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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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Skull of Sirindhorna khoratensis.(A) A composite skull reconstruction of Sirindhorna. Several elements are reversed. (B) Life restoration of the head of Sirindhorna by Yoko Ohnish. Scale bar equals 10 cm. Dashed line indicates missing elements.
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pone.0145904.g016: Skull of Sirindhorna khoratensis.(A) A composite skull reconstruction of Sirindhorna. Several elements are reversed. (B) Life restoration of the head of Sirindhorna by Yoko Ohnish. Scale bar equals 10 cm. Dashed line indicates missing elements.

Mentions: The Early Cretaceous hadrosauroid dinosaur, Sirindhorna khoratensis, is described based upon cranial elements. This is the first report of well-preserved ornithopod skull in Southeast Asia (See reconstruction, in Fig 16). Sirindhorna shows general morphological features of hadrosauriforms, such as the low-triangle shaped maxilla, a broad leaf-shaped dentary tooth crown with one prominent primary and one secondary ridges, exclusion of the supraoccipital from the foramen magnum, and the closure of the antorbital fenestra. Uniquely, the craniocaudally-elongated parietals form a long saggital crest extending to the frontoparietal suture in Sirindhorna. Moreover, upper and lower jaws of Sirindhorna show evident differences from the other two Thailand hadrosauriforms, Siamodon nimingami and Ratchasimasaurus suranareae. Phylogenetic analysis recovers Sirindhorna as the most basal hadrosauroid.


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)

Skull of Sirindhorna khoratensis.(A) A composite skull reconstruction of Sirindhorna. Several elements are reversed. (B) Life restoration of the head of Sirindhorna by Yoko Ohnish. Scale bar equals 10 cm. Dashed line indicates missing elements.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0145904.g016: Skull of Sirindhorna khoratensis.(A) A composite skull reconstruction of Sirindhorna. Several elements are reversed. (B) Life restoration of the head of Sirindhorna by Yoko Ohnish. Scale bar equals 10 cm. Dashed line indicates missing elements.
Mentions: The Early Cretaceous hadrosauroid dinosaur, Sirindhorna khoratensis, is described based upon cranial elements. This is the first report of well-preserved ornithopod skull in Southeast Asia (See reconstruction, in Fig 16). Sirindhorna shows general morphological features of hadrosauriforms, such as the low-triangle shaped maxilla, a broad leaf-shaped dentary tooth crown with one prominent primary and one secondary ridges, exclusion of the supraoccipital from the foramen magnum, and the closure of the antorbital fenestra. Uniquely, the craniocaudally-elongated parietals form a long saggital crest extending to the frontoparietal suture in Sirindhorna. Moreover, upper and lower jaws of Sirindhorna show evident differences from the other two Thailand hadrosauriforms, Siamodon nimingami and Ratchasimasaurus suranareae. Phylogenetic analysis recovers Sirindhorna as the most basal hadrosauroid.

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