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''Graculavus'' is a prehistoric bird genus that was described in the 19th century by American paleontologist O. C. Marsh. Its remains were found in the Late Cretaceous Austin Chalk of Texas, USA, and Lance Formation (late Maastrichtian faunal stage, or Lancian land mammal age), and the controversial Hornerstown Formation which straddles the Cretaceous–Paleocene boundary, possibly dating to the Danian stage. These birds lived on the shores of the northwestern Atlantic and the Western Interior Seaway some . ==Classification== ''Graculavus'' is the namesake for the form taxon "Graculavidae", a plesiomorphic assembly of unrelated birds that were believed to hold a key position in avian evolution as "transitional shorebirds." Two species are known: ''Graculavus augustus'' from the Western Interior Seaway and ''Graculavus velox'' from the Atlantic Seaboard.〔Chiappe, Luis M. and Witmer, Lawrence M. (2002): ''Mesozoic Birds: Above the Heads of Dinosaurs'', University of California Press, 2002. ISBN 0-520-20094-2, ISBN 978-0-520-20094-4〕 Several species have been named, but most are considered synonyms of ''G. velox'' or have been referred to other genera. Most scientists considered ''G. velox'' the only valid ''Graculavus'' species until 1999, when ''G. augustus'' was described. An additional name, ''Graculavus'' "idahensis", was included erroneously in a table of species by Shufeldt in 1915.〔 ''"Graculavus" lentus'' was for some time placed in ''Ichthyornis'' or ''Pedioecetes'' after being removed from the present genus. It is not related to either however and is nowadays considered an early galliform or close relative and placed in the genus ''Austinornis''.〔Clarke, Julia A. (2004): Morphology, Phylogenetic Taxonomy, and Systematics of ''Ichthyornis'' and ''Apatornis'' (Avialae: Ornithurae). ''Bulletin of the American Museum of Natural History'' 286: 1–179 (PDF fulltext )〕 ==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「Graculavus」の詳細全文を読む スポンサード リンク
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