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''Aublysodon'' (uncertain derivation; perhaps "backwards-flowing tooth"?) is a genus of carnivorous dinosaurs known only from the Judith River Formation in Montana, which has been dated to the late Campanian age of the late Cretaceous period (about 75 million years ago). The only currently recognized species, ''Aublysodon mirandus'', was named by paleontologist Joseph Leidy in 1868. It is now considered dubious, because the type specimen consists only of an isolated premaxillary (front) tooth. Although this specimen is now lost, similar teeth have been found in many US states, western Canada, and Asia.〔 These teeth almost certainly belong to juvenile tyrannosaurine tyrannosaurids, but most have not been identified to species level. However, it is likely that the type tooth (and therefore the name ''Aublysodon mirandus'' itself) belongs to one of the species in the genus ''Daspletosaurus'', which was present in contemporary formations, and which matches specific details of the original tooth.〔 The synapomorphies alleged to distinguish the Aublysodontinae, especially lack of serrations on premaxillary teeth could have been caused by tooth wear in life, postmortem abrasion, or digestion.〔 Most other "aublysodontine"-type teeth may be from ontogenetic stages or sexual morphs of other tyrannosaurids.〔 Apart from the type species ''Aublysodon mirandus'' over the years several other species have been named. These are now all considered either dubious or identical to other species or as having no close connection to ''A. mirandus''. ==History== In the mid-to-late 19th century many dinosaur taxa were named for isolated teeth; such genera include ''Trachodon'', ''Palaeoscincus'', and ''Troodon''. Even before the badlands of North America started revealing the bones of ''Tyrannosaurus'', teeth turning up in many localities in the Western United States revealed the presence of large predatory dinosaurs. In 1856 Joseph Leidy had named fourteen teeth collected by Ferdinand Vandeveer Hayden in 1854 and 1855 from the Judith River Badlands of Montana〔 as the species ''Deinodon horridus''.〔Leidy, J., 1856, "Notices of the remains of extinct reptiles and fishes, discovered by Dr. F.V. Hayden in the badlands of the Judith River, Nebraska Territory", ''Proceedings of the Academy of Natural Sciences'' 8(2): 72〕 In 1866 Edward Drinker Cope chose three nonserrated teeth from the original syntype series of fourteen as the lectotypes of ''Deinodon horridus''.〔Cope, E.D., 1866, "Discovery of a gigantic dinosaur in the Cretaceous of New Jersey", ''Proceedings of the Academy of Natural Sciences of Philadelphia'', 18: 275-279〕 Leidy named these same three teeth ''Aublysodon mirandus'' in 1868. The meaning of the generic name is uncertain because Leidy himself gave no etymology or explanation of the intended meaning. The genus name is derived from Greek αὖ, ''au'', "again", "backwards", "contrariwise", βλύζω, ''blyzo'', "to spout", "to flow" and ὀδών, ''odon'', "tooth". The specific name means "wonderful" or "strange" in Latin. Because the name ''Aublysodon mirandus'' was based on the same type, it was at first a junior objective synonym of ''Deinodon horridus'', which latter name thus had priority. Cope in 1868 mistakenly thought the name ''Deinodon'' was preoccupied by the snake ''Dinodon'' and renamed ''Deinodon horridus'' into a ''Aublysodon horridus''.〔Cope, E.D., 1868, "On some Cretaceous Reptilia", ''Proceedings of the Academy of Natural Sciences of Philadelphia'', 20: 233-242〕 If ''Deinodon'' really had been preoccupied, this would have made ''Aublysodon'' a valid genus. In 1899 Oliver Perry Hay pointed out Cope's mistake; ''Aublysodon horridus'' is a junior objective synonym of ''Deinodon horridus'', just as ''Aublysodon mirandus'' had been.〔Hay, O.P., 1899, "On the nomenclature of certain American fossil vertebrates", ''American Geologist'' 24: 345-349〕 However, in 1892 ''Aublysodon'' became an independent genus when Othniel Charles Marsh further limited its type by choosing a single small nonserrated premaxillary tooth with a D-shaped cross-section, specimen ANSP 9535, as the lectotype of ''Aublysodon mirandus''.〔Marsh, O.C., 1892, "Notes on Mesozoic vertebrate fossils", ''American Journal of Science'', 44: 170-176〕 The two other teeth, ANSP 9533 and ANSP 9534, remained as the lectotypes of ''Deinodon horridus''. The names were thus separated.〔Carpenter, K., 1982, "Baby dinosaurs from the Late Cretaceous Lance and Hell Creek formations and a description of a new species of theropod", ''Contributions to Geology, University of Wyoming'', 20(2): 123-134〕 The tooth-based taxon ''Aublysodon'' was a mystery for a long time since no further skeletal elements were found that could be assigned with certainty to the teeth. In the early twentieth century it was assumed by some workers that it represented a member of the Ornithomimidae when it was not yet known this group was toothless. Lawrence Morris Lambe in 1902 referred the tooth to ''Struthiomimus'';〔 *Lambe, L.M., 1902, "New genera and species from the Belly River Series (mid-Cretaceous)", ''Geological Survey of Canada Contributions to Canadian Palaeontology'' 3(2): 25-81〕 Hay in 1930 renamed ''A. mirandus'' into ''Ornithomimus mirandus'',〔Hay, O.P., 1930, ''Second Bibliography and Catalogue of the Fossil Vertebrata of North America''. Carnegie Institution of Washington. 390(II), pp 1-1074〕 forgetting in that case ''Aublysodon'' would have priority. Today it is known that similar teeth are found in juvenile specimens of ''Daspletosaurus'', and it is likely that teeth referred to ''Aublysodon'' came from that genus.〔Currie, P. (2005). "Theropods, including birds." Pp. 367-397 in Currie and Koppelhus (eds)., ''Dinosaur Provincial Park: A Spectacular Ancient Ecosystem Revealed''. Bloomington: Indiana University Press.〕 In October 2000, the type specimen of ''Aublysodon'' went missing when being sent by registered mail from the Academy of Natural Sciences of Philadelphia to the Field Museum of Natural History. Because of the presence of ''Aublysodon''-type teeth in other juvenile tyrannosaurines than ''Daspletosaurus'', such as those of ''Tyrannosaurus'', remains of which can also be found in Montana, Thomas Carr no longer considered the name to represent a real biological taxon, but to be a ''nomen dubium''.〔 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「Aublysodon」の詳細全文を読む スポンサード リンク
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