[D] Equijubus normani [Su] [sG] [T]
Describer
You, Luo, Shubin, Witmer, Tang Z. & Tang F., 2003
Time
Cretaceous Early Barremian Aptian Albian
Classification
Ornithischia Ornithopoda Hadrosauridae
Diet
Herbivore
Fossilsite
Gobi Desert, Gongpoquan Basin, Mazongshan area, Middle Grey Unit of Xinminbao Group, Gansu Province, China.
Info
Genus - Typespecies - Skull
Holotype
IVPP (Institute of Vertebrate Paleontology and Paleoanthropology) V 12534, a complete skull (57 cm in length, laterally compressed) with articulated lower jaw, plus incomplete postcranium.
Etymology
Latin Equus, horse and juba, mane. Horse Mane is what ‘Ma Zong’ means in Chinese, and Ma Zong Mountain is where the fossil was discovered.
Equijubus normani was discovered in the Gobi Desert of northwest China. It is more closely related to Late Cretaceous hadrosaurids than to Early Cretaceous iguanodontids . It occupies the most basal position in the phylogeny of all duck-billed dinosaurs, or the Hadrosauroidea.
This early hadrosauroid sheds new light on the origin of the herbivorous feeding specializations of the Late Cretaceous duck-billed dinosaurs, and corroborates the view that the Iguanodontidae and the Hadrosauridae are monophyletic clades, with the former characterized by an enlarged maxilla as the main mechanism for mastication, and the latter diagnosed by a smaller yet more mobile maxilla with an elaborate dental battery, separated by a diastema from the enlarged premaxilla.
Equijubus normani is characterized by a unique, finger-like process extending dorsally from the rostral process of the jugal to the lacrimal, and a very large lower temporal fenestra. Distinguished from nonhadrosauroid iguanodontians in having a long lacrimal with a rostroventral process positioned above the dorsal margin of the maxilla. Distinguished from other hadrosauroids in lacking the median primary ridge on the crown of the dentary teeth.
E. normani was introduced and informally described by You (2002) in his unpublished yet available Ph.D. dissertation on the Mazongshan dinosaur assemblage from the \\\\\\\'late Early\\\\\\\"[=middle] Cretaceous of northwest China.
Equijubus has several derived features in the premaxilla and lacrimal that are diagnostic of hadrosauroids, but absent in iguanodontids (Norman, 1998)
The maxilla of Equijubus is similar to that of other hadrosauroids, and lacks the key features diagnostic for iguanodontids. It is shaped like an isosceles triangle in lateral view, with the ventral border measuring 30 cm long. Its rostral 7 cm is edentulous, and tapers into a process that inserts medial to the oral portion of the premaxilla. The tooth-bearing edge of the maxilla is slightly arched and possesses 23 teeth. Neither lacrimal nor jugal process exists in Equijubus. (Norman, 1998)
Carpenter & Ishida (2010) Early and “Middle” Cretaceous Iguanodonts in Time and Space Journal of Iberian Geology 36 (2) 145-164
Equijubus normani You et al., 2003a
Locality
near Gongpoquan, Gansu Province, China.
Horizon
Middle Grey Unit of Xinminbao Group.
Age
Albian (Tang et al., 2001).
Comments
The ilium (not previously described) most closely resembles that of “Iguanodon mantelli” in being deep, having a highly arched dorsal margin, short postacetabular process, and knob-like lateral process. It differs however in the much deeper body relatively to its length. The ischial peduncle is ventrally offset from the postacetabular process resulting in a well-developed postacetabular notch. The peduncle is expanded onto the lateral surface of the ilium.
You, Luo, Shubin, Witmer, Tang Z. & Tang F., 2003
Time
Cretaceous Early Barremian Aptian Albian
Classification
Ornithischia Ornithopoda Hadrosauridae
Diet
Herbivore
Fossilsite
Gobi Desert, Gongpoquan Basin, Mazongshan area, Middle Grey Unit of Xinminbao Group, Gansu Province, China.
Info
Genus - Typespecies - Skull
Holotype
IVPP (Institute of Vertebrate Paleontology and Paleoanthropology) V 12534, a complete skull (57 cm in length, laterally compressed) with articulated lower jaw, plus incomplete postcranium.
Etymology
Latin Equus, horse and juba, mane. Horse Mane is what ‘Ma Zong’ means in Chinese, and Ma Zong Mountain is where the fossil was discovered.
Equijubus normani was discovered in the Gobi Desert of northwest China. It is more closely related to Late Cretaceous hadrosaurids than to Early Cretaceous iguanodontids . It occupies the most basal position in the phylogeny of all duck-billed dinosaurs, or the Hadrosauroidea.
This early hadrosauroid sheds new light on the origin of the herbivorous feeding specializations of the Late Cretaceous duck-billed dinosaurs, and corroborates the view that the Iguanodontidae and the Hadrosauridae are monophyletic clades, with the former characterized by an enlarged maxilla as the main mechanism for mastication, and the latter diagnosed by a smaller yet more mobile maxilla with an elaborate dental battery, separated by a diastema from the enlarged premaxilla.
Equijubus normani is characterized by a unique, finger-like process extending dorsally from the rostral process of the jugal to the lacrimal, and a very large lower temporal fenestra. Distinguished from nonhadrosauroid iguanodontians in having a long lacrimal with a rostroventral process positioned above the dorsal margin of the maxilla. Distinguished from other hadrosauroids in lacking the median primary ridge on the crown of the dentary teeth.
E. normani was introduced and informally described by You (2002) in his unpublished yet available Ph.D. dissertation on the Mazongshan dinosaur assemblage from the \\\\\\\'late Early\\\\\\\"[=middle] Cretaceous of northwest China.
Equijubus has several derived features in the premaxilla and lacrimal that are diagnostic of hadrosauroids, but absent in iguanodontids (Norman, 1998)
The maxilla of Equijubus is similar to that of other hadrosauroids, and lacks the key features diagnostic for iguanodontids. It is shaped like an isosceles triangle in lateral view, with the ventral border measuring 30 cm long. Its rostral 7 cm is edentulous, and tapers into a process that inserts medial to the oral portion of the premaxilla. The tooth-bearing edge of the maxilla is slightly arched and possesses 23 teeth. Neither lacrimal nor jugal process exists in Equijubus. (Norman, 1998)
Carpenter & Ishida (2010) Early and “Middle” Cretaceous Iguanodonts in Time and Space Journal of Iberian Geology 36 (2) 145-164
Equijubus normani You et al., 2003a
Locality
near Gongpoquan, Gansu Province, China.
Horizon
Middle Grey Unit of Xinminbao Group.
Age
Albian (Tang et al., 2001).
Comments
The ilium (not previously described) most closely resembles that of “Iguanodon mantelli” in being deep, having a highly arched dorsal margin, short postacetabular process, and knob-like lateral process. It differs however in the much deeper body relatively to its length. The ischial peduncle is ventrally offset from the postacetabular process resulting in a well-developed postacetabular notch. The peduncle is expanded onto the lateral surface of the ilium.