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''Probrachylophosaurus bergei'' is a species of large herbivorous brachylophosaurin hadrosaurid dinosaur known from the Late Cretaceous Campanian Judith River Formation, of Montana. The significance of this particular hadrosaur taxon is that it is a transitional species between the genera ''Acristavus'' and ''Brachylophosaurus'' evolving from a crestless ancestor (the former genus) to its crested descendant (the latter genus) while changing the morphology of its nasal bones.〔(Fowler, Elizabeth A. Freedman, and John R. Horner. "A New Brachylophosaurin Hadrosaur (Dinosauria: Ornithischia) with an Intermediate Nasal Crest from the Campanian Judith River Formation of Northcentral Montana." ''PloS one'' 10.11 (2015): e0141304. )〕 ==Discovery and naming== In 1981 and 1994, Mark Goodwin of the University of California Museum of Paleontology excavated limb bones and a vertebra near Rudyard in the north of Montana, at a site originally discovered by Kyoko Kishi. After a school class found some more bones, in 2007 and 2008 a team of the Museum of the Rockies secured the remainder of a hadrosaur skeleton, among which the skull. The fossil was donated to the Museum of the Rockies by land owners Nolan and Cheryl Fladstol; and John and Claire Wendland.〔 In 2009, 2010 and 2011, the find was reported in the scientific literature as a possible new species of ''Brachylophosaurus''.〔Freedman, E.A., 2009, "Variation in nasal crest size of ''Brachylophosaurus canadensis'' (Dinosauria: Hadrosauridae): Ontogenetic and stratigraphic implications of a large new specimen from the Judith River Formation of northcentral Montana", ''Abstracts of papers, Sixty-ninth Annual Meeting, Society of Vertebrate Paleontology. Journal of Vertebrate Paleontology'' 29 (3): 99A-100A〕〔Freedman, E.A., and Fowler, D.W., 2010, "Stratigraphic correlation of Judith River Formation (Campanian, Upper Cretaceous) exposures in Kennedy Coulee (northcentral Montana) to the Foremost Formation (Alberta): implications for anagenesis in hadrosaurid dinosaurs", ''Journal of Vertebrate Paleontology, SVP Program and Abstracts Book'', 92〕〔Freedman, E.A., 2011, "A new species of ''Brachylophosaurus'' (Ornithischia: Hadrosauridae) from the Judith River Formation (Late Cretaceous: Campanian) of northcentral Montana", ''International Hadrosaur Symposium, Royal Tyrrell Museum, Drumheller, Alberta. Abstract Volume'', 53-54〕 In 2015, the type species ''Probrachylophosaurus bergei'' was named and described by Elizabeth A. Freedman Fowler and Jack Horner. The generic name is a combination of Latin ''pro'', "before", and ''Brachylophosaurus'' and refers to the genus being situated in a lower position in the stratification than its relative ''Brachylophosaurus''. The specific name honours Sam Berge, one of the landowners, and his friends who have supported the research.〔 The holotype, MOR 2919, was found in a layer of the Judith River Formation dating from the Campanian and being between 79.8 and 79.5 million years old, plus or minus two hundred thousand years. It consists of a partial skeleton with skull, of an adult individual. It contains the right premaxilla, both maxillae, the left jugal, a part of the right lacrimal, the rear of a left nasal bone, the middle part of a right nasal bone, the skull roof from the frontal bones to the exoccipitals, both squamosals, both quadrate bones, the predentary of the lower jaws, both dentaries, a right surangular, eleven neck vertebrae, eleven back vertebrae, twenty-nine tail vertebrae, nineteen chevron bones, nineteen ribs, the entire pelvis, both lower legs, a right second metatarsal and a right fourth metatarsal. The bones have not been found in articulation.〔 Specimen MOR 1097, a fragmentary skull of a subadult individual, was referred to the species. It had been found at a kilometre distance from the holotype.〔 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「Probrachylophosaurus」の詳細全文を読む スポンサード リンク
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