumVertebrata
superclassGnathostomata
Osteichthyes()
subclassSarcopterygii()
subclassDipnotetrapodomorpha(Nelson 2006)
subclassTetrapodomorpha()
Tetrapoda
Reptiliomorpha
Anthracosauria
subclassAmphibiosauriaKuhn 1967
Cotylosauria()
Amniota
Sauropsida
classReptilia
subclassEureptilia()
RankNameAuthor
Romeriida
Diapsida()
Archosauromorpha(Huene 1946)
Crocopoda
ArchosauriformesGauthier 1986
Eucrocopoda
Archosauria()
informalAvemetatarsalia
Ornithodira
Dinosauromorpha
Dinosauriformes
Dinosauria()
Ornithischia()
Genasauria
Cerapoda
Marginocephalia
Pachycephalosauria()
Eupachycephalosauria
genusStegoceras

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.

G. †Stegoceras Lambe 1902
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Stegoceras novomexicanum Jasinski and Sullivan 2011
Stegoceras validum Lambe 1902
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Invalid names: Ornatotholus browni Wall and Galton 1979 [synonym]
Invalid names: Hanssuessia Sullivan 2003 [synonym], Ornatotholus Galton and Sues 1983 [synonym]
Diagnosis
ReferenceDiagnosis
C. M. Sternberg 1945Small to medium-sized; thickness and position of dome variable: face short; skull more or less ornamented; premaxillae with teeth; premaxillary teeth pointed, with trenchant edges, faint marginal denticulations, faces of crown ribbed, posterior "heel"; maxillary and dentary teeth with well-pronounced denticulations extending onto both faces as flutings; supratemporal fossa nearly or quite closed; infratemporal fossa much reduced; premaxilla nearly excluded from lateral view; fore limb much reduced; four digits in the pes, first reduced.
S. E. Jasinski and R. M. Sullivan 2011Differs from all other pachycephalosaurid genera 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 adn as many as two nodes on the posteromedial extension of the parietal. Posteromedial extension of the parietal either sub-rectangular or trapezoidal in shape. Supratemporal fenetrae closed or open and relatively small, and positioned either adjacent or lateral to the midline. Stegoceras (sensu stricto) is late middle Campanian through early late Campanian (late Judithian-early Kirtlandian).
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
Maximum body mass: 100 kgg
Minimum body mass: 10 kgg
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

Age range: base of the Late/Upper Campanian to the top of the Late/Upper Maastrichtian or 83.50000 to 66.00000 Ma

Collections (41 total)


Time interval Ma Country or state Original ID and collection number
Campanian83.6 - 72.1Canada (Alberta) Psalisauridae indet. (64647 64657 64662) S. sp. (64661) S. validus (64646 64652 64658 64660) Troodon validus (64659 64663 64665)
Late/Upper Campanian83.5 - 70.6USA (New Mexico) Sphaerotholus goodwini (53514) S. novomexicanum (144518 144519 144520) S. validum, S. novomexicanum (76714)
Late/Upper Campanian83.5 - 70.6Canada (Alberta) Ornatotholus browni (47629 48619) S. validum (230768) S. validus (48618 60876) Stygimoloch sp. (76752) Troodon validus (53976 59107)
Middle Campanian83.5 - 70.6USA (Montana) S. sp. (14437)
Middle Campanian - Late/Upper Campanian83.5 - 70.6USA (Montana) Ornatotholus browni (50829) Pachycephalosauridae indet. (50830) S. sp. (48620 50828 50906 50907) S. validum (14470 14491 50825 50826 50827 61452) S. validus (14446)
Middle Campanian - Late/Upper Campanian83.5 - 70.6Canada (Saskatchewan) S. sp. (14494)
Late/Upper Maastrichtian70.6 - 66.0USA (Montana) S. sp. (52903 72143)