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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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Related in: MedlinePlus

Right suranguar (NRRU3001-137) of Sirindhorna.In lateral (A), medial (B), ventral (C), and dorsal (D) views. Abbreviations: a.fs, adductor fossa; a.fc, articular facet; an.fc, angular facet; gl, glenod; l.l, lateral lip; sr.f, surangular foramen. Scale bar equals 10 cm.
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pone.0145904.g011: Right suranguar (NRRU3001-137) of Sirindhorna.In lateral (A), medial (B), ventral (C), and dorsal (D) views. Abbreviations: a.fs, adductor fossa; a.fc, articular facet; an.fc, angular facet; gl, glenod; l.l, lateral lip; sr.f, surangular foramen. Scale bar equals 10 cm.

Mentions: A single right surangular (Fig 11; NRRU3001-137) is known, although the rostral portion articulated is missing. There is a small surangular foramen positioned rostroventral to the glenoid on the lateral surface of this bone (Fig 11A). The lateral lip extends rostrodorsally and forms a narrow horizontal shelf. The portion caudal to the glenoid becomes hooked dorsally and compressed transversely (Fig 11A and 11D); the articular would have contacted the medial side of this part (Fig 11B). The angular was possibly visible in lateral view when it was articulated with the surangular (Fig 11A). Medially, the adductor fossa is developed rostral to the glenoid, and the surangular foramen is visible (Fig 11B). The ventral surface of the surangular (Fig 11C), where the angular fits, is relatively flat and rostrally bifurcated.


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)

Right suranguar (NRRU3001-137) of Sirindhorna.In lateral (A), medial (B), ventral (C), and dorsal (D) views. Abbreviations: a.fs, adductor fossa; a.fc, articular facet; an.fc, angular facet; gl, glenod; l.l, lateral lip; sr.f, surangular foramen. Scale bar equals 10 cm.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0145904.g011: Right suranguar (NRRU3001-137) of Sirindhorna.In lateral (A), medial (B), ventral (C), and dorsal (D) views. Abbreviations: a.fs, adductor fossa; a.fc, articular facet; an.fc, angular facet; gl, glenod; l.l, lateral lip; sr.f, surangular foramen. Scale bar equals 10 cm.
Mentions: A single right surangular (Fig 11; NRRU3001-137) is known, although the rostral portion articulated is missing. There is a small surangular foramen positioned rostroventral to the glenoid on the lateral surface of this bone (Fig 11A). The lateral lip extends rostrodorsally and forms a narrow horizontal shelf. The portion caudal to the glenoid becomes hooked dorsally and compressed transversely (Fig 11A and 11D); the articular would have contacted the medial side of this part (Fig 11B). The angular was possibly visible in lateral view when it was articulated with the surangular (Fig 11A). Medially, the adductor fossa is developed rostral to the glenoid, and the surangular foramen is visible (Fig 11B). The ventral surface of the surangular (Fig 11C), where the angular fits, is relatively flat and rostrally bifurcated.

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