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Tholodus
''Tholodus'' is an extinct genus of basal ichthyopterygian known from the Middle Triassic (mid-late Anisian to late Ladinian stage) of Germany, northeastern Italy and possibly China. It was first named by Christian Erich Hermann von Meyer in 1851 and the type species is ''Tholodus schmidi''. It is known from many disarticulated and fragmentary remains, mainly teeth and jaw fragments. Most specimens were collected from various localities across the Ladinian-aged Muschelkalk, Germany, mainly from the Jena Formation of the upper Lower Muschelkalk, where the holotype was found. Dalla Vecchia (2004) recently described two additional specimens, a mandibular ramus and a maxilla, both bearing teeth and nearly uncrushed, and some postcranial remains, from a single late Anisian outcrop, from the southern Alps of Italy. The humerus resembled that of immature individuals of the Chinese genus ''Chaohusaurus'', suggesting possible affinities to Grippidia.
Jiang ''et al.'' (2008) described and named ''Xinminosaurus'' from the mid-late Anisian Guanling Formation of Guizhou, China. Maisch (2010) suggested that ''Xinminosaurus'' might be a subjective junior synonym of ''Tholodus''. Although Jiang ''et al.'' (2008) regarded ''Tholodus'' to be a possible ''nomen dubium'', Maisch (2010) rejected this opinion, stating that ''Tholodus'' is easily recognized and characterized by unequivocal dental autapomorphies, so that even jaw and tooth fragments are diagnostic, and it is thus a valid taxon. Furthermore, he noted that ''Tholodus'' is clearly distinguishable from all other known marine reptiles, including the possible relative ''Omphalosaurus'', except ''Xinminosaurus''. The only difference between the taxa, according to Maisch (2010), is that ''Tholodus'' specimens are at average twice as large as ''Xinminosaurus'' holotype.
==References==
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「Tholodus」の詳細全文を読む
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