Onychochilidae
Encyclopedia
Onychochilidae is an extinct family
of small, upper Cambrian
to lower Devonian
, hyperstrophically coiled molluscs, generally with smooth whorls and elongate apertures, commonly regarded as gastropods.
The Onychochilidae is included in the Macluritacea
in the Treatise, Part I, 1960, as part of the Archaeogastropoda where it is divided into two subfamilies, the Onychochilina for those with high basal spires, and the Scaevogyranae for those with low basal spires. Robert M. Linsely and William M. Kier, 1984 reassigned the Onychochilidea to the Paragastropoda, a new class of molluscs proposed for gastropod-like forms which they interpreted as being untorted - that is viscerally untwisted. The Onychochilidae was at that time placed in the Onychochilacea, a superfamily included in a new order, the Hyperstophina, named for paragastropods with hyperstrophic to depressed-orthstrophic shells.
Bouchet and Rocroi,, 2005 tentatively retained the Onychochilidae in the Gastropoda, including them along with the Clisospiridae in the superfamily Clisospiroidea and added a third subfamily, the Hyperstropheminae, named for Hyperstrophema Horney, 1964, its sole known genus.
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...
of small, upper Cambrian
Cambrian
The Cambrian is the first geological period of the Paleozoic Era, lasting from Mya ; it is succeeded by the Ordovician. Its subdivisions, and indeed its base, are somewhat in flux. The period was established by Adam Sedgwick, who named it after Cambria, the Latin name for Wales, where Britain's...
to lower Devonian
Devonian
The Devonian is a geologic period and system of the Paleozoic Era spanning from the end of the Silurian Period, about 416.0 ± 2.8 Mya , to the beginning of the Carboniferous Period, about 359.2 ± 2.5 Mya...
, hyperstrophically coiled molluscs, generally with smooth whorls and elongate apertures, commonly regarded as gastropods.
The Onychochilidae is included in the Macluritacea
Macluritoidea
The Macluritoidea,Macluritacea as originally spelled is a superfamily of hyperstrophically coiled, Upper Cambrian to Devonian, archaeogastropods, or paragastropods according to Linsely and Kier ....
in the Treatise, Part I, 1960, as part of the Archaeogastropoda where it is divided into two subfamilies, the Onychochilina for those with high basal spires, and the Scaevogyranae for those with low basal spires. Robert M. Linsely and William M. Kier, 1984 reassigned the Onychochilidea to the Paragastropoda, a new class of molluscs proposed for gastropod-like forms which they interpreted as being untorted - that is viscerally untwisted. The Onychochilidae was at that time placed in the Onychochilacea, a superfamily included in a new order, the Hyperstophina, named for paragastropods with hyperstrophic to depressed-orthstrophic shells.
Bouchet and Rocroi,, 2005 tentatively retained the Onychochilidae in the Gastropoda, including them along with the Clisospiridae in the superfamily Clisospiroidea and added a third subfamily, the Hyperstropheminae, named for Hyperstrophema Horney, 1964, its sole known genus.