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Bactrosaurus johnsoni

Reptilia -

Taxonomy
Bactrosaurus johnsoni was named by Gilmore (1933). Its type specimen is AMNH 6553, a partial skeleton, and it is a 3D body fossil. Its type locality is Johnson Quarry, Iren Dabasu, which is in a Campanian/Campanian fluvial-lacustrine horizon in the Iren Dabasu Formation of China. It is the type species of Bactrosaurus.

It was considered a nomen dubium by Dalla Vecchia (2014).

Synonymy list
YearName and author
1933Bactrosaurus johnsoni Gilmore p. 50
1935Bactrosaurus johnsoni Young
1939Bactrosaurus johnsoni Riabinin p. 15
1944Bactrosaurus johsoni Young p. 201
1951Bactrosaurus johnsoni Chow p. 93
1958Bactrosaurus johnsoni Young pp. 110-111
1960Bactrosaurus johnsoni Langston p. 351
1964Bactrosaurus johnsoni Kuhn p. 15
1964Bactrosaurus johnsoni Tatarinov p. 561
1965Bactrosaurus johnsoni Rozhdestvensky
1974Bactrosaurus johnsoni Rozhdestvensky p. 147
1977Bactrosaurus johnsoni Rozhdestvensky p. 113
1979Bactrosaurus johnsoni Brett-Surman p. 561
1980Bactrosaurus johnsoni Chao
1981Bactrosaurus johnsoni Maryanska and Osmólska p. 8
1983Bactrosaurus johnsoni Weishampel and Weishampel p. 44
1984Bactrosaurus johnsoni Brinkmann p. 302 fig. 4
1986Bactrosaurus johnsoni Li et al. p. 134
1986Bactrosaurus johnsoni Yu and Qi p. 164
1986Bactrosaurus johnsoni Zhao p. 71
1990Bactrosaurus johnsoni Weishampel and Horner p. 557
1991Bactrosaurus johnsoni Weishampel et al. p. 204
1992Bactrosaurus johnsoni Dong p. 166
1993Bactrosaurus johnsoni Currie and Eberth p. 138
1994Bactrosaurus johnsoni Matsukawa and Obata p. 113
1998Bactrosaurus johnsoni Godefroit et al. p. 8
1999Bactrosaurus johnsoni Casanovas et al. p. 352
2004Bactrosaurus johnsoni Godefroit et al. p. 147
2004Bactrosaurus johnsoni Horner et al. p. 439
2006Bactrosaurus johnsoni Lund and Gates p. 270
2006Bactrosaurus johnsoni Prieto-Márques et al. p. 938
2007Bactrosaurus johnsoni Gilpin et al. p. 80
2007Bactrosaurus johnsoni Paul p. 72 fig. 4.2
2008Bactrosaurus johnsoni Godefroit et al. p. 65
2009Bactrosaurus johnsoni Kim et al. p. 1394
2009Bactrosaurus johnsoni Pereda-Suberbiola et al. p. 568
2010Bactrosaurus johnsoni Godefroit and Motchurova-Dekova p. 165
2010Bactrosaurus johnsoni McDonald et al. p. 33 fig. 39
2010Bactrosaurus johnsoni McDonald et al. p. 808 fig. 10
2010Bactrosaurus johnsoni Prieto-Marquez p. 853
2010Bactrosaurus johnsoni Prieto-Marquez and Salinas p. 816
2010Bactrosaurus johnsoni Prieto-Márquez p. 3
2010Bactrosaurus johnsoni Prieto-Márquez and Wagner p. 1241
2011Bactrosaurus johnsoni Juárez Valieri et al. p. 221
2011Bactrosaurus johnsoni Prieto-Márquez p. 62
2011Bactrosaurus johnsoni Wang et al. p. 137
2012Bactrosaurus johnsoni Godefroit et al. p. 15
2012Bactrosaurus johnsoni Prieto-Márquez p. 526
2012Bactrosaurus johnsoni Ramírez-Velasco et al. p. 389
2013Bactrosaurus johnsoni Cruzado-Caballero et al.
2013Bactrosaurus johnsoni Zheng et al.
2014Bactrosaurus johnsoni Tsogtbaatar et al. p. 115
2015Bactrosaurus johnsoni Ohashi et al. p. 4
2015Bactrosaurus johnsoni Tan et al. p. 249
2016Bactrosaurus johnsoni Prieto-Márquez and Gutarra p. 144
2017Bactrosaurus johnsoni Cruzado-Caballero and Powell p. 3

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RankNameAuthor
kingdomAnimalia()
Triploblastica
Nephrozoa
Deuterostomia
phylumChordataHaeckel 1847
subphylumVertebrata
superclassGnathostomata
Osteichthyes()
Sarcopterygii
subclassDipnotetrapodomorpha(Nelson 2006)
subclassTetrapodomorpha()
Tetrapoda()
Reptiliomorpha
Anthracosauria
Batrachosauria()
Cotylosauria()
Amniota
Sauropsida
classReptilia
subclassEureptilia()
Romeriida
Diapsida()
Eosuchia()
RankNameAuthor
Neodiapsida
SauriaGauthier 1984
Archosauromorpha(Huene 1946)
Crocopoda
ArchosauriformesGauthier 1986
Eucrocopoda
Archosauria()
informalAvemetatarsalia
Ornithodira
Dinosauromorpha
Dinosauriformes
Dinosauria()
Ornithischia()
Neornithischia()
Ornithopoda()
Iguanodontia()
Dryomorpha
Ankylopollexia
Styracosterna
Hadrosauriformes
Hadrosauroidea()
genusBactrosaurus
speciesjohnsoni

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
C. W. Gilmore 1933Dentition reduced, twenty-three vertical rows of teeth in dentary, twenty-eight in maxillary. Posterior dorsal vertebra with tall spines, club-shaped. Sacrum with seven co6ssified vertebrae. Ilium strongly arched, preacetabular process decurved; ischium stout with expanded foot-like end. Pubis short with greatly expanded blade. Terminal phalanges of pes with thickened truncate anterior borders.
P. Godefroit et al. 1998Non-hadrosaurid Hadrosauroidea characterized by the long and rounded rostral processes of its jugal, bearing a very elongated and excavated maxillary facet (1); caudal process of the jugal rather narrow (2); postcotyloid process of squamosal markedly curved backwards (3); club-shaped neural spines of the last dorsal vertebrae, in fully ossified adult specimens (4); distal blade of the scapula very regularly widening towards its end, ratio "length of the scapula / maximal width of the distal blade" < 3.5 (5); promiment and angular deltopectoral crest of the humerus (6); ulnar condyle of the humerus distinctly more developed than radial condyle (7); preacetabular process of the ilium very deflected ventrally (8); ischial shaft very thick and ischial foot greatly expanded (9); femur perfectly straight in lateral view (10); ungual phalanges thick and truncated in adults (11).
The following characters are considered to be plesiomorphic in Bactrosaurus johnsoni: maxilla markedly asymmetrical in lateral view (12); about 20 maxillary and dentary tooth positions in adults (13); laterally positioned antorbital fenestra (14); paraquadrate foramen developed (15); massive supraorbitals (16); dentary rostrally downturned (17); dentary teeth bearing one caudal secondary ridge (18); large pubic peduncle (19) and simple ischial peduncle of ilium (20).