{{Short description|Extinct family of molluscs}} {{Distinguish|Stenothecoida}} {{Automatic taxobox | fossil_range = {{geological range | Lower Cambrian | Mid Cambrian | ref = <ref name=Yochelson1969/>}} | taxon = Stenothecidae | authority = Runegar & Jell, 1980<ref>Runegar & Jell. 1980. Alcheringa, 4(2): 111.</ref> | subdivision_ranks = Genera | subdivision = See text | synonyms = }}
'''Stenothecidae''' is an extinct family of fossil univalved Cambrian molluscs which may be either gastropods or monoplacophorans.
The name of this taxon should not be confused with that of the class Stenothecoida, a group of problematic Cambrian invertebrates that have a bivalved (dorsal and ventral) shell.<ref name=Yochelson1969>{{Cite journal | doi = 10.1111/j.1502-3931.1969.tb01250.x | title = Stenothecoida, A Proposed New Class of Cambrian Mollusca | year = 1969 | last1 = Yochelson | first1 = E. L. | journal = Lethaia | volume = 2 | issue = 1 | pages = 49–62| bibcode = 1969Letha...2...49Y }}</ref>
== Morphology == The group comprises conical laterally compressed shells that may be smooth or ornamented with folds or ribs.<ref name=Runnegar1974>{{Cite journal | first1=B. | first2= J.| last2= Pojeta Jr| title = Molluscan Phylogeny: the Paleontological Viewpoint| volume = 186| last1= Runnegar| journal = Science| issue = 4161| pages = 311–317| date=Oct 1974 | jstor = 1739764| pmid = 17839855| doi = 10.1126/science.186.4161.311|bibcode = 1974Sci...186..311R }}</ref> The shells are broadly limpet-like, which led to their initial consideration as monoplacophoran molluscs.<ref name=Yochelson1969/>
== Taxonomy ==
The taxonomic position of the group is unclear;<ref>{{Bouchet 2005}}</ref> it has been classified as a Yochelcionelloid or Helcionelloid.<ref name=Parkhaev/> It is not obviously in the stem group of any modern molluscan class, and has been referred to the monoplacophora,<ref name=Runnegar1974/> although the monoplacophora are no longer considered to be a clade, and thus that classification means little more than "primitive mollusc".<ref name=Budd2000>{{cite journal |last1=Budd |first1=G. E. |last2=Jensen |first2=S. |year=2000 |title=A critical reappraisal of the fossil record of the bilaterian phyla |volume=75 |issue=2 |pages=253–95 |journal=Biological Reviews of the Cambridge Philosophical Society |doi=10.1111/j.1469-185X.1999.tb00046.x |pmid=10881389 }}</ref>
== Genera == The family Stenothecidae consists of two subfamilies and the following genera: * Stenothecinae Runegar & Jell, 1980 - synonym: Mellopegmidae Missarzhevsky, 1989<ref>{{in lang|ru}} Missarzhevsky. (after 10 July) 1989. ''Drevneishie skeletnye okamenelosti i stratigrafiia pogranichnykh tolshch Dokembriia i Kembiia''. (English translation: ''Oldest skeletal fossils and stratigraphy of Precambrian and Cambrian boundary beds''.) Trudy Geologicheskogo Instituta, Akademia Nauk SSSR<!-- Academy of Sciences of the USSR -->, 443, 237 pp., 32 plates. Mellopegmidae is on the page 179.</ref> ** ''Stenotheca'' Salter [in Hicks], 1872 – type genus of the family Stenothecidae ** ''Mellopegma'' Runegar & Jell, 1976 * Watsonellinae Parkhaev, 2001<ref name=Parkhaev>Parkhaev P. Yu. 2001. ''Molluscs and siphonoconchs''. In: Alexander E. M. et al. (eds.) ''The Cambrian biostratigraphy of the Stansbury basin, South Australia''. Transactions of the Paleontological Institute, Russian Academy of Sciences, 282: 133–210, plates 24–54. Watsonellinae on the page 187.</ref> ** ''Watsonella'' Grabau, 1900<ref>Grabau A. W. 1900. ''Palaeontology of the Cambrian terranes of the Boston Basin''. Occasional Papers of the Boston Society of Natural History 4:601–694.</ref> – type genus of the subfamily Watsonellinae *** ''Watsonella crosbyi'' Grabau – type species of the genus ''Watsonella''
==References== {{Reflist}}
== Further reading == * {{cite journal | last = Kouchinsky | first = A. V. | year = 1999 | title = Shell microstructures of the Early Cambrian ''Anabarella'' and ''Watsonella'' as new evidence on the origin of the Rostroconchia | journal = Lethaia | volume= 32| issue= 2 |pages= 173–180 | doi = 10.1111/j.1502-3931.1999.tb00537.x| bibcode = 1999Letha..32..173K }} * http://www.palaeos.org/Stenothecoida {{Webarchive|url=https://web.archive.org/web/20091119050555/http://www.palaeos.org/Stenothecoida |date=2009-11-19 }}
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Category:Helcionelloida Category:Prehistoric mollusc families
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