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Edmontosaurus and Shantungosaurus compared (free pdf)

Ben Creisler

A new paper (open access at link):

XING Hai,  ZHAO Xijin,  WANG Kebai,  LI Dunjing,  CHEN Shuqing,
Jordan C. MALLON,  ZHANG Yanxia &  XU Xing (2014)
Comparative Osteology and Phylogenetic Relationship of Edmontosaurus
and Shantungosaurus (Dinosauria: Hadrosauridae) from the Upper
Cretaceous of North America and East Asia.
Acta Geologica Sinica 88(6): 1623-1652  (English Edition)

The close affinity between Edmontosaurus and Shantungosaurus is
corroborated on the basis of the following shared features: an
occipital condyle deflected strongly posteroventrally; a
posterodorsally reflected, lip-shaped oral margin of the premaxilla,
with a deep, oval concavity at the anteromedial corner of the bone; a
well-demarcated posterodorsal margin of the deeply excavated
circumnarial fossa formed by a prominent arched ridge along the entire
posterior half of the lateroventral border of the nasal; an
anteroposteriorly broad jugal process of the postorbital; a strongly
concave dorsal surface of the paired frontals; seven teeth per
alveolus in the middle of the dentary tooth row; and a circular distal
blade of the pubis that is much more expanded ventrally than dorsally.
A revised phylogenetic analysis of Hadrosauroidea recovers a sister
taxon relationship between Edmontosaurus and Shantungosaurus.
Kerberosaurus is recovered as the sister taxon to the clade formed
exclusively by these two genera. The clade Edmontosaurini could be
defined as the least inclusive clade containing Kerberosaurus and
Edmontosaurus, which is currently composed of the genera
Kerberosaurus, Edmontosaurus, and Shantungosaurus. Zhuchengosaurus and
Huaxiaosaurus, both from the Upper Cretaceous Wangshi Group in
Zhucheng, are interpreted as junior synonyms of Shantungosaurus.
Kundurosaurus is likewise considered a junior synonym of
Kerberosaurus. The strict consensus tree together with biogeographic
information indicates that the clade Edmontosaurini originated in Asia
and subsequently dispersed into North America.