Stenothecidae 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 univalved Cambrian molluscs. (Do not confuse with Cambrian problematic invertebrates with bivalved (dorsal and ventral) shell, members of the class Stenothecoida).

Morphology

The group comprises conical laterally compressed shells that may be smooth or ornamented with folds or ribs. The shells are broadly limpet-like, which led to their initial consideration as monoplacophoran molluscs.

Taxonomy

The taxonomic position of the group is unclear; it has been classified as a Yochelcionelloid or Helcionelloid,. It is not obviously in the stem group of any modern molluscan class and has been referred to the monoplacophora, although the monoplacophora are no longer considered to be a clade, and thus the classification means little more than "primitive mollusc".

Genera

The family Stenothecidae consists of two subfamilies and the following genera:

• Stenothecinae Runegar & Jell, 1980 - synonym: Mellopegmidae Missarzhevsky, 1989
  • Stenotheca Salter [in Hicks], 1872 - 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 Stenothecidae
  • Mellopegma Runegar & Jell, 1976

• Watsonellinae Parkhaev, 2001
  • Watsonella Grabau
    Amadeus William Grabau
    Amadeus William Grabau was a German-American paleontologist and geologist who was born on January 9, 1870 in Cedarburg, Wisconsin in the United States and died on March 20, 1946 in Peking, China. He was employed as faculty at MIT and Rensselaer Polytechnic Institute...
    
    , 1900 - type genus of the subfamily Watsonellinae
    • Watsonella crosbyi Grabau - type species of the genus Watsonella