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A New Basal Hadrosauroid Dinosaur from the Lower Cretaceous Khok Kruat Formation in Nakhon Ratchasima Province, Northeastern Thailand.

Shibata M, Jintasakul P, Azuma Y, You HL - PLoS ONE (2015)

Bottom Line: The new taxon is based on composite skull and mandible including premaxilla, maxilla, jugal, quadrate, braincases, predentary, dentaries, surangular, and maxillary and dentary teeth.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.

View Article: PubMed Central - PubMed

Affiliation: Institute of Dinosaur Research, Fukui Prefectural University, 4-1-1 Kenjojima, Matsuoka, Eiheiji-Cho, Fukui, 910-1195, Japan.

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.

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Comparison of the skull roof in dorsal view.(A) Holotype of Sirindhorna (NRRU3001-166), (B) referred material of Sirindhorna (NRRU-A2035), (C) Dakodadon (SDSM 8656), (D) Jinzhousaurus (IVPP-V12691), (E) Mantellisaurus (after [38]) and (F) Probactrosaurus (after [5]). Abbreviations; F, frontal; fp.st, frontoparietal suture; P. parietal; Po, Postorbital; Pro, prootic; s.cr, sagittal crest; Sq, squamousal. Scale bar equals 10 cm.
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pone.0145904.g013: Comparison of the skull roof in dorsal view.(A) Holotype of Sirindhorna (NRRU3001-166), (B) referred material of Sirindhorna (NRRU-A2035), (C) Dakodadon (SDSM 8656), (D) Jinzhousaurus (IVPP-V12691), (E) Mantellisaurus (after [38]) and (F) Probactrosaurus (after [5]). Abbreviations; F, frontal; fp.st, frontoparietal suture; P. parietal; Po, Postorbital; Pro, prootic; s.cr, sagittal crest; Sq, squamousal. Scale bar equals 10 cm.

Mentions: The configuration of the supratemporal fenestra is varied in iguanodontians (Fig 13). The rostrocaudally elongated oval-shaped supratemporal fenestra of Sirindhorna (Fig 13A and 13B) is similar to that in Mantellisaurus [38], Proa [44], Probactrosaurus [5] and Levnesovia [12], but different from the rostrolaterally directed oval-shaped supratemporal fenestra in Lurdusaurus arenatus [45], Ouranosaurus nigeriensis [46], Equijubus [47], Jinzhousaurus [48], Xuwulong [11], Jintasaurus [8] and possibly in Yunganglong [1], and the transversely wide one in Gongpoquansaurus [40]. However, the transversely straight frontoparietal sutural line of Sirindhorna is exceptional among those non-hadrosaurid styracosternans that having a ā€œVā€-shaped or rostrally excavated frontoparietal sutural line at the center (Fig 13). In addition, the sagittal (parietal) crest of the parietals extends along entire dorsal surface of the parietal, reaching the frontoparietal suture in Sirindhorna, but not in other non-hadrosaurid styacosternans (Fig 13).


A New Basal Hadrosauroid Dinosaur from the Lower Cretaceous Khok Kruat Formation in Nakhon Ratchasima Province, Northeastern Thailand.

Shibata M, Jintasakul P, Azuma Y, You HL - PLoS ONE (2015)

Comparison of the skull roof in dorsal view.(A) Holotype of Sirindhorna (NRRU3001-166), (B) referred material of Sirindhorna (NRRU-A2035), (C) Dakodadon (SDSM 8656), (D) Jinzhousaurus (IVPP-V12691), (E) Mantellisaurus (after [38]) and (F) Probactrosaurus (after [5]). Abbreviations; F, frontal; fp.st, frontoparietal suture; P. parietal; Po, Postorbital; Pro, prootic; s.cr, sagittal crest; Sq, squamousal. Scale bar equals 10 cm.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4696827&req=5

pone.0145904.g013: Comparison of the skull roof in dorsal view.(A) Holotype of Sirindhorna (NRRU3001-166), (B) referred material of Sirindhorna (NRRU-A2035), (C) Dakodadon (SDSM 8656), (D) Jinzhousaurus (IVPP-V12691), (E) Mantellisaurus (after [38]) and (F) Probactrosaurus (after [5]). Abbreviations; F, frontal; fp.st, frontoparietal suture; P. parietal; Po, Postorbital; Pro, prootic; s.cr, sagittal crest; Sq, squamousal. Scale bar equals 10 cm.
Mentions: The configuration of the supratemporal fenestra is varied in iguanodontians (Fig 13). The rostrocaudally elongated oval-shaped supratemporal fenestra of Sirindhorna (Fig 13A and 13B) is similar to that in Mantellisaurus [38], Proa [44], Probactrosaurus [5] and Levnesovia [12], but different from the rostrolaterally directed oval-shaped supratemporal fenestra in Lurdusaurus arenatus [45], Ouranosaurus nigeriensis [46], Equijubus [47], Jinzhousaurus [48], Xuwulong [11], Jintasaurus [8] and possibly in Yunganglong [1], and the transversely wide one in Gongpoquansaurus [40]. However, the transversely straight frontoparietal sutural line of Sirindhorna is exceptional among those non-hadrosaurid styracosternans that having a ā€œVā€-shaped or rostrally excavated frontoparietal sutural line at the center (Fig 13). In addition, the sagittal (parietal) crest of the parietals extends along entire dorsal surface of the parietal, reaching the frontoparietal suture in Sirindhorna, but not in other non-hadrosaurid styacosternans (Fig 13).

Bottom Line: The new taxon is based on composite skull and mandible including premaxilla, maxilla, jugal, quadrate, braincases, predentary, dentaries, surangular, and maxillary and dentary teeth.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.

View Article: PubMed Central - PubMed

Affiliation: Institute of Dinosaur Research, Fukui Prefectural University, 4-1-1 Kenjojima, Matsuoka, Eiheiji-Cho, Fukui, 910-1195, Japan.

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.

Show MeSH
Related in: MedlinePlus