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Tryblidiida is a taxon of monoplacophoran molluscans containing the only extant representatives: 29 species are still alive today, inhabiting the ocean at depths of between 175 and 6500 metres (531.34 and 21,325.5 feet). == History of discoveries == Before 1952, these organisms were known only from the fossil record, ranging from the early Cambrian to the mid-Devonian periods (ca. 550 - 380 million years ago).〔Heinz A. Lowenstam and Stephen Weiner, ''On Biomineralization'', Oxford University Press, New York, p. 89 (1989)〕 The first captured living monoplacophoran was ''Veleropilina zografi'' in 1896, but at that time it was described as if it were an archaeogastropod, a true limpet, mainly because of its patelliform (limpet-like) shell. This species was finally revealed to be monoplacophoran 87 years later, in 1983. In April 1952, a living specimen was collected from deep depths in the Middle America Trench off Costa Rica's Pacific coast.〔(Enrico Schwabe, ''A summary of reports of abyssal and hadal Monoplacophora and Polyplacophora (Mollusca)'', Zootaxa 1866: 2005-222 (2008) ).〕 In 1957 that species was described and named ''Neopilina galatheae'' by its discoverer, Danish biologist Henning Mourier Lemche (1904–1977).〔"New Pilina": ''Pilina'' was a monoplacophore that lived during Silurian times. ''Galathea'' was the name of the Danish research vessel that recovered it.〕 An expert in the field has called this discovery "one of the greatest sensations in the () century."〔Schwabe, above, at p. 205.〕 As of 2008, there were 31 living species known, discovered in waters from 200 meters in depth to hadal depths, or more than 6,000 meters in the deepest ocean trenches.〔〔A list of species names is in (WoRMS World Register of Marine Species )〕 The first specimen photographed alive was ''Vema hyalina'', at a depth of 400 meters off Catalina Island, California, in 1977.〔Lynn Margulis and Karlene V. Schwartz, ''Five Kingdoms: An Illustrated Guide to the Phyla of Life on Earth'' (third edition (1997), p. 290).〕 Scientists believe that the taxon Monoplacophora is probably polyphyletic and have proposed including all the living members in the order Tryblidiida.〔 An attempt at a common name for Monoplacophores, ''gastroverm'', proved unsuccessful, the term being called "singularly unattractive".〔Sara S. Bretsky, in reviewing R. Tucker Abbott's popularization, "Kingdom of the Seashell" in ''The Quarterly Review of Biology'' (vol. 49.1 (March 1974), p. 85)〕 By and large, writers since have tacitly agreed; "Monoplacophores" remains the common usage. In 1989, fossils in Italy from the middle Pleistocene were described which appear to be identical with the living species ''Micropilina minuta''. 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「Tryblidiida」の詳細全文を読む スポンサード リンク
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