Biology:Stenothecoida

From HandWiki
Short description: Extinct class of molluscs

Stenothecoida
Temporal range: Early–mid-Cambrian, 525–500 Ma[1][2]
Scientific classification e
Domain: Eukaryota
Kingdom: Animalia
Superphylum: Lophotrochozoa
Class: Stenothecoida
Yochelson, 1968[3]
Genera
  • Makarakia Bagenoviella
  • Stenothecoides Resser
  • Radugin Aksarina
  • Sulcocarina Cambridium
  • Aksarina Aksarin
  • Bagenovia Horný, 1957
  • Aksarina Kaschkadakia
(given in JSTOR 1739764)

Stenothecoida is a taxon of bivalved fossils from the Early to middle Cambrian period. They look a bit like brachiopods or bivalve molluscs.

Affinity

Their affinity is uncertain. They were considered by E. L. Yochelson 1968[citation needed] to belong to Mollusca, whereas Runnegar and Pojeta (1974) suggested that they might be 'bivalved monoplacophorans'. This said, the morphology of the shell does not resemble the shell of any other class of molluscs;[4] they also look a little like brachiopods[1] It's not clear whether their two valves are each other's mirror images, as in bivalve molluscs, though they aren't identical to one another [?].[1] It's more likely that the valves each have a single plane of symmetry (as in brachiopods), suggesting a brachiopod affiliation.[1]

As with many other Cambrian taxa,[5][6] it has been suggested that they arise through reduction of a Halkieria-like ancestor.[1]

Mineralogy

Thought to be low-Mg calcite.[7]

Occurrence

The earliest occurrence dates to 525 Ma.[2]

These fossil shells have been found in Canada , China , Greenland, Kazakhstan, Kyrgyzstan, and the United States of America .

References

  1. 1.0 1.1 1.2 1.3 1.4 Kouchinsky, Artem V. (2000). "15. Mollusks, Hyoliths, Stenothecoids, and Coeloscleritophorans". Molluscs, hyoliths, stenothecoids, and coeloscleritiphorans. pp. 326–349. doi:10.7312/zhur10612-015. ISBN 9780231505161. https://www.researchgate.net/publication/264808572. 
  2. 2.0 2.1 Kouchinsky, A. V., Bengtson, S., Runnegar, B.N., Skovsted, C.B., Steiner, M., and Vendrasco, M.J. (2012). Chronology of early Cambrian biomineralization. Geol. Mag. 149, 221–251.
  3. Yochelson, Ellis L. (1969). "Stenothecoida, A Proposed New Class of Cambrian Mollusca". Lethaia 2: 49–62. doi:10.1111/j.1502-3931.1969.tb01250.x. 
  4. Peel (2021). Peel,J.S. 2021, Pseudomyona from the Cambrian of... Bulletin of Geosciences, 96, 195-215. http://www.geology.cz/bulletin/contents/art1827. 
  5. 1. Cohen, B.L., Holmer, L.E., and Lüter, C. (2003). The brachiopod fold: a neglected body plan hypothesis. Palaeontology 46, 59–65.
  6. Skovsted, C.B., Betts, M.J., Topper, T.P., and Brock, G.A. (2015). The early Cambrian tommotiid genus Dailyatia from South Australia. Mem. Assoc. Australas. Palaeontol. 48, 1–117.
  7. Kouchinsky, A. V. et al. Chronology of early Cambrian biomineralization. Geol. Mag. 149, 221–251 (2012).

Wikidata ☰ Q16948595 entry