The Aipoceratidae are a small family of

Carboniferous The Carboniferous ( ) is a geologic period and system of the Paleozoic that spans 60 million years from the end of the Devonian Period million years ago ( Mya), to the beginning of the Permian Period, million years ago. The name ''Carbonifero ...

nautilids which have smooth shells and loosely coiled to faintly impressed

whorls A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs). Whorls in nature File:Photograph and axial plane floral ...

and in which the

aperture In optics, an aperture is a hole or an opening through which light travels. More specifically, the aperture and focal length of an optical system determine the cone angle of a bundle of rays that come to a focus in the image plane. An opt ...

may be modified at maturity. The Aipoceratidae include the Lower Carboniferous ''

Aipoceras ''Aipoceras'' is a genus of loosely coiled aipoceratid 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 ...

'' and '' Asymptoceras'', and '' Librovitschiceras'' from the Upper Carboniferous. The Solenochilidae are closely related.Bernhard Kummel, 1964. Nautiloidea - Nautilida; Treatise on Invertebrate Paleontology, Park K. Geological Society of America and University of Kansas Press.

References

Prehistoric nautiloid families Mississippian first appearances Pennsylvanian extinctions {{paleo-nautiloid-stub