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Praenuculinae
Praenuculinae is an extinct subfamily of prehistoric bivalves in the family Praenuculidae. Praenuculinae species lived from the middle Ordovician through the late Devonian.〔(The Paleobiology Database Praenuculinae entry ) accessed 5 February 2012.〕〔(The Paleobiology Database ''Praenucula'' entry ) accessed 5 February 2012.〕 Praenuculinae fossils are found in Europe, Africa, North America and South America,〔(The Paleobiology Database Praenuculidae entry ) accessed 24 January 2012.〕 and species are though to have been stationary attached to substrate in shallow infaunal marine water environments where they formed shells of an aragonite composition.〔 The subfamily Praenuculinae was named by Teresa M. Sánchez in 1999.
==Description==
The majority of Praenuculidae genera possess teeth with a chevron concavity that faces towards the outer sides of the shell and a chevron point facing the umbo.〔 These genera are grouped into the larger subfamily, Praenuculinae. Three of the genera in the family are placed into the second subfamily, Concavodontinae, based on the teeth having chevron concavities which face in the reverse, towards the center of the hinge and points facing the outside edges of the shell.〔
Praenuculinae is composed of eleven described genera including ''Praenucula'',the type genus for the family. ''Praenucula'' is composed of six species found across Europe, in northwestern Africa, and Argentina. Three of the genera, ''Cuyopsis'', ''Trigonoconcha'', and ''Villicumia'' are monotypic and known only from the Argentine precordillera. The monotypic ''Fidera'' was first described in 1977 by John Pojeta & Joyce Gilbert-Tomlinson and is known only from Tasmania. ''Ledopsis'' was named in 1884 and is restricted to Ordovician sediments exposed in Europe. Leo Pfab in 1934 erected the genus ''Praeleda'' from bohemian fossils which had been placed as the species ''Nucula compar'' by Joachim Barrande. The 1969 Treatise on Invertebrate Paleontology volume on bivalves placed ''Praeleda'' as a synonym of the genus ''Deceptrix'', a placement that was not fully accepted by subsequent authors. In 1999 Cope suggested the two genera were distinct, an opinion that has since been accepted. ''Palaeoconcha'' is known from at least four species ranging across Europe, Asia, North America, and South America.〔(The Paleobiology Database ''Palaeoconcha'' entry ) accessed 5 February 2012.〕 Both ''Paulinea'' and ''Pensarnia'' were described by Cope in 1997 from fossils found in early Arenig sediments of South Wales. The genus ''Similodonta'' is known from several species which range across North America, Asia, and Europe.〔(The Paleobiology Database ''Similodonta'' entry ) accessed 5 February 2012.〕
The genus ''Eritropis'' was formerly included in the subfamily, however it was moved to a new family, Eritropidae by John C. Cope in 2000.〔 ''Deceptrix'' was included in Praenuculinae and the genus ''Cardiolaria'' was listed in Praenuculidae, without subfamily placement, by Teresa M. Sánchez in her 1999 description of the Praenuculidae subfamilies. However both ''Deceptrix'' and ''Cardiolaria'' are currently accepted as members of the family Cardiolariidae erected by Cope in 1997.[(The Paleobiology Database Cardiolariidae entry ) accessed 5 February 2012.〕]
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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