title: A new basal hadrosauroid dinosaur (Dinosauria: Ornithopoda) with transitional features from the late cretaceous of Henan Province, China.
abstract: 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.
  
  
  RESULTS
  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
  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.
authors.affiliation: College of Earth Sciences and Resources, China University of Geosciences, Beijing, China; Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China; Paleobiology, Canadian Museum of Nature, Ottawa, Ontario, Canada.
authors.forename: Hai
authors.initials: H
authors.lastname: Xing
authors.affiliation: Henan Academy of Land and Resources Sciences, Zhengzhou, Henan, China.
authors.forename: Deyou
authors.initials: D
authors.lastname: Wang
authors.affiliation: Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China; Graduate University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Fenglu
authors.initials: F
authors.lastname: Han
authors.affiliation: Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Corwin
authors.initials: C
authors.lastname: Sullivan
authors.affiliation: School of Earth Sciences, University of Bristol, Bristol, United Kingdom.
authors.forename: Qingyu
authors.initials: Q
authors.lastname: Ma
authors.affiliation: Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China; Graduate University of Chinese Academy of Sciences, Beijing, China.
authors.forename: Yiming
authors.initials: Y
authors.lastname: He
authors.affiliation: School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom.
authors.forename: David W E
authors.initials: DW
authors.lastname: Hone
authors.affiliation: Xixia Museum of Dinosaur Fossil Eggs of China, Xixia, Henan, China.
authors.forename: Ronghao
authors.initials: R
authors.lastname: Yan
authors.affiliation: Xixia Museum of Dinosaur Fossil Eggs of China, Xixia, Henan, China.
authors.forename: Fuming
authors.initials: F
authors.lastname: Du
authors.affiliation: Key Laboratory of Vertebrate Evolution and Human Origins of Chinese Academy of Sciences, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Xing
authors.initials: X
authors.lastname: Xu
mesh_terms: D000818:Animals; D002681:China; D025061:Dinosaurs / Q000033:anatomy & histology* / Q000145:classification*; D005580:Fossils; D005843:Geography; D010163:Paleontology