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Dicynodontia (dicynodont)

Taxonomy
Dicynodontia was named by Owen (1859). It is not extant.

It was reranked as the family Dicynodontia by Owen (1861); it was reranked as the order Dicynodontia by Osborn (1904) and Maisch and Gebauer (2005); it was synonymized subjectively with Anomodontia by Roxo (1937); it was reranked as the infraorder Dicynodontia by Barry (1974), Kemp (1982), King and Jenkins (1997) and Battail and Surkov (2000); it was reranked as the unranked clade Dicynodontia by Gardiner (1982), Rybczynski (2000), Modesto et al. (2002), Kammerer and Angielczyk (2009), Angielczyk and Rubidge (2010), Kammerer et al. (2011), Fröbisch and Reisz (2011), Hancox et al. (2013), Kammerer et al. (2013) and Angielczyk et al. (2016).

It was assigned to Therochelonia by Seeley (1895); to Anomodontia by Osborn (1904); to Theromorpha by Swinton (1934) and Kuhn (1946); to Testudinata by Gardiner (1982); to Therapsida by Carroll (1988) and King and Jenkins (1997); to Anomodontia by Barry (1974), Kemp (1982) and Battail and Surkov (2000); to Therapsida by Modesto et al. (2002); to Therapsida by Gauthier et al. (1989) and Maisch and Gebauer (2005); to Anomodontia by Owen (1861), Woodward (1898), Osborn (1903), Rubidge and Sidor (2001), Ivakhnenko (2003) and Ivakhnenko (2008); to Anomodontia by Rybczynski (2000), Kammerer et al. (2011), Hancox et al. (2013) and Kammerer et al. (2013); and to Chainosauria by Kammerer and Angielczyk (2009), Angielczyk and Rubidge (2010), Fröbisch and Reisz (2011) and Angielczyk et al. (2016).

View classification of included taxa

Synonyms
Synonymy list
YearName and author
1845Dicynodon strigiceps Owen
1859Dicynodontia Owen
1861Dicynodontia Owen p. 256
1876Cistecephalus leptorhinus Owen
1876Oudenodon strigiceps Owen
1889Dicynodon oweni Lydekker
1889Eurycarpus oweni Seeley
1895Dicynodontia Seeley
1898Dicynodontia Woodward p. 141
1900Dicranozygoma Seeley
1900Dicranozygoma leptoscelus Seeley
1903Dicynodontia Osborn p. 276
1904Chelyoposaurus Broom
1904Chelyoposaurus williamsi Broom
1904Dicynodontia Osborn p. 103
1911Taognathus megalodon Broom
1911Taognathus Broom p. 1076
1913Chelyoposaurus Broom
1913Chelyoposaurus williamsi Broom
1913Taognathus Broom
1913Taognathus megalodon Broom
1932Dicynodon leptorhinus Broom
1932Dicynodon leptoscelus Broom
1934Dicynodontia Swinton p. 51
1934Oudenodon leptoscelus Van Hoepen
1938Haughtoniana Boonstra
1938Haughtoniana magna Boonstra
1946Dicynodontia Kuhn p. 58
1948Koupia Boonstra
1948Koupia koupensis Boonstra
1974Dicynodontia Barry p. 121
1978Fukangolepis barbaros Yang p. 60
1982Dicynodontia Gardiner p. 228
1982Dicynodontia Kemp p. 348
1988Dicynodontia Carroll
1988Haughtoniana Carroll
1988Koupia Carroll
1988Taognathus Carroll
1988Chelyoposaurus King
1988Dicynodon leptoscelus King
1989Dicynodontia Gauthier et al. p. 341
1997Dicynodontia King and Jenkins p. 150
2000Dicynodontia Battail and Surkov
2000Dicynodontia Rybczynski p. 199
2001Dicynodontia Rubidge and Sidor
2002Dicynodontia Modesto et al. p. 1756
2003Dicynodontia Ivakhnenko
2005Dicynodontia Maisch and Gebauer
2008Dicynodontia Ivakhnenko
2009Dicynodontia Kammerer and Angielczyk
2010Dicynodontia Angielczyk and Rubidge
2011Dicynodontia Fröbisch and Reisz
2011Dicynodontia Kammerer et al.
2013Dicynodontia Hancox et al. p. 656
2013Dicynodontia Kammerer et al. p. 3
2016Dicynodontia Angielczyk et al.

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RankNameAuthor
kingdomAnimalia()
Triploblastica
Nephrozoa
Deuterostomia
phylumChordataHaeckel 1847
OlfactoresJefferies 1991
subphylumVertebrata
Gnathostomata()
Osteichthyes()
Sarcopterygii
subclassDipnotetrapodomorpha(Nelson 2006)
subclassTetrapodomorpha()
RankNameAuthor
Tetrapoda()
Reptiliomorpha
Anthracosauria
Batrachosauria()
Cotylosauria()
Amniota
Synapsida()
Therapsida()
Anomodontia(Owen 1859)
Chainosauria()
Dicynodontia(Owen 1859)
Dicynodontia(Owen 1859)

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. Owen 1861A long ever-growing tusk in each maxillary bone; pre-maxillaries connate, forming with the lower jaw a beakshaped mouth, probably sheathed with horn.
H. G. Seeley 1895Premaxillary bone single without teeth. Nares never extending in advance of the anterior extremity of the palate. No developed coronoid process to the lower jaw. Squamosal bone produced below the zygomatic arch. The only teeth known at present are canine teeth in the skull. Articular faces of vertebrae flat.
C. F. Kammerer and K. D. Angielczyk 2009Several authors have presented autapomorphies for Dicynodontia (e.g., Cluver & King 1983; King 1988; Angielczyk 2001; Angielczyk & Kurkin 2003a; Ray 2006). Here, we focus on autapomorphies that were listed by or can be derived from Modesto et al. (1999, 2003a), Modesto & Rybczynski (2000), Angielczyk (2004, 2007), Fröbisch (2007), and Fröbisch & Reisz (2008). Because all dicynodonts, including Eodicynodon, possess highly distinct skull and jaw morphologies compared to most other therapsids, Dicynodontia is characterized by considerable numbers of autapomorphies in most recent analyses. The most frequently cited autapomorphies are: (1) nasal bosses present as a median swelling with a continuous posterior margin; (2) premaxillary teeth absent; (3) anterior maxillary teeth absent; (4) caniniform present and long; (5) caniniform process present; (6) internal narial shelf well developed and formed primarily by premaxilla and maxilla; (7) posterior median ridge on palatal surface of premaxilla present with a flattened, expanded anterior area; (8) lateral palatal foramen present at level of the anterior expanded palatal exposure of the palatines; (9) vomer contributes to interpterygoid vacuity; (10) transverse flange of pterygoid ventrally directed and relatively large, wing-like; (11) interpterygoid vacuity relatively long but does not reach the level of the palatal exposure of the palatines; (12) quadratojugal plate-like distally; (13) squamosal anterior process dorsoventrally compressed; (14) squamosal with a distinct dorsolateral notch in occipital view; (15) surangular vertical lamina absent; (16) prearticular without lateral exposure posteriorly.