Aipocerataceae

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== Introduction and Definition==
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The '''Aipocerataceae''' is the smallest superfamily in the order [[Nautilida]], which range from the Lower Mississippian to the Middle Permian, characterized by rapidly expanding, [[cephalopod shell morphology|cyrtoconic]] to coiled, generally smooth shells with nearly straight sutures and ventrally located [[siphuncle]]s. [[siphuncle|Septal necks]] are orthochoanitic ventrally and orthochoanitic or cyrtochoanitic dorsally. The Aipocerataceae (Kummel 1964) is mostly equivalent to the Solenochilaceae included in the Rutoceratina of Shimanskiy.
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A superfamily (sensu Kummel 1964) in the order Nautilida having a range from the Lower Mississippian to the Middle Permian which constitute the smallest group in the [[Nautilida]] and possibly the least known. Shimanskiy's Solenochilaceae included in his suborder, [[Rutoceratina]] is essentially equivalent although somewhat expanded. (Kummel 1964, K397),
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===Taxonomy===
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The Aipoceraticeae contains two small families, the [[Aipoceratidae]] and the [[Solenocheilidae]]. The Aipoceratidae are the earlier, known only from the Mississippian and Pennsylvanian and represented by loosely coiled to faintly impressed smooth shells with a modified mature aperture. The later and more evolved Solenochilidae, known from the upper Mississippian through the lower Permian, are characterized by shells in which the whorls are all in contact and in which there are pronounced lateral spines projecting from the mature aperture. The connecting rings in the solenocheilids are typically expanded dorsally into the chambers.  
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==Aipocerataceae (Kummel)==
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The Aipoceraticeae (Kummel) are characterized by a rapidly expanding, [[cephalopod shell morphology|cyrtoconic]] to coiled, generally smooth shell with nearly straight sutures and a ventrally located [[siphuncle]]. The [[siphuncle|septal necks]] are orthochoantiic ventrally and orthochoanitic or cyrtochoanitic dorsally.(ibid, K440)
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The Aipoceraticeae contains two small families, the Aipoceratidae and the Solenocheilidae. The Aipoceratidae are the earlier, known only from the [[Carboniferous]] (Mississippian and Pennsylvanian) and respesented by loosely coiled to faintly impressed smooth shells with a modified mature aperture. The later and more evolved Solenochilidae known from the upper Mississippian through the lower Permian are characterised by shells in which the whorls are all in contact and inwhich there are pronounced lateral spines projecting from the mature aperture. The connecting rings in the solenocheilids are typically exanded dorsally into the chambers. (ibid K440-441)
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The Aipoceratidae includes three genera, ''Aipoceras'', ''Asymptoceras'', and ''Librovitschiceras''; the Solenochilidae two genera, ''Solenochilus'' and ''Acanthonautilus''.  
The Aipoceratidae includes three genera, ''Aipoceras'', ''Asymptoceras'', and ''Librovitschiceras''; the Solenochilidae two genera, ''Solenochilus'' and ''Acanthonautilus''.  
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A straight forward evolutionary sequence can be seen going from the [[cephalopod shell morphology|cyrtoconic]] to [[cephalopod shell morphology|gyroconic]]''Aipoceras'' to the rapidly exanding [[cephalopod shell morphology|evolute]]''Asymptoceras'' and from ''Acanthonautilus'' with moderately curved [[siphuncle|septal necks]] and slightly examanded connecting rings to ''Solenochilus'' with strongly curved necks and well expanded conneciting rings (ibid K438,K441)
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===Evolution and phylogeny===
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A straight forward evolutionary sequence can be seen going from the cyrtoconic to gyroconic ''Aipoceras'' to the rapidly expanding evolute ''Asymptoceras'' and from ''Acanthonautilus'' with moderately curved septal necks and slightly expanded connecting rings to ''Solenochilus'' with strongly curved necks and well expanded connecting rings.  
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== Solenochilaceae (Shimanskiy)==
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The Solenochilaceae are included in the Rutoceratina, a suborder in the Nautilida in Shimanskiy's taxonomy (Kummel 1964) which contains four families, the Litogyroceratidae, Solenochilidae,  Scyphocdatidae, and Dentoceratidae.  
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== Origin and Descendants ==
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The Aipocerataceae are probably derived from the [[Rutoceratidae]] near the end of the Devonian although from which genus is hard to determine. No descendants are known.
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The Aipocerataceae,(Solenocerataceae sensu Shimanskiy) are probably derived from the Rutoceratidae near the end of the Devonian although from which genus is hard to determine. No descendants are known.
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==='' References''===
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== Reference==
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*Kummel 1964. Nautiloidea-Nautilida; Treatise on Invertebrate Paleontology, Part K; Curt Teichert and R.C. Moore, (eds); GSA and U Kansas press. pp K383-K457
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*Kummel1964; Nautiloidea-Nautlida; in the Treatise on Invertebrate Paleontology, vol K Nautiloidea;Curt Teichert and R.C. Moore, eds;  GSA and University of Kansas press. pp K383-K457
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Creduts: [[user:John M|John M]] 13 June 2012

Latest revision as of 18:37, 13 June 2012

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