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Zhanghenglong, new hadrosaurid from Late Cretaceous of Henan Province, China



From: Ben Creisler
bcreisler@gmail.com

New in PLoS ONE:

Hai Xing, Deyou Wang, Fenglu Han, Corwin Sullivan, Qingyu Ma, Yiming
He, David W. E. Hone, Ronghao Yan, Fuming Du & Xing Xu (2014)
A New Basal Hadrosauroid Dinosaur (Dinosauria: Ornithopoda) with
Transitional Features from the Late Cretaceous of Henan Province,
China.
PLoS ONE 9(6): e98821.
doi:10.1371/journal.pone.0098821
http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0098821


Background

Southwestern Henan Province in central China contains many
down-faulted basins, including the Xixia Basin where the Upper
Cretaceous continental sediments are well exposed. The Majiacun
Formation is a major dinosaur-bearing stratigraphic unit that occurs
in this basin.

Methodology/Principal Findings

A new basal hadrosauroid dinosaur, Zhanghenglong yangchengensis gen.
et sp. nov., is named based on newly collected specimens from the
middle Santonian Majiacun Formation of Zhoujiagou Village, Xixia
Basin. Two transitional features between basal hadrosauroids and
hadrosaurids are attached to the diagnosis of the new taxon, namely
five maxillary foramina consisting of four small scattered ones
anteroposteriorly arranged in a row and a large one adjacent to the
articular facet for the jugal, and dentary tooth crowns bearing both
median and distally offset primary ridges. Zhanghenglong also displays
a unique combination of plesiomorphic and derived features of
hadrosauroids, and is clearly morphologically transitional between
basal hadrosauroids and hadrosaurids. Furthermore, some measurement
attributes in osteology are applied to the quantitative analysis of
Zhanghenglong. For these attributes, the partition of the dataset on
most hadrosauroid species resulting from model-based cluster analysis
almost matches taxonomic separation between basal hadrosauroids and
hadrosaurids. Data of Zhanghenglong on selected measurement attributes
straddle the two combinations of intervals of partitioned datasets
respectively related to basal hadrosauroids and hadrosaurids. This
condition is similar to mosaic evolution of morphological characters
present in the specimens of the taxon. The phylogenetic analysis of
Hadrosauroidea recovers a clade composed of Zhanghenglong,
Nanyangosaurus, and Hadrosauridae with an unresolved polytomy.

Conclusions/Significance

Zhanghenglong is probably a relatively derived non-hadrosaurid
hadrosauroid, based on the inferences made from the morphological
comparisons, quantitative evaluation of measurements, and cladistic
analysis. In combination with information on the stratigraphy,
phylogeny and biogeography, the material of Zhanghenglong provides
direct evidence for the hypothesis that hadrosaurids might have
originated in Asia.