New Hadrosauroid Material Found In China, With The Study On Its Morphology, Phylogeny, And Ontogeny

Cretaceous continental strata in China are very developed, and have well-exposed rock outcrops. A large number of Cretaceous dinosaur fossils have been discovered in China, notably the hadrosauroid material. Based on the published literature and new specimens obtained from the fieldwork during the last decade, the morphology, phylogeny, ontogeny, biogeography and biostratigraphy of Chinese hadrosauroids are deeply and comprehensively evaluated in this dissertation.The new basal hadrosauroid dinosaur, Zhanghenglong yangchengensis gen. et sp. nov., is named and described based on newly collected specimens from the middle Santonian middle part of the Majiacun Formation in Zhoujiagou Village, Xixia Basin, Henan Province. Model-based cluster analysis was utilized to statistically partition the datasets of measurements derived from phylogenetic characters of Hadrosauroidea. For some measurements, the partition of the dataset on all hadrosauroid species almost matches the taxonomic separation between basal hadrosauroids and hadrosaurids. These measurements are applied to the quantitative analysis of Zhanghenglong, so as to evaluate the taxonomic status of the taxon.The Upper Cretaceous Iren Dabasu Formation in the Iren Nor region of Inner Mongolia is typically referred to continental clastic sediments consisting of light grey fine sandstones, coarse sandstones and glutenites as well as mottled claystones and siltstones. This lithological unit has yielded plentiful dinosaur remains in quantity and variety, as well as some microfossil material. The stratigraphic sequence, sedimentary system, and morphological characters and assemblages of the fossil taxa of the Iren Dabasu Formation are summarized herein. By regarding the microfossils in the Upper Cretaceous of the Songliao Basin and their stratigraphic ages as the standard, the age of the Iren Dabasu Formation is also revised.One incomplete, partially articulated skeleton assigned to the juvenile form of Gilmoreosaurus mongoliensis was collected from the Iren Dabasu Formation in the Hashatu region, Abag Banner, Inner Mongolia. The anatomic information and diagnosis of this species are therefore supplemented and revised. The osteological study indicates that the ilium of G. mongoliensis is clearly morphologically transitional between basal hadrosauroids and hadrosaurids. To test the inference, a planar geometric morphometric analysis(i.e. relative warp analysis) was conducted to process the coordinate data of the iliac lateral profiles from global hadrosauroid taxa. In the bivariate plot composed of the first and second principal components, three coordinate points representing the ilia of G. mongoliensis fall within the overlapping area between the 95% confidence ellipses of non-hadrosaurid hadrosauriforms and hadrosaurids.Given that the preliminary identifications made by Godefroit et al.(2008) on the hadrosaurid material collected from the Wulaga bonebed of the Yuliangzi Formation are problematic, the hadrosaurine specimens in the layer are re-assessed herein. The diagnosis and systematic position of the erected hadrosaurine Wulagasaurus dongi are revised. In addition, the material of lambeosaurine origin previously incorrectly referred to W. dongi is excluded from the available specimens of this taxon.A series of synapomorphies between Edmontosaurus and Shantungosaurus have been identified by means of detailed morphological and statistical comparisons. These features sufficiently corroborate the close affinity between the two genera. Based on the suggested phylogenetic topology in the dissertation, the information of Edmontosaurini and its genera and species on systematic paleontology is revised.In order to ascertain the phylogenetic interrelationships among all hadrosauroid taxa, the data matrix of 346 characters and 59 species-level taxonomic units was analyzed using the maximum parsimony method. The unstable taxa of the initial analysis were identified by the procedure Iter PCR. The alternate cladistic analysis excludes the unstable taxa from the data matrix, and has yielded a well-resolved strict consensus tree that is entirely consistent with the reduced strict consensus obtained from the initial analysis. In light of the tree topology of the strict consensus resulting from the alternate analysis and biogeographic information of all hadrosauroid species, the ancestral area and dispersal pattern of each clade within the Hadrosauroidea were inferred via the probabilistic algorithm.The ontogenetic study on the incomplete humeral growth series of Shantungosaurus giganteus is conducted herein. Both qualitative osteological comparisons and quantitative reduced major axis regression analysis recover a distinct morphological change of the humeral deltopectoral crest during ontogeny. 6 ontogenetic stages were recognized from 14 humeri of S. giganteus, based on histological features of these elements. The humerus ZCDM HP0128 has provided several cross sections of the humeral neck that display at least 12 annual growth rings. The growth ring spacing method was used to retrocalculate the lost number of the initial annual growth rings for the sections. The best growth model and skeletal age framework of S. giganteus were chosen by applying the growth curve fitting approach. The age of the initial sexual maturity and maximum growth rate of the taxon were estimated on the basis of the best growth curve with the lowest value of the Akaike Information Criterion.