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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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One MPT showing the phylogenetic position of Sirindhorna khoratensis based upon the data matrix of [37].Definitions of the clade follow [37]. Bremer support indices are indicated on the right side of relevant branches.
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pone.0145904.g014: One MPT showing the phylogenetic position of Sirindhorna khoratensis based upon the data matrix of [37].Definitions of the clade follow [37]. Bremer support indices are indicated on the right side of relevant branches.

Mentions: Our tree recovers the same topology as that of [37], (Fig 14) with Sirindhorna settled as the sister taxon of (Altirhinus + more derived taxa). Therefore, Sirindhorna is the most basal hadrosauroid. Here, Hadrosauroidea is defined as all hadrosauriforms closer to Saurolophus osborni than to Iguanodon bernissartensis, and Hadrosuriformes is defined as the most recent common ancestor of Saurolophus osborni and Iguanodon bernissartensis and all of its decedents [28]. This position corresponds well with the result of above comparisons.


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)

One MPT showing the phylogenetic position of Sirindhorna khoratensis based upon the data matrix of [37].Definitions of the clade follow [37]. Bremer support indices are indicated on the right side of relevant branches.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0145904.g014: One MPT showing the phylogenetic position of Sirindhorna khoratensis based upon the data matrix of [37].Definitions of the clade follow [37]. Bremer support indices are indicated on the right side of relevant branches.
Mentions: Our tree recovers the same topology as that of [37], (Fig 14) with Sirindhorna settled as the sister taxon of (Altirhinus + more derived taxa). Therefore, Sirindhorna is the most basal hadrosauroid. Here, Hadrosauroidea is defined as all hadrosauriforms closer to Saurolophus osborni than to Iguanodon bernissartensis, and Hadrosuriformes is defined as the most recent common ancestor of Saurolophus osborni and Iguanodon bernissartensis and all of its decedents [28]. This position corresponds well with the result of above comparisons.

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