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Thescelosauridae is a clade or family of small ornithopod ornithischians which have previously been generally allied to hypsilophodontids. ==Classification== |label2=Thescelosaurinae |2= }} }} }} Although Hypsilophodontidae was interpreted as a natural group in the early 1990s, this hypothesis has fallen out of favor and Hypsilophodontidae has been found to be an unnatural family composed of a variety of animals more or less closely related to Iguanodontia (paraphyly), with various small clades of closely related taxa.〔 "Hypsilophodontidae" and "hypsilophodont" are better understood as informal terms for an evolutionary grade, not a true clade. ''Thescelosaurus'' has been regarded as both very basal〔 and very derived〔 among the hypsilophodonts. One issue that has potentially interfered with classifying ''Thescelosaurus'' is that not all of the remains assigned to ''T. neglectus'' necessarily belong to it. Clint Boyd and colleagues found that while the clade ''Thescelosaurus'' included the genus ''Bugenasaura'' and the species that had been assigned to that genus, there were at least two and possibly three species within ''Thescelosaurus'', and several specimens previously assigned to ''T. neglectus'' could not yet be assigned to a species within the genus.〔 It appears to be closely related to ''Parksosaurus''.〔〔 The dissolution of Hypsilophodontidae has been followed by the recognition of the distinct family Thescelosauridae. This area of the dinosaur family tree has historically been complicated by a lack of research, but papers by Clint Boyd and colleagues〔 and Caleb Brown and colleagues〔〔 have specifically addressed these dinosaurs. Boyd ''et al.'' (2009) and Brown ''et al.'' (2011) found North American "hypsilophodonts" of Cretaceous age to sort into two related clusters, one consisting of ''Orodromeus'', ''Oryctodromeus'', and ''Zephyrosaurus'', and the other consisting of ''Parksosaurus'' and ''Thescelosaurus''.〔〔 Brown ''et al.'' (2013) recovered similar results, with the addition of the new genus ''Albertadromeus'' to the ''Orodromeus'' clade and several long-snouted Asian forms (previously described under Jeholosauridae)〔 to the ''Thescelosaurus'' clade. They also formally defined Thescelosauridae (''Thescelosaurus neglectus'', ''Orodromeus makelai'', their most recent common ancestor, and all descendants) and the smaller clades Orodrominae and Thescelosaurinae.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Thescelosauridae」の詳細全文を読む スポンサード リンク
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