''Permoceras'', the sole member of the family Permoceratidae, is a genus of coiled

nautiloid Nautiloids are a group of marine cephalopods ( Mollusca) which originated in the Late Cambrian and are represented today by the living ''Nautilus'' and ''Allonautilus''. Fossil nautiloids are diverse and speciose, with over 2,500 recorded species ...

s with a smooth, compressed involute shell, whorls higher than wide, earlier whorls hidden from view. The venter is rounded as are the ventral and umbilical shoulders, the flanks flattened. The

siphuncle The siphuncle is a strand of tissue passing longitudinally through the shell of a cephalopod mollusk. Only cephalopods with chambered shells have siphuncles, such as the extinct ammonites and belemnites, and the living nautiluses, cuttlefish, and ...

is ventrally subcentral. The suture, which is most characteristic, has a deep, narrow pointed ventral lobe and large, asymmetrical pointed lobes on either side. ''Permoceras'' is included in the nautilid superfamily, Trigonocerataceae, and is derived from the Mississippian (L Carb) -

Triassic The Triassic ( ) is a geologic period and system which spans 50.6 million years from the end of the Permian Period 251.902 million years ago ( Mya), to the beginning of the Jurassic Period 201.36 Mya. The Triassic is the first and shortest period ...

Grypoceratidae. ''Permoceras'' was first identified in the Lower Permian of

Timur Timur ; chg, ''Aqsaq Temür'', 'Timur the Lame') or as ''Sahib-i-Qiran'' ( 'Lord of the Auspicious Conjunction'), his epithet. ( chg, ''Temür'', 'Iron'; 9 April 133617–19 February 1405), later Timūr Gurkānī ( chg, ''Temür Kür ...

in the East Indies and named by Miller and Collinson in 1953 The coiling and whorl structure of ''Permoceras'' almost precisely resembles those of '' Pseudonautilus'' from the Upper Jurassic.

References

* 1964; Nautiloidea-Nautilida,

Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology'' (or ''TIP'') published by the Geological Society of America and the University of Kansas Press, is a definitive multi-authored work of some 50 volumes, written by more than 300 paleontologists, and co ...

, Part K Nautiliodea, Geological Society of America and University of Kansas press * Sepkoski, J.J. Jr. 2002. A compendium of fossil marine animal genera. D.J. Jablonski & M.L. Foote (eds.). ''Bulletins of American Paleontology'' 363: 1–560
Sepkoski's Online Genus Database (CEPHALOPODA)
Prehistoric nautiloid genera {{paleo-Nautiloidea-stub

See also

References