Biology:Shankouclava
| Shankouclava | |
|---|---|
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| Restoration of S. anningense. | |
Scientific classification 
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Subphylum: | Tunicata |
| Genus: | †Shankouclava Chen et al., 2003 |
| Type species | |
| †Shankouclava anningense Chen et al., 2003
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| Species | |
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Shankouclava is an extinct genus of tunicates. It represents the oldest candidate member of this group, dating to 518 million years ago. It has been found in the Lower Cambrian Maotianshan Shale at Shankou village, Anning, near Kunming (South China). Each of the eight specimens found and used for description were isolated, suggesting that the genus was solitary and not colonial.[2]
Morphology
Shankouclava had a soft, sac-like body that was elongated and pointed proximally. The body lengths of individuals vary from 2 cm (0.8 in) to 4 cm (1.6 in).[2]
Degan Shu asserts that some fossil specimens exhibit tentacles, which would make the genus similar to the deuterostome Phlogites.[3] Expanding on this idea, Shu and colleagues argue against a tunicate affinity for Shankouclava.[4]
Etymology
The generic name is composed of the fossil locality, Shankou, and the Latin word clava (club-shaped).[2]
Classification
A stem group tunicate affinity for Shankouclava has been broadly accepted, though some authors have expressed reservations that the evidence in favour of this affinity is not conclusive.[5]
Another Cambrian tunicate, Megasiphon, known from a single specimen, resembles more closely the morphology of surviving tunicates.[6]
References
- ↑ Yang, C.; Li, X.-H.; Zhu, M.; Condon, D. J.; Chen, J. (2018). "Geochronological constraint on the Cambrian Chengjiang biota, South China" (in en). Journal of the Geological Society 175 (4): 659–666. doi:10.1144/jgs2017-103. ISSN 0016-7649. Bibcode: 2018JGSoc.175..659Y. http://nora.nerc.ac.uk/id/eprint/521412/1/2018-JGS-Chuan%20Yang%20et%20al.pdf.
- ↑ 2.0 2.1 2.2 Chen, Jun-Yuan; Huang, Di-Ying; Peng, Qing-Qing; Chi, Hui-Mei; Wang, Xiu-Qiang; Feng, Man (2003). "The first tunicate from the Early Cambrian of South China". Proceedings of the National Academy of Sciences 100 (14): 8314–8318. doi:10.1073/pnas.1431177100. PMID 12835415. Bibcode: 2003PNAS..100.8314C.
- ↑ Shu (2008). "Cambrian explosion: Birth of tree of animals". Gondwana Research 14 (1–2): 219–240. doi:10.1016/j.gr.2007.08.004. Bibcode: 2008GondR..14..219S. https://www.sciencedirect.com/science/article/abs/pii/S1342937X07001694.
- ↑ Shu, D.-G.; Conway Morris, S.; Zhang, Z.-F.; Han, J. (2010). "The earliest history of the deuterostomes: The importance of the Chengjiang Fossil-Lagerstätte". Proceedings of the Royal Society B: Biological Sciences 277 (1679): 165–174. doi:10.1098/rspb.2009.0646. PMID 19439437.
- ↑ Conway Morris (29 June 2006). "Darwin's dilemma: the realities of the Cambrian 'explosion'". Philos Trans R Soc Lond B Biol Sci 361 (1470): 1069–1083. doi:10.1098/rstb.2006.1846. PMID 16754615.
- ↑ Nanglu, Karma; Lerosey-Aubril, Rudy; Weaver, James C.; Ortega-Hernández, Javier (2023). "A mid-Cambrian tunicate and the deep origin of the ascidiacean body plan". Nature Communications 14 (1): 3832. doi:10.1038/s41467-023-39012-4. PMID 37414759.
Wikidata ☰ Q55633006 entry
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