Nautilaceae

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(Evolution and Phylogeny)
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'''Characteristics''' (from Kummel 1964): Involute, generally smooth, with sinuous plications or ribs in some species; whorl section compressed or depressed. Sutures straight to strongly sinuous. Siphuncle central or dorsal.
'''Characteristics''' (from Kummel 1964): Involute, generally smooth, with sinuous plications or ribs in some species; whorl section compressed or depressed. Sutures straight to strongly sinuous. Siphuncle central or dorsal.
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==Evolution and Phylogeny==
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The Nautilaceae began with ''Cenoceras'', the sole servivor of the near extincition of the Nautiloidea at the end of the Triassic,  derived from the Trigonocerataean Syrigonautilidae. All of the Paleozoic nautiloid families had become extinct by the end of the period.
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From ''Cenoceras'', included in the Nautilidae, developed ''Eutrephoceras'' which gave rise to the other genera of that family. ''Cenoceras'' also gave rise, early in the Jurassic, to the Paracenoceratidae, Pseudonautilidae, and Cymatoceratidae. A fifth family, the Hercoglossidae has its orgin in the Nautilidae later in the Jurassic and gave rise to the monogeneric Aturiidae in the Paleocene. 
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Of the six families included in the Nautilaceae, the Nautilidae has the longest duration, including the oldest genus ''Cenoceras'' and well as the most recent, ''Nautilus'' and ''Allonautilus'' 
==Taxonomy==
==Taxonomy==
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[[Nautilida|<==]]Nautilaceae [Digonioceratida]
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[[Nautilida|<==]]Nautilaceae [Digonioceratida]
     |--Paracenoceratidae K64
     |--Paracenoceratidae K64
     |    |--''Paracenoceras'' Spath 1927 K64
     |    |--''Paracenoceras'' Spath 1927 K64

Revision as of 17:48, 29 May 2011

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