title: A New Basal Hadrosauroid Dinosaur from the Lower Cretaceous Khok Kruat Formation in Nakhon Ratchasima Province, Northeastern Thailand.
abstract: A new basal hadrosauroid dinosaur from the Lower Cretaceous Khok Kruat Formation of Thailand, Sirindhorna khoratensis gen. et sp. nov is described. The new taxon is based on composite skull and mandible including premaxilla, maxilla, jugal, quadrate, braincases, predentary, dentaries, surangular, and maxillary and dentary teeth. It is diagnostic by such characters as, sagittal crest extending along entire dorsal surface of the parietal and reaching the frontoparietal suture (autapomorphy), transversely straight frontoparietal suture, caudodorsally faced supraoccipital, no participation of the supraoccipital in the foramen magnum, mesiodistally wide leaf-shaped dentary tooth with primary and secondary ridges on the lingual surface of the crown, perpendicularly-erected and large coronoid process of dentary, and nonvisible antorbital fossa of the maxilla in lateral view. Phylogenetic analysis revealed S. khoratensis as among the most basal hadrosauroids. Sirindhorna khoratensis is the best-preserved iguanodontian ornithopod in Southeast Asia and sheds new light to resolve the evolution of basal hadrosauriforms.
authors.affiliation: Institute of Dinosaur Research, Fukui Prefectural University, 4-1-1 Kenjojima, Matsuoka, Eiheiji-Cho, Fukui, 910-1195, Japan.|Fukui Prefectural Dinosaur Museum, 51-11 Muroko, Terao, Katsuyama, Fukui, 911-8601, Japan.
authors.forename: Masateru
authors.initials: M
authors.lastname: Shibata
authors.affiliation: Northeastern Research Institute of Petrified Wood and Mineral Resources, Nakhon Ratchasima Rajabhat University, 184 Moo 7 Suranaree Subdistict, Mueang, Nakhon Ratchasima District, Nakhon Ratchasima, 30000, Thailand.
authors.forename: Pratueng
authors.initials: P
authors.lastname: Jintasakul
authors.affiliation: Institute of Dinosaur Research, Fukui Prefectural University, 4-1-1 Kenjojima, Matsuoka, Eiheiji-Cho, Fukui, 910-1195, Japan.|Fukui Prefectural Dinosaur Museum, 51-11 Muroko, Terao, Katsuyama, Fukui, 911-8601, Japan.
authors.forename: Yoichi
authors.initials: Y
authors.lastname: Azuma
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, 100044, PR China.
authors.forename: Hai-Lu
authors.initials: HL
authors.lastname: You
mesh_terms: D000818:Animals; D005075:Biological Evolution; D025061:Dinosaurs / Q000033:anatomy & histology / Q000145:classification; D005580:Fossils / Q000033:anatomy & histology; D008334:Mandible / Q000033:anatomy & histology; D008437:Maxilla / Q000033:anatomy & histology; D010802:Phylogeny; D012886:Skull / Q000033:anatomy & histology; D013785:Thailand; D014070:Tooth / Q000033:anatomy & histology