Sinuitidae is an extinct family

Family

In human context, a family is a group of people affiliated by consanguinity, affinity, or co-residence. In most societies it is the principal institution for the socialization of children...

 of paleozoic molluscs of uncertain position (Gastropoda

Gastropoda

The Gastropoda or gastropods, more commonly known as snails and slugs, are a large taxonomic class within the phylum Mollusca. The class Gastropoda includes snails and slugs of all kinds and all sizes from microscopic to quite large...

 or Monoplacophora

Monoplacophora

Monoplacophora, meaning "bearing one plate", is a polyphyletic class of mollusks with a cap-like shell, living on the bottom of deep sea. Extant representatives were unknown until 1952; previously they were known only from the fossil record.- Definition :...

) with isostrophically coiled shells.

Taxonomy

The taxonomy of the Gastropoda by Bouchet & Rocroi, 2005

Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005)

The taxonomy of the Gastropoda as it was revised by Philippe Bouchet and Jean-Pierre Rocroi is currently the most up-to-date overall system for classifying gastropod mollusks...

 categorizes Sinuitidae in the superfamilia Bellerophontoidea

Bellerophontoidea

The Bellerophontoidea, , common name "bellerophonts", is a superfamily of extinct planospirally coiled globose molluscs, generally included in the Gastropoda that first appeared late in the Cambrian and continued until late in the Triassic.-Biology:Unlike normal gastropods, the shells of...

 within the
Paleozoic molluscs of uncertain systematic position with isostrophically coiled shells (Gastropoda or Monoplacophora).

This family consists of the following subfamilies (according to the taxonomy of the Gastropoda by Bouchet & Rocroi, 2005

Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005)

The taxonomy of the Gastropoda as it was revised by Philippe Bouchet and Jean-Pierre Rocroi is currently the most up-to-date overall system for classifying gastropod mollusks...

):

• Sinuitinae Dall, 1913 - synonym: Protowarthiidae Ulrich & Scofield, 1897 (inv.)
• Aiptospirinae Wang, 1980
• Hispanosinuitinae Frýda & Gutierrez-Marco, 1996

Genera

Genera in the family Sinuitidae include:

• Sinuites Koken, 1896 - type genus
  Type genus
  In biological classification, a type genus is a representative genus, as with regard to a biological family. The term and concept is used much more often and much more formally in zoology than it is in botany, and the definition is dependent on the nomenclatural Code that applies:* In zoological...
  
   of the family Sinuitidae. Genus Sinuites has large aperture
  Aperture (mollusc)
  The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where part of the body of the animal emerges for locomotion, feeding, etc....
  
  , its outer lip is bilobate. The dorsal side is convex. The umbilicus is closed.