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

Ornithischia (ornithischian)

Osteichthyes

Taxonomy
Ornithischia was named by Seeley (1888). It was considered monophyletic by Nesbitt (2011), unknown by Zheng et al. (2012).

It was synonymized subjectively with Orthopoda by Hay (1902); it was synonymized subjectively with Postpubici by Jaekel (1910), Jaekel (1911); it was synonymized subjectively with Orthopoda by Hay (1930); it was reranked as the suborder Ornithischia by Parks (1935), Young (1935); it was reranked as the subclass Ornithischia by Bakker and Galton (1974); it was reranked as the superorder Ornithischia by Cooper (1985), Watabe et al. (2011); it was reranked as the unranked clade Ornithischia by Swinton (1934), Gauthier and Padian (1985), Gauthier (1986), Brinkman and Sues (1987), Gauthier et al. (1989), Novas (1989), Benton (1990), Buffetaut and Ingavat (1992), Novas (1993), Sereno et al. (1993), Novas (1996), Sereno (1997), Sereno (1998), Sereno (1999), Langer and Benton (2006), Ezcurra (2006), Martínez and Alcober (2009), Zheng et al. (2009), Cruzado-Caballero et al. (2010), Nesbitt (2011), Jasinski and Sullivan (2011), Shibata et al. (2011), Zheng et al. (2012), Yang et al. (2013), Evans et al. (2013), Arbour et al. (2014), Escaso et al. (2014), Freedman Fowler and Horner (2015), Gasulla et al. (2015), Shibata et al. (2015), Leahey et al. (2015), Rivera-Sylva et al. (2017), Penkalski and Tumanova (2017), Wang et al. (2017), Brown et al. (2017), Arbour and Evans (2017), Madzia et al. (2018), Zheng et al. (2018), Murray et al. (2019), Martz and Small (2019), Ibiricu et al. (2019), Novas et al. (2019), Napoli et al. (2019), Kobayashi et al. (2019), Prieto-Márquez et al. (2019), Arbour and Evans (2019), Müller and Garcia (2020), Fowler and Freedman Fowler (2020), Wilson et al. (2020), Ibiricu et al. (2021), Rozadilla et al. (2021), Moyano-Paz et al. (2022), Ryan et al. (2023), Tanaka et al. (2024), Zafaty et al. (2024), Agnolín et al. (2024), Carrano (2025), Yang et al. (2025), Woodruff et al. (2025), Bertozzo et al. (2025), Jung et al. (2026), Yao et al. (2026), Magyar et al. (2026), Huang et al. (2026).

It was assigned to Archosauromorpha by Huene (1948), Huene (1954); to Dinosauria by Bakker and Galton (1974); to Reptilia by Seeley (1888), Lull (1924), Kuhn (1946), Sternberg (1954), Estes (1964), Ellenberger (1972), Madsen and Miller (1979), Benton (1979); to Archosauria by Haughton and Brink (1954), Parsch (1963), Kuhn (1964), Romer (1966), Charig (1967), Haubold (1971), Haubold (1974), Thulborn (1975), Thurmond and Jones (1981); to Ornithischiformes by Cooper (1985); to Archosauria by Roxo (1937), Romer (1956), Ostrom (1980), Carroll (1988); to Dinosauria by Seeley (1888), Seeley (1888), Huene (1909), Lull (1915), Swinton (1934), Parks (1935), Young (1935), Zhao (1983), Long and Murry (1995); to Dinosauria by Peng et al. (2001); to Archosauria by Kuhn (1966), Martinelli and Forasiepi (2004); to Dinosauria by Tatarinov (1964), Coria et al. (2012), Apesteguía et al. (2012); to Eudinosauria by Novas (1992), Carrano (2025); and to Dinosauria by Gardiner (1982), Gauthier and Padian (1985), Gauthier (1986), Brinkman and Sues (1987), Gauthier et al. (1989), Novas (1989), Benton (1990), Buffetaut and Ingavat (1992), Novas (1993), Sereno et al. (1993), Novas (1996), Sereno (1997), Sereno (1998), Sereno (1999), Langer and Benton (2006), Ezcurra (2006), Martínez and Alcober (2009), Zheng et al. (2009), Cruzado-Caballero et al. (2010), Nesbitt (2011), Jasinski and Sullivan (2011), Watabe et al. (2011), Shibata et al. (2011), Zheng et al. (2012), Yang et al. (2013), Evans et al. (2013), Arbour et al. (2014), Escaso et al. (2014), Freedman Fowler and Horner (2015), Gasulla et al. (2015), Shibata et al. (2015), Leahey et al. (2015), Rivera-Sylva et al. (2017), Penkalski and Tumanova (2017), Wang et al. (2017), Brown et al. (2017), Arbour and Evans (2017), Madzia et al. (2018), Zheng et al. (2018), Murray et al. (2019), Martz and Small (2019), Ibiricu et al. (2019), Novas et al. (2019), Napoli et al. (2019), Kobayashi et al. (2019), Prieto-Márquez et al. (2019), Arbour and Evans (2019), Müller and Garcia (2020), Fowler and Freedman Fowler (2020), Wilson et al. (2020), Ibiricu et al. (2021), Rozadilla et al. (2021), Moyano-Paz et al. (2022), Ryan et al. (2023), Tanaka et al. (2024), Zafaty et al. (2024), Agnolín et al. (2024), Yang et al. (2025), Woodruff et al. (2025), Bertozzo et al. (2025), Jung et al. (2026), Yao et al. (2026), Magyar et al. (2026), Huang et al. (2026).

Synonyms
Synonymy list
YearName and author
1866Orthopoda Cope
1869Orthopoda Cope p. 90
1870Orthopoda Cope p. 90
1871Orthopoda Cope p. 234
1875Orthopoda Cope p. 13
1877Orthopoda Cope p. 572
1879Orthopoda Seeley p. 183
1883Orthopoda Cope p. 98
1887Orthopoda Baur p. 101
1887Omosauria Seeley p. 562
1888Ornithischia Seeley
1889Orthopoda Cope p. 16
1890Orthopoda Zittel pp. 450, 736
1891Orthopoda Cope p. 43
1897Orthopoda Gadow p. 204
1898Orthopoda Cope p. 68
1898Orthopoda Gadow p. 22
1900Orthopoda Van Den Broeck p. 82
1901Orthopoda Gadow p. 424
1901Orthopoda Nopcsa p. 207
1902Orthopoda Hay p. 495
1902Orthopoda Huene
1903Orthopoda Osborn p. 456
1904Orthopoda Lull p. 479
1904Orthopoda Osborn p. 114
1905Orthopoda Lambe p. 48
1909Orthopoda Arldt p. 263
1909Ornithischia Huene p. 16
1909Orthopoda Huene p. 17
1914Orthopoda Huene p. 38
1915Ornithischia Lull p. 117
1915Orthopoda Lull p. 117
1917Orthopoda Lull p. 117
1922Orthopoda Joleaud p. 59
1923Orthopoda Nopcsa p. 126
1924Ornithischia Lull p. 236
1927Orthopoda Huene p. 259
1928Orthopoda Nopcsa p. 184
1928Orthopoda Perrier p. 3118
1929Orthopoda Huene p. 155
1930Orthopoda Hay p. 201
1934Ornithischia Swinton p. 40
1935Ornithischia Parks p. 184
1935Ornithischia Young p. 5
1937Ornithischia Roxo p. 44
1946Ornithischia Kuhn p. 66
1948Ornithischia Huene p. 93
1954Ornithosuchia Haughton and Brink p. 4
1954Ornithischia Huene p. 48
1954Ornithischia Sternberg p. 383
1956Ornithischia Romer p. 624
1963Ornithischia Parsch p. 4
1964Ornithischia Estes p. 144
1964Fabrosaurus Ginsburg pp. 2366-2368
1964Fabrosaurus australis Ginsburg p. 2367 fig. 1
1964Ornithischia Kuhn p. 312
1964Ornithischia Tatarinov p. 552
1966Ornithischia Kuhn p. 99
1966Ornithischia Romer p. 370
1967Ornithischia Charig p. 715
1970Fabrosaurus australis Demathieu p. 19
1970Fabrosaurus Ellenberger p. 349
1970Fabrosaurus australis Ellenberger p. 349
1970Fabrosaurus australis Thulborn p. 414
1970Fabrosaurus Thulborn p. 430
1971Ornithischia Haubold p. 86
1971Fabrosaurus Thulborn pp. 76-77
1972Fabrosaurus australis Ellenberger p. 10
1972Ornithischia Ellenberger p. 152
1972Fabrosaurus Galton p. 465
1972Fabrosaurus Thulborn p. 50
1972Fabrosaurus australis Thulborn p. 50
1973Fabrosaurus Galton p. 17
1974Fabrosaurus Bakker and Galton p. 170
1974Ornithischia Bakker and Galton p. 171
1974Fabrosaurus Galton p. 150
1974Ornithischia Haubold p. 46
1974Fabrosaurus Maryańska and Osmólska p. 101
1974Fabrosaurus australis Maryańska and Osmólska p. 101
1974Fabrosaurus australis Thulborn p. 152
1974Fabrosaurus Thulborn p. 171
1975Alocodon Thulborn p. 90
1975Alocodon kuehnei Thulborn p. 90
1975Fabrosaurus australis Thulborn p. 99
1975Trimucrodon Thulborn pp. 118-119
1975Trimucrodon cuneatus Thulborn pp. 118-119 fig. 25
1975Alocodon Thulborn p. 133
1975Fabrosaurus Thulborn p. 133
1975Trimucrodon Thulborn p. 133
1975Ornithischia Thulborn p. 267
1976Fabrosaurus Bonaparte p. 815
1976Fabrosaurus Santa Luca et al. p. 324
1978Fabrosaurus Anderson and Cruickshank p. 31
1978Fabrosaurus Galton p. 156
1978Fabrosaurus australis Galton p. 156
1978Trimucrodon Galton p. 159
1978Alocodon Galton p. 230
1978Amtosaurus Kurzanov and Tumanova p. 371 fig. 2
1978Amtosaurus magnus Kurzanov and Tumanova p. 371 fig. 2
1978Fabrosaurus Thuborn p. 187
1978Fabrosaurus australis Thuborn p. 187
1979Ornithischia Benton p. 142
1979Ornithischia Madsen and Miller p. 5
1980Trimucrodon Galton p. 88
1980Ornithischia Ostrom p. 22
1981Ornithischia Thurmond and Jones p. 144
1982Ornithischia Gardiner p. 229
1983Trimucrodon Galton p. 11
1983Trimucrodon cuneatus Galton p. 11
1983Alocodon Weishampel and Weishampel p. 44
1983Alocodon kuehnei Weishampel and Weishampel p. 44
1983Fabrosaurus Weishampel and Weishampel p. 44
1983Fabrosaurus australis Weishampel and Weishampel p. 44
1983Trimucrodon Weishampel and Weishampel p. 44
1983Trimucrodon cuneatus Weishampel and Weishampel p. 44
1983Ornithischia Zhao p. 295
1984Alocodon Milner and Norman p. 146
1984Trimucrodon Milner and Norman p. 146
1984Alocodon Norman p. 342
1984Trimucrodon Norman p. 342
1984Fabrosaurus Olsen and Galton p. 91
1984Fabrosaurus australis Olsen and Galton p. 91
1984Fabrosaurus Santa Luca
1985Ornithischia Cooper p. 284
1985Ornithischia Gauthier and Padian pp. 189-190 fig. 2
1986Fabrosaurus Battail p. 50
1986Ornithischia Gauthier p. 44
1987Ornithischia Brinkman and Sues p. 502 fig. 7
1987Amtosaurus Tumanova p. 17
1987Amtosaurus magnus Tumanova p. 18
1988Amtosaurus Carroll
1988Fabrosaurus Carroll
1988Ornithischia Carroll
1988Trimucrodon Carroll
1989Fabrosaurus australis Frances and Sanz p. 141
1989Ornithischia Gauthier et al. p. 346
1989Ornithischia Novas p. 686 fig. 2
1990Ornithischia Benton p. 19
1991Alocodon Antunes and Sigogneau-Russell p. 113
1991Alocodon Galton p. 300
1991Alocodon kuehnei Galton p. 300
1991Trimurodon Galton p. 300
1991Trimurodon cuneatus Galton p. 300
1991Alocodon Sereno pp. 172-173
1991Alocodon kuehnei Sereno pp. 172-173
1991Trimucrodon Sereno pp. 172-173
1991Trimucrodon cuneatus Sereno pp. 172-173
1992Ornithischia Buffetaut and Ingavat
1992Ornithischia Novas pp. 59-60 fig. 6
1993Ornithischia Novas p. 110
1993Ornithischia Sereno et al. p. 65 fig. 2
1994Fabrosaurus australis Chure et al. p. 306
1994Trimucrodon cuneatus Galton p. 256
1994Trimucrodon Galton p. 265
1994Fabrosaurus Hunt and Lucas p. 238
1994Fabrosaurus australis Hunt and Lucas p. 238
1995Ornithischia Long and Murry p. 191
1996Ornithischia Novas p. 737 fig. 10
1997Amtosaurus Barsbold p. 450
1997Amtosaurus magnus Barsbold p. 450
1997Fabrosaurus Peng p. 237–238
1997Fabrosaurus australis Peng p. 237–238
1997Ornithischia Sereno p. 443
1998Ornithischia Sereno p. 61
1999Fabrosaurus Knoll p. 65
1999Ornithischia Sereno p. 2138 fig. 2
2000Amtosaurus Ford p. 176
2000Amtosaurus magnus Ford p. 176
2000Trimucrodon Ruiz-Omeñaca p. 69
2000Amtosaurus Tumanova p. 522
2000Amtosaurus magnus Tumanova p. 522
2001Ornithischia Peng et al. p. 33
2002Amtosaurus Averianov
2004Ornithischia Martinelli and Forasiepi p. 260
2004Amtosaurus Vickaryous et al. p. 367
2004Amtosaurus magnus Vickaryous et al. p. 367
2006Ornithischia Ezcurra p. 657 fig. 3
2006Ornithischia Langer and Benton pp. 345-347 fig. 15
2006Trimucrodon cuneatus Mateus p. 231
2007Fabrosaurus Gand et al. p. 74
2007Fabrosaurus australis Gand et al. p. 74
2009Ornithischia Martínez and Alcober p. 11 fig. 10
2009Alocodon kuehnei Ortega et al. p. 48
2009Trimucrodon cuneatus Ortega et al. p. 48
2009Ornithischia Zheng et al. p. 333
2010Ornithischia Cruzado-Caballero et al.
2010Trimucrodon cuneatus Mateus and Milàn p. 253
2010Alocodon Mateus and Milàn p. 254
2010Alocodon kuehnei Mateus and Milàn p. 254
2010Trimucrodon Mateus and Milàn p. 254
2011Amtosaurus magnus Carpenter et al. p. 2
2011Ornithischia Jasinski and Sullivan p. 202
2011Ornithischia Nesbitt p. 210 fig. 52
2011Ornithischia Shibata et al. p. 970
2011Ornithischia Watabe et al. p. 490
2012Ornithischia Apesteguía et al.
2012Ornithischia Coria et al. p. 3
2012Ornithischia Zheng et al. p. 210
2013Ornithischia Evans et al. p. 2
2013Ornithischia Yang et al. p. 268
2014Ornithischia Arbour et al.
2014Ornithischia Escaso et al. p. 1103
2015Ornithischia Freedman Fowler and Horner
2015Ornithischia Gasulla et al.
2015Ornithischia Leahey et al.
2015Ornithischia Shibata et al.
2017Ornithischia Arbour and Evans p. 7
2017Ornithischia Brown et al.
2017Ornithischia Penkalski and Tumanova
2017Ornithischia Rivera-Sylva et al.
2017Ornithischia Wang et al.
2018Ornithischia Madzia et al.
2018Ornithischia Zheng et al.
2019Ornithischia Arbour and Evans
2019Ornithischia Ibiricu et al.
2019Ornithischia Kobayashi et al.
2019Ornithischia Martz and Small p. 54 fig. 23
2019Ornithischia Murray et al.
2019Ornithischia Napoli et al.
2019Ornithischia Novas et al. p. 230
2019Ornithischia Prieto-Márquez et al.
2020Alocodon Carvalho p. 14
2020Alocodon kuehnei Carvalho p. 14
2020Ornithischia Fowler and Freedman Fowler
2020Ornithischia Müller and Garcia p. 3 fig. 1
2020Alocodon kuehnei Rotatori et al. p. 36
2020Trimucrodon cuneatus Rotatori et al. p. 36
2020Ornithischia Wilson et al.
2021Ornithischia Ibiricu et al.
2021Ornithischia Rozadilla et al. p. 2
2022Ornithischia Moyano-Paz et al. p. 17
2023Ornithischia Ryan et al.
2024Ornithischia Agnolín et al.
2024Ornithischia Tanaka et al. p. 5
2024Ornithischia Zafaty et al. p. 347
2025Ornithischia Bertozzo et al.
2025Ornithischia Carrano p. 128
2025Ornithischia Woodruff et al.
2025Ornithischia Yang et al.
2026Ornithischia Huang et al.
2026Ornithischia Jung et al.
2026Ornithischia Magyar et al.
2026Ornithischia Yao et al.

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

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

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.

Unr. †Ornithischia Seeley 1888 [ornithischian]
show all | hide all
G. †Apulosauripus Nicosia et al. 1999
+
†Apulosauripus federicianus Nicosia et al. 1999
G. †Archaeocursor Yao et al. 2025
+
†Archaeocursor asiaticus Yao et al. 2025
Subor. †Armatosauria Zhao 1983
+
Superfm. †Polysacralosauroidea Zhao 1983
+
G. †Sangonghesaurus Zhao 1983
Invalid names: Oligosacralosauroidea Zhao 1983 [empty], Scelidosauroidea Zhao 1983 [empty]
Fm. †Cairanoolithidae Sellés and Galobart 2016
+
G. †Cairanoolithus Vianey-Liaud et al. 1994
+
†Cairanoolithus dughii Vianey-Liaud et al. 1994
†Cairanoolithus roussetensis Vianey-Liaud et al. 1994
Invalid names: Dughioolithus Vianey-Liaud et al. 1994 [synonym]
G. †Chilesaurus Novas et al. 2015
+
†Chilesaurus diegosuarezi Novas et al. 2015
Fm. †Delatorrichnopodidae Bordy et al. 2020
+
G. †Afrodelatorrichnus Bordy et al. 2020
+
†Afrodelatorrichnus ellenbergeri Bordy et al. 2020
G. †Delatorrichnus Casamiquela 1964
+
†Delatorrichnus goyenechei Casamiquela 1964
Fm. †Fabrosauridae Galton 1972
+
G. †Eugongbusaurus Knoll 1999
G. †Gongbusaurus Dong et al. 1983
+
†Gongbusaurus shiyii Dong et al. 1983
G. †Xiaosaurus Dong and Tang 1983 [small lizard]
+
†Xiaosaurus dashanpensis Dong and Tang 1983
G. †Ferganocephale Averianov et al. 2005
+
†Ferganocephale adenticulatum Averianov et al. 2005
G. †Gregaripus Weems 1987
+
†Gregaripus bairdi Weems 1987
G. †Gyrotrisauropus Ellenberger 1970
+
†Gyrotrisauropus planus Ellenberger 1970
G. †Komlosaurus Kordos 1983
+
†Komlosaurus carbonis Kordos 1983
G. †Krzyzanowskisaurus Heckert 2005
+
†Krzyzanowskisaurus hunti Heckert 2002
G. †Ligabueichnium Leonardi 1984
+
†Ligabueichnium bolivianum Leonardi 1984
G. †Minisauripus Zhen et al. 1994
+
†Minisauripus chuanzhuensis Zhen et al. 1994
†Minisauripus zhenshuonani Lockley et al. 2008
Unr. †Neornithischia Cooper 1985
+
G. †Agilisaurus Peng 1990
+
G. †Enigmacursor Maidment and Barrett 2025
+
†Enigmacursor mollyborthwickae Maidment and Barrett 2025
G. †Hexinlusaurus Barrett et al. 2005
+
†Hexinlusaurus multidens He and Cai 1983
Fm. †Jeholosauridae Han et al. 2012
+
G. †Kulindapteryx Alifanov and Saveliev 2014
+
†Kulindapteryx ukureica Alifanov and Saveliev 2014
G. †Minimocursor Manitkoon et al. 2023
+
†Minimocursor phunoiensis Manitkoon et al. 2023
G. †Nanosaurus Marsh 1877
+
†Nanosaurus agilis Marsh 1877
+
Invalid names: Drinker nisti Bakker et al. 1990 [synonym], Nanosaurus rex Marsh 1877 [synonym], Othnielosaurus consors Marsh 1894 [synonym]
Invalid names: Drinker Bakker et al. 1990 [synonym], Othnielosaurus Galton 2007 [synonym]
G. †Pulaosaurus Yang et al. 2025
+
†Pulaosaurus qinglong Yang et al. 2025
Unr. †Pyrodontia Fonseca et al. 2024
+
Unr. †Cerapoda Sereno 1986
+
Unr. †Marginocephalia Sereno 1986
+
Subor. †Ceratopsia Marsh 1890 [ceratopsian]
+
Invalid names: Ponderopoda Huene 1948 [synonym]
Subor. †Pachycephalosauria Maryańska and Osmólska 1974
Subor. †Ornithopoda Marsh 1881 [ornithopod]
+
Fm. †Anomoepodidae Lull 1904
G. †Burianosaurus Madzia et al. 2018
Unr. †Clypeodonta Norman 2014
+
Invalid names: Hypsilophodontia Cooper 1985 [synonym]
G. †Dakotasaurus Branson and Mehl 1932
G. †Dinosauropodes Douglass 1932
Unr. †Euornithopoda Sereno 1986
Subor. †Fabrosauria Cooper 1985
G. †Hypsiloichnus Stanford et al. 2004
Fm. †Hypsilophodontidae Dollo 1882 [hypsilophodontid]
+
Invalid names: Kalodontidae Nopcsa 1901 [synonym], Laosauridae Marsh 1895 [synonym], Macelognathidae Marsh 1884 [synonym]
Infraor. †Iguanodontia Baur 1891
Fm. †Iguanodontipodidae Vyalov 1987
Fm. †Iguanodontipodidae Lockley et al. 2014
Fm. †Moyenisauropodidae Ellenberger 1974
G. †Ningxiapus Zong et al. 2013
G. †Ponerosteus Olshevsky 2000
+
Invalid names: Procerosaurus Fritsch 1905 [replaced]
G. †Psilotrisauropus Ellenberger 1972
Fm. †Tetrapodosauridae Sternberg 1932
G. †Unespichnium Bertini and Carvalho 2003
G. †Walmadanyichnus Salisbury et al. 2016
G. †Wintonopus Thulborn and Wade 1984
+
Invalid names: Skartopus Thulborn and Wade 1984 [synonym]
Invalid names: Bonaparteichnium Calvo 1991 [nomen dubium], Brachypoda Thulborn 1974 [empty], Camptosaurichnus Casamiquela and Fasola 1968 [nomen dubium], Camptosauropus Gabuniya and Kurbatov 1988 [nomen dubium], Dolichopoda Thulborn 1974 [empty], Gilmoreosaurus arkhangelskyi Nessov 1995 [nomen dubium], Goseongosauripus Kim 1986 [nomen dubium], Jiayinosauropus Dong et al. 2003 [nomen dubium], Kalodontoidea Huene 1948 [empty], Laosaurus Marsh 1878 [nomen dubium], Laosaurus celer Marsh 1878 [nomen dubium], Laosaurus minimus Gilmore 1924 [nomen dubium], Ornithopodoidea Nopcsa 1929 [synonym], Ornithopoidea Nopcsa 1929 [empty], Othnielia Galton 1977 [nomen dubium], Phyllodon Thulborn 1975 [nomen dubium], Siluosaurus Dong 1997 [nomen dubium], Taponichnus Alonso and Marquillas 1986 [nomen dubium], Telosichnus Alonso and Marquillas 1986 [nomen dubium], Trachodontoidea Huene 1948 [empty]
Invalid names: Chasmatopia Buchholz 2002 [empty]
G. †Kulindadromeus Godefroit et al. 2014
+
†Kulindadromeus zabaikalicus Godefroit et al. 2014
G. †Sanxiasaurus Hu Dai et al. 2019
+
†Sanxiasaurus modaoxiensis Hu Dai et al. 2019
G. †Stormbergia Butler 2005
Fm. †Thescelosauridae Sternberg 1937
+
G. †Doolysaurus Jung et al. 2026
+
†Doolysaurus huhmini Jung et al. 2026
Subfm. †Orodrominae Brown et al. 2013
+
G. †Albertadromeus Brown et al. 2013
+
†Albertadromeus syntarsus Brown et al. 2013
G. †Koreanosaurus Huh et al. 2011
+
†Koreanosaurus boseongensis Huh et al. 2011
G. †Nevadadromeus Bonde et al. 2022
+
†Nevadadromeus schmitti Bonde et al. 2022
G. †Orodromeus Horner and Weishampel 1988
+
†Orodromeus makelai Horner and Weishampel 1988
G. †Oryctodromeus Varricchio et al. 2007
+
†Oryctodromeus cubicularis Varricchio et al. 2007
G. †Zephyrosaurus Sues 1980
+
†Zephyrosaurus schaffi Sues 1980
Subfm. †Thescelosaurinae Sternberg 1940
+
G. †Changchunsaurus Zan et al. 2005
+
†Changchunsaurus parvus Zan et al. 2005
G. †Changmiania Yang et al. 2020
+
†Changmiania liaoningensis Yang et al. 2020
G. †Fona Avrahami et al. 2024
+
†Fona herzogae Avrahami et al. 2024
G. †Haya Makovicky et al. 2011
+
†Haya griva Makovicky et al. 2011
G. †Jeholosaurus Xu et al. 2000
+
†Jeholosaurus shangyuanensis Xu et al. 2000
G. †Parksosaurus Sternberg 1937
+
†Parksosaurus warreni Parks 1926
G. †Thescelosaurus Gilmore 1913
+
†Thescelosaurus assiniboiensis Brown et al. 2011
†Thescelosaurus edmontonensis Sternberg 1940
†Thescelosaurus garbanii Morris 1976
†Thescelosaurus neglectus Gilmore 1913
Invalid names: Bugenasaura Galton 1995 [synonym], Bugenasaura infernalis Galton 1995 [nomen dubium]
G. †Yueosaurus Zheng et al. 2012
+
†Yueosaurus tiantaiensis Zheng et al. 2012
G. †Yandusaurus He 1979
+
Invalid names: Neornithopoda Norman 1984 [empty]
Unr. †Parapredentata Norman 2022
+
G. †Pisanosaurus Casamiquela 1967
+
†Pisanosaurus mertii Casamiquela 1967
Unr. †Saphornithischia Madzia et al. 2001
+
G. †Eocursor Butler et al. 2007
+
†Eocursor parvus Butler et al. 2007
Unr. †Prionodontia Owen 1874
+
Unr. †Genasauria Sereno 1986
+
Unr. †Thyreophora Nopcsa 1915
Fm. †Heterodontosauridae Romer 1966 [heterodontosaurid]
+
G. †Echinodon Owen 1861
G. †Fruitadens Butler et al. 2010
Subfm. †Heterodontosaurinae Sereno 2012
G. †Tianyulong Zheng et al. 2009
Invalid names: Geranosaurus Broom 1911 [nomen dubium], Geranosaurus atavus Broom 1911 [nomen dubium], Lycorhinidae Thulborn 1971 [synonym]
Unr. †Silesauridae Langer et al. 2010
+
G. †Amanasaurus Müller and Garcia 2023
+
†Amanasaurus nesbitti Müller and Garcia 2023
G. †Asilisaurus Nesbitt et al. 2010
+
†Asilisaurus kongwe Nesbitt et al. 2010
G. †Gamatavus Pretto et al. 2022
+
†Gamatavus antiquus Pretto et al. 2022
G. †Lewisuchus Romer 1972
+
†Lewisuchus admixtus Romer 1972
+
Invalid names: Pseudolagosuchus major Arcucci 1987 [synonym]
Invalid names: Pseudolagosuchus Arcucci 1987 [synonym]
G. †Soumyasaurus Sarigul et al. 2018
+
†Soumyasaurus aenigmaticus Sarigul et al. 2018
Unr. †Sulcimentisauria Martz and Small 2019
+
G. †Diodorus Kammerer et al. 2012
+
†Diodorus scytobrachion Kammerer et al. 2012
G. †Eucoelophysis Sullivan and Lucas 1999
+
†Eucoelophysis baldwini Sullivan and Lucas 1999
G. †Kwanasaurus Martz and Small 2019
+
†Kwanasaurus williamparkeri Martz and Small 2019
G. †Lutungutali Peecook et al. 2013
+
†Lutungutali sitwensis Peecook et al. 2013
G. †Sacisaurus Ferigolo and Langer 2007
+
†Sacisaurus agudoensis Ferigolo and Langer 2007
G. †Silesaurus Dzik 2003
+
†Silesaurus opolensis Dzik 2003
G. †Technosaurus Chatterjee 1984
+
†Technosaurus smalli Chatterjee 1984
Invalid names: Lewisuchinae Paul 1988 [invalid subgroup]
Unr. †Predentata Marsh 1894
+
Invalid names: Orbitoscuta Bakker 1986 [empty]
Fm. †Prismatoolithidae Hirsch 1994
+
G. †Laiyangoolithus Wang et al. 2018
+
†Laiyangoolithus lixiangensis Wang et al. 2018
G. †Preprismatoolithus Zelenitsky and Hills 1996
+
Invalid names: Prismatoolithus Hirsch 1994 [replaced]
G. †Prismatoolithus Zhao and Li 1993
+
†Prismatoolithus caboti Garcia et al. 2000
†Prismatoolithus gebiensis Zhao and Li 1993
†Prismatoolithus hirschi Jackson and Varricchio 2010
†Prismatoolithus hukouensis Zhao et al. 1999
†Prismatoolithus ilekensis Skutschas et al. 2017
†Prismatoolithus levis Zelenitsky and Hills 1996
†Prismatoolithus matellensis Vianey-Liaud and Crochet 1994
†Prismatoolithus tenuis Vianey-Liaud and Crochet 1994
†Prismatoolithus tiantaiensis Fang et al. 2000
†Prismatoolithus trempii Sellés et al. 2014
Invalid names: Prismatoolithus Vianey-Liaud and Crochet 1994 [synonym]
G. †Protoceratopsidovum Mikhailov 1994
+
†Protoceratopsidovum minimum Mikhailov 1994
†Protoceratopsidovum sincerum Mikhailov 1994
G. †Sankofa López-Martínez and Vicens 2012
+
†Sankofa pyrenaica López-Martínez and Vicens 2012
G. †Trigonoolithus Moreno-Azanza et al. 2014
+
†Trigonoolithus amoae Moreno-Azanza et al. 2014
G. †Tacuarembovum Mones 1980
+
Invalid names: Alocodon Thulborn 1975 [nomen dubium], Amtosaurus Kurzanov and Tumanova 1978 [nomen dubium], Enoplosauria Swinton 1970 [empty], Fabrosaurus Ginsburg 1964 [nomen dubium], Heterodontosauriformes Xu et al. 2006 [empty], Lesothosauria Olshevsky 1991 [empty], Omosauria Seeley 1887 [synonym], Orthopoda Cope 1866 [synonym], Trimucrodon Thulborn 1975 [nomen dubium]
Diagnosis
ReferenceDiagnosis
E. D. Cope 1869 (Orthopoda)Proximal tarsal bones distinct from each other and from the tibia, articulating with a tibia and with a terminal face of a well developed fibula. The ilium with a massive narrowed anterior prolongation.
K. A. v. Zittel 1890 (Orthopoda)Zwischenkiefer zahnlos oder nur seitlich mit Zähnen besetzt. Unterkiefer mit einem zahnlosen Symphysenbein (Praedentale). Zähne blattförmig, zusammengedrückt, am Vorder- und Hinterrand meist schief oder parallel der Längsaxe gezackt, bei längerem Gebrauch abgekaut. Nasenlöcher sehr gross, weit vorne. Prae orbitale Oeffnung klein oder fehlend. Wirbel massiv, opisthocöl, platycöl oder amphicöl. Schambeine entweder nach unten und vorn gerichtet, distal verbreitert und in der Symphyse verbunden (Ceratopsia) oder aus einem kurzen, frei nach vorn gerichteten Fortsatz und einem langen, dem Ischium parallelen Postpubis bestehend (Stegosauria, Ornithopoda). Extremitätenknochen hohl (Ornithopoda) oder massiv (Stegosauria, Ceratopsia). Vorderbeine meist sehr kurz, so dass der Körper beim Gehen von den langen Hinterbeinen getragen wird. Füsse digitigrad (Ornithopoda) oder plantigrad (Stegosauria, Ceratopsia). Hinterfüsse in der Regel mit drei, seltener mit vier functionirenden Zehen. Hautskelet sehr stark entwickelt (Stegosauria) oder fehlend {Ornithopoda).
H. Gadow 1898 (Orthopoda)Each pubis consisting of an anterior (prepubis) and a posterior (postpubis) arm, without symphyses.
Premaxilla without teeth, and with a predentary edentulous piece. Herbivorous.
H. Gadow 1901 (Orthopoda)Each pubic bone consists of an anterior or pre-pubic and a
posterior or post-pubic branch, neither of which forms a symphysis. Premaxillae without teeth. With a premandibular predentary piece. Herbivorous.
B. F. Nopcsa 1901 (Orthopoda)Intermaxillare rendesen fogatlan: alsó állkapocs praedentaléval. A fogak levélalaknak, fürészelt élüek, hosszabb használat után rágó felülettel. Orrlyukak nagyok, igen elöl fekszenek, Praeorbitalis nyílás kicsiny vagy hiányzik; opistocöl, platicöl vagy amphicöl csigolyák. Erös processus pectinealis. Pubis hátrafelé irányitott, nagysága változó. Lábszárcsontok üresek vagy tömörek. Lábuk plantigrad vagy digitigrad. (Zittel szerint röviditve.)

[Intermaxillary normally toothless: lower jaw with predentary. The teeth are leaf-shaped, saw-edged, with a chewing surface after prolonged use. Nasal holes large, very frontal, Preorbital opening small or missing; opistocoelous, platicoelous or amphicoelous vertebrae. Strong processus pectinealis. Pubis directed backwards, its size variable. Tibia hollow or solid. Their legs are plantigrade or digitigrade. (Abbreviated according to Zittel.)]
R. S. Lull 1924The distinguishing feature of this order of predentate or beaked dinosaurs lies in the tetraradiate pelvis, in which the pubis has two branches, a forwardly directed prepubis, and a slender postpubis, varying in its development in the different families, but lying approximately parallel with the ischium. A further distinction is the direct outcome of their herbivorous mode of life, in that the teeth are confined almost entirely to the posterior part of the mouth, maxillaries and dentaries, while with but two known exceptions (Hypsilophodon and Protoceratops, see below) the premaxillae are toothless. The two rami of the mandible are united by a toothless symphyseal bone, the predentary. The Ceratopsia have in addition a rostral bone above in front of the premaxillaries. The anterior or prehensile part of the mouth was sheathed by a leathery or horny beak. The crowns of the teeth are generally more or less leaf-shaped, and the cutting surface faced inward in the upper jaws and outward in the lower. The anterior nares are very large and lateral in position, while the antorbital fenestrae are small, sometimes wanting; vertebral centra generally solid, opistho-, amphi- to platycoelous ; limb bones hollow or solid; digitigrade or semiplantigrade feet, generally depressed unguals, sometimes hoof-like; astragalus without ascending process; dermal skeleton sometimes very strongly developed, sometimes lacking; Upper Trias to Uppermost Cretaceous.
B. F. Nopcsa 1928 (Orthopoda)predentary bone on mandibular symphysis; pubes rotated backward; pubic protuberance of ilium short; never rapacious
E. Perrier 1928 (Orthopoda)Pubis présentant une branche antérieure (prépubis) et une branche postérieure (post-pubis), l'une et l'autre non réunies à leur congénère; prémaxillaires sans dents, mais avec une pièce préhensile prémandibulaire. Dents foliacées, disposées longitudinalement et dentées. Herbivores.
F. v. Huene 1948Probably originating from Chirotherioidea. Pubis bent backwards, pre-pubis new formation. Therefore, it can be concluded from the musculature (pubo-ischio-femoralis externus), that the body was vigorously pushed forwards and this results in an accelerated locomotion i.e. a protection from enemies. Herbivorous animals.
Premaxilla without teeth (with one exception); prerostral and predental are new dermal bones; preorbit small or absent; teeth more or less spatuliform; mandible with coronoid process; about 10 cervicals, numerous sacrals; often calcified dorsal tendons; often elongated lower arm; manus with 5 fingers; ilium with very long anterior spine, often antitrochanter; ischium with long peduncle; narrow pubis parallel to it, but of varying length; tibia not shorter than femur; pes digitigrad or secondarily plantigrade; two sternal plates; often armoured. Upper Triassic to Upper Cretaceous.
M. R. Cooper 1985Herbivorous ornithischiformes with wear facets to the cheek teeth, an opisthopubic pelvis, a supraorbital element, a predentary bone to the mandible, an inturned head to the femur, and a pendent 4th trochanter.
S. J. Nesbitt 2011The most inclusive clade containing Triceratops horridus Marsh, 1889, but not Passer domesticus Linnaeus, 1758, or Saltasaurus loricatus Bonaparte and Powell, 1980