The Rhiphaeoceratidae are a small family of nautilids included in the

superfamily SUPERFAMILY is a database and search platform of structural and functional annotation for all proteins and genomes. It classifies amino acid sequences into known structural domains, especially into SCOP superfamilies. Domains are functional, str ...

Tainoceratoidea The Tainoceratoidea are a superfamily in the cephalopod order Nautilida characterized by straight to loosely coiled shells, generally to a degree such that the width is greater than the height, to quadrate whorl section. Many bore spines, ribs, f ...

that comprises four very similar genera. These genera are characterized by a perforate

umbilicus Umbilicus may refer to: *The navel or belly button *Umbilicus (mollusc), a feature of gastropod, Nautilus and Ammonite shell anatomy *Umbilicus (plant), ''Umbilicus'' (plant), a genus of over ninety species of perennial flowering plants *Umbilicus ...

and little more than a single evolute coil. Whorl sections are oval, subquadrate, or subtrapezoidal. Sutures bend forward on the outer rim, forming wide shallow ventral saddles and dip strongly to the rear on the inner rim, forming deep dorsal lobes. Rhiphaeoceratidae was named by Ruzhencev and Shimansky in 1954 are, according to Kümmel (1964), derived from the

Tainoceratidae Tainoceratidae is a family of late Paleozoic and Triassic nautiloids that are a part of the order Nautilida, characterized by large, generally evolute shells with quadrate to rectangular whorl sections. Shells may bear ribs or nodes, or both. ...

, although no genus stands out as possible ancestor. They date from the

Early Permian 01 or 01 may refer to: * The year 2001, or any year ending with 01 * The month of January * 1 (number) Music * '01 (Richard Müller album), ''01'' (Richard Müller album), 2001 * 01 (Urban Zakapa album), ''01'' (Urban Zakapa album), 2011 * ''01011 ...

to Late Permian in age and are found in parts of Eurasia, south

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, and

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. Genera included, also named by Ruzhencev and Shimansky, 1954 are: *'' Rhiphaeoceras'': a riphaeoceritid first found the south Urals (L Perm) with an oval whorl section; flanks with faint, narrow radial ribs; suture with broad ventral saddle and deep dorsal lobe. *'' Pararhiphaeoceras'': a riphaeoceratid with a subtrapezoidal whorl section, widest across the venter, narrowing to the dorsum; flanks with short oblique ribs; suture as for ''Rhiphaeoceras''. Found in L Permian in Azerbaijan and Tajikistan. *'' Rhiphaeonautilus'': a riphaeoceratid like Pararhiphaeoceras, with a subtrapezoidal whorl section, but with short inflated ribs on the lateral areas and with a shallow lobe modifying the ventral saddle. Also first found in the south Urals, as with ''Rhiphaeoceras''. *''

Sholakoceras ''Sholakoceras'' is an extinct genus of nautiloid cephalopods from the Lower Permian of southern Russia, included in the Tainoceratacean family Rhiphaeoceratidae, (order Nautilida). The shell of ''Shalakoceras'' is evolute with a perforate (see t ...

'': a riphaeoceratid with a subquadrate whorl section, venter and sides flattened, lateral areas bearing slightly oblique ribs. The suture is similar to that of Rhiphaeonautilus, with a broad ventral saddle modified by a shallow lobe.

References

* Bernhard Kümmel, 1964. Nautiloidea-Nautilida.

Treatise on Invertebrate Paleontology The ''Treatise on Invertebrate Paleontology,'' published from 1953–2007 by the Geological Society of America and the University of Kansas, then 2009–present by the University of Kansas Paleontological Institute, is a definitive multi-authore ...

, Part K. Geological Soc. of America and University of Kansas press. Teichert and Moore (eds)
Rhipaeoceratidae-Paleodb
{{Taxonbar, from=Q7320694 Nautiloids Lopingian first appearances Lopingian extinctions Prehistoric nautiloid families

See also

References