| Stenothecoida Temporal range: Early–mid-Cambrian, 525–500 Ma PreꞒ Ꞓ O S D C P T J K Pg N | |
|---|---|
Scientific classification 
| |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Superphylum: | Lophotrochozoa |
| Class: | †Stenothecoida Yochelson, 1968 |
| Genera | |
| |
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 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; they also look a little like brachiopods 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 . It's more likely that the valves each have a single plane of symmetry (as in brachiopods), suggesting a brachiopod affiliation. There is also evidence for a pedicle.
As with many other Cambrian taxa, it has been suggested that they arise through reduction of a Halkieria-like ancestor.
Mineralogy
Thought to be low-Mg calcite.
Occurrence
The earliest occurrence dates to 525 Ma.
These fossil shells have been found in Canada, China, Greenland, Kazakhstan, Kyrgyzstan, and the USA.
References
- ^ 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.
- ^ 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.
- 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.
- Peel (2021). "Peel,J.S. 2021, Pseudomyona from the Cambrian of... Bulletin of Geosciences, 96, 195-215".
{{cite journal}}: Cite journal requires|journal=(help) - Johnston, Paul; Streng, Michael (2021). "Morphology and relationships of the enigmatic stenothecoid pan-brachiopod Stenothecoides—New data from the middle Cambrian Burgess Shale Formation". Acta Palaeontologica Polonica. 66. doi:10.4202/app.00928.2021. Retrieved 2025-01-17.
- 1. Cohen, B.L., Holmer, L.E., and Lüter, C. (2003). The brachiopod fold: a neglected body plan hypothesis. Palaeontology 46, 59–65.
- 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.
- Kouchinsky, A. V. et al. Chronology of early Cambrian biomineralization. Geol. Mag. 149, 221–251 (2012).
- Start of article at Springer Reference
- Paleobiology Database info on this class
- Abstract of a Yochelson 2007 article on the proposed class
| Taxon identifiers | |
|---|---|
| Stenothecoida | |
 | This prehistoric mollusc article is a stub. You can help Misplaced Pages by expanding it. |